Changes in organ size and nutrient reserves of arctic terns (Sterna paradisaea) breeding near a High Arctic polynya

ABSTRACT

The arctic tern (Sterna paradisaea) is a ubiquitous migratory seabird of the High Arctic, currently thought to be in decline in most of the circumpolar world, but surprisingly little is known of its biology at high latitudes. We studied organ size and nutrient reserves of arctic terns breeding beside a High Arctic polynya in Nunavut, Canada, from their arrival at the colony into the chick-rearing period. Both males and females had a decrease in gizzard size through breeding, with gizzard mass during chick-rearing 39 percent lower than on arrival at the breeding grounds. Through the duration of the breeding season, heart, liver, and small intestine showed little change, but females had higher fat and protein stores than males. Terns from this colony likely have increasing fat levels and high body condition due to proximity to a highly productive polynya, where terns appear to gain more energy than they expend during foraging trips. This suggests that though terns at this colony may be near the northern limit of their range, local conditions have a strong impact on organ and nutrient reserve dynamics of these arctic seabirds.

KEYWORDS:

• Arctic
• Charadriiformes
• gizzard
• lipid reserves
• protein

Acknowledgments

We thank Jason Akearok, Kelly Boadway, Josh Boadway, and Alain Fontaine for help with collections. All research activities were conducted in accordance with valid scientific and animal care permits (WL000952, NUN-SCI-06-01). Finally, thanks to three referees for very insightful and supportive comments that helped improve the article.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Environment and Climate Change Canada (Canadian Wildlife Service; internal operational funding); the Natural Sciences and Engineering Research Council (NSERC; No. 1248212); Natural Resources Canada (Polar Continental Shelf Project; No. 245-07) and Acadia University. JLF was supported by a Garfield Weston Fellowship in Northern Research provided by the Association of Canadian Universities for Northern Studies (ACUNS), and JEB was supported by an NSERC scholarship.