High annual variability in reproductive success and survival of an Antarctic seabird, the snow petrel Pagodroma nivea

Abstract

Demographic parameters were estimated for snow petrels Pagodroma nivea nesting at Pointe Géologie Archipelago, Adélie Land, Antarctica between 1963 and 1990; 21 years of data on adult survival and 27 years of data on breeding success are available. The average age of first return and first breeding were 8.1 and 9.9 years respectively and there was no signifcant difference between the sexes. The overall breeding success averaged 51.3% and was very variable between years (21-80%). Breeding failure was mostly due to incubation failure and annual breeding success was negatively correlated with average snow falls in October-November and October-March. Breeding frequency was very low, averaging 52% of seasons during a reproductive lifetime. Good quality sites, with high occupancy rate and high breeding success were few in the study plots. Poor years in 1966-1967, 1976-1977 and 1983-1984, with low breeding success, very low proportions of nets with breeding attempts and high numbers of non-breeders, occurred 1 year after large-scale El Niño Southern Oscillation (ENSO) events. Snow petrels exhibited very low philopatry. Only 45 birds have been recovered in the study plots from a total of 1115 banded fledglings giving an estimated rate of return of 12.9% between fledging and 3 years old. Annual survival between 3 and 10 years was 91.4%. Annual adult survival (93.4%), though variable, was low during poor years of 1977-1978 and 1983-1984. Adult survival of males (94.7%) was not significantly different from that of females (93.9%). Over the study period, the population of Pointe Géologie was stable. Using the estimated parameters, a Leslie model gave a growth rate of 0.948%, which was probably compensated by immigration (5.7% per year). Restricted numbers of good-quality sites at the place of birth could have led young birds to prospect other colonies and could have selected low philopatry. High adult survival, strong site tenacity and capacity to spread breeding over a long lifetime are probably part of the adaptive strategy of this small fulmarine petrel facing highly variable environmental conditions.

Variations of snow petrel breeding success in relation to sea-ice extent: detecting local response to large-scale processes?

“…Mean breeding performance parameters were similar between the study colony at Ile des Pe´trels (1963, Chastel et al 1993) and Reeve Hill (1984 Table 1, Fig. 2).…”

“…Additional data analysis methods are also explored. In the study conducted at Ile des Pe´trels (Chastel et al 1993) demographic parameters for the study colony were calculated over a slightly increasing set of nests. The colony on Reeve Hill comprises up to 95 nests individually marked with yellow paint numbers on the rocks near the nest entrance.…”

“…With the long-term data set available for the snow petrel colony at Ile des Pe´trels (Terre Ade´lie), Chastel et al (1993) studied interannual variations in the breeding performance and adult survival of snow petrels over 27 years . Correlations were found between the reproductive success of the snow petrel study colony and large-scale variations in the marine environment and weather.…”

“…SIE was suggested to modulate food availability during two critical periods: first, in the winter and pre-breeding season, by controlling breeding effort; second, during the breeding season, when breeding success relies on the ability of the parents to both maintain acceptable body condition and feed their chick (Barbraud and Weimerskirch 2001). Chastel et al (1993) emphasized the need for longterm monitoring of the same species at different sites because the effects of large-scale (circum Antarctic) environmental variations such as ENSO might affect seabirds differently at separate sites. Because of the limitations associated with interpreting the effect of sea-ice on breeding performance variations based on a single data set (Croxall et al 2002), the present paper aims to analyse snow petrel breeding performance variability with the only other long-term snow petrel data set available to date.…”

“…The 19-year long time series of Reeve Hill colony near Casey station, East Antarctica (located 600 miles from Terre Ade´lie) is examined in order to support or refine previous ecological interpretations on the mechanisms explaining variations related to large-scale environmental parameters, with particular emphasis on SIE. Results obtained were systematically compared with the demographic parameters obtained for the snow petrel colony at Ile des Pe´trels in Terre Ade´lie, (Chastel et al 1993;Barbraud and Weimerskirch 2001). Comparing two long-term data sets, on the same species at separate locations can help assessing how breeding performance might reflect varying responses of the species to the same environmental variables at the regional and local scales.…”