Investigators have an obligation to identify and assess the consequences of their research activities on wild animals, populations and the environment. Whenever possible, action should be taken to avoid, alleviate or minimize any adverse effects. Research activities should include the collection of adequate samples to ensure valid research results, yet be balanced to minimize adverse effects. Investigators should always weigh potential gain in knowledge against the negative consequences of disturbance. Although short-term detrimental effects may result from research activities, research can ultimately yield long-term positive effects for the affected population.
Observer-related disturbance can be characterized in at least two ways. First, disturbances may create biases that affect both the gathering and analysis of data if the actual process of measurement acts to alter the parameter being measured. Second, research activities might effect the status and well-being of the study subjects themselves. Both effects vary along a continuum from those that are overtly obvious to those that are subtle and difficult to detect.
Although they are usually less severe, many of the effects of field investigations are similar in nature to those that result from non-scientific human activities such as tourism and other general recreational pursuits.
In bird research, adverse effects are most commonly associated with nest visits, aircraft surveillance, working in or passing through sensitive areas, approaching the birds too closely or the trapping, handling, marking and collecting of birds.
The potential for detrimental effects arising from nest visits are well documented, and may include decreased reproductive success in both terrestrial and aquatic birds and the collection of biased data by the researcher. All studies of avian breeding biology should consider the potential consequences of nest visitation and should strive to minimize the number of visits as long as sound scientific results are not compromised.
The following provides general guidelines for checking the nests of colonial bird species that will minimize investigator disturbance, and maximize data yield. Some of the principles can also be applied to visits involving solitary nesting species or groups of birds in sensitive locales:
Low flying aircraft are often used in avian censusing, and have the potential to disrupt bird activities, especially in those species which nest in colonies or open nests. Regular and census related movements of fixed and rotary winged aircraft have had negligible or minimal effects on cliff nesting and wading bird colonies. However, other species have shown moderate to severe effects when disturbed by aircraft, indicating a sensitivity to chronic disturbance.
The following procedures have been recommended for aircraft overflights:
Investigators must also take into consideration the response birds may have to the sounds, the behaviour and the simple presence of humans. In addition, species that are not under study may be disturbed.
Whether one is collecting study birds for eventual release or for museum preparation, the same humane considerations should apply. These birds should not be exposed to excessive or inappropriate handling, conspecific aggression, predation, temperature extremes, or undue suffering.
Each investigator should observe and pass on to students and co-workers 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 the population and habitat as undisturbed as possible.
The permanent removal of large numbers of birds from any breeding or roosting aggregation should be avoided, unless justified for very specific scientific reasons. Similarly, the collection of large numbers of females from any population for destructive sampling should be avoided. Systematists should investigate extant collections for suitable specimens before conducting any field work. If the purpose of an experiment is to alter behaviour, reproductive potential or survivability, the interference should be no more than is determined necessary by the investigator to accurately test the hypotheses under question.
Investigators must obtain and comply with all permits required for the capture, handling and collection of those birds of the correct species and in the appropriate jurisdiction. In addition, they must be familiar with the current list of threatened and endangered species and must comply with all rules and regulations pertaining to these and all other categories of birds.
Investigators should be familiar with traps and trapping techniques and should choose a trap type that is best suited to the species and type of study. Capture techniques should prevent or minimize injury or damage to the bird. Care should be exercised to avoid accidental capture of non-target species. Special consideration should be given to the setting of capture devices in areas that are frequented by pets and children. Trapping and handling equipment should be routinely inspected and maintained in good working order. At the end of each collecting period traps should be properly closed or removed.
Birds can be sensitive to heat, cold, thirst, energy deprivation and stress, and investigators must make every effort to avoid trap deaths from such factors as temperature extremes, stress, shock, and capture myopathy. Birds should not be left in traps longer than is absolutely necessary, although the time can may vary with the species, weather, objectives of the study, and trap type. Traps should be shaded or positioned to avoid full exposure to the sun and, where possible, trapping or netting should be avoided in windy, cold and rainy weather. Nets and traps should be watched or checked at least every 20 minutes during the nesting season or when the weather is unfavourable (intense sun or inclement weather), and at least every 30 minutes during the rest of the year. Captured birds can injure themselves trying to escape, and these injuries reduce the specimen's scientific value and cause needless wounds and suffering. Under extenuating circumstances there may be a need to position traps a long distance from the researcher. In these instances the traps should only be set when weather stresses can be minimized and they should be checked as frequently as possible .
Dependent Young: The trapping of wild birds with dependent young should, as a general principle, be avoided. When this is unavoidable, it must be accompanied by a program to either remove or kill the dependents if the parent cannot return. Every effort should be made, in advance of trapping, to locate nesting areas to minimize the inadvertent capture of these birds.
In some instances, avian research may necessitate the judicious collection of birds in the field. This may be done to provide information on species identification, genetics, population structure and dynamics, comparative anatomy and physiology, evolutionary relationships, behaviour, parasites and diseases, economic factors, geographic and microhabitat distributions, and bird ecology in natural or disturbed habitats. The knowledge that results from the science of ornithology may be applicable to other biological sciences and may help to facilitate decisions involving management policies for all species, whether endangered or economically important, for the conservation of habitats, ecosystem analysis, pest and disease control, retrospective studies, predator control and domestication of species.
Many bird specimens removed from the field are used collaboratively and deposited in the collections of natural history museums or biological data banks for future studies. Museum collections are curated 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), eggs, or embryos. Both kinds of repositories allow qualified researchers access to study collections. It is strongly recommended that, when appropriate, voucher specimens and biological samples should be retained at the conclusion of field investigations. These specimens should be deposited in collections that meet the minimal standards of maintenance established by the American Ornithologists' Union, so that they will be available for use by future investigators. Communication with researchers in other jurisdictions is recommended in order to maximize the use of and information gathered from biological samples.
Humane kill trapping and shooting kills the bird instantly while avoiding injury to the body parts required for the investigation. Shooting may be the most effective and humane way to collect some species, but its use is rarely justified or required.
Researchers planning to use firearms must be experienced in their proper and safe use and must comply with laws and regulations governing their use. 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 by either thoracic compression (cardiopulmonary) or pithing in the case of small birds, and cervical dislocation of large birds. Other methods of euthanasia are reviewed (see section on Euthanasia), but some may not be practical under certain field conditions.
Mist nets can be used to collect specimens in those situations where there is dense vegetation, where shooting is difficult, where the specimens may be damaged by shooting or where the use of firearms is prohibited. Mist nets must be checked frequently. The number of nets set up should reflect the amount of people available to check them. Net sets for diurnal species should be closed at dusk to avoid accidental capture of nocturnal species and vice versa.