Maine Department of Inland Fisheries and Wildlife, Adult Cow and Calf Moose Survival StudyLee Kantar, MDIFW State Moose Biologist

PROJECT UPDATE JANUARY 2016

BackgroundIn the early 2000’s, New Hampshire Fish and Game identi�ed periodic winter tick epizootics as a signi�cant factor in overwintering calf mortality. As far back as the 1990’s, winter tick infestations were recognized as a potential in�uence on population dynamics because they could create an energy drain, particularly in young moose (calves and yearlings). Over the past decade, mortality data, necropsies, and winter tick surveys on fall-harvested moose have provided additional insight into factors contributing to the species' population trends. Observation, recovery, and necropsies of moose calves have shown that the anemia associated with winter tick infestations increases mortality, and that lungworm (Dictyocaulus sp.) and tapeworm cysts (Echinococcus granulosus canadensis) may also contribute to mortality by reducing lung function.

Calves enter their �rst winter in a negative energy balance and may even lose weight because there are no fat reserves to draw upon over winter. In winters that have deep snow and extreme cold temperatures the energetic demands of calves increase even more. These environmental elements, when combined with both external and internal parasite loads, may lead to increased winter mortality; in years with heavy tick loads, an epizootic may occur. Increased calf loss can have a profound e�ect on recruitment and population size in moose.

The in�uence of winter ticks on all age classes of moose is related to annual winter tick abundance, moose density, habitat, and environmental conditions

(fall/spring temperatures, winds, and snow depth). Currently, we are working with New Hampshire Fish and Game and University of New Hampshire to understand this dynamic, evaluate causes of mortality in moose, and compare regional di�erences. To this end we will be able to compare moose population densities and environmental conditions between study sites in Coos County, New Hampshire, the Jackman-Moose River area of Maine, and the Fish River Lake area between Allagash and Portage, Maine.

Cow and Calf Capture and CollaringIn January 2014, New Hampshire and Maine initiated a coordinated and parallel study of adult cow and calf survival. New Hampshire captured and radio-collared 43 moose and Maine captured and radio-collared 60 moose. In 2015, a total of 44 moose were captured in NH, and total of 45 in ME. This past month, Maine added a second study area on the northern border with New Brunswick, Canada. Thirty-�ve adult cows and 35 calves were collared, in addition to 36 additional calves in the original (western) study area. NH collared 45 moose in 2016. Since the collaring study was initiated in 2014, a total of 149 moose in Maine are currently �tted with GPS collars. These collars forward an email to biologists when reduced activity is detected so that the situation and potential mortality can be investigated within 24 hours. They also send location data that provide valuable information on moose movements, habitat usage, and the location and timing of calving. This is one of the largest GPS collar studies on moose in North America.

During collaring, biological samples including blood, feces and hair were collected from all individuals and standardized winter tick counts were done (Fig. 1). Collared moose in NH and ME are then monitored daily for mortalities and are recovered for necropsy. This winter, for the �rst time in the study, moose calves

The Northeast Wildlife Disease CooperativeOffering wildlife health and disease services in the Northeast U.S.

Phone: 508-887-4933Email: nwdc@tufts.edu

http://sites.tufts.edu/nwdc

NWDC NOTESQUARTERLY NEWSLETTER FROM THE NORTHEAST WILDLIFE DISEASE COOPERATIVE

Volume 3, Number 1, January 2016

were weighed at capture, providing a measure of body condition as they enter the winter. In addition to weighing calves, winter tick counts (4-10 cm transects) were also conducted on the shoulder and rump of each calf using the same methods as used in our winter tick counts on hunter harvested moose done in the fall.

Calf Weights and Tick Burdens: ResultsThere was no statistical di�erence in weight at capture between Maine’s two study areas. In our western study area, calf capture weights averaged 428lb with no di�erence between males and females. In our northern study area, calf capture weights averaged 414lbs, with females averaging 406 and males 425. Weighing calves at death will enable us to detect signi�cant changes in body condition between capture and mortality, providing critical information relating to potential cause of death.

There was no di�erence between the two study areas in counts of winter ticks on the shoulders of live calves. However, the counts were higher than the mean of fall hunter harvested winter tick counts of both adults and calves. Winter tick counts were also higher during the 2016 collaring than in 2014 and 2015 capture events. Although it is not clear what this means in terms of survival, it could predict increased winter/spring calf mortality.

NecropsyMDIFW biologists recover and necropsy moose using

a protocol adapted from Minnesota Department of Natural Resources and further modi�ed by the University of Maine-Animal Health Lab (UMAHL), New Hampshire Fish and Game Department, and the University of New Hampshire Diagnostic Lab. This protocol includes assessment of the mortality site, winter tick count, blood collection, �eld necropsy, aging, and collection of tissue samples from all organs for diagnostics and analysis. University of Maine-Animal Health Lab (UMAHL) receives all blood and fecal samples after live capture and after death. UMAHL catalogues and processes all tissue samples and analyzes blood parameters and internal parasites from capture. Blood samples are also sent to additional labs to test for pregnancy of adult cows, to examine physiological parameters/body condition assessment (blood chemistry), heavy metal toxicity, screening of vector borne diseases as well as other pathogenic agents known to moose. Results from the New Hampshire and Maine moose studies will be compared and further assessed, and summarized for subsequent reports.

Cow/Calf “Walk-ins”Part of MDIFW’s moose survival project includes examining cow productivity and survival of calves in order to understand population trends. Each year of the study, beginning in May, biologists monitor the status and fate of radio-collared adult female moose and their potential calves. Current knowledge of neonatal moose survival would suggest that losses of 50% or more can occur due to factors such as bear predation and malnutrition. Due to concerns over the impact of

radio-collaring neonates, and in consultation with moose researchers from Minnesota as well as work done in Ontario and Scandinavia, MDIFW adopted a non-invasive monitoring

approach based on research done at the University of New Hampshire. This includes monitoring GPS locations and movements of adult cows to con�rm initiation of calving. Researchers have documented long range movements of pregnant cows to calving areas followed by clusters of GPS locations where the cow has potentially calved. By pinpointing these locations, biologists can stalk the cow using traditional VHF telemetry and determine whether the cow has a calf at heel or not. Biologists “walk-in” to the location indicated by telemetry several times a week until a calf is documented to be with the cow or it is determined that no calf was born. Once a calf is documented, walk-ins are reduced to one per week until the calf dies or until the probability of its survival is signi�cantly higher, usually after about 12 weeks of life.

Moose are an icon of the North Woods. This collaborative study with New Hampshire will provide a greater understanding of the in�uence of winter ticks on moose populations in the Northeast. Assessing survival rates of adult cows and calves over time and across the North Woods will help guide future moose management. We hope that this study, following an unprecedented number of collared moose across three study areas, will provide insight into moose population dynamics that will help conserve these magni�cent animals for future generations.

We gratefully acknowledge the work of Dr. Peter Pekins at the University of New Hampshire Wildlife and Conservation Biology Department; Kristine Rines, Moose Project Leader for the New Hampshire Department of Fish and Game; Dr. Anne Lichtenwalner, Director of the Animal Health Lab at the University of Maine Orono; and, Dr. Inga Sidor, Senior Pathologist with the University of New Hampshire, Veterinary Diagnostic Laboratory.

For additional details, see the following references:Bontaites, K. M., and K. Gustafson. 1993. The history and status of moose and moose management in New Hampshire. Alces 29:163-167.

Musante, A. R., P. J. Pekins, and D. L. Scarpitti. 2007. Metabolic impacts of winter tick infestations on calf moose. Alces 43:101-110.

Samuel, W. M. 2007. Factors a�ecting epizootics of winter ticks and mortality of moose. Alces 43:39-48.

Schwartz, C.C. 2007. Reproduction, natality and growth. Pages 141-171 In A.W. Franzmann and C.C. Schwartz. Editors.

Ecology and Management of the North American Moose. University Press of Colorado. Boulder, Colorado. USA.

What’s New with LPDV?Turkeys with Pox-like Lesions in NJ and VTIn October 2015, Bill Stansley of the NJ Division of Fish and Wildlife submitted a male turkey to the NJ Animal Health Diagnostic Laboratory (NJAHDL) for diagnosis. The bird was in a �ock on a private property where the resident observed it lying on the ground and noted that it was easily approachable. The bird died on the property soon thereafter and had proliferative lesions on the head and neck (Fig. 3) suggestive of either avian pox or lymphoproliferative disease virus (LPDV).

Dr. Angelique Leone, pathologist at the NJAHDL, examined the bird and determined that it had avian pox, and probably not LPDV disease, based on histolog-ic examination. Avian pox causes dermatitis character-ized by intracytoplasmic inclusions (sites of virus replication within a cell) within the hyperplastic epider-mis (skin surface with abnormal cell growth). In contrast, while LPDV can cause pox-like skin lesions, it also induces lymphoid tumors. The turkey in this case did not have the lymphoid tumors characteris-tic of LPDV.

In late October 2015, a hunter- killed adult wild turkey was submitted to VT Wildlife Division for examination because of the abnormal appearance of its head and legs. The turkey was examined by Alyssa Bennet and Joel Flewelling in the Rutland o�ce who found the raised, nodular, scab-like lesions of the skin that are characteristic of both LPDV and avian pox (Fig. 4). Their gross necropsy revealed none of the internal lesions associated with LPDV, especially any swelling or discoloration of the spleen or liver (Fig. 5).

In both the NJ and VT cases, LPDV could also have been present in the birds, but did not appear to be causing any overt disease.

LPDV Discovery and Distribution in N. AmericaOutbreaks of LPDV were originally documented in domestic turkeys in the European-Middle Eastern region during the 1970s, but the virus had never been detected anywhere else until recently. In 2009, LPDV was identi�ed by researchers at the Southeastern Cooperative Wildlife Disease Study (SCWDS) in a wild turkey from Arkansas. This was the �rst reported case of LPDV in a wild bird and in North America. The inability

to culture the virus has hampered researcher’s progress in further understanding LPDV, and made it challenging to interpret PCR results.

In domestic turkeys, disease due to LPDV

infections is typically �rst observed around 8-10 weeks of age, with variable �ock mortality that can reach 25%. The most commonly a�ected organs were spleen, thymus, pancreas, and liver, although smaller lesions can be present in other tissues as well. It appears that the natural host range of the virus is restricted to birds of the order Galliformes.

A recent study that screened for LPDV DNA using PCR in asymptomatic hunter harvested birds in the eastern U.S. revealed that, across 17 states, a total of 47% of turkeys were positive for LPDV. The highest prevalence was in the Northeast, followed by the Mid-Atlantic, Southeastern, and Central states. Causes of regional di�erences in prevalence are unknown, but could relate to turkey population densities, habitat availability, arti�cial movement of infected birds, or interactions among di�erent domestic and wild turkey �ocks. Overall, the known distribution of LPDV in wild turkeys extends from Maine to Florida and as far west as Colorado. The high prevalence of asymptomatic turkeys that are positive for LPDV also indicates that infection is common but only occasionally causes disease. The conditions that induce LPDV disease in wild turkeys are unknown.

It appears that adult wild turkeys are more likely to be positive for LPDV than are juveniles. Though the cause

of the higher prevalence in adults is unknown, it is possible that increased age simply allows for a longer period for virus exposure. Surveillance for LPDV has not been conducted in wild turkey poults, which may have higher levels of mortality than juvenile and adult turkeys.

Update on Diagnostic and Surveillance TechniquesAs stated above, it has not been possible to isolate LPDV using cell culture, a method that has long been considered the gold standard for viral diagnostics. Therefore, researchers have relied on PCR in turkey bone marrow, liver and spleen. A recent study comparing detection rates using PCR on liver, spleen, and bone marrow of wild turkeys in the eastern U.S. showed that bone marrow provided the highest level of detection for both hunter harvested turkeys and diagnostic cases. Bone marrow is easily and e�ciently collected from dead animals, making it very useful for post-mortem LPDV surveillance and archiving. A separate study showed that PCR on whole blood produces results comparable to bone marrow, making whole blood collection a useful tool for surveillance in live birds.

Further ResearchIn sum, surveillance data suggest that LPDV is endemic in wild turkeys in the eastern USA, but only causes occasional disease. It may be more likely to cause disease when an animal is already infected by another immunosuppressive virus (e.g. avian pox), or is otherwise immune compromised. Further research is needed to understand modes of transmission and

pathogenesis in wild turkeys, and to determine the impacts of LPDV on their populations.

For additional details on LPDV, see the following references:Allison, A.B. et al.

(2013) Avian oncogenesis induced by lymphoproliferative disease virus: a neglected or emerging retroviral pathogen? Virology 450–451: 2–12. doi: 10.1016/j.virol.2013.12.013 PMID: 24503077

Maine Department of Inland Fisheries and Wildlife, Adult Cow and Calf Moose Survival StudyLee Kantar, MDIFW State Moose Biologist

PROJECT UPDATE JANUARY 2016

BackgroundIn the early 2000’s, New Hampshire Fish and Game identi�ed periodic winter tick epizootics as a signi�cant factor in overwintering calf mortality. As far back as the 1990’s, winter tick infestations were recognized as a potential in�uence on population dynamics because they could create an energy drain, particularly in young moose (calves and yearlings). Over the past decade, mortality data, necropsies, and winter tick surveys on fall-harvested moose have provided additional insight into factors contributing to the species' population trends. Observation, recovery, and necropsies of moose calves have shown that the anemia associated with winter tick infestations increases mortality, and that lungworm (Dictyocaulus sp.) and tapeworm cysts (Echinococcus granulosus canadensis) may also contribute to mortality by reducing lung function.

Calves enter their �rst winter in a negative energy balance and may even lose weight because there are no fat reserves to draw upon over winter. In winters that have deep snow and extreme cold temperatures the energetic demands of calves increase even more. These environmental elements, when combined with both external and internal parasite loads, may lead to increased winter mortality; in years with heavy tick loads, an epizootic may occur. Increased calf loss can have a profound e�ect on recruitment and population size in moose.

The in�uence of winter ticks on all age classes of moose is related to annual winter tick abundance, moose density, habitat, and environmental conditions

(fall/spring temperatures, winds, and snow depth). Currently, we are working with New Hampshire Fish and Game and University of New Hampshire to understand this dynamic, evaluate causes of mortality in moose, and compare regional di�erences. To this end we will be able to compare moose population densities and environmental conditions between study sites in Coos County, New Hampshire, the Jackman-Moose River area of Maine, and the Fish River Lake area between Allagash and Portage, Maine.

Cow and Calf Capture and CollaringIn January 2014, New Hampshire and Maine initiated a coordinated and parallel study of adult cow and calf survival. New Hampshire captured and radio-collared 43 moose and Maine captured and radio-collared 60 moose. In 2015, a total of 44 moose were captured in NH, and total of 45 in ME. This past month, Maine added a second study area on the northern border with New Brunswick, Canada. Thirty-�ve adult cows and 35 calves were collared, in addition to 36 additional calves in the original (western) study area. NH collared 45 moose in 2016. Since the collaring study was initiated in 2014, a total of 149 moose in Maine are currently �tted with GPS collars. These collars forward an email to biologists when reduced activity is detected so that the situation and potential mortality can be investigated within 24 hours. They also send location data that provide valuable information on moose movements, habitat usage, and the location and timing of calving. This is one of the largest GPS collar studies on moose in North America.

During collaring, biological samples including blood, feces and hair were collected from all individuals and standardized winter tick counts were done (Fig. 1). Collared moose in NH and ME are then monitored daily for mortalities and are recovered for necropsy. This winter, for the �rst time in the study, moose calves

NWDC NOTES – Quarterly Newsletter From The Northeast Wildlife Disease Cooperative

2Volume 3, Number 1, January 2016

were weighed at capture, providing a measure of body condition as they enter the winter. In addition to weighing calves, winter tick counts (4-10 cm transects) were also conducted on the shoulder and rump of each calf using the same methods as used in our winter tick counts on hunter harvested moose done in the fall.

Calf Weights and Tick Burdens: ResultsThere was no statistical di�erence in weight at capture between Maine’s two study areas. In our western study area, calf capture weights averaged 428lb with no di�erence between males and females. In our northern study area, calf capture weights averaged 414lbs, with females averaging 406 and males 425. Weighing calves at death will enable us to detect signi�cant changes in body condition between capture and mortality, providing critical information relating to potential cause of death.

There was no di�erence between the two study areas in counts of winter ticks on the shoulders of live calves. However, the counts were higher than the mean of fall hunter harvested winter tick counts of both adults and calves. Winter tick counts were also higher during the 2016 collaring than in 2014 and 2015 capture events. Although it is not clear what this means in terms of survival, it could predict increased winter/spring calf mortality.

NecropsyMDIFW biologists recover and necropsy moose using

a protocol adapted from Minnesota Department of Natural Resources and further modi�ed by the University of Maine-Animal Health Lab (UMAHL), New Hampshire Fish and Game Department, and the University of New Hampshire Diagnostic Lab. This protocol includes assessment of the mortality site, winter tick count, blood collection, �eld necropsy, aging, and collection of tissue samples from all organs for diagnostics and analysis. University of Maine-Animal Health Lab (UMAHL) receives all blood and fecal samples after live capture and after death. UMAHL catalogues and processes all tissue samples and analyzes blood parameters and internal parasites from capture. Blood samples are also sent to additional labs to test for pregnancy of adult cows, to examine physiological parameters/body condition assessment (blood chemistry), heavy metal toxicity, screening of vector borne diseases as well as other pathogenic agents known to moose. Results from the New Hampshire and Maine moose studies will be compared and further assessed, and summarized for subsequent reports.

Cow/Calf “Walk-ins”Part of MDIFW’s moose survival project includes examining cow productivity and survival of calves in order to understand population trends. Each year of the study, beginning in May, biologists monitor the status and fate of radio-collared adult female moose and their potential calves. Current knowledge of neonatal moose survival would suggest that losses of 50% or more can occur due to factors such as bear predation and malnutrition. Due to concerns over the impact of

radio-collaring neonates, and in consultation with moose researchers from Minnesota as well as work done in Ontario and Scandinavia, MDIFW adopted a non-invasive monitoring

approach based on research done at the University of New Hampshire. This includes monitoring GPS locations and movements of adult cows to con�rm initiation of calving. Researchers have documented long range movements of pregnant cows to calving areas followed by clusters of GPS locations where the cow has potentially calved. By pinpointing these locations, biologists can stalk the cow using traditional VHF telemetry and determine whether the cow has a calf at heel or not. Biologists “walk-in” to the location indicated by telemetry several times a week until a calf is documented to be with the cow or it is determined that no calf was born. Once a calf is documented, walk-ins are reduced to one per week until the calf dies or until the probability of its survival is signi�cantly higher, usually after about 12 weeks of life.

Moose are an icon of the North Woods. This collaborative study with New Hampshire will provide a greater understanding of the in�uence of winter ticks on moose populations in the Northeast. Assessing survival rates of adult cows and calves over time and across the North Woods will help guide future moose management. We hope that this study, following an unprecedented number of collared moose across three study areas, will provide insight into moose population dynamics that will help conserve these magni�cent animals for future generations.

We gratefully acknowledge the work of Dr. Peter Pekins at the University of New Hampshire Wildlife and Conservation Biology Department; Kristine Rines, Moose Project Leader for the New Hampshire Department of Fish and Game; Dr. Anne Lichtenwalner, Director of the Animal Health Lab at the University of Maine Orono; and, Dr. Inga Sidor, Senior Pathologist with the University of New Hampshire, Veterinary Diagnostic Laboratory.

For additional details, see the following references:Bontaites, K. M., and K. Gustafson. 1993. The history and status of moose and moose management in New Hampshire. Alces 29:163-167.

Musante, A. R., P. J. Pekins, and D. L. Scarpitti. 2007. Metabolic impacts of winter tick infestations on calf moose. Alces 43:101-110.

Samuel, W. M. 2007. Factors a�ecting epizootics of winter ticks and mortality of moose. Alces 43:39-48.

Schwartz, C.C. 2007. Reproduction, natality and growth. Pages 141-171 In A.W. Franzmann and C.C. Schwartz. Editors.

Ecology and Management of the North American Moose. University Press of Colorado. Boulder, Colorado. USA.

What’s New with LPDV?Turkeys with Pox-like Lesions in NJ and VTIn October 2015, Bill Stansley of the NJ Division of Fish and Wildlife submitted a male turkey to the NJ Animal Health Diagnostic Laboratory (NJAHDL) for diagnosis. The bird was in a �ock on a private property where the resident observed it lying on the ground and noted that it was easily approachable. The bird died on the property soon thereafter and had proliferative lesions on the head and neck (Fig. 3) suggestive of either avian pox or lymphoproliferative disease virus (LPDV).

Dr. Angelique Leone, pathologist at the NJAHDL, examined the bird and determined that it had avian pox, and probably not LPDV disease, based on histolog-ic examination. Avian pox causes dermatitis character-ized by intracytoplasmic inclusions (sites of virus replication within a cell) within the hyperplastic epider-mis (skin surface with abnormal cell growth). In contrast, while LPDV can cause pox-like skin lesions, it also induces lymphoid tumors. The turkey in this case did not have the lymphoid tumors characteris-tic of LPDV.

In late October 2015, a hunter- killed adult wild turkey was submitted to VT Wildlife Division for examination because of the abnormal appearance of its head and legs. The turkey was examined by Alyssa Bennet and Joel Flewelling in the Rutland o�ce who found the raised, nodular, scab-like lesions of the skin that are characteristic of both LPDV and avian pox (Fig. 4). Their gross necropsy revealed none of the internal lesions associated with LPDV, especially any swelling or discoloration of the spleen or liver (Fig. 5).

In both the NJ and VT cases, LPDV could also have been present in the birds, but did not appear to be causing any overt disease.

LPDV Discovery and Distribution in N. AmericaOutbreaks of LPDV were originally documented in domestic turkeys in the European-Middle Eastern region during the 1970s, but the virus had never been detected anywhere else until recently. In 2009, LPDV was identi�ed by researchers at the Southeastern Cooperative Wildlife Disease Study (SCWDS) in a wild turkey from Arkansas. This was the �rst reported case of LPDV in a wild bird and in North America. The inability

to culture the virus has hampered researcher’s progress in further understanding LPDV, and made it challenging to interpret PCR results.

In domestic turkeys, disease due to LPDV

infections is typically �rst observed around 8-10 weeks of age, with variable �ock mortality that can reach 25%. The most commonly a�ected organs were spleen, thymus, pancreas, and liver, although smaller lesions can be present in other tissues as well. It appears that the natural host range of the virus is restricted to birds of the order Galliformes.

A recent study that screened for LPDV DNA using PCR in asymptomatic hunter harvested birds in the eastern U.S. revealed that, across 17 states, a total of 47% of turkeys were positive for LPDV. The highest prevalence was in the Northeast, followed by the Mid-Atlantic, Southeastern, and Central states. Causes of regional di�erences in prevalence are unknown, but could relate to turkey population densities, habitat availability, arti�cial movement of infected birds, or interactions among di�erent domestic and wild turkey �ocks. Overall, the known distribution of LPDV in wild turkeys extends from Maine to Florida and as far west as Colorado. The high prevalence of asymptomatic turkeys that are positive for LPDV also indicates that infection is common but only occasionally causes disease. The conditions that induce LPDV disease in wild turkeys are unknown.

It appears that adult wild turkeys are more likely to be positive for LPDV than are juveniles. Though the cause

of the higher prevalence in adults is unknown, it is possible that increased age simply allows for a longer period for virus exposure. Surveillance for LPDV has not been conducted in wild turkey poults, which may have higher levels of mortality than juvenile and adult turkeys.

Update on Diagnostic and Surveillance TechniquesAs stated above, it has not been possible to isolate LPDV using cell culture, a method that has long been considered the gold standard for viral diagnostics. Therefore, researchers have relied on PCR in turkey bone marrow, liver and spleen. A recent study comparing detection rates using PCR on liver, spleen, and bone marrow of wild turkeys in the eastern U.S. showed that bone marrow provided the highest level of detection for both hunter harvested turkeys and diagnostic cases. Bone marrow is easily and e�ciently collected from dead animals, making it very useful for post-mortem LPDV surveillance and archiving. A separate study showed that PCR on whole blood produces results comparable to bone marrow, making whole blood collection a useful tool for surveillance in live birds.

Further ResearchIn sum, surveillance data suggest that LPDV is endemic in wild turkeys in the eastern USA, but only causes occasional disease. It may be more likely to cause disease when an animal is already infected by another immunosuppressive virus (e.g. avian pox), or is otherwise immune compromised. Further research is needed to understand modes of transmission and

pathogenesis in wild turkeys, and to determine the impacts of LPDV on their populations.

For additional details on LPDV, see the following references:Allison, A.B. et al.

(2013) Avian oncogenesis induced by lymphoproliferative disease virus: a neglected or emerging retroviral pathogen? Virology 450–451: 2–12. doi: 10.1016/j.virol.2013.12.013 PMID: 24503077

Figure 1. Lee Kantar conducting winter tick count on a female calf that was captured and collared. From left to right: Sam Davison (Native Range Wildlife Capture), Lee Kantar, Jeanne Ross (Wildlife Veterinarian).

Figure 2. Winter tick infestation on rump of dead moose calf. Photo by Lee Kantar.

Maine Department of Inland Fisheries and Wildlife, Adult Cow and Calf Moose Survival StudyLee Kantar, MDIFW State Moose Biologist

PROJECT UPDATE JANUARY 2016

BackgroundIn the early 2000’s, New Hampshire Fish and Game identi�ed periodic winter tick epizootics as a signi�cant factor in overwintering calf mortality. As far back as the 1990’s, winter tick infestations were recognized as a potential in�uence on population dynamics because they could create an energy drain, particularly in young moose (calves and yearlings). Over the past decade, mortality data, necropsies, and winter tick surveys on fall-harvested moose have provided additional insight into factors contributing to the species' population trends. Observation, recovery, and necropsies of moose calves have shown that the anemia associated with winter tick infestations increases mortality, and that lungworm (Dictyocaulus sp.) and tapeworm cysts (Echinococcus granulosus canadensis) may also contribute to mortality by reducing lung function.

Calves enter their �rst winter in a negative energy balance and may even lose weight because there are no fat reserves to draw upon over winter. In winters that have deep snow and extreme cold temperatures the energetic demands of calves increase even more. These environmental elements, when combined with both external and internal parasite loads, may lead to increased winter mortality; in years with heavy tick loads, an epizootic may occur. Increased calf loss can have a profound e�ect on recruitment and population size in moose.

The in�uence of winter ticks on all age classes of moose is related to annual winter tick abundance, moose density, habitat, and environmental conditions

(fall/spring temperatures, winds, and snow depth). Currently, we are working with New Hampshire Fish and Game and University of New Hampshire to understand this dynamic, evaluate causes of mortality in moose, and compare regional di�erences. To this end we will be able to compare moose population densities and environmental conditions between study sites in Coos County, New Hampshire, the Jackman-Moose River area of Maine, and the Fish River Lake area between Allagash and Portage, Maine.

Cow and Calf Capture and CollaringIn January 2014, New Hampshire and Maine initiated a coordinated and parallel study of adult cow and calf survival. New Hampshire captured and radio-collared 43 moose and Maine captured and radio-collared 60 moose. In 2015, a total of 44 moose were captured in NH, and total of 45 in ME. This past month, Maine added a second study area on the northern border with New Brunswick, Canada. Thirty-�ve adult cows and 35 calves were collared, in addition to 36 additional calves in the original (western) study area. NH collared 45 moose in 2016. Since the collaring study was initiated in 2014, a total of 149 moose in Maine are currently �tted with GPS collars. These collars forward an email to biologists when reduced activity is detected so that the situation and potential mortality can be investigated within 24 hours. They also send location data that provide valuable information on moose movements, habitat usage, and the location and timing of calving. This is one of the largest GPS collar studies on moose in North America.

During collaring, biological samples including blood, feces and hair were collected from all individuals and standardized winter tick counts were done (Fig. 1). Collared moose in NH and ME are then monitored daily for mortalities and are recovered for necropsy. This winter, for the �rst time in the study, moose calves

3Volume 3, Number 1, January 2016

NWDC NOTES – Quarterly Newsletter From The Northeast Wildlife Disease Cooperative

were weighed at capture, providing a measure of body condition as they enter the winter. In addition to weighing calves, winter tick counts (4-10 cm transects) were also conducted on the shoulder and rump of each calf using the same methods as used in our winter tick counts on hunter harvested moose done in the fall.

Calf Weights and Tick Burdens: ResultsThere was no statistical di�erence in weight at capture between Maine’s two study areas. In our western study area, calf capture weights averaged 428lb with no di�erence between males and females. In our northern study area, calf capture weights averaged 414lbs, with females averaging 406 and males 425. Weighing calves at death will enable us to detect signi�cant changes in body condition between capture and mortality, providing critical information relating to potential cause of death.

There was no di�erence between the two study areas in counts of winter ticks on the shoulders of live calves. However, the counts were higher than the mean of fall hunter harvested winter tick counts of both adults and calves. Winter tick counts were also higher during the 2016 collaring than in 2014 and 2015 capture events. Although it is not clear what this means in terms of survival, it could predict increased winter/spring calf mortality.

NecropsyMDIFW biologists recover and necropsy moose using

a protocol adapted from Minnesota Department of Natural Resources and further modi�ed by the University of Maine-Animal Health Lab (UMAHL), New Hampshire Fish and Game Department, and the University of New Hampshire Diagnostic Lab. This protocol includes assessment of the mortality site, winter tick count, blood collection, �eld necropsy, aging, and collection of tissue samples from all organs for diagnostics and analysis. University of Maine-Animal Health Lab (UMAHL) receives all blood and fecal samples after live capture and after death. UMAHL catalogues and processes all tissue samples and analyzes blood parameters and internal parasites from capture. Blood samples are also sent to additional labs to test for pregnancy of adult cows, to examine physiological parameters/body condition assessment (blood chemistry), heavy metal toxicity, screening of vector borne diseases as well as other pathogenic agents known to moose. Results from the New Hampshire and Maine moose studies will be compared and further assessed, and summarized for subsequent reports.

Cow/Calf “Walk-ins”Part of MDIFW’s moose survival project includes examining cow productivity and survival of calves in order to understand population trends. Each year of the study, beginning in May, biologists monitor the status and fate of radio-collared adult female moose and their potential calves. Current knowledge of neonatal moose survival would suggest that losses of 50% or more can occur due to factors such as bear predation and malnutrition. Due to concerns over the impact of

radio-collaring neonates, and in consultation with moose researchers from Minnesota as well as work done in Ontario and Scandinavia, MDIFW adopted a non-invasive monitoring

approach based on research done at the University of New Hampshire. This includes monitoring GPS locations and movements of adult cows to con�rm initiation of calving. Researchers have documented long range movements of pregnant cows to calving areas followed by clusters of GPS locations where the cow has potentially calved. By pinpointing these locations, biologists can stalk the cow using traditional VHF telemetry and determine whether the cow has a calf at heel or not. Biologists “walk-in” to the location indicated by telemetry several times a week until a calf is documented to be with the cow or it is determined that no calf was born. Once a calf is documented, walk-ins are reduced to one per week until the calf dies or until the probability of its survival is signi�cantly higher, usually after about 12 weeks of life.

Moose are an icon of the North Woods. This collaborative study with New Hampshire will provide a greater understanding of the in�uence of winter ticks on moose populations in the Northeast. Assessing survival rates of adult cows and calves over time and across the North Woods will help guide future moose management. We hope that this study, following an unprecedented number of collared moose across three study areas, will provide insight into moose population dynamics that will help conserve these magni�cent animals for future generations.

We gratefully acknowledge the work of Dr. Peter Pekins at the University of New Hampshire Wildlife and Conservation Biology Department; Kristine Rines, Moose Project Leader for the New Hampshire Department of Fish and Game; Dr. Anne Lichtenwalner, Director of the Animal Health Lab at the University of Maine Orono; and, Dr. Inga Sidor, Senior Pathologist with the University of New Hampshire, Veterinary Diagnostic Laboratory.

For additional details, see the following references:Bontaites, K. M., and K. Gustafson. 1993. The history and status of moose and moose management in New Hampshire. Alces 29:163-167.

Musante, A. R., P. J. Pekins, and D. L. Scarpitti. 2007. Metabolic impacts of winter tick infestations on calf moose. Alces 43:101-110.

Samuel, W. M. 2007. Factors a�ecting epizootics of winter ticks and mortality of moose. Alces 43:39-48.

Schwartz, C.C. 2007. Reproduction, natality and growth. Pages 141-171 In A.W. Franzmann and C.C. Schwartz. Editors.

Ecology and Management of the North American Moose. University Press of Colorado. Boulder, Colorado. USA.

What’s New with LPDV?Turkeys with Pox-like Lesions in NJ and VTIn October 2015, Bill Stansley of the NJ Division of Fish and Wildlife submitted a male turkey to the NJ Animal Health Diagnostic Laboratory (NJAHDL) for diagnosis. The bird was in a �ock on a private property where the resident observed it lying on the ground and noted that it was easily approachable. The bird died on the property soon thereafter and had proliferative lesions on the head and neck (Fig. 3) suggestive of either avian pox or lymphoproliferative disease virus (LPDV).

Dr. Angelique Leone, pathologist at the NJAHDL, examined the bird and determined that it had avian pox, and probably not LPDV disease, based on histolog-ic examination. Avian pox causes dermatitis character-ized by intracytoplasmic inclusions (sites of virus replication within a cell) within the hyperplastic epider-mis (skin surface with abnormal cell growth). In contrast, while LPDV can cause pox-like skin lesions, it also induces lymphoid tumors. The turkey in this case did not have the lymphoid tumors characteris-tic of LPDV.

In late October 2015, a hunter- killed adult wild turkey was submitted to VT Wildlife Division for examination because of the abnormal appearance of its head and legs. The turkey was examined by Alyssa Bennet and Joel Flewelling in the Rutland o�ce who found the raised, nodular, scab-like lesions of the skin that are characteristic of both LPDV and avian pox (Fig. 4). Their gross necropsy revealed none of the internal lesions associated with LPDV, especially any swelling or discoloration of the spleen or liver (Fig. 5).

In both the NJ and VT cases, LPDV could also have been present in the birds, but did not appear to be causing any overt disease.

LPDV Discovery and Distribution in N. AmericaOutbreaks of LPDV were originally documented in domestic turkeys in the European-Middle Eastern region during the 1970s, but the virus had never been detected anywhere else until recently. In 2009, LPDV was identi�ed by researchers at the Southeastern Cooperative Wildlife Disease Study (SCWDS) in a wild turkey from Arkansas. This was the �rst reported case of LPDV in a wild bird and in North America. The inability

to culture the virus has hampered researcher’s progress in further understanding LPDV, and made it challenging to interpret PCR results.

In domestic turkeys, disease due to LPDV

infections is typically �rst observed around 8-10 weeks of age, with variable �ock mortality that can reach 25%. The most commonly a�ected organs were spleen, thymus, pancreas, and liver, although smaller lesions can be present in other tissues as well. It appears that the natural host range of the virus is restricted to birds of the order Galliformes.

A recent study that screened for LPDV DNA using PCR in asymptomatic hunter harvested birds in the eastern U.S. revealed that, across 17 states, a total of 47% of turkeys were positive for LPDV. The highest prevalence was in the Northeast, followed by the Mid-Atlantic, Southeastern, and Central states. Causes of regional di�erences in prevalence are unknown, but could relate to turkey population densities, habitat availability, arti�cial movement of infected birds, or interactions among di�erent domestic and wild turkey �ocks. Overall, the known distribution of LPDV in wild turkeys extends from Maine to Florida and as far west as Colorado. The high prevalence of asymptomatic turkeys that are positive for LPDV also indicates that infection is common but only occasionally causes disease. The conditions that induce LPDV disease in wild turkeys are unknown.

It appears that adult wild turkeys are more likely to be positive for LPDV than are juveniles. Though the cause

of the higher prevalence in adults is unknown, it is possible that increased age simply allows for a longer period for virus exposure. Surveillance for LPDV has not been conducted in wild turkey poults, which may have higher levels of mortality than juvenile and adult turkeys.

Update on Diagnostic and Surveillance TechniquesAs stated above, it has not been possible to isolate LPDV using cell culture, a method that has long been considered the gold standard for viral diagnostics. Therefore, researchers have relied on PCR in turkey bone marrow, liver and spleen. A recent study comparing detection rates using PCR on liver, spleen, and bone marrow of wild turkeys in the eastern U.S. showed that bone marrow provided the highest level of detection for both hunter harvested turkeys and diagnostic cases. Bone marrow is easily and e�ciently collected from dead animals, making it very useful for post-mortem LPDV surveillance and archiving. A separate study showed that PCR on whole blood produces results comparable to bone marrow, making whole blood collection a useful tool for surveillance in live birds.

Further ResearchIn sum, surveillance data suggest that LPDV is endemic in wild turkeys in the eastern USA, but only causes occasional disease. It may be more likely to cause disease when an animal is already infected by another immunosuppressive virus (e.g. avian pox), or is otherwise immune compromised. Further research is needed to understand modes of transmission and

pathogenesis in wild turkeys, and to determine the impacts of LPDV on their populations.

For additional details on LPDV, see the following references:Allison, A.B. et al.

(2013) Avian oncogenesis induced by lymphoproliferative disease virus: a neglected or emerging retroviral pathogen? Virology 450–451: 2–12. doi: 10.1016/j.virol.2013.12.013 PMID: 24503077

Figure 3. Pox lesions on a wild turkey from New Jersey. Photo by Angelique Leone.

Maine Department of Inland Fisheries and Wildlife, Adult Cow and Calf Moose Survival StudyLee Kantar, MDIFW State Moose Biologist

PROJECT UPDATE JANUARY 2016

BackgroundIn the early 2000’s, New Hampshire Fish and Game identi�ed periodic winter tick epizootics as a signi�cant factor in overwintering calf mortality. As far back as the 1990’s, winter tick infestations were recognized as a potential in�uence on population dynamics because they could create an energy drain, particularly in young moose (calves and yearlings). Over the past decade, mortality data, necropsies, and winter tick surveys on fall-harvested moose have provided additional insight into factors contributing to the species' population trends. Observation, recovery, and necropsies of moose calves have shown that the anemia associated with winter tick infestations increases mortality, and that lungworm (Dictyocaulus sp.) and tapeworm cysts (Echinococcus granulosus canadensis) may also contribute to mortality by reducing lung function.

Calves enter their �rst winter in a negative energy balance and may even lose weight because there are no fat reserves to draw upon over winter. In winters that have deep snow and extreme cold temperatures the energetic demands of calves increase even more. These environmental elements, when combined with both external and internal parasite loads, may lead to increased winter mortality; in years with heavy tick loads, an epizootic may occur. Increased calf loss can have a profound e�ect on recruitment and population size in moose.

The in�uence of winter ticks on all age classes of moose is related to annual winter tick abundance, moose density, habitat, and environmental conditions

(fall/spring temperatures, winds, and snow depth). Currently, we are working with New Hampshire Fish and Game and University of New Hampshire to understand this dynamic, evaluate causes of mortality in moose, and compare regional di�erences. To this end we will be able to compare moose population densities and environmental conditions between study sites in Coos County, New Hampshire, the Jackman-Moose River area of Maine, and the Fish River Lake area between Allagash and Portage, Maine.

Cow and Calf Capture and CollaringIn January 2014, New Hampshire and Maine initiated a coordinated and parallel study of adult cow and calf survival. New Hampshire captured and radio-collared 43 moose and Maine captured and radio-collared 60 moose. In 2015, a total of 44 moose were captured in NH, and total of 45 in ME. This past month, Maine added a second study area on the northern border with New Brunswick, Canada. Thirty-�ve adult cows and 35 calves were collared, in addition to 36 additional calves in the original (western) study area. NH collared 45 moose in 2016. Since the collaring study was initiated in 2014, a total of 149 moose in Maine are currently �tted with GPS collars. These collars forward an email to biologists when reduced activity is detected so that the situation and potential mortality can be investigated within 24 hours. They also send location data that provide valuable information on moose movements, habitat usage, and the location and timing of calving. This is one of the largest GPS collar studies on moose in North America.

During collaring, biological samples including blood, feces and hair were collected from all individuals and standardized winter tick counts were done (Fig. 1). Collared moose in NH and ME are then monitored daily for mortalities and are recovered for necropsy. This winter, for the �rst time in the study, moose calves

4Volume 3, Number 1, January 2016

NWDC NOTES – Quarterly Newsletter From The Northeast Wildlife Disease Cooperative

were weighed at capture, providing a measure of body condition as they enter the winter. In addition to weighing calves, winter tick counts (4-10 cm transects) were also conducted on the shoulder and rump of each calf using the same methods as used in our winter tick counts on hunter harvested moose done in the fall.

Calf Weights and Tick Burdens: ResultsThere was no statistical di�erence in weight at capture between Maine’s two study areas. In our western study area, calf capture weights averaged 428lb with no di�erence between males and females. In our northern study area, calf capture weights averaged 414lbs, with females averaging 406 and males 425. Weighing calves at death will enable us to detect signi�cant changes in body condition between capture and mortality, providing critical information relating to potential cause of death.

There was no di�erence between the two study areas in counts of winter ticks on the shoulders of live calves. However, the counts were higher than the mean of fall hunter harvested winter tick counts of both adults and calves. Winter tick counts were also higher during the 2016 collaring than in 2014 and 2015 capture events. Although it is not clear what this means in terms of survival, it could predict increased winter/spring calf mortality.

NecropsyMDIFW biologists recover and necropsy moose using

a protocol adapted from Minnesota Department of Natural Resources and further modi�ed by the University of Maine-Animal Health Lab (UMAHL), New Hampshire Fish and Game Department, and the University of New Hampshire Diagnostic Lab. This protocol includes assessment of the mortality site, winter tick count, blood collection, �eld necropsy, aging, and collection of tissue samples from all organs for diagnostics and analysis. University of Maine-Animal Health Lab (UMAHL) receives all blood and fecal samples after live capture and after death. UMAHL catalogues and processes all tissue samples and analyzes blood parameters and internal parasites from capture. Blood samples are also sent to additional labs to test for pregnancy of adult cows, to examine physiological parameters/body condition assessment (blood chemistry), heavy metal toxicity, screening of vector borne diseases as well as other pathogenic agents known to moose. Results from the New Hampshire and Maine moose studies will be compared and further assessed, and summarized for subsequent reports.

Cow/Calf “Walk-ins”Part of MDIFW’s moose survival project includes examining cow productivity and survival of calves in order to understand population trends. Each year of the study, beginning in May, biologists monitor the status and fate of radio-collared adult female moose and their potential calves. Current knowledge of neonatal moose survival would suggest that losses of 50% or more can occur due to factors such as bear predation and malnutrition. Due to concerns over the impact of

radio-collaring neonates, and in consultation with moose researchers from Minnesota as well as work done in Ontario and Scandinavia, MDIFW adopted a non-invasive monitoring

approach based on research done at the University of New Hampshire. This includes monitoring GPS locations and movements of adult cows to con�rm initiation of calving. Researchers have documented long range movements of pregnant cows to calving areas followed by clusters of GPS locations where the cow has potentially calved. By pinpointing these locations, biologists can stalk the cow using traditional VHF telemetry and determine whether the cow has a calf at heel or not. Biologists “walk-in” to the location indicated by telemetry several times a week until a calf is documented to be with the cow or it is determined that no calf was born. Once a calf is documented, walk-ins are reduced to one per week until the calf dies or until the probability of its survival is signi�cantly higher, usually after about 12 weeks of life.

Moose are an icon of the North Woods. This collaborative study with New Hampshire will provide a greater understanding of the in�uence of winter ticks on moose populations in the Northeast. Assessing survival rates of adult cows and calves over time and across the North Woods will help guide future moose management. We hope that this study, following an unprecedented number of collared moose across three study areas, will provide insight into moose population dynamics that will help conserve these magni�cent animals for future generations.

We gratefully acknowledge the work of Dr. Peter Pekins at the University of New Hampshire Wildlife and Conservation Biology Department; Kristine Rines, Moose Project Leader for the New Hampshire Department of Fish and Game; Dr. Anne Lichtenwalner, Director of the Animal Health Lab at the University of Maine Orono; and, Dr. Inga Sidor, Senior Pathologist with the University of New Hampshire, Veterinary Diagnostic Laboratory.

For additional details, see the following references:Bontaites, K. M., and K. Gustafson. 1993. The history and status of moose and moose management in New Hampshire. Alces 29:163-167.

Musante, A. R., P. J. Pekins, and D. L. Scarpitti. 2007. Metabolic impacts of winter tick infestations on calf moose. Alces 43:101-110.

Samuel, W. M. 2007. Factors a�ecting epizootics of winter ticks and mortality of moose. Alces 43:39-48.

Schwartz, C.C. 2007. Reproduction, natality and growth. Pages 141-171 In A.W. Franzmann and C.C. Schwartz. Editors.

Ecology and Management of the North American Moose. University Press of Colorado. Boulder, Colorado. USA.

What’s New with LPDV?Turkeys with Pox-like Lesions in NJ and VTIn October 2015, Bill Stansley of the NJ Division of Fish and Wildlife submitted a male turkey to the NJ Animal Health Diagnostic Laboratory (NJAHDL) for diagnosis. The bird was in a �ock on a private property where the resident observed it lying on the ground and noted that it was easily approachable. The bird died on the property soon thereafter and had proliferative lesions on the head and neck (Fig. 3) suggestive of either avian pox or lymphoproliferative disease virus (LPDV).

Dr. Angelique Leone, pathologist at the NJAHDL, examined the bird and determined that it had avian pox, and probably not LPDV disease, based on histolog-ic examination. Avian pox causes dermatitis character-ized by intracytoplasmic inclusions (sites of virus replication within a cell) within the hyperplastic epider-mis (skin surface with abnormal cell growth). In contrast, while LPDV can cause pox-like skin lesions, it also induces lymphoid tumors. The turkey in this case did not have the lymphoid tumors characteris-tic of LPDV.

In late October 2015, a hunter- killed adult wild turkey was submitted to VT Wildlife Division for examination because of the abnormal appearance of its head and legs. The turkey was examined by Alyssa Bennet and Joel Flewelling in the Rutland o�ce who found the raised, nodular, scab-like lesions of the skin that are characteristic of both LPDV and avian pox (Fig. 4). Their gross necropsy revealed none of the internal lesions associated with LPDV, especially any swelling or discoloration of the spleen or liver (Fig. 5).

In both the NJ and VT cases, LPDV could also have been present in the birds, but did not appear to be causing any overt disease.

LPDV Discovery and Distribution in N. AmericaOutbreaks of LPDV were originally documented in domestic turkeys in the European-Middle Eastern region during the 1970s, but the virus had never been detected anywhere else until recently. In 2009, LPDV was identi�ed by researchers at the Southeastern Cooperative Wildlife Disease Study (SCWDS) in a wild turkey from Arkansas. This was the �rst reported case of LPDV in a wild bird and in North America. The inability

to culture the virus has hampered researcher’s progress in further understanding LPDV, and made it challenging to interpret PCR results.

In domestic turkeys, disease due to LPDV

infections is typically �rst observed around 8-10 weeks of age, with variable �ock mortality that can reach 25%. The most commonly a�ected organs were spleen, thymus, pancreas, and liver, although smaller lesions can be present in other tissues as well. It appears that the natural host range of the virus is restricted to birds of the order Galliformes.

A recent study that screened for LPDV DNA using PCR in asymptomatic hunter harvested birds in the eastern U.S. revealed that, across 17 states, a total of 47% of turkeys were positive for LPDV. The highest prevalence was in the Northeast, followed by the Mid-Atlantic, Southeastern, and Central states. Causes of regional di�erences in prevalence are unknown, but could relate to turkey population densities, habitat availability, arti�cial movement of infected birds, or interactions among di�erent domestic and wild turkey �ocks. Overall, the known distribution of LPDV in wild turkeys extends from Maine to Florida and as far west as Colorado. The high prevalence of asymptomatic turkeys that are positive for LPDV also indicates that infection is common but only occasionally causes disease. The conditions that induce LPDV disease in wild turkeys are unknown.

It appears that adult wild turkeys are more likely to be positive for LPDV than are juveniles. Though the cause

of the higher prevalence in adults is unknown, it is possible that increased age simply allows for a longer period for virus exposure. Surveillance for LPDV has not been conducted in wild turkey poults, which may have higher levels of mortality than juvenile and adult turkeys.

Update on Diagnostic and Surveillance TechniquesAs stated above, it has not been possible to isolate LPDV using cell culture, a method that has long been considered the gold standard for viral diagnostics. Therefore, researchers have relied on PCR in turkey bone marrow, liver and spleen. A recent study comparing detection rates using PCR on liver, spleen, and bone marrow of wild turkeys in the eastern U.S. showed that bone marrow provided the highest level of detection for both hunter harvested turkeys and diagnostic cases. Bone marrow is easily and e�ciently collected from dead animals, making it very useful for post-mortem LPDV surveillance and archiving. A separate study showed that PCR on whole blood produces results comparable to bone marrow, making whole blood collection a useful tool for surveillance in live birds.

Further ResearchIn sum, surveillance data suggest that LPDV is endemic in wild turkeys in the eastern USA, but only causes occasional disease. It may be more likely to cause disease when an animal is already infected by another immunosuppressive virus (e.g. avian pox), or is otherwise immune compromised. Further research is needed to understand modes of transmission and

pathogenesis in wild turkeys, and to determine the impacts of LPDV on their populations.

For additional details on LPDV, see the following references:Allison, A.B. et al.

(2013) Avian oncogenesis induced by lymphoproliferative disease virus: a neglected or emerging retroviral pathogen? Virology 450–451: 2–12. doi: 10.1016/j.virol.2013.12.013 PMID: 24503077

Figure 4. Pox lesions on the leg of a wild turkey from Vermont. Photo by Kerry Monahan.

S

L

L

Figure 5. Normal viscera found on necropsy of turkey from Vermont. Photo by Kerry Monahan.L = liver; S = spleen

Figure 6. Geographic extent of Common Eiders testing positive for WFBV antibodies and tagged with satellite transmitters from Boston Harbor breeding colonies, 2013-2014.

Maine Department of Inland Fisheries and Wildlife, Adult Cow and Calf Moose Survival StudyLee Kantar, MDIFW State Moose Biologist

PROJECT UPDATE JANUARY 2016

BackgroundIn the early 2000’s, New Hampshire Fish and Game identi�ed periodic winter tick epizootics as a signi�cant factor in overwintering calf mortality. As far back as the 1990’s, winter tick infestations were recognized as a potential in�uence on population dynamics because they could create an energy drain, particularly in young moose (calves and yearlings). Over the past decade, mortality data, necropsies, and winter tick surveys on fall-harvested moose have provided additional insight into factors contributing to the species' population trends. Observation, recovery, and necropsies of moose calves have shown that the anemia associated with winter tick infestations increases mortality, and that lungworm (Dictyocaulus sp.) and tapeworm cysts (Echinococcus granulosus canadensis) may also contribute to mortality by reducing lung function.

Calves enter their �rst winter in a negative energy balance and may even lose weight because there are no fat reserves to draw upon over winter. In winters that have deep snow and extreme cold temperatures the energetic demands of calves increase even more. These environmental elements, when combined with both external and internal parasite loads, may lead to increased winter mortality; in years with heavy tick loads, an epizootic may occur. Increased calf loss can have a profound e�ect on recruitment and population size in moose.

The in�uence of winter ticks on all age classes of moose is related to annual winter tick abundance, moose density, habitat, and environmental conditions

(fall/spring temperatures, winds, and snow depth). Currently, we are working with New Hampshire Fish and Game and University of New Hampshire to understand this dynamic, evaluate causes of mortality in moose, and compare regional di�erences. To this end we will be able to compare moose population densities and environmental conditions between study sites in Coos County, New Hampshire, the Jackman-Moose River area of Maine, and the Fish River Lake area between Allagash and Portage, Maine.

Cow and Calf Capture and CollaringIn January 2014, New Hampshire and Maine initiated a coordinated and parallel study of adult cow and calf survival. New Hampshire captured and radio-collared 43 moose and Maine captured and radio-collared 60 moose. In 2015, a total of 44 moose were captured in NH, and total of 45 in ME. This past month, Maine added a second study area on the northern border with New Brunswick, Canada. Thirty-�ve adult cows and 35 calves were collared, in addition to 36 additional calves in the original (western) study area. NH collared 45 moose in 2016. Since the collaring study was initiated in 2014, a total of 149 moose in Maine are currently �tted with GPS collars. These collars forward an email to biologists when reduced activity is detected so that the situation and potential mortality can be investigated within 24 hours. They also send location data that provide valuable information on moose movements, habitat usage, and the location and timing of calving. This is one of the largest GPS collar studies on moose in North America.

During collaring, biological samples including blood, feces and hair were collected from all individuals and standardized winter tick counts were done (Fig. 1). Collared moose in NH and ME are then monitored daily for mortalities and are recovered for necropsy. This winter, for the �rst time in the study, moose calves

were weighed at capture, providing a measure of body condition as they enter the winter. In addition to weighing calves, winter tick counts (4-10 cm transects) were also conducted on the shoulder and rump of each calf using the same methods as used in our winter tick counts on hunter harvested moose done in the fall.

Calf Weights and Tick Burdens: ResultsThere was no statistical di�erence in weight at capture between Maine’s two study areas. In our western study area, calf capture weights averaged 428lb with no di�erence between males and females. In our northern study area, calf capture weights averaged 414lbs, with females averaging 406 and males 425. Weighing calves at death will enable us to detect signi�cant changes in body condition between capture and mortality, providing critical information relating to potential cause of death.

There was no di�erence between the two study areas in counts of winter ticks on the shoulders of live calves. However, the counts were higher than the mean of fall hunter harvested winter tick counts of both adults and calves. Winter tick counts were also higher during the 2016 collaring than in 2014 and 2015 capture events. Although it is not clear what this means in terms of survival, it could predict increased winter/spring calf mortality.

NecropsyMDIFW biologists recover and necropsy moose using

a protocol adapted from Minnesota Department of Natural Resources and further modi�ed by the University of Maine-Animal Health Lab (UMAHL), New Hampshire Fish and Game Department, and the University of New Hampshire Diagnostic Lab. This protocol includes assessment of the mortality site, winter tick count, blood collection, �eld necropsy, aging, and collection of tissue samples from all organs for diagnostics and analysis. University of Maine-Animal Health Lab (UMAHL) receives all blood and fecal samples after live capture and after death. UMAHL catalogues and processes all tissue samples and analyzes blood parameters and internal parasites from capture. Blood samples are also sent to additional labs to test for pregnancy of adult cows, to examine physiological parameters/body condition assessment (blood chemistry), heavy metal toxicity, screening of vector borne diseases as well as other pathogenic agents known to moose. Results from the New Hampshire and Maine moose studies will be compared and further assessed, and summarized for subsequent reports.

Cow/Calf “Walk-ins”Part of MDIFW’s moose survival project includes examining cow productivity and survival of calves in order to understand population trends. Each year of the study, beginning in May, biologists monitor the status and fate of radio-collared adult female moose and their potential calves. Current knowledge of neonatal moose survival would suggest that losses of 50% or more can occur due to factors such as bear predation and malnutrition. Due to concerns over the impact of

radio-collaring neonates, and in consultation with moose researchers from Minnesota as well as work done in Ontario and Scandinavia, MDIFW adopted a non-invasive monitoring

approach based on research done at the University of New Hampshire. This includes monitoring GPS locations and movements of adult cows to con�rm initiation of calving. Researchers have documented long range movements of pregnant cows to calving areas followed by clusters of GPS locations where the cow has potentially calved. By pinpointing these locations, biologists can stalk the cow using traditional VHF telemetry and determine whether the cow has a calf at heel or not. Biologists “walk-in” to the location indicated by telemetry several times a week until a calf is documented to be with the cow or it is determined that no calf was born. Once a calf is documented, walk-ins are reduced to one per week until the calf dies or until the probability of its survival is signi�cantly higher, usually after about 12 weeks of life.

Moose are an icon of the North Woods. This collaborative study with New Hampshire will provide a greater understanding of the in�uence of winter ticks on moose populations in the Northeast. Assessing survival rates of adult cows and calves over time and across the North Woods will help guide future moose management. We hope that this study, following an unprecedented number of collared moose across three study areas, will provide insight into moose population dynamics that will help conserve these magni�cent animals for future generations.

We gratefully acknowledge the work of Dr. Peter Pekins at the University of New Hampshire Wildlife and Conservation Biology Department; Kristine Rines, Moose Project Leader for the New Hampshire Department of Fish and Game; Dr. Anne Lichtenwalner, Director of the Animal Health Lab at the University of Maine Orono; and, Dr. Inga Sidor, Senior Pathologist with the University of New Hampshire, Veterinary Diagnostic Laboratory.

For additional details, see the following references:Bontaites, K. M., and K. Gustafson. 1993. The history and status of moose and moose management in New Hampshire. Alces 29:163-167.

Musante, A. R., P. J. Pekins, and D. L. Scarpitti. 2007. Metabolic impacts of winter tick infestations on calf moose. Alces 43:101-110.

Samuel, W. M. 2007. Factors a�ecting epizootics of winter ticks and mortality of moose. Alces 43:39-48.

Schwartz, C.C. 2007. Reproduction, natality and growth. Pages 141-171 In A.W. Franzmann and C.C. Schwartz. Editors.

Ecology and Management of the North American Moose. University Press of Colorado. Boulder, Colorado. USA.

What’s New with LPDV?Turkeys with Pox-like Lesions in NJ and VTIn October 2015, Bill Stansley of the NJ Division of Fish and Wildlife submitted a male turkey to the NJ Animal Health Diagnostic Laboratory (NJAHDL) for diagnosis. The bird was in a �ock on a private property where the resident observed it lying on the ground and noted that it was easily approachable. The bird died on the property soon thereafter and had proliferative lesions on the head and neck (Fig. 3) suggestive of either avian pox or lymphoproliferative disease virus (LPDV).

Dr. Angelique Leone, pathologist at the NJAHDL, examined the bird and determined that it had avian pox, and probably not LPDV disease, based on histolog-ic examination. Avian pox causes dermatitis character-ized by intracytoplasmic inclusions (sites of virus replication within a cell) within the hyperplastic epider-mis (skin surface with abnormal cell growth). In contrast, while LPDV can cause pox-like skin lesions, it also induces lymphoid tumors. The turkey in this case did not have the lymphoid tumors characteris-tic of LPDV.

In late October 2015, a hunter- killed adult wild turkey was submitted to VT Wildlife Division for examination because of the abnormal appearance of its head and legs. The turkey was examined by Alyssa Bennet and Joel Flewelling in the Rutland o�ce who found the raised, nodular, scab-like lesions of the skin that are characteristic of both LPDV and avian pox (Fig. 4). Their gross necropsy revealed none of the internal lesions associated with LPDV, especially any swelling or discoloration of the spleen or liver (Fig. 5).

In both the NJ and VT cases, LPDV could also have been present in the birds, but did not appear to be causing any overt disease.

LPDV Discovery and Distribution in N. AmericaOutbreaks of LPDV were originally documented in domestic turkeys in the European-Middle Eastern region during the 1970s, but the virus had never been detected anywhere else until recently. In 2009, LPDV was identi�ed by researchers at the Southeastern Cooperative Wildlife Disease Study (SCWDS) in a wild turkey from Arkansas. This was the �rst reported case of LPDV in a wild bird and in North America. The inability

to culture the virus has hampered researcher’s progress in further understanding LPDV, and made it challenging to interpret PCR results.

In domestic turkeys, disease due to LPDV

infections is typically �rst observed around 8-10 weeks of age, with variable �ock mortality that can reach 25%. The most commonly a�ected organs were spleen, thymus, pancreas, and liver, although smaller lesions can be present in other tissues as well. It appears that the natural host range of the virus is restricted to birds of the order Galliformes.

A recent study that screened for LPDV DNA using PCR in asymptomatic hunter harvested birds in the eastern U.S. revealed that, across 17 states, a total of 47% of turkeys were positive for LPDV. The highest prevalence was in the Northeast, followed by the Mid-Atlantic, Southeastern, and Central states. Causes of regional di�erences in prevalence are unknown, but could relate to turkey population densities, habitat availability, arti�cial movement of infected birds, or interactions among di�erent domestic and wild turkey �ocks. Overall, the known distribution of LPDV in wild turkeys extends from Maine to Florida and as far west as Colorado. The high prevalence of asymptomatic turkeys that are positive for LPDV also indicates that infection is common but only occasionally causes disease. The conditions that induce LPDV disease in wild turkeys are unknown.

It appears that adult wild turkeys are more likely to be positive for LPDV than are juveniles. Though the cause

of the higher prevalence in adults is unknown, it is possible that increased age simply allows for a longer period for virus exposure. Surveillance for LPDV has not been conducted in wild turkey poults, which may have higher levels of mortality than juvenile and adult turkeys.

Update on Diagnostic and Surveillance TechniquesAs stated above, it has not been possible to isolate LPDV using cell culture, a method that has long been considered the gold standard for viral diagnostics. Therefore, researchers have relied on PCR in turkey bone marrow, liver and spleen. A recent study comparing detection rates using PCR on liver, spleen, and bone marrow of wild turkeys in the eastern U.S. showed that bone marrow provided the highest level of detection for both hunter harvested turkeys and diagnostic cases. Bone marrow is easily and e�ciently collected from dead animals, making it very useful for post-mortem LPDV surveillance and archiving. A separate study showed that PCR on whole blood produces results comparable to bone marrow, making whole blood collection a useful tool for surveillance in live birds.

Further ResearchIn sum, surveillance data suggest that LPDV is endemic in wild turkeys in the eastern USA, but only causes occasional disease. It may be more likely to cause disease when an animal is already infected by another immunosuppressive virus (e.g. avian pox), or is otherwise immune compromised. Further research is needed to understand modes of transmission and

pathogenesis in wild turkeys, and to determine the impacts of LPDV on their populations.

For additional details on LPDV, see the following references:Allison, A.B. et al.

(2013) Avian oncogenesis induced by lymphoproliferative disease virus: a neglected or emerging retroviral pathogen? Virology 450–451: 2–12. doi: 10.1016/j.virol.2013.12.013 PMID: 24503077

5Volume 3, Number 1, January 2016

NWDC NOTES – Quarterly Newsletter From The Northeast Wildlife Disease Cooperative

Thomas, J.M., et al. 2015. Molecular Surveillance for Lymphoproliferative Disease Virus in Wild Turkeys (Meleagris gallopavo) from the Eastern United States. PLoS ONE 10(4): e0122644. doi:10.1371/journal.pone.0122644

Alger, K., et al. 2015. Diagnosing lymphoproliferative disease virus in live wild turkeys (Meleagris gallopavo) using whole blood. Journal of Zoo and Wildlife Medicine. 46(4):806-814.

Narrowing the Focus of the Wellfleet Bay Virus Investigation: Annual Movement Patterns of Satellite- marked Common Eiders Breeding in Boston Harbor, MassachusettsLucas Savoy, Biodiversity Research Institute, Portland, Maine

Between 1998 and 2015, 14 recognized mortality events occurred in Common Eiders (Somateria mollissima) along the coast of Cape Cod, Massachusetts. The numbers of eiders involved in each outbreak ranged from 30 to 2,800 individuals, with estimated total losses exceeding 7,000 birds. In 2010, a novel orthomyxovirus named Well�eet Bay Virus (WFBV) was isolated from tissues of four of these birds.

In 2012, biologists along the North Atlantic coast visited several Common Eider nesting colonies to collect blood samples to screen for the presence of antibodies to WFBV. The presence of these antibodies would indicate whether birds had been exposed to the virus. Eiders nesting in Nova Scotia, Quebec, Maine and Massachusetts were sampled, as were wintering eiders in Rhode Island. Overall, 6% of eiders from Nova Scotia, 0% from Maine, and 4% from Rhode Island had antibodies to WFBV. The largest percentage of eiders with WFBV antibodies (41%) occurred in Massachusetts, and most of these birds (96%) were located on one nesting island in Boston Harbor.

Eider banding conducted in breeding and molting areas along the Atlantic has provided information on geographic distribution via hunter-harvested recoveries of banded birds. However, detailed information on movements were lacking, and prior to 2012, there were no bandings of eiders associated with Boston Harbor breeding colonies. Therefore, in the spring of 2013, an interagency team1 initiated a study aimed at identifying the annual movements of eiders breeding in Boston Harbor, and determining the

potential for mixing between Boston Harbor eiders and eiders in other geographic areas. A total of 47 adult eiders breeding in Boston Harbor were marked with satellite transmitters from 2013-2015 (n = 12 in 2013; n = 19 in 2014; n = 16 in 2015). The transmitters have the ability to provide location data for 4 hours at 72-hour intervals for 2.5 years. So far, a total of 38 eiders have provided location data. These data reveal that the eiders marked in Boston Harbor molted in areas of Maine, Massachusetts (including Boston Harbor), the Gulf of St. Lawrence and Labrador, Canada. The birds wintered in Boston Harbor, Nantucket Sound area, and Long Island Sound. One of the marked birds died in November 2013 at Well�eet Bay during the same time period as the eider WFBV die-o� that season, indicating that some eiders nesting in Boston Harbor are involved in the cyclical mass mortality events. This observation is supported by a concurrent study of the genetic composition of eiders, which shows that approximately 30% of eiders found dead at Well�eet are genetically similar to samples collected from nesting females in Boston Harbor. Overall, results from transmitters show that eiders nesting in Boston Harbor can travel throughout the entire range of the American common eider, which extends from Long Island, NY to Labrador, Canada. This means that eiders from a potential virus source area (Boston Harbor) may mix with several other Atlantic populations of eiders throughout their annual cycle. 1Biologists who collaborated in this study were from the USFWS, Biodiversity Research Institute, Massachusetts Division of Fisheries and Wildlife, USGS Patuxent Wildlife Research Center, and Massachusetts Department of

Conservation and Recreation, with logistical support from the Massachusetts Water Resources Authority, Winthrop, MA.