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A national review of the status of trapping for bird control

  • Author(s): Gorenzel, W. Paul
  • Salmon, Terrell P.
  • Crabb, A. Charles
  • et al.
Abstract

We examined the status of trapping to control bird damage based on a nation-wide questionnaire, literature, and on-site visits of trapping programs. We mailed 464 questionnaires to Agriculture Commissioners in California, Cooperative Extension Wildlife Specialists, USDA APHIS Wildlife Services personnel, state Department of Agriculture personnel, and members of the National Animal Damage Control Association. Two hundred fifty questionnaires (54%) were returned from 50 states, 1 territory, and 51 California counties. Fifty-four percent of the respondents indicated they either trap, monitor, or provide information on bird trapping. Regarding specific activities, 49% actively trapped while 43% provided information only. By affiliation, 90% of private respondents trapped, followed by 60% of federal respondents. Respondents listed 53 species of birds causing damage. Cited most often were rock doves (Columbo livia), European starlings (Sturnus vulgaris), blackbirds, Canada geese (Branta canadensis), American crows (Corvus brachyrhynchos), house finch (Carpodacus mexicanus), and house sparrows (Passer domesticus). Respondents listed 52 crops, 18 types of animal production facilities, and 16 non-crop sites that were subject to bird damage. Respondents listed 25 species that were trapped. Modified Australian crow traps, walk-in traps, and drive traps were used most frequently. Most respondents (80%) rated trapping as moderate to excellent for ducks, geese, rock doves, and house sparrows. Trapping for starlings was rated as moderate to excellent by 75% of private industry respondents (mostly non-agricultural damage), but 80% of California county returns (dealing mostly with agricultural damage) rated it as slight. Differences in control ratings for some species related to the type of damage site, geographic location, and organizational affiliation. Most (57%) respondents felt trapping was not important in overall bird control in any crop. California Agriculture Commissioners (>70%), however, indicated trapping was important for starling and house finch control, particularly in grapes. Most respondents (71%) felt trapping for bird control stayed at the same level or increased since 1990, and 82% thought it would stay the same or increase in the future. This sentiment was strongest among respondents from private industry (93% ). We identified literature on general trapping concepts, specific traps, trapping techniques, and operational trapping programs. We found no rigorous evaluations of trapping’s effectiveness or the factors influencing results. Three studies provided partial economic analyses, but most evaluations of trapping put emphasis on the numbers of birds caught rather than the amount of damage eliminated in relation to the cost of control. New trap designs or trapping strategies that may have application to current bird problems include the impact trap, the Modesto funnel trap, noose-covered wickets, glue-coated perches, decoy-crop trapping, trammel nets, and mist nets. We identified five California counties currently monitoring house finch trapping. From 1991 to 1995, an average of nearly 100,000 house finch have been trapped annually. Only Sonoma County currently traps with county personnel, taking an average of 1,000 starlings/year from 1991 to 1995. We conclude trapping for bird control: 1) is commonly used across the country by a broad segment of wildlife damage control practitioners; 2) is important for the control of selected species, such as starlings and house finch in California; 3) is important for bird control in certain crops such as grapes in California, and non-crop sites such as around buildings in urban areas; 4) will continue to be used at the same or increased levels in the future; 5) has not been rigorously evaluated from a cost-benefit standpoint; 6) can be improved with new trap designs and strategies; and 7) merits additional research.

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