Thomas W. Seamans

Importance of landfills to nesting Herring Gulls

We determined the importance of three landfills to a population of nesting Herring Gulls (Larus urgent&us, 3,250 pairs) on Lake Erie, Ohio, from May-July 1992. Fish was the dominant food ofadults and chicks throughout the study. Occurrence ofgarbage in the diet of adults and chicks remained low through chick-rearing then increased after fledging. Presence of telemetered adults at their nest sites decreased from incubation through post-fledging, in contrast to their increased presence at landfills during the same periods. Overall, females visited landfills more frequently and stayed longer than males; however, use of landfills by both sexes was minimal (~4% of total time) during all periods. Overall, gulls spent 43% and 4% of their time daily at the nest site and landfills, respectively. We estimate ?80% of the time remaining was spent on Lake Erie, presumably to forage. The estimated daily mean number of adult Herring Gulls at the landfills increased from incubation (143) to chick-rearing (723) to post-fledging (1,912). We estimate that 5-7%, 1219%, and 35-55% of the adult nesting population was present at landfills at least once during incubation, chick-rearing, and post-fledging, respectively. The population turnover rate of adult Herring Gulls at one landfill decreased 50% from incubation and chick-rearing to postfledging. Significantly more gulls at the landfills were observed on areas other than exposed refuse and were not actively foraging, suggesting that landfills are important to Herring Gulls for other reasons such as loafing or social interaction. We conclude that landfills are unimportant to nesting Herring Gulls when alternate, higher quality food (e.g., fish) is available. The increased use of landfills by Herring Gulls during post-fledging, however, suggests that gull activity at landfills located near airports could dramatically affect aircraft safety during this time of year.

Anthraquinone Formulation (Flight Control trademark) Shows Promise as Avian Feeding Repellent

We evaluated the effectiveness of Flight Control (FC), which contains 50% anthraquinone (AQ), as a grazing repellent for Canada geese (Branta canadensis) and as a seed-treatment repellent for brown-headed cowbirds (Molothrus ater) in northern Ohio in 1997. For the turf test, FC was applied at 4.5 L/ha in 6 18.3- × 30.5-m pens. There were 2.5 times more (P < 0.01) bill contacts/min observed on untreated plots (26.4 ± 6.0: x + SE) compared to treated plots (10.4 ± 3.8) during a 7-day test uith captive geese. Mean numbers of geese per observation were also greater (P = 0.02) on untreated plots (2.6 ± 0.4) compared to treated plots (1.4 ± 0.4). Residue analyses indicated AQ declined from 2.02 kg/ha at application to 0.22 kg/ha after 1 week. Individually caged cowbirds were presented untreated millet or millet treated with FC at 0.1, 0.5 and 1,0% (g/g) levels in 1- and 2-choice tests for 3-4 days. Flight Control was repellent to cowbirds at all levels in both 1- and 2-choice tests. In the 2-choice test, birds in the 1.0% treatment level lost body mass (P = 0.04), whereas birds at the other levels did not. Each group of treated birds in the 1-choice test lost mass (P ≤ 0.01), whereas the control group did not. Birds in the 0.5 and 1,0% groups ate minimal amounts; 3 of 12 birds died, We conclude that FC was an effective foraging repellent for Canada geese in a 7-day pen experiment and for brown-headed cowbirds as a seed repellent in aviary experiments. Flight Control shows promise as an avian feeding repellent. Further lab and field studies are needed to refine minimum repellent levels and to enhance retention of AQ on treated vegetation.

Avian Visual System Configuration and Behavioural Response to Object Approach

Antipredator behaviour theory provides a framework to understand the mechanisms behind human– wildlife interactions; however, little is known about the role of visual systems in the responses to humans. We quantified responses of brown-headed cowbirds, Molothrus ater (Boddaert), and mourning doves, Zenaida macroura (Linnaeus), to object approach (a ground-based vehicle) and vehicle lighting regimen, and we examined two visual properties (visual acuity and visual fields) that could influence antipredator behaviour. Brown-headed cowbird groups exposed to vehicle approach and constant illumination of the vehicle-mounted lamp showed alert behaviour earlier than did groups exposed to pulsating treatments or no lamp. Interestingly, light treatments interacted with ambient light; cowbird alert response occurred sooner under sunny conditions and constant illumination of the lamp. Mourning doves were not affected by light treatments. Between species, mourning dove groups had a quicker alert response (and slower flight response) than brown-headed cowbirds. Visual acuity was higher and the visual field was wider in mourning doves than in brown-headed cowbirds. We speculate that brownheaded cowbirds might flush sooner to reduce predation risk costs associated with a relatively lower ability to visually track a given object. Our findings have theoretical and applied implications, as our model species belong to families that show different antipredator responses, and provide insight as to how object lighting might be used to reduce bird–structure/vehicle collisions, an increasing source of mortality in birds. The Association for the Study of Animal Behaviour. Published by Elsevier Ltd.

Evaluation of propane exploders as white-tailed deer deterrents

Abstract 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 1994–1995. 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 0–6 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.

Enhancing the Perceived Threat of Vehicle Approach to Deer

Abstract In North America and Europe, deer (Cervidae)–vehicle collisions (DVCs) are common and result not only in injury and death to the animals involved, but also human injury and property damage. Given that most DVCs occur during crepuscular periods, we questioned whether the perceived threat to deer posed by vehicle approach could be enhanced. We hypothesized that a vehicle-based lighting system that better complements peak visual capabilities of deer at night relative to standard tungsten-halogen (TH) lighting alone would elicit a greater flight-initiation distance (FID) by free-ranging white-tailed deer (Odocoileus virginianus). Our lighting system comprised 2 TH lamps and one Xenarc high-intensity discharge (HID) lamp. We defined an a priori logistic model comprising 4 variables potentially explaining deer FID relative to vehicle approach: 1) starting distance of the approach, 2) lighting treatment, 3) season, and 4) deer group size. Deer exposed to the combination of TH lamps and constant illumination of the HID lamp exhibited a mean (SD) FID of 136 (127) m. In contrast, deer exposed to TH lamps only initiated flight on average at 116 (127) m, and those exposed to the combination of TH lamps and the HID lamp pulsed at 2 Hz exhibited a mean FID of 89 (98) m. We contend that the pulsing of the HID lamp while TH lamps were illuminated resulted in consistent loss (over approx. 0.5-sec intervals) of a portion of the image on approach, possibly interfering with sensory information relative to the position of the potential threat. In contrast, the combination of TH lamps and constant illumination of the HID lamp contributed (P = 0.033) to the probability of a FID ≥94 m. We suggest, therefore, that deer FID can be increased by combining currently available TH and HID lamps, or use of HID lamps alone, to enhance detection of an approaching vehicle at night. Also, we encourage research into new lamp designs to better complement deer visual capabilities as well as continued research to quantify deer FID in response to vehicle approach at night and lamp-specific properties that can enhance deer detection of the vehicle.

Evaluation of ElectroBraid™ Fencing as a White-Tailed Deer Barrier

Abstract White-tailed deer (Odocoileus virginianus) populations continue to increase, resulting in direct threats to public safety and increased agricultural losses. A variety of fencing methods are used to reduce deer presence at airports and agricultural areas. Electric fences may offer a less expensive alternative to expensive woven-wire fences. We tested an electric fence product, ElectroBraid™ (Yarmouth, N.S., Canada), on free-ranging deer in northern Ohio. We conducted both 1- and 2-choice tests, measuring deer intrusions and corn consumption at 10 sites encompassed with charged, noncharged or no fence. Mean daily deer intrusions decreased in each test when the fence was powered. When power was immediately applied to the fence, intrusions decreased 88–99%. When power was delayed for 10 weeks, intrusions were reduced 90%. When power was turned on and off within a 4-week period, intrusions decreased 57%. Mean corn consumption differed between treated (< 2–6.4 kg/day) and control sites (15–32 kg/day). Under the conditions and time duration of this test, the fence was an effective deer barrier. (WILDLIFE SOCIETY BULLETIN 34(1):8–15; 2006)

Speed kills: ineffective avian escape responses to oncoming vehicles.

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−1. 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−1; however, at higher speeds (more than or equal to 180 km h−1) 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−1. 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.

EXPOSURE TIME OF ORAL RABIES VACCINE BAITS RELATIVE TO BAITING DENSITY AND RACCOON POPULATION DENSITY

Oral rabies vaccination (ORV) baiting programs for control of raccoon (Procyon lotor) rabies in the USA have been conducted or are in progress in eight states east of the Mississippi River. However, data specific to the relationship between raccoon population density and the minimum density of baits necessary to significantly elevate rabies immunity are few. We used the 22-km2 US National Aeronautics and Space Administration Plum Brook Station (PBS) in Erie County, Ohio, USA, to evaluate the period of exposure for placebo vaccine baits placed at a density of 75 baits/km2 relative to raccoon population density. Our objectives were to 1) estimate raccoon population density within the fragmented forest, old-field, and industrial landscape at PBS; and 2) quantify the time that placebo, Merial RABORAL V-RG® vaccine baits were available to raccoons. From August through November 2002 we surveyed raccoon use of PBS along 19.3 km of paved-road transects by using a forward-looking infrared camera mounted inside a vehicle. We used Distance 3.5 software to calculate a probability of detection function by which we estimated raccoon population density from transect data. Estimated population density on PBS decreased from August (33.4 raccoons/km2) through November (13.6 raccoons/km2), yielding a monthly mean of 24.5 raccoons/km2. We also quantified exposure time for ORV baits placed by hand on five 1-km2 grids on PBS from September through October. An average 82.7% (SD=4.6) of baits were removed within 1 wk of placement. Given raccoon population density, estimates of bait removal and sachet condition, and assuming 22.9% nontarget take, the baiting density of 75/km2 yielded an average of 3.3 baits consumed per raccoon and the sachet perforated.

Foraging Locations of Double-crested Cormorants on Western Lake Erie: Site Characteristics and Spatial Associations with Prey Fish Densities

Abstract Radio-tagged double-crested cormorants ( Phalacrocorax auritus ) nesting on Middle Island, Ontario and unmarked cormorants in the western basin of Lake Erie were monitored in 1999. Radio-tagged cormorants were located by aircraft and by boat along regular survey routes. In addition, foraging flocks of radio-tagged and unmarked cormorants were located during the boat surveys. Approximately 79% of foraging radio-tagged individuals, and approximately 65% of all foraging flocks were observed within 2.5 km of shore. These percentages were greater than expected, based on the percentage of the area of water within 2.5 km of shore. All size classes of flocks examined were found more frequently than expected on water ≤10 m deep. Trawling data collected annually from 1988 to 1999 during the month of August were used to determine the historical distributions of the four fish species found to comprise the majority of the diet of cormorants in the area. August corresponded to a period when there is maximal overlap in the diets of cormorants and walleye ( Stizostedion vitreum ) in the area and when the number of foraging cormorants in the area is large. Flocks of cormorants of all size classes examined were not found proportionately more in regions that contained higher than the historical median annual catches of any of the four prey species. These results, coupled with previous bioenergetics studies, suggest that the impact of cormorants on the fishery of the western basin of Lake Erie is localized with respect to depth and distance from shore.

Repellency of methyl anthranilate to pre-exposed and naive Canada geese

To improve our understanding of the effectiveness of avian feeding repellents, we evaluated whether Canada geese (Branta canadensis) exhibited learned avoidance of ReJeX-iT AG-36 (AG-36), a methyl anthranilate (MA) formulation containing 14.5% MA (vol/vol). During 2 experiments in August-September 1995, we pre-exposed geese orally to 0.0, 1.3, or 4.0 g AG-36 and released them onto 10- x 10-m grass plots treated with AG-36 at rates of 22.6 and 67.8 kg/ha. Mean numbers of bill contacts and mean numbers of geese observed on control and treated plots were similar (P ≥ 0.21) for geese pre-exposed or naive to AG-36. Overall, mean numbers of bill contacts and mean numbers of geese also were similar (P ≥ 0.56) on control and treated plots. Mean mass of droppings on control and treated plots was similar (P > 0.99) during the experiment with 22.6 kg/ha AG-36 but was greater (P = 0.01) on control plots during the experiment with 67.8 kg/ha AG-36. We conclude that learned avoidance of AG-36 by Canada geese pre-exposed orally to 1.3 or 4.6 g AG-36 did not occur and that AG-36 applied to turf in enclosures at rates of 22.6 and 67.8 kg/ha was not effective as a grazing repellent for geese.