Time-Activity Budgets of Mottled Ducks in Louisiana in WinterAuthor(s): Stuart L. PaulusSource: The Journal of Wildlife Management, Vol. 52, No. 4 (Oct., 1988), pp. 711-718Published by: Allen PressStable URL: http://www.jstor.org/stable/3800935Accessed: 13/12/2010 18:23

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TIME-ACTIVITY BUDGETS OF MOTTLED DUCKS IN LOUISIANA IN WINTER

STUART L. PAULUS,' Department of Zoology-Entomology, Auburn University, Auburn, AL 36849

Abstract: I related time-activity budgets of mottled ducks (Anas fulvigula) in coastal southwestern Louisiana from September-February 1981-82 to sex, pair status, and environmental factors. Mottled ducks spent 43% of their time feeding, 36% resting, 9% preening, 7% alert, 6% locomoting, and <1% each in courtship and agonistic activities. Paired and unpaired ducks spent similar amounts of time feeding (P = 0.937). Feeding rates were lowest during October-December. Mottled ducks fed more at night than during the day (P < 0.01). Pairs spent more time resting than unpaired ducks (P < 0.001). Time spent resting was similar among months during winter and between night and day (P = 0.359). Unpaired ducks spent more time locomoting (P < 0.01) and alert (P < 0.01) than pairs. Preening, alert, and locomotor activities were observed less often at night than day and occurred at similar rates each month throughout winter. Courtship and agonistic activities were most common during September-December. By December, 90% of females were paired. Activity patterns of mottled ducks, which breed in a semitropical region, were similar to ducks wintering in Louisiana and breeding in more temperate regions. Because nearly all (95%) foraging by mottled ducks occurred in water depths <15 cm, management should provide shallow-water wetlands with abundant plant and animal foods. Deeper, open-water areas should be provided for loafing habitat and escape from predators.

J. WILDL. MANAGE. 52(4):711-718

The mottled duck is 1 of 5 mallard-like ducks found in North America (Johnsgard 1961). Mot- tled ducks inhabit the Gulf coast region from Laguna de Tamiahua south of Tampico, Mex- ico, north to the Pearl River in Mississippi and are found in greatest numbers in Louisiana and Texas (Stutzenbaker 1984).

Krapu (1981) suggested that condition of mal- lards (A. platyrhynchos) during winter may in- fluence subsequent breeding success. Because mottled ducks are nonmigratory, habitat man-

agement programs designed to benefit these birds in winter may directly affect the number of birds breeding in and using the management area in the future. Recent surveys indicated that mottled duck numbers declined by about 50%

during the past decade (Stutzenbaker 1984). In- tensive management of winter habitat may be crucial for restoring numbers of mottled ducks to former levels.

Social behaviors and habitat use of mottled ducks have been studied during the breeding (Allen 1980, Baker 1983, Paulus 1984) and non-

breeding (Weeks 1969, White and James 1978) periods. However, little is known of the impor- tance of other activities during winter. I ex- amined time-activity budgets of mottled ducks

during winter and the influence of sex, social status, time of day and year, habitat use, and

weather on time-activity budgets. These data were used to suggest management practices of benefit to mottled ducks.

I am especially grateful to K. A. R. Paulus for her support during the study. I thank G. A. Baldassarre, M. K. Causey, T. Joanen, J. E. Ken- namer, L. McNease, R. E. Mirarchi, G. R. Mul- len, D. M. Richard, and L. C. Wit for their assistance in study design, data collection and evaluation, and manuscript preparation. I ap- preciate the help of A. B. Ensminger, H. A. Bateman, Jr., and J. W. Tarver, for securing financial assistance, providing logistical support, and sharing information on the ecology of mot- tled ducks. Financial support was provided by the Louisiana Department of Wildlife and Fish- eries.

STUDY AREA AND METHODS I observed mottled ducks in coastal south-

western Louisiana, primarily on Rockefeller State Wildlife Refuge (SWR). Rockefeller SWR, an area of 30,786 ha, was bounded on the south by the Gulf of Mexico and on the north by the Grand Chenier ridge complex (Wicker et al. 1983). A description of the area was presented in Paulus (1982).

In addition, I observed mottled ducks on pri- vately-owned fresh, intermediate, and brackish marshes within 35 km of Rockefeller SWR. Much of this area was impounded by dikes, spoil banks, or natural levees that modified natural water

Present address: Innovative Research Services, P.O. Box 371, North Bend, WA 98045.

711

712 TIME BUDGETS OF MOTTLED DUCKS * Paulus J. Wildl. Manage. 52(4):1988

movements. Impoundments provided perma- nent, semipermanent, and ephemeral wetlands used by mottled ducks (Gosselink et al. 1979). Water depths in these areas usually averaged <1 m. Vegetation was described by Chabreck (1972).

I determined time-activity budgets by in- stantaneous sampling procedures (Altmann 1974, Paulus 1984). Observations were made with a 15-40 x spotting scope, 7 x binoculars, and a 2 x night vision scope (Smith and Wesson, Bos- ton, Mass.). A tape recorder, stopwatch, and super-8 movie camera were used to record spe- cific events.

Instantaneous sampling of the activity of the focal individual was recorded every 20 seconds at the tone of a metronome (Wiens et al. 1970). The behavioral repertoire of mottled ducks was classified into 78 distinct behaviors in the field. However, activities were combined into 7 major categories for analyses: feeding, loco- moting (walking, swimming, and flying not as- sociated with courting activity), resting, preen- ing (preening or bathing), alert, courting (displaying or copulating), and agonistic (bill threats, chasing, biting, and inciting).

Diurnal activities were recorded during ran- domly selected 1-hour periods. Nocturnal ob- servations were recorded during nonrandom pe- riods. Nocturnal observation periods usually began at sunset and continued without stopping until birds were no longer visible or until sunrise. Most (93%) nocturnal observations were made with the aid of moonlight. Data were collected on <2 birds at one time during the day and on most nights. However, activities of >6 birds at one time were observed on some nights. Noc- turnal observations were limited to birds within 30 m of the observer. Data from observation periods lasting <30 minutes were not included in the analyses. For analyses, hours observed = birds observed x hours observed.

When possible, ducks wearing nasal saddles labeled with unique number-letter combina- tions were observed (Greenwood 1977). Un- marked birds selected for observations were chosen in the following manner. First, 1 of the 7 activities was randomly chosen until an activ-

ity was selected that was being performed by

_1 bird. If several birds were engaged in the

activity on different portions of the pond (i.e., mottled ducks were feeding along the edge of the shoreline and on open water), a pond lo- cation (on land, edge of shoreline, 2-6 m from the shoreline on water, or on water at >6 m

from the shoreline) was randomly chosen and individuals observed were chosen from birds using that location. The single duck or pair fi- nally chosen for observation were those individ- uals subjectively considered most likely to be in the field of view during the entire observation period.

Mottled ducks were observed from the ground or from elevated blinds located on towers 3-10 m off the ground. Twenty-five sites representing a variety of habitats used by mottled ducks were selected for behavioral observations. Sites were chosen for their availability of birds, accessibil- ity, and my ability to enter the blind while min- imizing disturbance to birds in the area. One to 3 sites that met these criteria were usually avail- able at any one time. The location used for each day's observations was chosen sequentially from suitable sites. During observation periods I de- termined the sex and pair status of individuals. Pair status was determined by observing asso- ciations of males and females. Mistakes resulting from chance or temporary associations were re- duced by classifying ducks as paired only if they (1) mutually avoided or threatened other birds; (2) exhibited synchronized activities, especially locomoting and agonistic behaviors; and (3) re- mained within 3 m of each other during most of the observation period (Paulus 1983, 1984). A limited number of observations were made of unpaired ducks because unpaired mottled ducks were uncommon during much of the non- breeding period.

I recorded date, time of day, ambient tem- perature, wind velocity (using a portable ane- mometer), cloud cover, precipitation intensity, water depth, and habitat. For analysis, cloud cover was coded as 0-25, 26-50, 51-75, or 76- 100%, and rainfall intensity as zero, light, mod- erate, or heavy.

Foods consumed by mottled ducks were de- termined from visual observation, core samples of aquatic habitats used by ducks during the observation period, or from gross analyses of esophageal contents of foraging mottled ducks shot at irregular intervals. While observing the activities of individuals, I recorded microhabi- tats used (i.e., edge of shoreline, on land, on open water) at 3-minute intervals. When ob- serving ?2 birds at 1 time, I recorded micro- habitat use for only 1 bird at each 3-minute interval and alternated among ducks being ob- served. Vegetation was identified from Fassett (1940), Radford et al. (1968), and Beal (1977).

The Kruskal-Wallis test and multiple-confi-

J. Wildl. Manage. 52(4):1988 TIME BUDGETS OF MOTTLED DUCKS * Paulus 713

Table 1. Percent time spent in activities by paired and unpaired mottled ducks in Louisiana from September to February, 1980-82.

Paired Unpaired

Activity Period Male Female Male Female Overalla

Feeding Day 39.1 39.2 40.1 39.2 39.0 Night 50.6 :b 39.1 39.2 40.1 39.2 42.5

Locomoting Day 6.2 6.3 16.5 11.8 7.2 Night 2.4 S6.2 6.3 16.5 11.8 5.7

Resting Day 37.5 38.4 20.8 24.0 36.4 Night 33.8 : 37.5 38.4 20.8 24.0 35.6

Preening Day 8.5 9.0 11.4 11.2 9.0 Night 7.2 f 8.5 9.0 11.4 11.2 8.5

Alert Day 8.1 6.6 10.6 14.7 7.9 Night 5.9 :8.1 6.6 10.6 14.7 7.3

Agonistic Day 0.2 0.3 0.1 0.1 0.2 Night 0.2

0.2 0.3 0.1 0.1 0.2

Courting Day 0.4 0.2 0.6 0.2 0.3 Night 0.3

0.4 0.2 0.6 0.2 0.2

Total hr observed Day 356.7 361.0 56.1 45.7 827.6 Night 360.6

a Includes 368.7 hr of data on mottled ducks whose sex or pair status were not determined. b Mean for 24-hr period.

dence-interval procedures (Marascuilo and

McSweeney 1977) were used to detect differ- ences among group means with each activity category as dependent variables and date, sex-

pair status, or environmental variables as in-

dependent variables. The Mann-Whitney U-test was used to compare time spent in activities

during day and night, at different temperatures, or while on or off Rockefeller SWR. Spearman correlation (r) analysis was used to examine re-

lationships between activities and environmen- tal variables.

RESULTS

Feeding Mottled ducks spent a mean of 43% of their

time feeding during the study. Bottom feeding (79%), tipping (9%), feeding while standing in water or on land (9%), and surface dabbling (2%) were important modes of feeding. Diving for food was observed on 3 occasions. Time spent feeding was similar among cohorts of sex and

pair status (P = 0.937) (Table 1). Though birds were not sexed at night, individuals of pairs

appeared to engage in feeding activities and feed at similar rates.

Diurnal feeding was most common during early morning and late afternoon (Fig. 1). Mot- tled ducks spent more (P < 0.001) time feeding at night (50.6%) than day (39.0%). Ducks usually fed in small groups or as pairs at night and most dabbled in shallow-water wetlands. Nocturnal

feeding was not observed when temperatures were >20 C or <-15 C.

Morning and evening flights were not quan- tified, but on most days mottled ducks used deeper water ponds with loafing sites and then flew to shallower marshes at dusk. However, evening flights were <200 m if suitable shallow- water marshes bordered deep-water ponds. If mottled ducks used shallow ponds during the

day, they usually remained in the same area at

night. Most birds using the refuge during the

day also remained at night. Mottled ducks spent more time feeding dur-

ing September, January, and February than oth- er months (P < 0.05) (Table 2). During Octo- ber-December mottled ducks spent <35% of their time feeding. Feeding rates increased dur-

714 TIME BUDGETS OF MOTTLED DUCKS * Paulus J. Wildl. Manage. 52(4):1988

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PERIOD OF DAY Fig. 1. Percent time spent in 7 activities during 6 periods of day and night (n in hr) for mottled ducks in Louisiana from September-February, 1980-82. Period 1 was 0-4 hours after sunrise, period 2 was 4 hours after sunrise-4 hours before sunset, period 3 was 4-0 hours before sunset, period 4 was 0-4 hours after sunset, period 5 was 4 hours after sunset-4 hours before sunrise, and period 6 was 4-0 hours before sun- rise. Percentages <0.05 are not shown.

ing January and February, and mottled ducks

appeared to select diets containing more inver- tebrates. Females often tore apart mounds of dirt and then strained the material through their beaks. Esophagi of 3 pairs collected in January were filled entirely with midge (Tendipedidae) larvae.

Time spent feeding increased with declining temperatures, cloud cover, and wind velocity (Table 3). Feeding rates (52%) were greater at

temperatures below the lower critical temper- ature (14 C) than above (39%) (P < 0.001). However, during 1 night when temperatures dropped to -8 C and ponds began to freeze, mottled ducks ceased feeding and moved onto land under vegetation. Shallow ponds remained frozen for several days and mottled ducks con- fined their feeding to deeper canals and ponds.

Ducks fed most often in water at the edge of the shore or on open water (Table 4). Feeding activity occurred at higher rates when birds were in open water, flooded vegetation, or within 2- 6 m from shoreline. Birds fed <1% of the time on land, and only 5% of the time in water depths >15 cm. In shallow-water impoundments, mot- tled ducks often moved in mass, stripping seed heads and apparently bottom feeding on seeds while knocking down standing vegetation. At

night, mottled ducks frequently fed in dense stands of sprangletop (Leptochloa fascicularis) or bullwhip (Scirpus americanus).

Feeding rates were greater when mottled ducks fed off (51%) than on (33%) Rockefeller SWR (P < 0.001, n = 1,187 hr). Hunting oc- curred on marshes adjacent to Rockefeller SWR but was not allowed on Rockefeller SWR. Al-

though mottled ducks were easily disturbed ear- ly in the hunting season, by late season mottled ducks often fed within 75 m of hunting blinds in use.

Resting and Preening Mottled ducks rested (36%) and preened (9%)

nearly half of their time. Pairs spent more time

resting than unpaired birds (P < 0.001) (Table 1). Mottled ducks usually rested on land within 2 m of water, facing into the sun or wind (Table 4). They often rested on elevated mounds of dirt or vegetation.

Resting activity was lowest after sunrise, high- est during midday, declining during early night, and increasing from midnight to sunrise (Fig.

Table 2. Percent time spent in activities by mottled ducks in Louisiana by month, 1980-82.

Activity Sep Oct Nov Dec Jan Feb

Feeding 61.1 31.2 34.4 29.0 48.7 44.7 Locomoting 4.9 8.0 5.6 6.8 4.3 5.0 Resting 19.0 39.6 43.5 42.4 38.7 33.4 Preening 7.5 12.0 9.5 10.1 4.9 7.8 Alert 7.2 8.4 6.4 11.2 3.0 8.7 Agonistic 0.2 0.5 0.3 0.1 0.1 0.2 Courting 0.1 0.3 0.4 0.4 0.2 0.2 Total hr observed 231.2 195.2 150.0 205.5 251.7 154.7

J. Wildl. Manage. 52(4):1988 TIME BUDGETS OF MOTTLED DUCKS * Paulus 715

Table 3. Simple correlation coefficients (r) of selected environmental variables, date, and activities of mottled ducks in Louisiana from September to February, 1980-82.

Environmental variable Feeding Locomoting Resting Preening Alert Agonistic Courting

Date -0.071*a -0.025 0.106*** -0.074* -0.024 -0.068* 0.017 Temperature (C) -0.136*** -0.029 0.077 0.142*** 0.041 0.088** -0.038 Cloud cover -0.150*** -0.074* 0.160*** 0.027 -0.029 -0.054 -0.137 Rainfall intensity 0.004 0.020 -0.012 0.012 0.003 -0.004 -0.116 Water depth (cm) -0.019 0.064* 0.017 -0.063* 0.005 -0.019 0.052 Wind velocity (km/hr) -0.204*** 0.112*** 0.180*** -0.064* 0.017 -0.050 0.004

a Activity and environmental variable are correlated: * P < 0.05, ** P < 0.01, *** P < 0.001.

1). Mottled ducks spent similar amounts of time

resting during the night (33.8%) and day (36.4%) (P = 0.359). Time spent preening occurred less often (P < 0.05) during night (7.2%) than day (9.0%). When the moon fell below the horizon, mottled ducks generally spent a short amount of time preening and then rested. The ducks

usually rested in groups.

Alert and Locomoting Mottled ducks averaged 7 and 6% of their

time alert and locomoting, respectively. Most locomotor activity consisted of swimming (89%), flying (4%), or walking on land (3%). Because

flying activity was not recorded once the bird left the observation area, time spent flying was underestimated.

Unpaired mottled ducks spent more time lo-

comoting than paired birds (P < 0.001 for F, < 0.01 for M) (Table 1). Unpaired males spent more time alert than pairs (P < 0.001) and un-

paired females more time alert than paired fe- males (P < 0.01). Time spent in locomotor and alert activities remained at similar levels for most of the nonbreeding season (Table 2). Mot- tled ducks spent less time locomoting (2.4 vs. 7.2%) and alert (5.9 vs. 7.9%) at night than dur-

ing the day. At night, mottled ducks did not

always remain at the same pond; individuals were observed arriving at, and leaving, the pond throughout the night.

Courting and Agonistic Courting activities comprised <1% of the time

budget of mottled ducks and time spent court-

ing was similar among paired and unpaired males and females (P = 0.760) (Table 1). Court- ship activities were first observed in August and reached highest levels in the fall. By December, 90% of females were paired.

Most courting occurred in early morning and late afternoon although some activity was ob-

served at night. Most courting occurred on shal- low-water impoundments or canals, especially where groups of >20 birds were gathered.

Of 63 copulations observed, 2 were in Sep- tember, 23 in October, 11 in November, 9 in December, 13 in January, and 5 in February. Precopulatory and copulatory displays com- prised 59.5% of courtship activities of mottled ducks.

Agonistic activities were observed infre-

quently and at similar rates among all mottled ducks (P = 0.705) (Table 1). Chasing was the predominant agonistic activity of pairs. Un- paired birds rarely chased other birds but mostly gave bill threats (M) or incited (F). Most ago- nistic activities lasted only a few seconds, al- though paired males were observed chasing oth- er birds >20 m. No differences were found in time spent in agonistic activities during day or

night (P = 0.280). Agonistic activities were observed most often

in October and November, when threat behav- iors comprised 0.5 and 0.3% of time spent by mottled ducks, respectively. During the re-

maining months mottled ducks spent <0.2% of their time in agonistic activities. Paulus (1988a) provided detailed descriptions of courting and

agonistic activities and displays.

DISCUSSION Mottled ducks spent more time feeding than

in other activities and time spent feeding was

comparable to that of pintails (A. acuta) and

green-winged teal (A. crecca) in Louisiana (Tamisier 1976) that consumed similar diets. As

foraging time increased, time spent resting de- clined while time spent in other activities showed little change. Time spent locomoting, preening, courting, alert, and in agonistic activities also was similar to that of other winter waterfowl (Paulus 1988b). This suggested that nonbreeding mottled ducks allocated sufficient time to these

716 TIME BUDGETS OF MOTTLED DUCKS * Paulus J. Wildl. Manage. 52(4):1988

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activities to meet their fundamental require- ments such as maintenance, predator detection, pair formation, and food search. However, be- cause these activities were energetically costly (Wooley and Owen 1978), individuals expended only as much time as needed to meet these re- quirements.

Activity budgets were similar among paired and unpaired males and females for most ac- tivities. However, unpaired ducks spent more time locomoting and alert and less time resting than paired individuals. Similar relationships have been observed among mallards (Jorde 1981), gadwalls (A. strepera) (Paulus 1984), and green-winged teal (Quinlan and Baldassarre 1984). Higher levels of alertness and locomoting by unpaired ducks may be attributed to time spent courting and avoiding dominant pairs while competing for resources.

Nocturnal feeding was not observed when temperatures were >20 C or < -15 C. At cold- est temperatures, it may have been energetically advantageous to forego feeding and seek shel- tered microhabitats. Ice formation on ponds also limited availability of foods.

Although mottled ducks were observed feed-

ing on nights without moonlight, ducks usually began preening and resting soon after the moon fell below the horizon. If feeding activity was

primarily limited to moonlit nights, nocturnal feeding rates may be lower than levels reported in this study.

Seasonal feeding activity was similar to that of pintails, green-winged teal (Tamisier 1976), and mallards (Jorde 1981). Foraging rates in September were high as ducks continued to re- place weight lost during laying, incubation, brood rearing (F), and molt (M) (S. L. Paulus, unpubl. data). Also, many seeds were unavail- able to mottled ducks due to the immaturity of seed heads or their inaccessibility to feeding birds.

During October-December mottled ducks consumed foods primarily to meet maintenance requirements. Seeds were readily available due to killing frosts and flooding of seed-producing wetlands. Because seeds were a more concen- trated source of nutrients than the leafy portion of aquatic vegetation (Bardwell et al. 1962, Pau- lus 1982), less foraging time was needed to meet nutrient demands. Twelve birds collected from November through December all had esophagi filled with seeds, primarily sprangletop.

Weather appeared to have little influence on

J. Wildl. Manage. 52(4):1988 TIME BUDGETS OF MOTTLED DUCKS * Paulus 717

time spent in activities except during periods of severe weather. Feeding activity increased with cooler weather, except at coldest temperatures, reflecting increased energetic requirements of thermoregulation. Mottled ducks usually fed in sheltered, shallow marshes. Consequently, se- vere weather with its attendant wave action and reduced visibility from rainfall, had little influ- ence on the ability of mottled ducks to find foods in shallow habitats.

MANAGEMENT IMPLICATIONS Most mottled ducks fed in shallow-water

marshes with abundant seed material. Im- poundments that allowed manipulation of water depths, allowed maintenance of diversified hab- itat at a high level of productivity, and produced large quantities of seeds (Chabreck 1979) were important to mottled ducks. Large numbers of mottled ducks fed in impoundments and other shallow-water wetlands at night when avian predators were least active. At night, mottled ducks used dense stands of bullwhip and spran- gletop that might not be used during daylight. Mottled ducks congregated on specific im-

poundments at certain times of the year rather than using all impoundments at once. By ma- nipulating water levels, managers could stagger use, reduce operating costs, and increase duck- use days for each impoundment.

Diurnal use of shallow-water wetlands con-

taining dense, flooded vegetation can be en- hanced for mottled ducks by making openings to form small ponds. This can be achieved me- chanically, by water level manipulation, or by temporarily flooding with salt water (T. Joanen, La. Dep. Wildl. and Fish., pers. commun.). Mot- tled ducks flew to these ponds from feeding areas to avoid harassment from avian predators and used them for courting and loafing.

Production of leafy aquatic vegetation used

by mottled ducks in deep-water areas depends upon periodic flooding and drainage needed for nutrient cycling (Gosselink et al. 1979). Weirs are effective in preventing complete drainage of wetlands, decreasing turbidity, and increas-

ing production of aquatic vegetation (Larrick 1975).

Deeper water areas also can be made more attractive to mottled ducks by providing islands for loafing. Sloping shorelines with little over- hanging vegetation were favored by mottled ducks. When shallow ponds froze over, deeper

ponds and ditches provided refuge for most mottled ducks.

Tamisier (1976, 1978) suggested that most ducks used separate areas for diurnal loafing and nocturnal feeding. At dawn and dusk, flights of mottled ducks were common as birds moved from deeper loafing areas to shallower feeding areas. However, mottled ducks used the same wetland during day and night if food and safe loafing areas were available. Providing deep ponds adjacent to shallow wetlands with abun- dant seed material is the most feasible means of attracting and holding mottled ducks in an area that meets their fundamental requirements.

LITERATURE CITED ALLEN, J. A. 1980. Nesting and productivity of

mottled ducks in marshlands of southwest Lou- isiana. M.S. Thesis, Louisiana State Univ., Baton Rouge. 87pp.

ALTMANN, J. 1974. Observational study of behavior: sampling methods. Behaviour 49:227-267.

BAKER, O. E., III. 1983. Nesting and brood rearing habits of the mottled duck in the coastal marsh of Cameron Parish, Louisiana. M.S. Thesis, Lou- isiana State Univ., Baton Rouge. 71pp.

BARDWELL, J. L., L. L. GLASGOW, AND E. A. EEPPS, JR. 1962. Nutritional analysis of foods eaten by pintail and teal in south Louisiana. Proc. South- east. Assoc. Game and Fish Comm. 16:209-217.

BEAL, E. 0. 1977. A manual of marsh and aquatic vascular plants of North Carolina. North Caro- lina Agric. Exp. Stn. Tech. Bull. 247. 298pp.

CHABRECK, R. H. 1972. Vegetation, water and soil characteristics of the Louisiana coastal region. Louisiana Agric. Exp. Stn. Bull. 664. 72pp.

1979. Winter habitat of dabbling ducks- physical, chemical, and biological aspects. Pages 133-142 in T. A. Bookhout, ed. Waterfowl and wetlands-an integrated review. LaCrosse Print- ing Co., Inc., LaCrosse, Wis.

FASSETT, N. C. 1940. A manual of aquatic plants. McGraw-Hill Book Co., New York, N.Y. 382pp.

GOSSELINK, J. G., C. L. CORDES, AND J. W. PARSONS. 1979. An ecological characterization study of the chenier plain coastal ecosystem of Louisiana and Texas. I. Narrative report. U.S. Fish and Wildl. Serv., Off. Biol. Serv., Slidell, La. 302pp.

GREENWOOD, R. J. 1977. Evaluation of a nasal marker for ducks. J. Wildl. Manage. 41:582-585.

JOHNSGARD, P. A. 1961. Evolutionary relationships among the North American mallards. Auk 78:3- 43.

JORDE, D. G. 1981. Winter and spring staging ecol- ogy of mallards in south central Nebraska. M.S. Thesis, Univ. North Dakota, Grand Forks. 116pp.

KRAPU, G. L. 1981. The role of nutrient reserves in mallard reproduction. Auk 98:29-38.

LARRICK, W. D., JR. 1975. The influence of weirs on vegetation of the coastal marshlands of Lou- isiana. M.S. Thesis, Louisiana State Univ., Baton Rouge. 104pp.

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Received 11 February 1986. Accepted 21 January 1988.

USE OF MAN-MADE PONDS BY DABBLING DUCK BROODS

LUC BELANGER,' Departement de Chimie-Biologie, Universite du Quebec A Trois-Rivibres, Case Postal 500, Trois-Rivibres, PQ G9A 5H7, Canada

RICHARD COUTURE, D6partement de Chimie-Biologie, Universite du Quebec A Trois-Rivieres, Case Postal 500, Trois-Rivibres,

PQ G9A 5H7, Canada

Abstract: We studied the use of sewage (n = 3), sand-pit (n = 6), excavated (n = 10), and annular ponds (n = 10) by dabbling duck broods in southern Quebec during 1982-83. Brood use was greater in sewage ponds (2.0 broods/ha) than in other types of ponds (f = 0.3 brood/ha) (P < 0.05). Benthos density was 5 x

greater in sewage ponds (345 organisms/m2) than in other ponds. Physical features (e.g., surface area and shoreline irregularity) had influenced (P < 0.01) brood use of all man-made ponds combined. Ponds

>0.5 ha with a shoreline irregularity index _ 1.5 were used most. Brood use was also greatest on ponds with

emergent vegetation covering >30% of the surface area (P < 0.05) and on those with >30 stems/m2 of emergent plants (P < 0.05). These features can be used in construction of man-made ponds in the northeastern

region of North America.

J. WILDL. MANAGE. 52(4):718-723

Construction of ponds for waterfowl is an im- portant practice to partially offset loss and deg- radation of natural wetlands (Uhler 1964). Wa- terfowl use several types of man-made ponds,

including sewage ponds (Swanson 1977), stock ponds (Lokemoen 1973), dug ponds (Evrard 1975), gravel pits (Street 1982), and flood or stormwater control impoundments (Adams et al. 1985), but relatively little research has been con- ducted to determine the importance of the dif- ferent types of man-made ponds for waterfowl breeding in the northeastern region of North

'Present address: D6partement de Biologie, Uni- versite Laval, Cite Universitaire, Ste.-Foy, PQ G;IK 7P4, Canada.