Does human scent bias the survival of bird nests?

Abstract

Human‐scent contamination of bird nests and the human‐made trails leading to them is suspected to influence nest survival by attracting or deterring predatory mammals. This paper (1) reviews studies in which human‐scent contamination was suspected to have biased the survival of real and artificial nests by influencing the behaviour of predatory mammals, (2) summarizes the procedures used in attempts to mitigate human‐scent contamination in nest‐survival studies, and (3) describes procedures to enhance the design and interpretation of nest‐survival experiments. The behaviour of various non‐domesticated mammals is confirmed or suspected to be affected by human scent, so similar effects on nest predators are plausible. However, suggestions that human scent affects nest survival by influencing the behaviour of predatory mammals are poorly supported, due to a dearth of appropriately designed experiments. Some studies failed to include measures to reduce human‐scent contamination, and the effectiveness of scent‐mitigation methods used in other studies has seldom been verified. In addition, volatile compounds arising from soil and vegetation disturbed underfoot by field researchers may have confounded many nest‐survival studies. Investigators have routinely inferred human‐scent effects from post hoc predation patterns or have simply acknowledged possible human‐scent effects among other potential influences of nest fate. Studies are needed of the effects of human scent using uniform methods of scent application and verified methods of scent mitigation, where the fates of different types of nests are examined under a range of field conditions. More fundamentally, studies of naïve and experienced mammals are needed to assess their responses to human scent and clarify its salience in wildlife disturbance.

Evaluating diversionary feeding as a method to resolve conservation conflicts in a recovering ecosystem

“…A 7 th egg was drained and filled with “Parasoy” soy wax blend, tethered to the ground, to aid in identifying predators through tooth and bill marks. To reduce human scent that may affect discovery rates (Weldon, 2021), eggs were stored on pheasant feathers for seven days before deployment, rubber gloves were worn when handling eggs, and rubber boots and field clothes worn during deployment were stored outdoors.…”

“…To reduce human scent that may affect discovery rates (Weldon, 2021), eggs were stored on pheasant feathers for seven days before deployment, rubber gloves were worn when handling eggs, and rubber boots and field clothes worn during deployment were stored outdoors.…”

Evaluating diversionary feeding as a method to resolve conservation conflicts in a recovering ecosystem

“…A seventh egg was drained and filled with 'Parasoy' soy wax blend, tethered to the ground, to aid in identifying predators through tooth and bill marks. To reduce human scent that may affect discovery rates (Weldon, 2021), eggs were stored on pheasant F I G U R E 1 Illustration of experimental design. The main map shows the forested areas of the Cairngorms connect landscape, which was our scope of inference.…”