Frequent and prolonged incubation recesses across European Black-tailed Godwit populations

Birds have a wide range of behaviours to minimize the impact of predators on clutch survival. Here, we examined whether leaving the nest for prolonged periods during incubation increases clutch survival in continental European Black-tailed Godwits Limosa limosa limosa. The population of this ground-nesting, grassland-breeding wader has sharply declined in its continental European breeding area, a decline which has been attributed in part to increased rates of nest predation. We put iButton thermologgers in 94 nests to determine the frequency and length of potential long incubation recesses (> 20 minutes) and the daily amount of time breeding pairs spent taking these recesses, in five European countries (France, the Netherlands, Poland, Estonia and Finland). We compared incubation recesses between day and night and related them to nest survival. Long incubation recesses occurred in all populations and differed between day and night in some populations, with no apparent relationship to local clutch predation rates. We also found weak evidence for a positive trend between frequent and prolonged long incubation recesses and daily clutch survival probabilities. Further study, using thermo-loggers that record much more frequently, on the direct links between predator presence and other likely causes of long disruptions in incubating behaviour, is needed to determine the function of incubation recesses in ground-nesting waders.