Understanding the relative hazards of wildlife to aircraft is important for developing effective management programs. We used Federal Aviation Administration National Wildlife Strike Database records from 1990 to 2009 in the United States to rank the relative hazard of wildlife to aircraft. We summarized data for 77 species or species groups with !20 records where collisions occurred 500 ft (152 m) above ground level. We also assessed the effects of avian body mass, body density, and group size on relative hazard scores. The 3 most hazardous species or species groups were mule deer (Odocoileus hemionus), white-tailed deer (O. virginianus), and domestic dogs. ''Other geese'' (snow goose [Chen caerulescens], brant [Branta bernicla], and greater white-fronted goose [Anser albifrons]) was the most hazardous bird group. Ten of the 15 most hazardous bird species or species groups are strongly associated with water. Avian body mass was strongly associated with percentage of all strikes that caused damage, but not for species exceeding median body mass (1,125 g) of birds in damaging strikes. In contrast, percentage of damaging strikes increased when multiple birds were involved, but only for those species with body mass !1,125 g. Managers should prioritize efforts that will reduce habitat suitability for those species most hazardous to aircraft. We recommend use of exclusion (e.g., fences) for managing large mammals and habitat modifications (e.g., reductions in standing water) accompanied by hazing for reducing bird use of airports. We also recommend that evaluations of jet turbine engine performance following bird ingestions consider using multiple birds with body mass >1,000 g. ß 2011 The Wildlife Society.

Animal-vehicle collisions cause high levels of vertebrate mortality worldwide, and what goes wrong when animals fail to escape and ultimately collide with vehicles is not well understood. We investigated alert and escape behaviours of captive brown-headed cowbirds (Molothrus ater) in response to virtual vehicle approaches of different sizes and at speeds ranging from 60 to 360 km h 21 . Alert and flight initiation distances remained similar across vehicle speeds, and accordingly, alert and flight initiation times decreased at higher vehicle speeds. Thus, avoidance behaviours in cowbirds appeared to be based on distance rather than time available for escape, particularly at 60-150 km h 21 ; however, at higher speeds (more than or equal to 180 km h 21 ) no trend in response behaviour was discernible. As vehicle speed increased, cowbirds did not have enough time to assess the approaching vehicle, and cowbirds generally did not initiate flight with enough time to avoid collision when vehicle speed exceeded 120 km h 21 . Although potentially effective for evading predators, the decision-making process used by cowbirds in our study appears maladaptive in the context of avoiding fast-moving vehicles. Our methodological approach and findings provide a framework to assess how novel management strategies could affect escape rules, and the sensory and cognitive abilities animals use to avoid vehicle collisions.

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Summary1. Bird-aircraft collisions (bird strikes) represent a substantial safety concern and financial burden to civil aviation world-wide. Despite an increase in the rate of damaging bird strikes, necessary steps to develop a mitigation method outside of the airport environment have not been empirically tested. 2.We assessed whether use of aircraft lighting might enhance detection of and reaction to the approach of an aircraft in flight by Canada geese Branta canadensis Linnaeus, a species responsible for a high rate of damaging bird strikes. We used a novel approach by estimating the visibility to the goose visual system of a standard radio-controlled (RC) aircraft (standard aircraft) exhibiting either a 2-Hz alternating pulse of two lights, or lights off; and another RC aircraft designed to mimic a raptor (predator model). We then exposed wing-clipped Canada geese to the approach of each aircraft and quantified behavioural responses to respective treatments. 3. Estimates of chromatic and achromatic contrasts indicated that the standard aircraft with lights on was more salient to the visual system of the Canada goose than with lights off or the predator model. 4. At individual and group levels, quicker alert responses were observed to the standard aircraft with lights compared with the lights off and predator model. Goose groups showed similar responses to approaches by the standard aircraft and the predator model, suggesting use of antipredator behaviour to avoid the aircraft. 5. Synthesis and applications. Understanding animal sensory ecology and associated behaviours can aid the development of methods exploiting certain behaviours to reduce negative humanwildlife interactions. For example, reducing the frequency of bird strikes requires the integration of wildlife management efforts within and outside of the airport environment that target species resource use and response to disturbance, with mitigation techniques focused on the aircraft. Moreover, the design of aircraft lighting systems to enhance detection and avoidance by birds is contingent upon understanding avian visual ecology and behaviour. Based on spectral sensitivity in Canada geese, aircraft-mounted lights that peak in the ultraviolet ⁄ violet range (380-400 nm) are likely to produce the maximal behavioural effect.

The avoidance of motorized vehicles is a common challenge for birds in the modern world. Birds appear to rely on antipredator behaviors to avoid vehicles, but modern vehicles (automobiles and aircraft) are faster than natural predators. Thus, birds may be relatively ill-equipped, in terms of sensory capabilities and behaviors, to avoid vehicles. We examined the idea that birds may be unable to accurately assess particularly high speeds of approaching vehicles, which could contribute to miscalculations in avoidance behaviors and ultimately cause collisions. We baited turkey vultures (Cathartes aura) to roads with animal carcasses and measured flight initiation distance and effective time-to-collision in response to a truck driving directly towards vultures from a starting distance of 1.13 km and at one of three speeds: 30, 60, or 90 kph (no vultures were struck). Flight initiation distance of vultures increased by a factor of 1.85 as speed increased from 30 to 90 kph. However, for 90-kph approaches there was no clear trend in flight initiation distance across replicates: birds appeared equally likely to initiate escape behavior at 40 m as at 220 m. Time-to-collision decreased by a factor of 0.62 with approach speeds from 30 to 90 kph. Also, at 90 kph, four vehicle approaches (17%) resulted in near collisions with vultures (time-to-collision ≤1.7 s), compared to none during 60 kph approaches and one during 30 kph approaches (4%). Our findings suggest that antipredator behaviors in turkey vultures, particularly stimulus processing and response, might not be well tuned to vehicles approaching at speeds ≥90 kph. The possible inability of turkey vultures to react appropriately to high-speed vehicles could be common among birds, and might represent an important determinant of bird-vehicle collisions.

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In response to increased white-tailed deer (Odocoileus virginianus) depredation of agricultural crops and encroachment on airports, we evaluated the effectiveness of systematic and motion-activated propane exploders as deer frightening devices. We conducted three experiments in a 2200 ha fenced facility in northern Ohio with high (91/km2) deer densities during 19941995. Systematic exploders were calibrated to detonate once at 8 to 10 min intervals, whereas motion-activated exploders detonated 8 times/deer intrusion. Systematic propane exploders were generally ineffective, deterring deer from corn for <2 days only, whereas motion-activated exploders repelled deer for O-6 weeks. Repellency of motionactivated exploders varied seasonally, possibly in response to variations in deer density, availability of alternate food, or reproductive and social behavior. We recommend motion-activated exploders over systematic exploders as deer frightening devices for crop damage mitigation and on airports; however, systematic exploders may have utility for short-term (a few days) use. Published by Elsevier Science Ltd.