Guidelines to the Use of Wild Birds in Research

IV. COLLECTING AND TRAPPING

A. Why Ornithologists Collect Specimens

Ornithological research often involves the judicious collecting of birds in the field. Information obtained from these specimens enables accurate identification of species and understanding of evolutionary relationships, genetics of wild populations, population structure and dynamics, comparative anatomy and physiology, adaptation, behavior, parasites and diseases, economic importance, geographic and microhabitat distributions, and ecology of birds in natural or disturbed habitats (AOU 1975). Knowledge from ornithology promotes knowledge in other biological sciences and affects policies concerning game and

non-game species, endangered species, economically important species, habitat conservation, ecosystem analysis, pest and disease control, predator control, and domestication.

Most bird specimens removed from the field are deposited in the collections of natural history museums or biological data banks for future studies. Museum collections are managed repositories for whole specimens and their parts, whereas biological banks are collections of histologically or cryobionically preserved organs, tissues (including live cultures), cells (including sperm and ova), or embryos. Both kinds of repositories permit qualified researchers to study their collections. The great value of these collections is demonstrated by the substantial funding that has been provided by federal, state, and private agencies for their care, as well as by the large scientific literature based on collected specimens. Voucher specimens should be retained at the conclusion of field investigations and deposited in collections that meet the minimal standards of maintenance established by the AOU and that have active loan programs, so that the specimens will be available for use by future investigators (Remsen 1991, 1995; Winker et al. 1996).

B. What is an Adequate Sample?

"Regulating agencies are often overly enthusiastic in restricting scientific collecting, which is the only kind of mortality that is so highly controlled and yet from which bird species might derive benefits, whereas the same or sister agencies often permit or even encourage activities that are responsible for massive mortality in bird populations. Given that (1) the goal of scientists, conservation agencies, and governments is protection of populations, not individual birds; (2) scientific collecting has no measurable impact on the vast majority of bird populations; (3) scientific specimens represent an important source of information on bird biology and conservation; and (4) existing scientific collections are largely inadequate for answering many questions that could be answered by greater numerical, seasonal, and geographic representation, then it follows that continued scientific collecting will benefit ornithology and conservation and should, therefore, be encouraged by conservation and government agencies." J. V. Remsen, Jr. (1995).

An adequate sample is the minimal number of specimens or other data necessary to ensure investigative and statistical validity. The sample size required for a study depends on the nature of the investigation and the extent of variation in the parameters being studied. Field studies require larger samples than do laboratory studies, because field investigators have less control over the conditions that produce variation, and many studies requiring specimens are studies of variation per se, and thus require large sample sizes. Computer modelling can help define and sometimes reduce sample size requirements.

The collection of scientific specimens typically has no lasting effect on avian populations. Few ornithologists collect more than 100 individuals in a given year, and the total number of specimens collected annually for research purposes in North America is fewer than 10,000. In contrast, an estimated 140 million birds are killed by collisions with vehicles and picture windows, and over 100 million are harvested by hunters (Banks 1979). Domestic cats kill many millions of birds per year (George, 1974; Mitchell, 1992; Jurek, 1994).

C. Methods for Collecting Specimens

Humane scientific methods of trapping and shooting are those that kill the bird instantly but avoid injury to the body parts required for the investigation. Shooting is the most effective way to collect many species. Ornithologists who collect birds with a shotgun should be experienced in the proper and safe use of firearms and must comply with laws and regulations governing their use. Humane use of firearms necessitates that birds be killed outright, so that the firearm and ammunition load should be appropriate for the species to be collected. Every effort should be made to avoid wounding birds, not only to minimize suffering, but also to maximize the probability of retrieving rather than losing the specimen. Wounded birds should be killed promptly, [see IX.G] The frequently used thoracic (cardiopulmonary) compression is not among the techniques recommended by the AMVA, but may be used when other techniques might damage portions of the carcass critical to the study. This technique is not appropriate for use in the laboratory, for large birds, or for diving birds. If, however, the bird has been rendered unconscious by administration of an anesthetic [ IX.D] then the mechanics by which the euthanasia is accomplished are not important. Prior administration of an anesthetic may be useful when euthanizing large birds under any conditions. Ideally, the collector would carry a supply of a euthanasia compound, but that is not practical (and may be illegal) in many cases. Methods of euthanasia are reviewed by the AVMA Panel on Euthanasia (Andrews et al. 1993), but may not be practical under most field conditions, [see IX.G]

Mist nets are used increasingly to collect specimens in dense vegetation where shooting is less effective, when shot holes will damage the specimen for study, and where use of firearms is prohibited. Mist nets must be checked frequently; therefore, the number of nets set up should reflect the manpower available to check them. Nets set for diurnal species should be closed at dusk to avoid accidental capture of nocturnal species and vice versa. Birds are sensitive to exposure to heat, cold, thirst, or hunger, and consequently should not be left in nets longer than necessary. If the substrate below a net becomes heated by insolation, temperatures lethal to small birds within very short time spans may be achieved. Similarly, extreme cold poses special problems, especially for small species. Nets should be shaded or positioned to avoid full exposure to the sun, and, where possible, trapping or netting should be avoided if the ambient temperature is below 0 ^oC or above 35 ^oC, or in windy, or rainy weather. Nets and traps should be watched or checked at least every 20 minutes during the nesting season or when the weather is unfavorable (intense sun or inclement weather), and about every 30 minutes (at least once per hour) during the rest of the year. Captured birds can injure themselves trying to escape, even from metal walk-in traps; these injuries reduce the specimen's scientific value and cause needless trauma. These same humane methods apply even more strongly to the trapping and netting of birds for purposes of marking and release.

Living animals are sometimes used as decoys to attract birds to traps or nets. Pigeons, starlings, or other non-protected species may be used to lure raptors. Conversely, raptors may be used to lure mobbing species. Such practices are invaluable for attracting difficult to capture birds (Bloom 1986). However, those using such procedures are ethically and legally responsible for the well-being of all the animals involved, not just the target species. Although decoys in such situations are clearly subject to stress or even death, everything possible should be done to reduce the stress of the lure species to the minimal level intrinsic to the technique. For example, food and water should be provided to lures in a dho-ghaza trap, but cannot be provided to those in a road-drop bal-chatri. [see VIII.H]

D. Habitat and Population Considerations

Each investigator should observe and pass on to students and coworkers a strict ethic of habitat conservation. Because many essential details of life history may remain unknown until a study is well along, collecting should always be conducted so as to leave habitat as undisturbed as possible. Permanent removal of large numbers of animals from any breeding or roosting aggregation should be avoided unless justified in writing for scientific reasons by the investigator. Similarly, relatively large collections of gravid nesting females from any population for destructive sampling should be avoided unless justified for scientific reasons. Systematists should search for suitable specimens in extant collections before conducting field work. If the purpose of an experiment is to alter behavior, reproductive potential, or survivability, the interference should be no more than that necessary to test hypotheses accurately. Investigators working with populations that are experiencing a short-term die-off or long-term decline must be especially sensitive to the effects of collecting.