Status and trend of glaucous gulls in Kongsfjorden, Spitsbergen. Final report ‐ Svalbard Miljøvernfond

Abstract

Little is known about the trend of glaucous gulls Larus hyperboreus in Svalbard. The population on Bjørnøya is sharply declining and a similar trend seems to exist on Hopen. However, on Spitsbergen, glaucous gull trend is unclear. In 2012, we successfully implemented a demographic and population monitoring of glaucous gulls breeding in Kongsfjorden to assess and understand this trend. This monitoring consists in estimating the total population size in Kongsfjorden (number of breeding pairs), capturing/ringing adults and chicks to estimate their survival rate and body condition and monitoring nests to estimate their success. In 2012, 55 breeding pairs were found in Kongsfjorden. Seventy per cent of these nests have been monitored to estimate glaucous gull reproductive success ; the other 30 % were either inaccessible nests or nests in areas surrounded by too high densities of breeding geese and eiders. Thirty‐six gull chicks and 18 adults have been captured and ringed in 2012. Those different sample sizes allow estimating, relatively accurately, the main demographic parameters of glaucous gulls breeding in Kongsfjorden and to compare them with Bjørnøya. Our work indicated no major difference in 2012 between demographic parameters (clutch size, breeding success, adult survival) on Bjørnøya and Kongfjorden. However, such results do not allow drawing conclusions about the trend and status of glaucous gull in Kongsfjorden. Long‐term time series are needed.