Ornithologists have an obligation to assess their research for potential negative effects on their study populations as well as on the environment in general, and to minimize such effects. Although research may further scientific knowledge, investigators should weigh any potential gain in knowledge against the consequences of disruption (ABS 1986). In assessing the consequences of disruption, however, it should be borne in mind that, although short-term adverse effects may result from research activities, populations usually recover rapidly, and research often yields long-term positive effects for the affected populations.
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Two important aspects of observer-caused disturbance can be recognized. First, disturbances may create biases that affect both the gathering and analysis of data. Second, research activities might have effects on the status and well-being of the study subjects themselves. Both effects vary along a continuum from obvious to subtle (e.g., MacArthur et al. 1982; Jordan and Burghardt 1986). Although slightly dated and dealing primarily with raptors, Fyfe and Olendorff's (1976) review of this entire topic is well worth the effort to find and read carefully.
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Many effects of field investigations are similar to the more overt effects caused by nonscientific human activities such as tourism, general recreational activity, etc., but they almost always occur to a much lesser degree and are usually very local. Although scientific activities may occasionally have severe effects (see reviews by Duffy 1979: Anderson and Keith 1980; and Fetterolf 1983), in other instances, detrimental effects are negligible (Willis 1973). The variation may depend on local conditions, including structure of the habitat (Brown and Morris 1995), or precise point in the breeding cycle (Fyfe and Olendorff 1976; Griere and Fyfe 1987). In field ornithology, adverse effects are most commonly associated with nest visits, aircraft surveillance, working in or passing through sensitive areas, approaching birds closely, and manipulating them. [see IV, V] Once again, responses to any activity vary from species to species, and what may be anathema for one is inconsequential for another. Therefore, neither blanket rules on the part of regulators nor universal research protocols on the part of investigators are appropriate.
Nest Visits: The potential detrimental effects of visits to nests long have been known (e.g., Evans and Wolfe 1967). Problems from nest visitation have resulted in potentially biased data and decreased reproductive success in both terrestrial birds (e.g., Willis 1973; Mayfield 1975; Howe 1979; Lenington 1979; Westmoreland and Best 1985) and aquatic birds (e.g., Hunt 1972: Gillett et al. 1975; Robert and Ralph 1975; Kury and Gochfeld 1975; Fetterolf and Blokpoel 1983; Rodway et al. 1996; see also reviews by Manuwal 1978; Anderson and Keith 1980; Burger 1981a,b; Hockey and Hallinan 1981). Again, however, there are cases in which nest visitation produced no evident adverse effects (Schreiber 1994, 1996, Skagen et al., 1999). Low or ground-level nests should be approached tangentially, with a 3 - 4 meter detour to the nest. The investigator should return along the detour to the tangential path and continue in the same direction. Ground predators can be discouraged by spreading naphthalene crystals along the detour segment. If flagging is used to mark nest sites, care should be taken that the flags do not impede the owner's access to the nest nor draw the attention of predators.
Aircraft Overflights: Low-flying aircraft may be used in censusing birds. Although such flights have the potential for disruption of bird activities, especially in colonial and open-nest species, Dunnet (1977) showed that regular movements of fixed- and rotary-wing aircraft in non-research activities had no observable effect on cliff-nesting seabirds, and Kushlan (1979) observed only minimal effects from carefully conducted helicopter censusing of wading bird colonies. Burger (1981 a) showed that Larus argentatus respond differently to various aircraft-related stimuli and that they seem to be more sensitive away from breeding colonies than at the colonies themselves. On the other end of the disturbance continuum, Pelecanus erythrorhynchos were seriously affected by low-flying aircraft, indicating that their population status could be affected by chronic disturbance (Bunnell et al. 1981).
Kushlan (1979) recommended the following procedures for aircraft overflights: gradual approach by first circling the study subjects at a distance, flying around the periphery of the sensitive area rather than directly over it, slow and quiet flight, and continual attention for signs of disturbance.
Approach and nearness to sensitive areas: Damage may also occur to species not under study. Hockey and Hallinan (1981) found that both near-approach and passage by people had detrimental effects in penguin colonies. Burger and Gochfeld (1981) demonstrated that Larus argentatus and L.marinus can discriminate between direct and tangential approaches by investigators, and that these birds more readily abandon nests when investigators looked directly at them. This suggests that investigator attitude and presentation may have an effect in creating or minimizing disturbances.
Researchers should be aware that their activities, if observed, may draw the attention of curious persons. Unfortunately, considerable disturbance may result from altogether innocent attempts of the general public to determine what a researcher is doing. Tourists and photographers may present special problems. When observation by the public is likely, researchers should consider diplomatic means to discourage invasion of the research area.
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D. Suggestions for Field Researchers
Investigators should monitor their studies for adverse effects of disturbance. Wherever possible, action should be taken to alleviate or minimize detrimental activities. Research activities should be consistent with the gathering of adequate samples for valid research results, yet be balanced to minimize adverse effects.
Mineau and Weseloh (1981) outlined a general system of nest-checking for colonial birds that minimizes investigator disturbance while maximizing data yield. Safina and Burger (1983) recommended minimizing visits by use of telescopic observation to look into a colony or sensitive area rather than entering it. Such methods may include the use of powerful lenses, other remote-sensing devices, and, if necessary, blinds that provide a nondisturbance entrance (see Shugart et al. 1981). Other researchers suggest visits timed (within and between days), for example, to minimize loss of regurgitated food by young birds, to avoid disturbance of nests during their most sensitive phenological stages (such as egg laying), and to avoid actions that might cause a chick to become separated from its parents (Parsons and Burger 1982).
Interspecific differences in response to disturbance require that field investigators be familiar with their study species (although personal experience is desirable, familiarity with the literature and consultation with others may suffice in the case of new investigators) such that they can reasonably predict reactions to certain field activities. Because some habituation to investigator disturbance is possible (see Parsons and Burger 1982), consistency in timing and intensity of visits may alleviate some problems. Selection of a study population already habituated to human activity sometimes may eliminate unwanted side effects of scientific research (Burger and Gochfeld 1981).
Finally, investigators should monitor the effects of their activities on a continual basis. Those effects may change with time, perhaps in response to conditions other than the investigator's activity per se.
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Investigators may be hesitant to publish evidence of investigator induced, negative effects in their own studies. Yet it is essential, both practically and ethically, that the failure of a procedure be made known. Otherwise remedial action becomes more difficult, and other investigators may encounter the same problem. Equally, it is essential that editors be willing to publish such negative results.
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Elimination of long-term damage to populations or the environment requires a reliance on the ethics of the investigator. Thus, all ornithologists are expected to observe a conservation ethic and to pass on such an ethic to those with whom they work (especially students). Since the ultimate goal of all research is to understand better the natural world, there can be no justification for taking part in long-term destruction of that which we seek to understand. The study of investigator impact on wild birds is, itself, a field that well deserves additional research attention.
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