Behavioral and Ecological Considerations for Managing Bird Damage to Cultivated Fruit

Many bird species eat fruits and, likewise, many plant species are dependent on birds for the dispersal of seeds. Through cultivation and selective breeding, attributes of wild fruit have been changed to make fruit more palatable to humans. For example, cultivated species bear fruits that are often thinner-skinned. are more succulent, have fewer seeds and are easier to pick than non-cultivated species. These same changes, however, have also increased the attractiveness of fruit to avian consumers. Ecological relationships that have developed across evolutionary time between wild plants and frugivores become emphasized by the introduction of cultivated fruits that have been carefully bred, unknowingly and unintentionally, with bird-friendly traits

Repellents: Integrating Sensory Modalities

Recommendations for managing wildlife damage situations often involve application of multiple methods or techniques. The basis for such recommendations is unclear as there is little evidence that such combinations of methods work more effectively than the individual methods alone. In order to improve beyond hit or miss repellent applications, we should adopt principles exhibited in nature and develop repellent treatments based on the design of signals used in animal communications. In particular, characteristics that increase detectability, discriminability, and memorability should be identified and incorporated into repellent design. To do so, the sensory capabilities of the target species need to be more completely understood

Trends in North American Vulture Populations

In recent years, interactions between vultures and human activities have noticeably increased. These interactions include nuisance roosts, damage to homes and businesses, livestock depredation, and collisions with aircraft. One major factor contributing to the upsurge in vulture problems is higher numbers of these birds. Both turkey vultures and black vultures appear to be experiencing major population increases throughout much of their ranges in the United States. During 1990-2002, Christmas Bird Count (CBC) data revealed annual nationwide increases of 1.79% and 5.97% for turkey wltures and black vultures, respectively. Estimates *om Breeding Bird Survey (BBS) data were 1.99% and 4.97% for the two species. Despite substantial differences in methodology associated with these two sets of data, they are consistent in charting overall increases in populations of both vulture species. Positive population trends are mostly codied to the eastern half of the counhy. The usefulness of survey data like the CBC and BBS is currently being seriously questioned, but for vultures I contend that the objections to the survey data are not critical. Nevertheless, suggestions for improved data collection procedures are offered

An Overview of Current Blackbird Research in the Southern Rice Growing Region of the United States

Red-winged blackbirds (Agelaius phoeniceus), common grackles (Quiscalus quiscula), and brown-headed cowbirds (Molothrus ater) cause extensive damage to newly planted and ripening rice. The blackbird-rice problem has generated considerable public pressure in states such as Louisiana, Texas, California, Arkansas and Missouri, to find more effective methods of reducing damage caused by blackbirds. USDA/ APHIS/WS National Wildlife Research Center (NWRC) works closely with various state rice growers associations and the USDA Wildlife Services (WS) state operational programs to address this high-priority issue. NWRC conducts a multi-faceted research program aimed at resolving blackbird-rice problems. Research focuses on determining the status of depredating species in southern rice growing states, assessing the impact of birds on production, evaluating and developing potential bird repellents, improving the effectiveness of DRC- 1339, and developing new strategies and/or tools to manage bird damage to rice

BIRD DAMAGE CHRONOLOGY AND FEEDING BEHAVIOR IN TWO SUNFLOWER FIELDS, SACRAMENTO, CALIFORNIA, 1982

Bird damage was assessed weekly from soon after anthesis until harvest in two sunflower fields in the Sacramento Valley, California, during 1982. Damage chronology was similar at both sites, with damage concentrated in the second to fourth weeks after anthesis when the seeds were in the doughy stage of development. Less than 10% of the total losses caused by birds occurred during the final month before harvest. Overall bird damage was quite low (0.20 and 0.26%) in each field and in one, damage by wind was 2.4 times greater than that caused by birds. Brewer\u27s blackbirds (Euphagus cyanocephalus) and house finches (Carpodacus mexicanus) both occurred in low-to-moderate numbers in one field, while high numbers of blackbirds, mostly red-winged blackbirds (Agelaius phoeniceus) occurred at the other field. At both fields, the numbers of blackbirds recorded peaked during the dough stage of sunflower development, whereas finches were most numerous somewhat later in the damage season. Analysis of the esophagi of 15 red-winged blackbirds collected

Avian perching deterrents on ultrasonic sensors at airport wind-shear alert systems

Preventing birds from perching on the sensor units of the Federal Aviation Administration’s Low Level Wind-shear Alert System (LLWAS) is crucial to its successful operation. In this study we evaluated, under controlled conditions, responses of brownheaded cowbirds (Molothrus ater), fish crows (Corvus ossifragus), great horned owls (Bubo virginianus), barred owls (Strix varia), and black vultures (Coragyps atratus) to several anti-perching devices. No device was totally successful against every species. Of the 5 original test devices, the most effective perching deterrent was a set of 17 stout spikes (“AgSpikes”) secured to the central portion of the sensor unit that point up 0o to 30o from the vertical. The central spikes were subsequently redesigned and combined with 9 metal bushings (3 for each arm of the sensor unit) that fit loosely on the sensor arms and that were armed with 5 sharp spikes each. This “AgSpikes and SpikedSpinner” combination unit was as effective as the original AgSpikes for all birds except owls, which were able to place their feet within the open spaces of the redesigned AgSpike portion of the device and perch on the 3 horizontal spikes. The combination units should adequately discourage most large and small birds from perching on LLWAS sensors. The availability of alternate perches in the field will likely enhance the effectiveness of the deterrent. Monitoring performance of the combination units deployed in the field is recommended to verify that they are working as expected