Wildlife in Airport Environments: Preventing Animal–Aircraft Collisions through Science-Based Management

8: Identification and Management of Wildlife Food Resources at Airports

Wildlife use airport habitats for a variety of reasons , including breeding, raising young, resting, taking refuge from predators, and locating sources of water. But the chief motivation for most individuals to encroach on airports is food. Depending on the speci fic habitat types present and habitat management strategies employed, airports can harbor large numbers of small mammals, insects, earthworms, and palatable vegetation that attract many species hazardous to aircraft. Often the best way to reduce populations of hazardous wildlife at airports is to determine which sources of food are being used, and then remove or modify those foods to make them less attractive (Washburn et al. 2011). Fortunately, the science of wildlife ecology and management has a long and productive history of research on wildlife food habits and foraging strategies, and the applied nature of most food habit studies conducted in airport environments facilitates straightforward specialization of investigational techniques . In this chapter we (1) discuss in more detail food resources as a primary motivation for wildlife use of airport properties, (2) consider some established principles of wildlife food habits and foraging strategies that affect airport wildlife management, (3) review techniques used to investigate wildlife food habits and identify those most useful for airports, (4) discuss methods for eliminating or modifying some preferred foods at airports, and (5) briefly consider future research needs. Although we focus our discussion on birds (>97% of all wildlife–aircraft strikes involve birds), white-tailed deer (Odocoileus virginianus; Biondi et al. 2011) and other mammals (Dolbeer et al. 2010) present significant hazards at some airports. Even so, deer and many other mammals can be managed effectively with exclusion techniques (Chapter 5). For airports without adequate fencing, the food habits of deer, coyotes (Canis latrans), and other hazardous mammals should be considered when developing wildlife hazard management protocols. For example, even though few birds regularly feed on soybeans (Sterner et al. 1984, Krapu et al. 2004), deer are major consumers of soybean plants (Humberg et al. 2007), and thus soybean cultivation should be discouraged at and near airports without adequate fencing. Food: A Primary Motivation for Wildlife Use of Airports Why are so many wildlife species attracted to airports? There are many reasons. Although they can contain a variety of habitat types (Blackwell et al. 2009, DeVault et al. 2009), airports are usually characterized by wide-open spaces relatively free from human activity. DeVault et al. (2012) calculated that airports in the USA certificated by the Federal Aviation Administration (FAA; see Appendix) contain an average of 297 ha of grassland. Airports also have stormwater treatment facilities and other water bodies that can attract hazardous wildlife (Chapter 9). If one considers the three basic needs of wildlife— food, water, and shelter—wildlife can readily obtain Travis L. DeVault Brian E. Washburn Identification and Management of Wildlife Food Resources at Airports 8 80 managing resources all three at an airport. On closer investigation, however , water and shelter may be less problematic overall and easier for airport biologists to manage than food resources. Water bodies certainly do attract waterfowl and other hazardous wildlife to airports, and at times offer considerable management challenges. Even so, water attractants are usually identified easily , and substantial progress has been made in recent years in the design and management of water bodies at airports to deter use by hazardous wildlife (Chapter 9). As for shelter, the overall homogeneity of airport lands relative to off-airport areas helps to limit refuge and loafing areas for some types of hazardous wildlife. Biologists can identify and remove mammal dens and raptor nests, and close hangars and other airport buildings to deny access to rock pigeons (Columba livia), European starlings (Sturnus vulgaris), and other birds closely associated with humans. But because wildlife food resources are so abundant and take so many different forms, it is difficult—if not impossible—to remove them completely. Even at airports employing full-time wildlife biologists, wildlife consistently forage on airport properties. An examination of the FAA’s National Wildlife Strike Database (Dolbeer et al. 2010) indicates that hazardous wildlife use airports primarily for foraging, as opposed to nesting, loafing, and other activities. Blackwell et al. (2013) reviewed database records from 1990 to 2008 and determined that of the nine grassland-associated bird species that caused the most damaging strikes to aircraft, only killdeer (Charadrius vociferous) commonly nest in airport grasslands. The remaining bird species—Canada goose (Branta canadensis) red-tailed hawk (Buteo jamaicensis), and European...