Sex-specific, inverted rhythms of breeding-site attendance in an Arctic seabird

Abstract

In contrast to daily rhythms that are common in the presence of the geophysical light-dark cycle, organisms at polar latitudes exhibit many diel activity patterns during natural periods of continuous solar light or darkness (polar day and night, respectively), from 24 h rhythms to arrhythmicity. In Arctic Greenland (73.78 N, 56.68 W) during polar day, we observed breeding-site attendance rhythms of thick-billed murres (Uria lomvia; n ¼ 21 pairs), a charadriiform seabird, which provide biparental care at the colony. We found that U. lomvia egg-incubation and chick-brooding attendance is rhythmic and synchronized to the geophysical day (mean period length [rhythm duration] + 95% confidence interval ¼ 24.13 + 0.52 h). Individual pair members had temporally segregated, sex-specific colony-attendance rhythms that were opposite (inverted) to each other, and these sex-specific rhythms were prominent at the population level. Our results provide a basis for investigating circadian systems at polar latitudes and sex-specific parental-care strategies.

Little auks under the midnight sun: diel activity rhythm of a small diving seabird during the Arctic summer

“…As some studies have demonstrated that daily activity patterns can be sex-specific (Steiger et al 2013;Bulla et al 2016), we examined periodicity and daily distribution of chick feeding separately for males and females. Importantly, recent research on another sub-polar and polar alcid, the Brünnich's guillemot (Uria lomvia), has shown inverted colony attendance patterns for the sexes (Huffeldt & Merkel 2016). Nevertheless, we did not find any pronounced inter-sex differences for the little auk.…”

“…Overall, both sexes fed the chick equally throughout the day. The sex differences found in the Brünnich's guillemot have been explained in terms of sex-specific variation in foraging strategies (Huffeldt & Merkel 2016). In the case of little auks, males and females also differ in their foraging strategies, with females spending more time at sea ) and delivering more food for the chick in single loads (Wojczulanis-Jakubas et al 2006).…”

“…Here we examined birds' activity patterns and periodicity at population and individual levels. As recent studies have shown that daily patterns can be sex-specific (e.g., Steiger et al 2013;Bulla et al 2016;Huffeldt & Merkel 2016), we considered males and females separately. We focused on the chick-rearing period for the studied population (July/August), as Stempniewicz did (1986).…”

Two sides of a coin: ecological and chronobiological perspectives of timing in the wild

“…Likewise, even within species, individuals or subsets of the population, for example, the sexes, can occupy different temporal niches (e.g. [58]). …”

Little auks under the midnight sun: diel activity rhythm of a small diving seabird during the Arctic summer

“…Overall, both sexes fed the chick equally throughout the day. The sex differences found in the Brünnich's guillemot have been explained in terms of sex-specific variation in foraging strategies (Huffeldt & Merkel 2016). In the case of little auks, males and females also differ in their foraging strategies, with females spending more time at sea ) and delivering more food for the chick in single loads (Wojczulanis- Jakubas et al 2006).…”