Use of decoy traps to protect blueberries from juvenile European starlings

Fruit consumption by large flocks of juvenile European starlings (Sturnus vulgaris) is a serious problem for growers of strawberries, grapes, apples, cherries, blueberries, and other small fruit. This study examined if numbers of juvenile European starlings foraging in blueberry orchards could be reduced by catching them in decoy traps and relocating the birds elsewhere. From late July through August of 1989, 620 juvenile starlings were captured in 2 decoy traps at a blueberry orchard in Connecticut. A similar number were caught during the same period in 1990. During these 2 years, numbers of juvenile starlings foraging daily in the orchard dropped from \u3e500 before the traps were opened to \u3c100 afterwards. During 1987 and 1988, when no trapping was conducted, starling numbers at the orchard remained high throughout the summer. Trapped starlings were banded and released unharmed 50–100 km away, and none were seen again at the blueberry orchard. During the 2 years of operation, traps caught only 19 nontarget birds of 6 species; all were released unharmed. Decoy traps were specific for juvenile starlings; no adult starlings were captured. These results indicate that decoy traps can be used in a nonlethal manner to reduce berry losses to flocks of juvenile starlings

MANAGEMENT OF FRUIT BAT AND RAT POPULATIONS IN THE MALDIVE ISLANDS, INDIAN OCEAN

The introduced black rat (Rattus rattus) and the endemic giant fruit bat (Pteropus giganteus ariel) are serious depredators of coconuts and fruits, respectively, in the Maldives. Differences in reproductive rate between rats (high) and bats (low) must be considered in implementing control programs. We estimate a rat population can fully recover from an island-wide reduction of 90% in less than 6 months. In contrast, a bat population may require 6 years to recover from a 90% reduction. Crown-baiting of coconut palms with anticoagulant rodenticides is effective in reducing rat damage, but villagers have been reluctant to adopt recommended baiting programs, allowing rat populations to quickly recover. We substantially reduced bat populations on islands (e.g., from 2.1 bats/ha to 0.7 bats/ha) after a few nights of mist netting and recommend this procedure for managing bat populations. Bat populations should not be reduced below 0.25 bats/ha on islands in the Maldives

MANAGEMENT OF FRUIT BAT AND RAT POPULATIONS IN THE MALDIVE ISLANDS, INDIAN OCEAN

The introduced black rat (Rattus rattus) and the endemic giant fruit bat (Pteropus giganteus ariel) are serious depredators of coconuts and fruits, respectively, in the Maldives. Differences in reproductive rate between rats (high) and bats (low) must be considered in implementing control programs. We estimate a rat population can fully recover from an island-wide reduction of 90% in less than 6 months. In contrast, a bat population may require 6 years to recover from a 90% reduction. Crown-baiting of coconut palms with anticoagulant rodenticides is effective in reducing rat damage, but villagers have been reluctant to adopt recommended baiting programs, allowing rat populations to quickly recover. We substantially reduced bat populations on islands (e.g., from 2.1 bats/ha to 0.7 bats/ha) after a few nights of mist netting and recommend this procedure for managing bat populations. Bat populations should not be reduced below 0.25 bats/ha on islands in the Maldives

Efficacy of an Acoustic Hailing Device as an Avian Dispersal Tool

Bird strikes are a major safety and financial concern for modern aviation. Audible stimuli are common bird dispersal techniques, but their effectiveness is limited by the saliency and relevance of the stimulus. Furthermore, high ambient sound levels present at airfields might require that effective audible stimuli rely more on total volume (i.e., exceeding physiological tolerances) than ecological relevance. Acoustic hailing devices (AHD) are capable of sound output with a narrow beamwidth and at volumes high enough to cause physical discomfort at long distances. We tested the effectiveness of anAHD as a dispersal tool on freeranging birds recognized as hazardous to aviation safety at the Savannah River Site and Phinizy Swamp Nature Park in South Carolina and Georgia, USA, respectively, between October 2013 and March 2015. Our study design included experimental trials with timed-interval counts of birds directly before and after AHD treatment. For most species, counts of birds associated with treatment periods (use of AHD) and control periods (no use of AHD) occurred on different days. Sound treatments yielded variable success at dispersing birds. Specifically, AHD treatment was effective for dispersing vultures (Coragyps atratus and Cathartes aura) and gulls (Laridae), but ineffective for dispersing blackbirds (Icteridae), diving ducks (Aythya spp., Bucephala spp., Oxyura spp.), and coots (Fulica americana). Trials were conducted in a relatively quiet environment with birds that were unhabituated to excessive noise; thus, we cannot unequivocally recommend an AHD as a universally effective avian dispersing tool. However, future research should consider AHD testing integrated with other methods, as well as investigation of treatments that might be salient to specific target species

Methiocarb-Treated Rice Seed Applied After Field Draining Fails to Repel Blackbirds from Sprouting Rice

Blackbirds, primarily Agelaius phoeniceus, cause extensive losses to sprouting rice in southwestern Louisiana. Methiocarb applied to seed prior to planting at rates above 1.0 g a.i./kg rice (0.1%) has provided excellent protection to sprouting rice in Louisiana under conditions of high bird pressure. To reduce treatment costs, some farmers have used over-flights of methiocarb-treated seed applied at low rates to part of the field after draining. This study showed this technique was not efficacious under conditions of high bird pressure. Four fields treated in this manner suffered 98% loss of sprouts compared to 100% loss in four untreated fields. Large flocks of blackbirds ( \u3e 3,000) fed in all treated and untreated fields during the first four days after draining. Blackbirds were evidently able to distinguish between treated (ungerminated) and untreated (germinated) seed. Large feeding flocks of blackbirds were composed almost entirely of females (x = 94%; n = 17); it is not known whether these birds were residents or migrants. We recommend that future studies investigate the efficacy of using mixtures of methiocarb-treated seed and untreated seed at planting time for reducing blackbird damage to sprouting rice. Blackbirds cause extensive losses to sprouting rice in southwestern Louisiana. Methiocarb applied to rice seed prior to planting at rates above 1.0 g a.i./kg seed provided excellent protection to sprouting rice in Louisiana under conditions of high bird pressure (Holler et al. 1985). Use of methiocarb by growers under emergency (Section 18) exemption from the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) has been low, largely due to the high cost of treating all rice seed used in planting (Holler et al. 1982, 1985). In 1985 we determined the feasibility of protecting newly planted rice fields from blackbird damage by aerially applying treated seed on the fields upon completion of drainage after planting. This method has been used by farmers in Louisiana and subjective evaluation of its effectivness has been inconclusive. If efficacious, this method would provide the grower with a measure that could be used after planting when bird pressure is known to be high. It would also reduce residues in drainage water and it would result in substantial reduction in the cost of protection. Personnel of the Crowley, Louisiana Field Station, U.S.D.A. (formerly U.S. Fish and Wildlife Service), provided logistical support. A. Wilson, Rice Research Station, Louisiana State University, Crowley, Louisiana collected sprout count data from one field. Mesurol®4/75% Seed Treater for this test was provided by the Mobay Chemical Corporation, Kansas City, Missouri. The study was conducted by the U.S. Fish and Wildlife Service, Department of the Interior. The Animal Damage Control Program, including the Denver Wildlife Research Center, was transferred to USDA-APHIS (Animal and Plant Health Inspection Service) on 3 March 1986

ALPHA-CHLORALOSE EFFICACY IN CAPTURING NUISANCE WATERFOWL AND PIGEONS AND CURRENT STATUS OF FDA REGISTRATION

During 1990 and 1991 we conducted safety, efficacy and clinical trials required to register alpha-chloralose (A-C) for capturing nuisance waterfowl and pigeons with the U.S. Food and Drug Administration (FDA). We determined the Most Effective Dose (MED) to be 30 and 60 mg of A-C/kg of body weight for capturing waterfowl and pigeons, respectively. We conducted 11 field trials in 4 states, capturing 587 waterfowl and 1,370 pigeons with 8% mortality for ducks, 0% for geese, and 6% for pigeons. We submitted a New Animal Drug Application to FDA in October 1991 and anticipate registration in 1992

Impacts of biomass production at civil airports on grassland bird conservation and aviation strike risk

Growing concerns about climate change, foreign oil dependency, and environmental quality have fostered interest in perennial native grasses (e.g., switchgrass [Panicum virgatum]) for bioenergy production while also maintaining biodiversity and ecosystem function. However, biomass cultivation in marginal landscapes such as airport grasslands may have detrimental effects on aviation safety as well as conservation efforts for grassland birds. In 2011–2013, we investigated effects of vegetation composition and harvest frequency on seasonal species richness and habitat use of grassland birds and modeled relative abundance, aviation risk, and conservation value of birds associated with biomass crops. Avian relative abundance was greater in switchgrass monoculture plots during the winter months, whereas Native Warm-Season Grass (NWSG) mixed species plantings were favored by species during the breeding season. Conversely, treatment differences in aviation risk and conservation value were not biologically significant. Only 2.6% of observations included avian species of high hazard to aircraft, providing support for semi-natural grasslands as a feasible landcover option at civil airports. Additionally, varied harvest frequencies across a mosaic of switchgrass monocultures and NWSG plots allows for biomass production with multiple vegetation structure options for grassland birds to increase seasonal avian biodiversity and habitat use

Wetland Bird Abundance and Safety Implications for Military Aircraft Operations

Wetlands with associated avifauna can pose a substantial hazard to aviation safety, potentially increasing bird–aircraft collision (strike) risk when located near air operations areas.We modeled year-round use by wetland avifauna of Drummond Flats Wildlife Management Area (Drummond Flats), a wetland complex located within 10 km of Vance Air Force Base (AFB), Enid, Oklahoma, USA. Our objectives were to 1) quantify seasonal avifauna abundances at Drummond Flats; 2) test a priori models reflecting use by bird species recognized as hazardous to aviation safety relative to environmental factors including flooded wetland habitat and vegetation cover; 3) use these models to predict maximal expected abundances of wetland avifauna during flood conditions; and 4) compare our findings with reported bird strikes at Vance AFB. Drought conditions influenced avian use during our study. Of the species expected to respond predictably to flooded wetland habitat, only ducks (Anatinae) occurred in numbers conducive to modeling. Using zero inflated Poisson models, we found that duck abundance was positively associated with permanent wetland habitat type and, excluding winter, available habitat area (i.e., standing water); whereas, \u3e50% vegetation cover was negatively correlated with abundance. No model predicted \u3e97.2 ducks/ha for any habitat type, except during winter. Our models also identified potential peaks in abundance not evident from raw count data, emphasizing the benefits of this approach. Identifying factors driving abundances also enables targeted management of hazardous species. Further, we found double-sampling to be a practical method for assessing detection bias during avian surveys at wetlands. Restricting to obligate wetland species associated with Drummond Flats, we found 1 strike/184,212 flight-hours, which was an order of magnitude lower than the average for U.S. civil aircraft (1990–2014). Thus, under drought conditions, bird use of Drummond Flats likely did not elevate strike risk for Vance AFB aircraft operations

Estimating Interspecific Economic Risk of Bird Strikes With Aircraft

The International Civil Aviation Organization promotes prioritization of wildlife management on airports, among other safety issues, by emphasizing the risk of wildlife–aircraft collisions (strikes). In its basic form, strike risk comprises a frequency component (i.e., how often strikes occur) and a severity component reflecting the cost of the incident. However, there is no widely accepted formula for estimating strike risk. Our goal was to develop a probabilistic risk metric that is adaptable for airports to use. Our specific objectives were to 1) update species-specific, relative hazard scores (i.e., the likelihood of aircraft damage or effect on flight when strikes occur) using recent U.S. Federal Aviation Administration (FAA) wildlife strike data (2010–2015); 2) develop 4 a priori risk models, reflecting species-specific strike data and updated relative hazard scores; 3) test these models against independent data (monetary costs associated with strikes); and 4) apply our best model to strike data from 4 large, FAA-certificated airports to illustrate its application at the local level. Our best-fitting risk model included an independent variable that was an interaction of quadratic transformed relative hazard score and number of wildlife strikes (r2=0.74). Top species in terms of estimated risk nationally were red-tailed hawk (Buteo jamaicensis), Canada goose (Branta canadensis), turkey vulture (Cathartes aura), rock pigeon (Columba livia), and mourning dove (Zenaida macroura). We found substantial overlap among the top 5 riskiest species locally across 3 of 4 airports considered, illustrating the degree of site specific differences that affect risk. Strike risk is dynamic; therefore, future work on risk estimation should allow for model adjustment to reflect ongoing wildlife management actions at airports that could influence future strike risk. Published 2018. This article is a U.S. Government work and is in the public domain in the USA