Breeding strategies of Antarctic Petrels Thalassoica antarctica and Southern Fulmars Fulmarus glacialoides in the high Antarctic and implications for reproductive success

Breeding strategies of two closely related fulmarine petrels were studied on Ardery Island, on the continental coast of East Antarctica, where short summers are expected to narrow the time-window for reproduction. Both species had a similar breeding period (97 days from laying to fledging) but Antarctic Petrels Thalassoica antarctica bred up to 16 days earlier than Southern Fulmars. During the pre-laying exodus, all Antarctic Petrels deserted the colony, whereas some Southern Fulmars Fulmarus glacialoides remained. Antarctic Petrels exhibited stronger synchronization in breeding, made longer foraging trips and spent less time guarding their chicks than Southern Fulmars. Overall breeding success of both species was similar but failures of Antarctic Petrels were concentrated in the early egg-phase and after hatching, when parents ceased guarding. Southern Fulmars lost eggs and chicks later in the breeding cycle and so wasted more parental investment in failed breeding attempts. Different breeding strategies may be imposed by flight characteristics; Southern Fulmars are less capable of crossing large expanses of pack ice and need to delay breeding until the sea ice retreats and breaks up. However, due to the short summer they risk chick failure when weather conditions deteriorate late in the season.     

Influence of weather on reproductive success of northern fulmars in the Canadian high Arctic

The northern fulmar (Fulmarus glacialis) is a common seabird of the North Atlantic Ocean, with breeding colonies broadly dispersed between 45°N and 80°N. At higher latitudes, breeding fulmars experience extensive sea-ice and presumably snow and low temperatures which do not affect fulmars in the southern part of the breeding range. We studied the relationship between weather and reproductive success of northern fulmars breeding at two colonies in the Canadian high Arctic. Collectively, hatching success, fledging success, and productivity (chicks fledged per egg laid) were similar between our study and results from colonies located south of the Arctic. However, a larger proportion of fulmars at apparently occupied sites (AOS) in high Arctic colonies appeared to forego egg-laying, resulting in lower proportions of chicks fledged per AOS. Extreme inclement weather was the major factor influencing nesting success, resulting in pulses of egg or chick loss during or immediately following major storms, although the mechanism of effects appeared to differ between the two colonies. For Arctic fulmars, the risks of nest failure due to stochastic, deleterious weather events may be offset by the predictable abundance of food supplies during chick-rearing in Arctic waters.     

Prebasic molt initiation and progress in northern fulmars of the High Arctic: do molt and breeding overlap?

We examined feather molt progress of northern fulmars (Fulmarus glacialis) at Cape Vera in the Canadian High Arctic through opportunistic observation of individuals in flight from 2003 to 2006, and examination of bodies and wings of 127 individuals collected at the site, from 2003 to 2005. We found no evidence suggesting that fulmars shed primary feathers during breeding. Prebasic molt was initiated in the head, neck, sides, belly and back approximately 1 week before hatch. We failed to detect a sex effect on molt progress, but molt among breeders was delayed compared to molt in non- or failed breeders. This study constitutes a baseline we feel may be useful to: (1) researchers interested in feather replacement chronology, wherein feathers are used as sources of biological information; and (2) researchers interested in eventual assessment of relationships among large-scale environmental processes and molt progress in this species, especially in light of predicted changes to Arctic regions.     

Autumn migration and wintering of northern fulmars (<Emphasis Type="Italic">Fulmarus glacialis</Emphasis>) from the Canadian high Arctic

Five northern fulmars (Fulmarus glacialis) were tracked by satellite transmitters from their breeding colony in the Canadian high Arctic (Cape Vera, Devon Island, NT) to their wintering grounds in the northwest Atlantic Ocean. In both 2004 and 2005, fulmars left northern Baffin Bay in mid- to late September, and migrated south to Davis Strait in less than 1 week, after which movements were erratic. In October and November, the birds were widely distributed, but by December through March, they tended to remain in the Labrador Sea between 50 and 55°N. Average flight speed was 35 km/h with a maximum of 64 km/h, and over their entire transmission periods, the five traveled on average 84 km/day. Our work suggests that the North Atlantic northern fulmar population may be panmictic in winter, with the Labrador Sea as a key wintering site for fulmars from high Arctic Canada.     

Species‐specific foraging strategies and segregation mechanisms of sympatric Antarctic fulmarine petrels throughout the annual cycle

Determining the year‐round distribution and behaviour of birds is necessary for a better understanding of their ecology and foraging strategies. Petrels form an important component of the high‐latitude seabird assemblages in terms of species and individuals. The distribution and foraging ecology of three sympatric fulmarine petrels (Southern Fulmar Fulmarus glacialoides, Cape Petrel Daption capense and Snow Petrel Pagodroma nivea) were studied at Adélie Land, East Antarctica, by combining information from miniaturized saltwater immersion geolocators and stable isotopes from feathers. During the breeding season at a large spatial scale (c. 200 km), the three species overlapped in their foraging areas located in the vicinity of the colonies but were segregated by their diet and trophic level, as indicated by the different chick δ¹⁵N values that increased in the order Cape Petrel < Southern Fulmar < Snow Petrel. During the non‐breeding season, the three fulmarines showed species‐specific migration strategies along a wide latitudinal gradient. Snow Petrels largely remained in ice‐associated Antarctic waters, Southern Fulmars targeted primarily the sub‐Antarctic zone and Cape Petrels migrated further north. Overall, birds spent less time in flight during the non‐breeding period than during the breeding season, with the highest percentage of time spent sitting on the water occurring during the breeding season and at the beginning of the non‐breeding period before migration. This activity pattern, together with the δ¹³C values of most feathers, strongly suggests that moult of the three fulmarine petrels occurred at that time in the very productive high Antarctic waters, where birds fed on a combination of crustaceans and fish. The study highlights different segregating mechanisms that allow the coexistence of closely related species, specifically, prey partitioning during the breeding season and spatial segregation at sea during the non‐breeding season.     

Fatty acid signatures of stomach oil and adipose tissue of northern fulmars (<Emphasis Type="Italic">Fulmarus glacialis</Emphasis>) in Alaska: implications for diet analysis of Procellariiform birds

Procellariiforms are unique among seabirds in storing dietary lipids in both adipose tissue and stomach oil. Thus, both lipid sources are potentially useful for trophic studies using fatty acid (FA) signatures. However, little is known about the relationship between FA signatures in stomach oil and adipose tissue of individuals or whether these signatures provide similar information about diet and physiology. We compared the FA composition of stomach oil and adipose tissue biopsies of individual northern fulmars (N = 101) breeding at three major colonies in Alaska. Fatty acid signatures differed significantly between the two lipid sources, reflecting differences in dietary time scales, metabolic processing, or both. However, these signatures exhibited a relatively consistent relationship between individuals, such that the two lipid sources provided a similar ability to distinguish foraging differences among individuals and colonies. Our results, including the exclusive presence of dietary wax esters in stomach oil but not adipose tissue, are consistent with the notion that stomach oil FA signatures represent lipids retained from prey consumed during recent foraging and reflect little metabolic processing, whereas adipose tissue FA signatures represent a longer-term integration of dietary intake. Our study illustrates the potential for elucidating short- versus longer-term diet information in Procellariiform birds using different lipid sources.