Wildlife in Airport Environments: Chapter 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 specific 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

Conclusions and Future Directions

Although the management of wildlife at airports has seen great progress in recent decades, wildlife col~ lisians with aircraft continue to pose risks to human safety and economic losses to the aviation industry and military (Allan 2002, Dolbeer 2009). Our understanding of physiological and behavioral responses of wildlife to various types of repellents and harassment techniques has grown tremendously. Substantial in· roads have been made in developing and optimizing exclusion devices, particularly for mammals. Research and management have increased considerably in recent years, allowing us to better understand aspects of re· source use (e.g., cover, food) by wildlife and the spatial scales at which they operate (Martin et al. 2011), as well as to improve current management strategies. We suggest that these two forms of management- repellents and harassment (e.g., Chapters 2-4) and habitat management (e.g., Chapters 8-H)-should be integrated to reduce hazardous wildlife use of airports. Direct control methods (e.g., hazing) typically work only in the short term; reducing habitat suitability for wildlife at airports will likely enhance long-term efficacy of these techniques

Conclusions and Future Directions

Although the management of wildlife at airports has seen great progress in recent decades, wildlife col~ lisians with aircraft continue to pose risks to human safety and economic losses to the aviation industry and military (Allan 2002, Dolbeer 2009). Our understanding of physiological and behavioral responses of wildlife to various types of repellents and harassment techniques has grown tremendously. Substantial in· roads have been made in developing and optimizing exclusion devices, particularly for mammals. Research and management have increased considerably in recent years, allowing us to better understand aspects of re· source use (e.g., cover, food) by wildlife and the spatial scales at which they operate (Martin et al. 2011), as well as to improve current management strategies. We suggest that these two forms of management- repellents and harassment (e.g., Chapters 2-4) and habitat management (e.g., Chapters 8-H)-should be integrated to reduce hazardous wildlife use of airports. Direct control methods (e.g., hazing) typically work only in the short term; reducing habitat suitability for wildlife at airports will likely enhance long-term efficacy of these techniques

Impact of the human footprint on anthropogenic mortality of North American reptiles

Human activities frequently result in reptile mortality, but how direct anthropogenic mortality compares to natural morality has not been thoroughly investigated. There has also been a limited examination of how anthropogenic reptile mortality changes as a function of the human footprint. We conducted a synthesis of causespecific North American reptile mortality studies based on telemetry, documenting 550 mortalities of known cause among 2461 monitored individuals in 57 studies. Overall 78% of mortality was the result of direct natural causes, whereas 22% was directly caused by humans. The single largest source of mortality was predation, accounting for 62% of mortality overall. Anthropogenic mortality did not increase with the human footprint or with species body mass, though predation mortality increased with decreasing human footprint. The relatively low amount of anthropogenic mortality compared to other taxa suggests that reptiles may be more impacted by indirect than direct anthropogenic mortality. As a result, mitigating these indirect impacts, which include habitat loss and introduction of invasive species, is essential for conservation of North American reptiles

Cause‐specific mortality of the world’s terrestrial vertebrates

Aim: Vertebrates are declining worldwide, yet a comprehensive examination of the sources of mortality is lacking. We conducted a global synthesis of terrestrial vertebrate cause‐specific mortality to compare the sources of mortality across taxa and determine predictors of susceptibility to these sources of mortality. Location: Worldwide. Time period: 1970–2018. Major taxa studied: Mammals, birds, reptiles and amphibians. Methods: We searched for studies that used telemetry to determine the cause of death of terrestrial vertebrates. We determined whether each mortality was caused by anthropogenic or natural sources and further classified mortalities within these two categories (e.g. harvest, vehicle collision and predation). For each study, we determined the diet and average adult body mass of the species and whether the study site permitted hunting. Mortalities were separated into juvenile or adult age classes. We used linear mixed effects models to predict the percentage of mortality from each source and the overall magnitude of mortality based on these variables. Results: We documented 42,755 mortalities of known cause from 120,657 individuals representing 305 vertebrate species in 1,114 studies. Overall, 28% of mortalities were directly caused by humans and 72% from natural sources. Predation (55%) and legal harvest (17%) were the leading sources of mortality. Main conclusions: Humans were directly responsible for more than one‐quarter of global terrestrial vertebrate mortality. Larger birds and mammals were harvested more often and suffered increased anthropogenic mortality. Anthropogenic mortality of mammals and birds outside areas that prohibited hunting was higher than within areas where hunting was prohibited. Mammals experienced shifts from predominately natural to anthropogenic mortality as they matured. Humans are a major contributor to terrestrial vertebrate mortality, potentially impacting evolutionary processes and ecosystem functioning

Quantification of avian hazards to military aircraft and implications for wildlife management

Collisions between birds and military aircraft are common and can have catastrophic effects. Knowledge of relative wildlife hazards to aircraft (the likelihood of aircraft damage when a species is struck) is needed before estimating wildlife strike risk (combined frequency and severity component) at military airfields. Despite annual reviews of wildlife strike trends with civil aviation since the 1990s, little is known about wildlife strike trends for military aircraft. We hypothesized that species relative hazard scores would correlate positively with aircraft type and avian body mass. Only strike records identified to species that occurred within the U.S. (n = 36,979) and involved United States Navy or United States Air Force aircraft were used to calculate relative hazard scores. The most hazardous species to military aircraft was the snow goose (Anser caerulescens), followed by the common loon (Gavia immer), and a tie between Canada goose (Branta canadensis) and black vulture (Coragyps atratus). We found an association between avian body mass and relative hazard score (r2 = 0.76) for all military airframes. In general, relative hazard scores per species were higher for military than civil airframes. An important consideration is that hazard scores can vary depending on aircraft type. We found that avian body mass affected the probability of damage differentially per airframe. In the development of an airfield wildlife management plan, and absent estimates of species strike risk, airport wildlife biologists should prioritize management of species with high relative hazard scores

Quantification of avian hazards to military aircraft and implications for wildlife management

Collisions between birds and military aircraft are common and can have catastrophic effects. Knowledge of relative wildlife hazards to aircraft (the likelihood of aircraft damage when a species is struck) is needed before estimating wildlife strike risk (combined frequency and severity component) at military airfields. Despite annual reviews of wildlife strike trends with civil aviation since the 1990s, little is known about wildlife strike trends for military aircraft. We hypothesized that species relative hazard scores would correlate positively with aircraft type and avian body mass. Only strike records identified to species that occurred within the U.S. (n = 36,979) and involved United States Navy or United States Air Force aircraft were used to calculate relative hazard scores. The most hazardous species to military aircraft was the snow goose (Anser caerulescens), followed by the common loon (Gavia immer), and a tie between Canada goose (Branta canadensis) and black vulture (Coragyps atratus). We found an association between avian body mass and relative hazard score (r2 = 0.76) for all military airframes. In general, relative hazard scores per species were higher for military than civil airframes. An important consideration is that hazard scores can vary depending on aircraft type. We found that avian body mass affected the probability of damage differentially per airframe. In the development of an airfield wildlife management plan, and absent estimates of species strike risk, airport wildlife biologists should prioritize management of species with high relative hazard scores