Repeatable timing of northward departure, arrival and breeding in Black-tailed Godwits Limosa l. limosa, but no domino effects

Abstract

When early breeding is advantageous, migrants underway to the breeding areas may be time stressed. The timing of sequential events such as migration and breeding is expected to be correlated because of a ''domino effect'', and would be of particular biological importance if timings are repeatable within individuals between years. We studied a colour-marked population of Black-tailed Godwits Limosa l. limosa both on staging areas in Portugal and on breeding areas in The Netherlands. For each individual, we measured the timing of the staging period, the arrival date on the breeding area and the egg laying date. We measured average egg volume as a measure of reproductive investment. The date of departure from the staging areas, the arrival date on the breeding areas, and the egg laying date were repeatable among years in individual Black-tailed Godwits. The arrival dates of paired males and females and the average annual male and female arrival dates were correlated. The dates of departure from Portugal, arrival in The Netherlands, and egg laying were not correlated. Earlier clutches had larger eggs than late clutches. If the length of the individually available pre-laying period is accounted for, early arriving birds spent more time on the breeding grounds before laying than late arriving birds. The repeatability of the itineraries and the correlation between arrival timing of males and females are consistent with observations in other migrants. Despite evidence for early breeding being advantageous, we found no evidence of a ''domino effect''.

Timing of arrival at breeding grounds determines spatial patterns of productivity within the population of white stork (Ciconia ciconia)

“…In contrast, the third quartile value should reflect arrival of birds of low phenotypic quality that are known to return to the breeding grounds later in the season (Møller 1994). Quartile-based division on early-and late-breeders is commonly applied in the studies on avian migration phenology (e.g., Louren1o et al 2011). Both variables (the first and the third quartiles) were subjected to the Box-Cox transformation to improve normality and standardized to equal unit variances (z scores) prior to analyses.…”

Opposing selective pressures may act on the colony size in a waterbird species

“…Laying dates from each colony were divided in quartiles; values below the lower quartile (hereafter early breeders) were used to assess the timing of breeding initiation, while laying dates above the upper quartile (hereafter late breeders) indicated length of nesting activity (e.g. Lauren1o et al 2011). Between-colony differences in the variances of laying dates were assessed with Levene's test.…”

Individual variability in the migratory path and stopovers of a long-distance pelagic migrant

“…Using a data set of birds that wintered in this area in different years (ranging from two to six migratory journeys per individual) we examined the consistency in migratory routes and stopovers of this species. Cory's shearwaters are highly consistent in their migratory schedules , like many other long-distance migrants (Battley 2006;Lourenço et al 2011;Vardanis et al 2011;Stanley et al 2012). Individual birds tend to depart repeatedly earlier (late October) or later (early December) from their breeding grounds in different years.…”