ENVIRONMENTAL ASSESSMENT FOR CONTROL OF FREE-RANGING RESIDENT MALLARDS IN FLORIDA

 

 

MAY 2002

 

Contact: Frank Bowers
U.S. Fish and Wildlife Service
1875 Century Blvd.
Atlanta, Georgia 30345
frank_bowers@fws.gov
404/679-7188
Fax 404/679-4180

 



PURPOSE AND NEED FOR ACTION

 Mallards (Anas platyrhynchos) historically occurred in Florida only as wild, winter migrants (Appendix A). Recently, however, some mallards have become present year-round and have begun to breed in the wild. The major introduction source of these birds is believed to be backyard releases (i.e., individuals purchasing a small number of ducks and releasing them in their backyards for aesthetic purposes; and in some cases, hunting clubs releasing large numbers of birds for hunting purposes). Based on the normal distribution and behavior of wild mallards (Bellrose 1980), it is reasonable to assume that any unconfined mallards present in Florida between May 1 and August 31 are free-ranging resident mallards or their offspring. These birds are referred to as resident mallards, and they are interbreeding with the endemic Florida mottled duck (Anas fulvigula fulvigula). Hybridization with resident mallards represents a significant threat to the future of the Florida mottled duck. Worldwide, mallard-type species have been partially or completely hybridized out-of-existence by such introduced mallards (Appendix A). In order to significantly decrease or eliminate such hybridization and genetic introgression to the native/wild Florida mottled duck, the Service is proposing to issue Florida a depredation permit to take resident mallards. The permit would authorize the State to issue/grant subpermits to its agency employees, contractors, designated agents, and private individuals who have written authority from the State - - to control (take) mallards present during the May-August periods. Actions permitted could involve lethal and non-lethal control of mallards in order to contribute to the protection of the Florida mottled duck.



INTRODUCTION

The Florida mottled duck (Anas f. fulvigula) is endemic to peninsular Florida, but resident mallards are interbreeding with Florida mottled ducks. Many mottled ducks in Florida are showing phenotypic expression of hybrid characteristics (Gray 1993). Phenotypic hybrid characteristics are minimum expressions of the hybridization rate because many mallard genes are not expressed phenotypcially (Barnes 1989). Hybridization with mallards represents a significant threat to the future of the Florida mottled duck. It is a potentially devastating problem, and accentuates the need for comprehensive resident mallard control in Florida. Unless the release of mallards is stopped, and hybrids and resident mallards are removed from the wild, mallard genetic introgression into the mottled duck population will continue. In addition to hybridization concerns, resident mallards can transmit diseases to wild waterfowl of any species, compete for food and other resources, and be a public nuisance. Control of resident mallards would help address all of these concerns.

Florida Fish and Wildlife Conservation Commission (FWC) statues/regulations prohibit the release of mallards into the wild (Appendix B). Public education on the problems associated with resident mallards is ongoing in the form of magazine and newsletter articles, official correspondence, information pamphlets, waterfowl-related workshops, and manuscript publication. The release of mallards can and will continue to be addressed by the FWC.

The U.S. Fish and Wildlife Service (Service) is the Federal Agency charged with governing the issuance of permits to take, capture, kill, possess, and transport migratory birds as authorized by the Migratory Bird Treaty Act (1918 with amendments), and such regulations are promulgated in 50 CFR parts 13 and 21. Both agencies are concerned about the conservation of the Florida mottled duck and a need to significantly limit or eliminate interbreeding with resident mallards.


PURPOSE OF THE PROPOSED ACTION

The primary purpose is to significantly reduce the chance of hybridization of the Florida mottled duck by minimizing interbreeding and competition with resident mallards, and to help reduce potential disease transmissions. The Service would issue a depredation permit that would authorize the reduction of resident mallards during a period when other wild, migratory mallards are not present in any appreciable numbers.


NEED FOR THE PROPOSED ACTION

There is a need to address the negative impact of resident mallards on the Florida mottled duck via issuance of depredation permits, because (1) the interbreeding problem is growing and could accelerate beyond human control; (2) genetically pure mottled duck densities appear to be decreasing; and (3) regular waterfowl season hunting is uneffective as a control. Regular waterfowl hunting is ineffective because a large proportion of resident mallards reside in urban/suburban areas where firearm discharge is prohibited. Also, hunting regulations are designed to maintain duck populations as opposed to significantly reducing population size. Controlling mallards outside the waterfowl hunting season requires a Service permit. 


DECISIONS THAT MUST BE MADE

The Service and FWC personnel must determine whether the biological concerns associated with resident mallards in Florida are sufficient to warrant facilitating control of the mallard population; what that control should consist of; and what provisions should be developed to guide the control actions. The USFWS Regional Director must decide if the proposed action merits a Finding of No Significant Impact, or constitutes a major federal action which would significantly affect the quality of the human environment.


ISSUES AND CONCERNS

The following is a list of potential issues and concerns associated with the control of resident mallards. 

  1. Lack of control and subsequent proliferation of resident mallards may lead to extirpation of mottled ducks as a separate species because of mottled duck x mallard hybridization.

  2. There may be some public opposed to the lethal take of resident mallards, preferring to use only nonlethal means.

  3. Proliferation of resident mallards also increases the risks for disease transmission to wild waterfowl. Domestic waterfowl can serve as a reservoir for diseases that can be devastating to wild waterfowl.

  4. Year-round mallards are not part of Florida’s native avifauna. They compete with native wildlife for food and other resources. Resident breeding mallards were introduced by humans to Florida; therefore, humans are responsible for solving the problems these birds create.

  5. Control measures must be accompanied by prevention of releases and education of the public to comprehensively address the problems posed by resident mallards.

  6. Reduction of resident mallards could reduce numbers occurring in backyards or community property. This may not be desired by some citizens. Some people enjoy having these resident birds around their homes for aesthetic reasons.

  7. If lethal control of resident mallards is allowed, accidental take of normal wild mallards and even Florida mottled ducks may occur.

  8.  Existing FWC regulations prohibiting release of mallards have not been that effective in preventing introductions.


COORDINATION AND CONSULTATION

This assessment was completed with input from the FWC, USFWS Regions 4 and 5, and the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service-Wildlife Services. The FWC’s position on the resident mallard issue has been publicized through magazine and newsletter articles, correspondence, waterfowl-related workshops, and regulation development. Public input regarding mallard interbreeding with mottled ducks has been possible at bi-monthly meetings of the Florida Fish and Wildlife Conservation Commission. Others also commenting on this proposal were the Service’s Division of Migratory Bird Management; Service Law Enforcement agents; Audubon managers in Florida; and the Service’s Atlanta Permit Branch.


ALTERNATIVES INCLUDING THE PROPOSED ACTION

Five alternatives have been developed for consideration as control methods for resident mallards in Florida.

Alternatives Considered: 

A.        ALTERNATIVE 1. NO ACTION

Under this alternative, no resident mallard control would be conducted in Florida beyond what is currently taking place. This includes a few birds taken under the current permitting process where small numbers of domestic mallards can be distinguished from normal, wild mallards based on plumage.

B.       ALTERNATIVE 2. COMBINED LETHAL AND NONLETHAL CONTROL (PREFERRED ALTERNATIVE)

Issuance of a depredation permit would occur for mallards and their nests/eggs that are present in Florida during May 1 - August 31 periods. The permit would be issued to Florida’s Division of Wildlife and also authorize the State to issue/grant subpermits to its agency employees, contractors, designated agents, and private individuals (who have written authority from the State agency and are authorized to conduct activities involving control and management of mallards). Actions permitted would include lethal and nonlethal control methods (trapping, euthanization, shooting, relocation, etc.) of resident mallards during the specified May-August period. Egg and nest manipulation and destruction would also be permitted. Such control on non-State owned lands could occur only if authorized by the landowner. The control activities must not be set-up to provide or constitute hunting opportunity (control activities must be clearly “control”, not hunting). No person should construe the permit as opening, reopening, or extending any hunting season contrary to any regulations established under Section 3 of the Migratory Bird Treaty Act.

The State would need to provide an annual report by January 31 to the Service office issuing the permit. The report would provide details on estimated numbers of mallards involved, location of activities, and numbers of eggs/nest controlled -- including the lethal and non-lethal techniques used. The State should have on-hand, names of others (subpermittees, agents, contractors, individuals, etc.) that were granted permission to take mallards, nests, and eggs via this permit. The permit could be revoked or suspended at anytime with written notice from the Service and the exact wording of such a depredation permit would follow the standard permit language.

C.       ALTERNATIVE 3. LETHAL AND NONLETHAL CONTROL (NO PERMITS OR REPORTING) 

The actions would be similar to ALTERNATIVE 2; however, no reporting requirements, issuance of permits, or tracking of mallards taken would be required. Essentially anyone in Florida would be allowed to take mallards without a permit or data recording during the specified period. The administrative State and Federal procedures for such an action would have to be agreed to, possibly via a memorandum of understanding (MOU) or other written agreements/policy formulation.

D.       ALTERNATIVE 4. NONLETHAL CONTROL

By permit - - allow public agencies, private animal control organizations, and the general public to control resident mallards using nonlethal methods during the period May 1 - August 31 of each year. Primarily this would involve capture of resident mallards for release into areas where less opportunity would occur for contact with the Florida mottled duck. It could also involve capture and sterilization/release of mallards at their capture site. A veterinarian would be required for proper surgical sterilization.

E.       ALTERNATIVE 5. LETHAL CONTROL ONLY

By permit - - allow public agencies, private control organizations, and some private landowners to control resident mallards using lethal control methods to the exclusion of nonlethal methods.


AFFECTED ENVIRONMENT

The final selected Alternative will occur throughout the State of Florida, with no expected consequences to habitat environment functions or processes. Resident mallard ducks (present during the May - August period) will be reduced in numbers. The incidence of avian diseases associated with dense waterfowl situations (avian cholepa, botulism, duck-virus-enteritis) should also be reduced. Continued control of resident mallards (over the long-term) is expected to significantly reduce mallard x mottled duck hybridizations.


ENVIRONMENTAL CONSEQUENCES

A.        ALTERNATIVE 1. NO ACTION

If no action is taken, the resident mallard population will continue to grow. Subsequent increases in hybridizations, disease outbreaks, and nuisance problems will occur. Ultimately, the mottled duck could be lost as a distinct species in Florida. 

B.       ALTERNATIVE 2. COMBINED NONLETHAL AND LETHAL CONTROL (PREFERRED ALTERNATIVE)

Allowing the use of lethal and nonlethal control methods (by permits) will reduce mallard x mottled duck hybridizations, disease transmission, resource competition, and nuisance problems.

Limiting control activities to the period May 1 through August 31 will avoid impacts to normal, wild mallards because, during this period, migratory mallards are at their northern breeding areas. Whenever nonlethal control becomes necessary due to physical location or private landowner wishes, some increased effectiveness can be obtained by pinioning the birds (removal) clipping some feathers, and then suggesting confinement to fenced yards or pens. Data on individuals involved in control activities and the results (e.g. mallard, other species take) of permittees will be available via record keeping and permit authorizations.

Most control activities will be first focused on sections of the State where larger concentrations or preferred habitats of the Florida mottled duck are known to occur. Some accidental take of mottled ducks may happen, but this can be reduced via identification training of permitted personnel. Also mottled ducks maintain a higher degree of human wariness whereas resident mallards do not. The potential minor to inconsequential accidental take of mottled ducks will be far less than benefits gained through removal of resident mallards.

Control on private lands will be by permission of the landowner, also an educational program and outreach to the general public by FWC to explain the interbreeding problem will help to show why control is needed. FWC will also take stronger steps to prohibit/minimize all mallard releases in Florida.

C.       ALTERNATIVE 3. LETHAL AND NONLETHAL CONTROL (NO PERMIT OR REPORTING REQUIRED)

Similar to ALTERNATIVE 2 these actions will reduce mallard x mottled duck by hybridizations, etc; however, less information will be available on (1) individuals involved and (2) the impact of take on mallards and other species. A greater likelihood of mottled duck take could occur without a large, general public duck-identification program. Less law enforcement control of the activities would be available; however, the administrative burden of issuing and tracking permits would be reduced.

D.       ALTERNATIVE 4. NONLETHAL CONTROL

Using only nonlethal control methods would not be effective in significantly reducing the incidence of contact between mallards and the mottled duck. Some minor reduction of interactions may occur, but only for a short-term on very limited capture sites. There is no way (except by sterilization) to assure captive mallards will not become free/feral, raise young, and eventually continue their offspring’s contact with mottled ducks. Even with current State laws already prohibiting the release of mallards, hybridization is occurring and will persist. Other potential nonlethal methods such as harassment and perhaps habitat modification will not address the conservation threat to mottled ducks. In fact, such actions could increase the chance of contact by driving resident mallards from developed areas into more natural habitats used by mottled ducks.

Capture and sterilization of an adult duck are difficult and expensive activities, is not commonly done, and could easily exceed costs of $85 - $125 per duck. It also involves a high risk of fatal outcome, particularly for female (hen) ducks. Chemo-sterilants and immuno-contraceptives have been used for some avian species, but not commonly forducks. Chemo-sterilants are not totally species specific (may impact non-target animals); have limited effectiveness; and must be repeatedly administered to maintain sterility. Additionally, current Florida laws do not allow the release of mallards (even sterilized); therefore, they would have to be maintained in fences or pens during their life-span.

Such methods would be more acceptable to some portions of the general public, and the probability of accidental harm to mottled ducks could be less than the preferred alternative (lethal/nonlethal control).

E.        ALTERNATIVE 5. LETHAL CONTROL

Utilization of only lethal control (e.g. shooting, capture and euthanization, etc.) would help reduce interbreeding interactions in some portions of Florida, but in other highly urban areas it would often be impractical and at times not acceptable from a public standpoint. Furthermore, it would unnecessarily restrict control options when an effective nonlethal method is available (e.g. when one is willing to continually hold pinioned birds or sterilized birds in a properly confined area). The result of this alternative would be an overall reduced level of resident mallard control due to the inability to deal with some problem situations.


IN SUMMARY 

The preferred alternative (2) will have no significant or cumulative environmental impacts resulting from the proposed actions, with the exception of impacts to resident mallards in Florida. Beneficial impacts are expected to be a reduced incidence of mallard x mottled duck hybridization, lower potential for disease transmission, and less resource competition between the species. Such an alternative, especially if combined with educational efforts and more strict adherence to State laws restricting/prohibiting the release of mallards, has the best chance of reducing the resident mallard population and conserving the Florida mottled duck.


Authors/Preparers


Literature Consulted/Cited

Andrews, E. J., B. T. Bennet, J. D. Clark, K. A. Houpt, P. J. Pascoe, G. W. Robinson, and J. R. Boyce, 1993. Report of the AVMA Panel on Euthanasia. JAVMA. Vol. 202, No. 2.

Barnes, G. G. 1989. Determination of mallard and black duck hybrids from wing feathers. J. Wildl. Manage. 53:1061-1064.

Bellrose, F. C. 1980. Ducks, geese and swans of North America. Stackpole Books, Harrisburg, PA. 540pp.

Gray, P. N. 1993. The biology of a southern mallard: Florida’s mottled duck. Ph.D. Dissert., Univ. Florida, Gainesville. 172pp.

Kale, H. W. and D. S. Maehr. 1990. Florida birds: a handbook and reference. Pineapple Press, Sarasota, FL. 288pp.



APPENDIX

Appendix A has a more in-depth fact sheet regarding the feral mallard problem.

Appendix B Florida letter describing State steps to reduce release of mallards.



U.S. Fish and Wildlife Service
Southeast Region

1875 Century Boulevard
Atlanta, GA 30345
404-679-7244

http://southeast.fws.gov