Annual survival of adult Atlantic Puffins Fratercula arctica is positively correlated with Herring Clupea harengus availability

摘要

Atlantic Herring is a keystone species in several marine ecosystems, supporting intensive fisheries as well as many predators including seabirds. Biomass of this stock in eastern North America has declined considerably in recent years, potentially putting at risk populations of its predators. Although adult survival in seabirds is considered robust to moderate changes in food availability, it is also the life-history component most critical to sustaining populations of long-lived birds. To investigate the possibility that Atlantic Puffin survival has been affected by reduced abundance of its main prey, we analysed the encounter histories of 2999 Atlantic Puffins ringed on Machias Seal Island to estimate annual adult survival for the years 1999-2011 and assess trends in survival and the effects of several biological and environmental covariates. Features of Puffin biology and resighting procedures likely to introduce heterogeneity into our resighting probabilities were accounted for and models of survival were assessed using standard methods. We used the variance components procedure in Program MARK and survival estimates from a time-varying model to estimate the process variance (biological variation in survival) accounted for by suspected covariates of survival. Two proxies of food availability each explained more than half of the variation in annual survival: fishery landings of Atlantic Herring (52%) and per cent (by mass) of 1-group Herring in the diet of Puffin chicks (51%). In addition to these proxies, May sea-surface temperature accounted for 37% of variance in survival, but winter values of North Atlantic Oscillation showed no effect. Of those parameters of Puffin biology examined, chick growth rate explained 19% of the process variance in annual survival; laying date, fledging condition and fledging date all explained no variance. A decline in fishery landings of Herring since the early 1990s, and a concurrent decline in adult Puffin survival, reinforces concern for the health of the population of Herring, a keystone forage fish in this region, and of the community of marine predators in the Gulf of Maine that rely on Herring for their survival and reproduction.