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Feral Swine Eradication in Havasu National Wildlife Refuge: Protecting Endangered Species from Feral Swine Damage

Posted by Jeanine Neskey, Extension Specialist, USDA, APHIS in Animals
Apr 17, 2018
Feral swine walking on path in Havasu National Wildlife Refuge
Feral swine walking on path in Havasu National Wildlife Refuge. The refuge is a vital nesting ground for many species of birds, many of which are federally threatened or endangered. U.S. Fish Wildlife Service photo

Havasu National Wildlife Refuge was established by Franklin D. Roosevelt in 1941, as a refuge and breeding ground for migratory birds and other wildlife. The refuge encompasses 37,515 acres of riverine, riparian, wetland, and desert upland habitats protecting one of the last remaining natural stretches of the lower Colorado River along the Arizona and California borders. The refuge is an important breeding ground and migratory flyway stopover for over 300 species of birds.

The refuge conducts land management and restoration activities intended to improve habitat for federally threatened and endangered species, including southwestern willow flycatchers, western yellow-billed cuckoos, and Yuma Ridgway’s rails, as well as other migratory and resident birds, waterfowl and terrestrial wildlife. In addition to habitat protection, the refuge provides extensive wildlife-oriented recreational activities, such as hunting, fishing, wildlife observation and photography, as well as interpretative and educational programs. Approximately, 2 million people visit the refuge annually.

Feral swine foraging
A feral swine sounder causing erosion by using a wallow on Havasu National Wildlife Refuge property. Removal of these invasive feral swine supports the refuge’s mission of conservation and recovery of native wildlife. U.S. Fish Wildlife Service photo

Feral swine are a hazard to the threatened, endangered, and native wildlife species of the refuge. Feral swine destroy vegetation, and damage fences, and their rooting, trails, and wallowing deteriorate the delicate habitat of the refuge. Of highest concern is the effect they may have on endangered Ridgway's rails and other marsh birds. Feral swine and marsh birds spend most of their lives in the same habitat and swine are omnivores known to prey on birds, particularly eggs and nestlings, as well as reptiles and amphibians.

Feral swine presence was first noted in the refuge in the 1950s, likely escapees from local farms or they were intentionally released by humans for hunting purposes. In addition to damaging habitats and wildlife, feral swine pose a risk to people who may be walking the expansive trails and roads of the refuge. Although feral swine will most likely run from a human, there is always the possibility of aggression with any wild animal, particularly if a pet is involved. Of higher risk to people is that feral swine can carry many zoonotic diseases. Feral swine in Havasu National Wildlife Refuge have tested positive for leptospirosis, E. coli, Salmonella, and pseudorabies; all diseases which can be transmitted to people or other mammals.

Managing feral swine in the refuge poses unique challenges. Much of the refuge has limited road access, some areas are only accessible by boat, and the cattail marshes are so dense that they are impenetrable by people. Feral swine, however, can tunnel through the cattails and evade management efforts.

Discussions between the U.S. Fish and Wildlife Service (FWS) and USDA-APHIS Wildlife Services (WS) National Feral Swine Damage Management Program to eradicate feral swine from Havasu National Wildlife Refuge began in 2015. Soon after, the FWS drafted a Feral Swine Eradication Plan, Environmental Assessment (EA), and National Environmental Policy Act documents. The first large scale removal operation took place in February 2017, the second occurred in February 2018. These efforts included a combination of aerial and targeted ground removal operations, the 2018 operations resulted in the removal of 67 feral swine. Since 2006, when feral swine where first recognized as a serious problem in the refuge, there have been 540 animals removed.

The goal of eradicating feral swine in Havasu National Wildlife Refuge is lofty, but achievable. Because it is highly unlikely that feral swine traversed mountain passes or vast deserts to access the refuge, it is expected that once the isolated population is removed, the refuge will be free of feral swine for the foreseeable future. Since the beginning of targeted removal efforts, visitors have seen fewer feral swine while in the refuge. Management and monitoring will continue for some time to ensure that feral swine are eradicated and that no new populations are introduced.

Feral swine captured by trail camera on the move at night
Feral swine captured by trail camera on the move at night. Since the beginning of targeted removal efforts, visitors have seen fewer feral swine while in the refuge. U.S. Fish Wildlife Service photo
Category/Topic: Animals