Effects of nest visits on predator activity and predation rate in a greater snow goose colony
2001
Bêty, Joël | Gauthier, Gilles
We assessed the effect of nest visits by researchers on the activity of nest predators and predation rate of eggs in a High Arctic Greater Snow Goose (Chen caerulescens atlantica) colony. The study was conducted in years of moderate (1996) and low (1997) overall nest predation rate. We first compared activity rate (number of presences per h) and behavior of nest predators in the colony with and without investigator disturbance. In one year out of two, activity rate and time spent in the colony were higher during nest visits than under undisturbed conditions for Glaucous Gulls (Larus hyperboreus) and Parasitic Jaegers (Stercorarius parasiticus). Moreover, presence of investigators significantly increased (4.8 times) the probability of nest attack by predators in one year. Nevertheless, the immediate revisit technique showed that the percentage of goose eggs robbed by predators in monitored nests was low (<0.7%) during a nest visit. In addition, we found no significant difference in mean clutch size at the end of incubation or nesting success between nests that were visited repeatedly (8 visits) and those less disturbed (<3 visits). Although some predators can be attracted by and take advantage of the presence of investigators, our results indicate that nesting parameters estimated for this snow goose colony are not biased by nest visits. However, the effect of investigator disturbance could be more important in other arctic nesting bird species that are unable to successfully defend their nest against predators or when predation pressure is very high.
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