Absence from the nest due to human disturbance induces higher nest predation risk than natural recesses in Common Eiders Somateria mollissima

Abstract

Human disturbance of nesting birds may cause reduced breeding success. It is therefore necessary to assess the impact of disturbance to identify steps that minimize negative impacts. We carried out a study of nesting success at two adjacent colonies of Common Eider Somateria mollissima on the islands of Grindøya and Håkøya in northern Norway between 2006 and 2011. Over the study period, nesting success was consistently higher on Håkøya (69–82%) than on Grindøya (35–60%). Between 2009 and 2011 we used camera monitoring of individual nests to identify determinants of nest survival and predation, focusing in particular on the effect of departures from the nest due to human disturbance, which differed between the colonies due to a long‐term research project on Grindøya. Overall, absence of Common Eiders from nests due to disturbance increased the predation risk by a factor of 6.42 for an increase of one additional daily disturbance. In contrast, absence due to natural recesses did not increase nest losses. Under high levels of human disturbance, camera monitoring indicated that the main cause of breeding failure was predation, primarily by Hooded Crows Corvus cornix, but also to some extent Great Black‐backed Gulls Larus marinus. The presence of cameras did not increase the predation risk. Both the presence of researchers and the sight of Common Eider females conspicuously departing from nests are likely to have provided cues to these predators. We suggest management trials to reduce nesting disturbance through the guarding of unoccupied nests to mitigate the effects of human disturbance on reproductive success.

Effects of industrial and investigator disturbance on Arctic‐nesting geese

“…Camera monitoring also provided supplemental information generally not obtainable through traditional visit-based data collection, including the ability to identify predators to species and document behavior of both predators and geese. Consistent with results from previous studies in the Arctic (Liebezeit and Zack 2008, McKinnon and Bêty 2009, Stien and Ims 2015, we found no effect of cameras on nest survival. Thus, remote cameras provide an opportunity to strengthen inference and reduce observer impacts when monitoring avian productivity, especially in cases where study objectives can be met without data obtained by recurring human visits to nests.…”

“…Observer nest visits were responsible for reductions of 7-35% in estimated nest survival probability over the 24-day incubation period, which was likely a function of the 5-fold increase in break length following observer visits as compared to those caused by other sources. These results demonstrate potential biases and deleterious consequences associated with visit-based studies of avian reproductive success in the Arctic, and are consistent with results from recent studies involving king eiders (Somateria spectabilis; Bentzen et al 2008), common eiders (Somateria mollissima; Stien and Ims 2015), and loons (Gavia spp. ;Uher-Koch et al 2015).…”

“…Further, visiting nests may influence behavior of nesting birds or predators (Bêty and Gauthier , Bolduc and Guillemette ). Nest monitoring with remote cameras has gained popularity as an approach to overcome such limitations, having been employed most frequently for predator identification (Pietz and Granfors , Anthony et al , Liebezeit and Zack ) and to quantify incubation constancy (Hoover et al , Jónsson et al ) but also for modeling nest survival probability and estimating effects of investigator disturbance (McKinnon and Bêty , Stien and Ims ). Camera monitoring improves resolution in discerning nest fate (i.e., on the scale of min rather than days), which allows for analysis of nest survival at finer temporal scales and may lead to gains in statistical inference.…”

“…Camera monitoring improves resolution in discerning nest fate (i.e., on the scale of min rather than days), which allows for analysis of nest survival at finer temporal scales and may lead to gains in statistical inference. Most studies suggest that camera effects are minimal (Coates et al , McKinnon and Bêty , Stien and Ims ), although in some cases, cameras may influence behavior of nesting birds and predators (Anthony et al , Richardson et al ).…”

“…Camera monitoring improves resolution in discerning nest fate (i.e., on the scale of min rather than days), which allows for analysis of nest survival at finer temporal scales and may lead to gains in statistical inference. Most studies suggest that camera effects are minimal (Coates et al 2008, McKinnon and Bêty 2009, Stien and Ims 2015, although in some cases, cameras may influence behavior of nesting birds and predators (Anthony et al 2006, Richardson et al 2009). We monitored white-fronted goose nests over 2 breeding seasons using digital time-lapse cameras and periodic nest visits to quantify patterns of nest attendance and survival in the vicinity of an industrial clean-up operation in Arctic Alaska.…”