Aquatic alien mammals introduced into Italy: their impact and possibility of control

Sandro BertolinoUniversity of Turin, DIVAPRAEntomoloy & Zoology

Genovesi PieroNational Wildlife Institute

Biological Invasion in Inland WatersInternational Workshop – Florence, May 5-7, 2005

Outline

• Aquatic Mammals introduced into Italy

who are they?

where are they?

what are they doing?

what are we doing?

• Control vs eradication: an example from the management of coypu in Italy and England

• An example of strategic approch to coypu control

• General conclusions

Outline

• Aquatic Mammals introduced into Italy

who are they?

where are they?

what are they doing?

what are we doing?

• Control vs eradication: an example from the management of coypu in Italy and England

• An example of strategic approch to coypu control

• General conclusions

Aquatic mammals introduced in Europe

North AmericaMustela visonAmerican mink

South AmericaMyocastor coypusCoypu

North AmericaOndatra zibethicusMuskrat

North AmericaCastor canadensisAmerican beaver

OriginSpecies

American mink Mustela vison

World spread and introduction

Source: J. L. Long, 2003 Introduced mammals of the world

American mink Mustela vison

•Escape from fur farms

•Deliberate releases

Introduction causes Italian distribution

American mink Mustela vison

Presently no damage is reported in Italy, but in other European countries the American mink threatens other species through:

• predation (ground nesting birds, water vole)

• competition (European mink)

American mink Mustela vison

Recent releases from fur farms in Italy

• 5000 animals Parma

• 3000 animals Forlì (2001)

• 5000 Treviso (2002)

• 20.000 Ferrara (2003)

• 200 Padova (2005)

Propagule pressure

American mink Mustela vison

To prevent new establishment it is important to build-up a rapid response system.

Thus the National Wildlife Institute is preparing an action plan,

with the constitution of task-forces at the Regional or Provincial level

in order to capture the animals in few days after their releases.

Prevention

Muskrat Ondatra zibethicus

World spread and introduction

Source: J. L. Long, 2003 Introduced mammals of the world

Muskrat Ondatra zibethicus

Italian distribution

•Escape from fur farms

•Deliberate introductions

Introduction causes

Muskrat spread

The beginning of an invasion: the spread of the muskrat from the point of introduction of five individuals near Prague in 1905 (modified from Ulbrich 1930).

Muskrat Ondatra zibethicus

Presently no damage is reported in Italy, but in other European countries the muskrat

• damage aquatic vegetation,

• undermines river banks and dikes for its burrowing activity,

• there is some evidence of negative impacts on invertebrates through the change in habitat structure

Coypu Myocastor coypus

World spread and introduction

Source: J. L. Long, 2003 Introduced mammals of the world

Coypu Myocastor coypus

•Escape from fur farms

•Deliberate introductions

Introduction causes

Source: Mitchell-Jones et al, 1999 The Atlas of European mammals

Italian distribution

Alien species management

The coypu is considered a pest because of

• the damage produced to crops,

• the damage produced by feeding on aquatic vegetation,

• for its burrowing activity that undermines river banks and dikes,

• a negative impact on birds nesting in the aquatic vegetation and near the rivers has been suggested.

Outline

• Aquatic Mammals introduced into Italy

who are they?

where are they?

what are they doing?

what are we doing?

• Control vs eradication: an example from the management of coypu in Italy and England

• An example of strategic approch to coypu control

• General conclusions

Cost/benefit analysis of two opposite approaches to pest speciesmanagement: permanent control of Myocastor coypus in Italy versuseradication in East Anglia (UK) Panzacchi et al. submitted

• Official eradication started in 1981 (intensive trapping before).

• 24 trappers involved, ensured salary for the entire period; reward for earlier completion of the eradication

• 31,822 coypus killed.

0

2000

4000

6000

8000

10000

12000

14000

16000

1978 1980 1982 1984 1986 1988 1990

• After 1989 no occurrence recorded

Coypu’s eradication in East Anglia(Gosling et al., 1981; Gosling & Baker, 1999)

• 24 trappers, 40-50 traps per person

• 10-15 rafts

• 4-5 boats

• Costs, actualised to yr 2000, about 5 million €

IS IT TOO MUCH?

Coypu’s eradication in East Anglia(Gosling et al., 1981; Gosling & Baker, 1999)

• Introduced in the 1960s

• Range = 68.599 Kmq

• Continuous range in North

and Central Italy

• Still scattered in the South

• Progressive expansion

• Recently introduced in Sicily

and Sardinia

Coypu’s range in Italy

• 297 public institutions contacted sending 2 questionnaires:

• Q1 (focusing on damage to agriculture and coypus control)

was sent to Regional and Provincial Wildlife Departments

and to Park Departments;

• Q2 (focusing on damage to river banks and drainage

channels) was sent to he Drainage Authorities.

… survey on the economic losses

• traps (8 yr amortisation)• kits for euthanasia• anaesthetics• bullets• plastic gloves• freezers (12 yr amortisation)• use of cars or boats• rafts, baits • plastic bags • disposal of carcasses (incinerated

or buried), • staff salary• volunteers reimbursement• training courses for the volunteers

Cost of control including :

… survey on the economic losses

MATERIAL

PERSONNEL

All costs were corrected to year 2000 value, using an economical revaluation coefficient table

€

0

50000

100000

150000

200000

250000

300000

350000

1995 1996 1997 1998 1999 2000

Damage to cropR2 = 0.93, P = 0.002

Co

mp

en

sate

d d

am

ag

e t

o

cro

ps

0

10000

20000

30000

40000

50000

60000

70000

Killed coypusR2 = 0.93, P = 0.002

N. k

ille

d c

oyp

us

Impact on crops and n° killed coypus

Pearson R = 0.92, P = 0.008

0

200.000

400.000

600.000

800.000

1.000.000

1.200.000

1.400.000

1.600.000

1.800.000

1995 1996 1997 1998 1999 2000€

Costs of floods not considered: e.g.: 7th August 1998 Brenta river bank collapsed devastated the community of Loreggia, destroying buildings and fields. Est. losses ca. 16 Mln €.

Damage to riverbanks

R2 = 0.96, p < 0.001

Cost of control

0100.000200.000300.000400.000500.000600.000700.000800.000

1994 1995 1996 1997 1998 1999 2000

R2 = 0.85, p = 0.006

Damage to crops

Costs of control

Damage to riverbanks

TOTAL R2 = 0.87, P = 0.007

Total costs

0500.000

1.000.0001.500.0002.000.0002.500.0003.000.0003.500.0004.000.000

1994 1995 1996 1997 1998 1999 2000 2001

€

€ 3.77 MILLIONS

• Present range = 68,599 Kmq

• Potential expansion (suitable habitat) 330%

• Total costs (yr 2000) = € 3,773,786

• Potential future costs > 12 mln €/yr

Ottaviani, 2003

0

2

4

6

8

10

12

UK eradication Mngmt cost/yrItaly

Predictedmngmt cost/yr

€ Million

Future costs of Coypu management in Italy

1. Widespread perception that costs of eradications

generally outweigh benefits, and that eradications in

most cases fail

2. But! … costs of permanent control largely exceed

costs of eradication

3. Thus, eradication, when feasible, is the best option

in the long term

Conclusions: control vs eradication

1. Competent authorities should eradicate small populations of the American mink and adopt a rapid response system to face new releases

2. and eradicate Muskrat in northeastern Italy, adopting a subsequent control campaign to prevent new arrivals from East

Recommendation for the management of aquatic species

1. Eradicate coypus in isolated and newly colonised areas where it is still technically possible and cost effective (eg. Sicily and Sardinia in Italy, but also Spain).

2. Carefully plan control activities of large populations

3. Always evaluate the efficacy of control operations and adjust future plans accordingly.

4. Concentrate control operation in the most vulnerable areas in terms of biodiversity (protected areas), economically valuable crops (vegetables) and important hydraulic systems.

5. Support research on more effective control methods and prevention strategies

Recommendation for the management of the coypu

Outline

• Aquatic Mammals introduced into Italy

who are they?

where are they?

what are they doing?

what are we doing?

• Control vs eradication: an example from the management of coypu in Italy and England

• An example of strategic approch to coypu control

• General conclusions

A strategic approch to coypu control in small wetland areasBertolino et al. 2005. Wildl. Soc. Bull.

Damage to natural vegetation in thePiedmont Region (Northwestern Italy)

A drastic reduction on aquatic vegetation has been observed

Phragmites australis, Thypa spp., Nymphaea alba, Nupharlutea, Trapa natans

In these protected areas:

• Garzaia di Valenza Natural Reserve

• Restoration area in the Garzaia di Valenza

• Biotope (Natura 2000) Fontana Gigante

• Biotope (Natura 2000) Palude di San Genuario

• Lago di Candia Park

Problem definition

Feasibility

Definition of objectives

Preparing a plan

Implementation of the plan

Monitoring and evaluation

A strategic approach to coypu controlAdapted from Braysher 1993

• In the 90s the coypu colonized an area, the lakes of La Spes, where the Po River Park was re-creatingsome wetlands in previous agricultural areas

Problem definition

• The animals with their foraging activities were stopping the colonization of the aquatic vegetation,limiting the naturalization of the area

The coypu was stopping theevolution of the area toward a

functional ecosystem

Yesterday

Today

Feasibility of control from literature

Trasimeno Lakes

Coypu control: YES

Campotto

Coypu control: NO

Source: Cocchi e Riga 2001

Time

Num

ber

of a

nim

als

Population growth curve of an introduced species

Carrying capacity

1

2

Possibility to control the population

Control not possible

From the literature: if the effort isappropriate and the density not too high, it is possible to control coypu populations with cage-trapsGosling 1990; Cocchi & Riga 2001

Definition of objectives

• Allow the natural vegetation to grow

• Recover the functional ecology of the area

• Prepare an action plan for the control of the coypu in other wetlands managed by the park

Trapping in 2 areas

• A closed area

surrounded by crop fields and poplar plantations, with a probable low degree of colonization by coypu dispersing from other areas

• An open area

a canal flowing into the River Po. Here coypus were part of alarger population distributed along the River Po

Feasibility: an experimental approach

0

4

8

12

0 1 2 3 4 5 6 7

Weeks of capture

Coy

pus r

emov

ed

048

1216

0 1 2 3 4 5 6 7 8

Weeks of capture

Coy

pus r

emov

ed

Closed area

Open area

Control results 1998

R2 = 0.89; P = 0.004

Difference between seasons Closed P<0.01

Open N.S.

3

11

2

13

25

1916 17

0

5

10

15

20

25

30

Winter Spring Summer Autumn

Co

ypu

s re

mo

ved

Closed area Open area

Control results 1999

• Control in 2 periods: winter and autumn

• Use of 5-10 cage-traps per area

• 1 person working

• Traps activated for 2-3 days a week

• For a period of 5-7 weeks

Implementation of the plan: Methods

Continuing the control started in 1998 in therestoration area (closed area)

In 2000 starting the control in the EU Biotope(Natura 2000) Fontana Gigante

In 2001 starting the control in the EU Biotope(Natura 2000) Palude di S. Genuario

Implementation of the plan: Areas

Fontana Gigante

Palude di S. Genuario

Monitoring and evaluation: results

05

101520253035404550

Win. Aut. Win. Aut. Win. Aut.

2001 2002 2003

Period

Ani

mal

s re

mov

ed

Valenza Fontana Gigante S. Genuario

Coypus removed in the 3 areas during the period: 2001-2003

0

5

10

15

20

25

30

Den

sity

(coy

pus/

ha)

Removal densities of coypu in the 3 areas and different periods (1998–2003, light blue dots) and density of coypu populations from other areas (red dots)

Red dots data from: Norris 1967, Brown 1975, Willner et al. 1979, Doncaster and Micol 1990, Velatta and Ragni 1991, Reggiani et al. 1993).

Monitoring and evaluation: results

Carrying capacity

1

2Other areas

Wetlands in the park

Coypu populations were limited by the controleffort in the 3 areas

… but this is not enough !

Thus did we meet all the objectives of the control plan?

Monitoring and evaluation: coypu populations

We were interested in the recoveryof natural vegetation !

Surface covered by yellow waterlilies in 3 ponds, before coypus colonization, during coypu feeding, and after coypu removal

01.0002.0003.0004.0005.0006.0007.0008.0009.000

Beforecolonization

Coypu feeding After control

Sur

face

(sq

m)

Pond 1 Pond 2 Pond 3

Monitoring and evaluation: natural vegetation

In small areas it is possible to control coypu inorder to let the natural vegetation to recover

Conclusion

When control campaign are planned it is important to evaluate the efficacy of the controloperations and adjust future plans accordingly

Outline

• Aquatic Mammals introduced into Italy

who are they?

where are they?

what are they doing?

what are we doing?

• Control vs eradication: an example from the management of coypu in Italy and England

• An example of strategic approch to coypu control

• General conclusions

General conclusion I

Prevention is a better strategy than eradicationor control !!

Every alien species needs to be managed as potentially invasive, until convincing evidence indicates that it is not threatening,

avoiding its release in the wild and maybe limiting the importation in the country

Considering the risks posed to biodiversity and human activities, Italy must adopt a precautonary principle, removing small nuclei of introduced species before they spread in large area.

Accordingly to the European strategy, Italy is called to build-up a rapid response system in order to avoid further releases of alien mammals in the wild.

General conclusion II

Thank you for your attention !!