Eiders in offshore pack ice show previously unknown courtship behavior: acceleration of readiness for a constrained breeding period?

Abstract

Migratory birds that nest in the Arctic must be prepared to complete breeding within the brief polar summer, but must also have means of adjusting their physiological and behavioral readiness under widely variable environmental conditions. For Arctic breeding sea ducks, which may start laying within a week of accessing nest sites, hormonal status needed for courtship, pairbonding, and ovarian development must be achieved before arrival, often in the context of extreme and rapidly changing weather. Spectacled eiders (Somateria Wscheri) winter in pack ice, migrate to oVshore openings in ice to await snowmelt on nest sites, and then move rapidly inland to start nesting. Using a camera that can Wlm from a helicopter at high altitudes, we recorded behavior of spectacled eiders wintering in Xocks containing tens of thousands of individuals within openings in Bering Sea pack ice, 70-90 km oVshore. Rather than typical courting parties of single females pursued by a few males, the eiders formed crowded swarms of up to hundreds of birds in which males and females intermingled excitedly while performing courtship displays. In these "courtship scrums," which occurred in patches throughout very large Xocks, it did not appear possible for one individual to track other individuals to assess their characteristics for mate selection. Instead, this previously unreported behavior, which occurred near the seasonal onset of courtship, may provide visual and auditory stimuli that accelerate hormonal development for rapid transition from harsh winter conditions to breeding readiness. Such deviations from typical behavior may facilitate adaptation to advanced phenologies in a warming climate.

The Pacific Arctic Region

“…This narrow migration corridor is only 10-30 m deep, and is accessible in the spring only through open-water leads between land-fast and moving pack ice. Even without high direct mortality, failure of females to achieve or maintain the minimum body reserves needed for breeding , or to complete courtship and pair bonding which may occur mostly during migration (Lovvorn et al 2012 ), might have important population impacts over a series of years with unfavorable weather. During spring migration, ice conditions are highly variable there, resulting in unpredictable access to benthic foods.…”

Limits to benthic feeding by eiders in a vital Arctic migration corridor due to localized prey and changing sea ice

“…Although such massive mortality events have not been reported along the Chukchi Sea coast, smaller die-offs have occurred such as for king eiders near Barrow in May 2011. Low percentages of hatching-year males (3-5%) among spectacled eiders in late winter (Lovvorn et al, 2012) indicate that either first-year survival is low, adult survival is high, or both. For king eiders satellite-tagged on breeding areas, annual survival rate of hatch-year birds was 0.67 and of adults 0.94 .…”

“…For large eiders that nest in the Arctic, breeding propensity and success in a given year are thought to be strongly affected by feeding conditions during spring migration that allow buildup of adequate body fat (Coulson, 1984;Oosterhuis and van Dijk, 2002;Bentzen et al, 2008). Moreover, it appears that for spectacled eiders and possibly king eiders, an important fraction of pair bonding may occur during spring migration and staging (Lovvorn et al, 2012). Although king eiders carrying satellite transmitters were located throughout this migration corridor, in the spring about 80% of radio locations were in the Ledyard Bay segment ( Fig.…”

Evolution and function of multimodal courtship displays

“…In salamander of the Plethodontidae family, sexual pheromones delivered by males during courtship shorten the latency of females to mate and increase female sexual receptivity (Houck & Reagan, 1990;Houck et al, 2008). Lovvorn, Mossotti, Wilson, and McKay (2012) described the courtship behaviour of spectacled eiders (Somateria fischeri) and hypothesized that the more likely role of courtship in this species was to accelerate female hormonal development in order for them to be ready to mate during the short time windows their polar habitat offers. Lovvorn, Mossotti, Wilson, and McKay (2012) described the courtship behaviour of spectacled eiders (Somateria fischeri) and hypothesized that the more likely role of courtship in this species was to accelerate female hormonal development in order for them to be ready to mate during the short time windows their polar habitat offers.…”