Off‐nest behaviour in a biparentally incubating shorebird varies with sex, time of day and weather

• Published in: Ibis
• Main Authors: Bulla, Martin, Stich, Elias, Valcu, Mihai, Kempenaers, Bart
• Other Authors: Burton, Niall, Max Planck Society
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2015
• Subjects: Arctic
• Online Access: http://dx.doi.org/10.1111/ibi.12276; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fibi.12276; https://onlinelibrary.wiley.com/doi/pdf/10.1111/ibi.12276; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/ibi.12276

Biparental incubation is a form of cooperation between parents, but it is not conflict‐free because parents trade off incubation against other activities (e.g. self‐maintenance, mating opportunities). How parents resolve such conflict and achieve cooperation remains unknown. To understand better the potential for conflict, cooperation and the constraints on incubation behaviour, investigation of the parents' behaviour, both during incubation and when they are off incubation‐duty, is necessary. Using a combination of automated incubation‐monitoring and radiotelemetry we simultaneously investigated the behaviours of both parents in the biparentally incubating Semipalmated Sandpiper Calidris pusilla , a shorebird breeding under continuous daylight in the high Arctic. Here, we describe the off‐nest behaviour of 32 off‐duty parents from 17 nests. Off‐duty parents roamed on average 224 m from their nest, implying that direct communication with the incubating partner is unlikely. On average, off‐duty parents spent only 59% of their time feeding. Off‐nest distance and behaviour (like previously reported incubation behaviour) differed between the sexes, and varied with time and weather. Males roamed less far from the nest and spent less time feeding than did females. At night, parents stayed closer to the nest and tended to spend less time feeding than during the day. Further exploratory analyses revealed that the time spent feeding increased over the incubation period, and that at night, but not during the day, off‐duty parents spent more time feeding under relatively windy conditions. Hence, under energetically stressful conditions, parents may be forced to feed more. Our results suggest that parents are likely to conflict over the favourable feeding times, i.e. over when to incubate (within a day or incubation period). Our study also indicates that Semipalmated Sandpiper parents do not continuously keep track of each other to optimize incubation scheduling and, hence, that the off‐duty parent's decision to remain ...