In a new paper in Ecology & Evolution, Rosemarie Kentie and her colleagues investigate whether there are differences in timing of breeding and breeding success between Black-tailed Godwits that spend the winter in Africa and those that only travel as far as Iberia. Do European wintering birds start breeding earlier, do they choose the best breeding territories and do they have a higher chance of successfully raising chicks?
“Migrating long distances requires time and energy, and may interact with an individual’s performance during breeding. These seasonal interactions in migratory animals are best described in populations with disjunct nonbreeding distributions.
The black-tailed godwit (Limosa limosa limosa), which breeds in agricultural grasslands in Western Europe, has such a disjunct nonbreeding distribution: The majority spend the nonbreeding season in West Africa, while a growing number winters north of the Sahara on the Iberian Peninsula. To test whether crossing the Sahara has an effect on breeding season phenology and reproductive parameters, we examined differences in the timing of arrival, breeding habitat quality, lay date, egg volume, and daily nest survival among godwits (154 females and 157 males), individually marked in a breeding area in the Netherlands for which wintering destination was known on the basis of resightings. We also examined whether individual repeatability in arrival date differed between birds wintering north or south of the Sahara. Contrary to expectation, godwits wintering south of the Sahara arrived two days earlier and initiated their clutch six days earlier than godwits wintering north of the Sahara. Arrival date was equally repeatable for both groups, and egg volume larger in birds wintering north of the Sahara. Despite these differences, we found no association between wintering location and the quality of breeding habitat or nest survival. This suggests that the crossing of an important ecological barrier and doubling of the migration distance, twice a year, do not have clear negative reproductive consequences for some long-distance migrants.”