Spring phenology and timing of breeding in short‐distance migrant birds: phenotypic responses and offspring recruitment patterns in common goldeneyes

Abstract

Understanding how organisms adjust breeding dates to exploit resources that affect fitness can provide insights into impacts of climate change on avian demography. For instance, mismatches have been reported in long‐distance migrant bird species when environmental cues experienced during spring migration are decoupled from conditions on breeding grounds. Short‐distance migrant bird species that store reproductive nutrients prior to breeding may avoid or buffer adverse phenological effects. Furthermore, reduced short‐term reproductive success could be offset by higher future recruitment of surviving offspring. We evaluated whether recruitment of locally‐hatched female offspring was related to hatching date alone or strength of mismatched breeding date for 405 individually‐marked adult female common goldeneyes Bucephala clangula (a short‐distance migrant) and their ducklings from a site in central Finland where ice‐out date has advanced by ∼ 2 weeks over 24 yr. Path analyses revealed that older, early‐nesting females with good body condition and larger broods recruited the most female offspring. Offspring recruitment decreased strongly among females that bred late relative to other females in the population each year; the extent of mismatched breeding date, i.e. hatching date scaled to annual ice‐out date, was less influential. Overall, most females advanced breeding dates when ice‐out occurred earlier in spring, but some females exhibited greater flexibility in response to ice‐out conditions than did others. In general, directional selection favoured early breeding over a wide range of ice‐out dates. Our results seem most consistent with a hypothesis that some short‐distance migrant species like goldeneyes have the capacity to track and respond appropriately to changing environmental conditions prior to onset of breeding.

Why do earlier‐arriving migratory birds have better breeding success?

“…Quantifying the recruitment probabilities of individuals that hatch and fledge at different points in the season requires long‐term tracking of individuals from the first year of life. Developments in tracking technologies have facilitated an increase in the number of studies capable of generating such data, and seasonal declines in recruitment probabilities are commonly reported in these studies (Alves et al, ; Clark et al, ; Lok et al, ; Visser et al, ). The mechanisms underpinning the costs of late fledging are likely to include the having less time available to locate resources and suitable wintering locations and, potentially, having fewer opportunities to gain social information from adults which may have already departed for winter sites (Gunnarsson, Gill, Newton, Potts, & Sutherland, ), and density‐dependent costs associated with fledging into local populations comprising large numbers of fledglings from earlier nests (Verhulst, ).…”

“…Seasonal variation in nest success rates can arise through seasonal variation in factors such as local predator abundance and activity (DeGregorio, Weatherhead, Ward, & Sperry, ; Sperry, Peak, Cimprich, & Weatherhead, ), weather conditions (Skagen & Adams, ) and nest concealment (Borgmann, Conway, & Morrison, ). Seasonal declines in offspring recruitment probability have been reported in many species (Alves, Gunnarsson, Sutherland, Potts, & Gill, ; Clark, Pöysä, Runko, & Paasivaara, ; Harris, Buckland, Russell, & Wanless, ; Lok, Veldhoen, Overdijk, Tinbergen, & Piersma, ; Visser et al, ), potentially reflecting difficulties facing late‐hatched young in locating and amassing resources during the postfledging and winter periods. Lower recruitment of late‐hatched young would be likely to reduce the benefits associated with replacement clutches.…”

Do environmental conditions experienced in early life affect recruitment age and performance at first breeding in common goldeneye females?

“…Breeding of goldeneye females in nest boxes has been monitored annually since 1984 (Clark et al ). Adult female goldeneyes were captured in nest boxes a few days prior to hatch, weighed (with a spring scale, ± 1 g), measured (wing length, with a wing rule, ± 1 mm), and marked with standard numbered leg bands.…”

“…It is thus possible that winter severity in the Baltic Sea affects the body condition of goldeneye females and hence could have an impact on recruitment age. We also evaluated effects of temperature during the early growth period and severity of the first two winters on the relative timing of breeding in the year of recruitment for those females that recruited at age two years; relative timing of breeding is the most important determinant of reproductive success (Milonoff et al , Clark et al ). We included characteristics reflecting a mother's quality as a breeder and a measure of population density in the analyses (see above).…”

The early birds and the rest: do first nesters represent the entire colony?

“…Early nesting individuals generally are in optimal physical condition, often lay large clutches or attain a high nesting success (Erikstad et al 1993;Arnold et al 2004;Bêty et al 2004). Clutch size commonly is inversely related to nest date and survival of subsequent young can be negatively related to hatch date (Traylor and Alisauskas 2006;Ö st and Steele 2010;Clark et al 2014;Westneat et al 2014). A potential drawback of very early nesting and subsequent early hatch is a temporary high exposure to predators, which can incur costs on the earliest individuals (Lepage et al 2000;Bêty et al 2004;Pálsdóttir 2016).…”