Influence of nest location, density and topography on breeding success in the black-browed albatross Thalassarche melanophris
The Black-browed Albatross Thalassarche melanophris is a long-lived procellariiform that typically nests colonially and exhibits low fecundity. Previous studies on albatrosses have focussed on the bottom-up effects of food supply and their impact on breeding success and have ignored the potential deleterious consequences of top-down predation. To determine whether nest position and adult age
influence breeding success, and whether there is evidence that predation affects reproductive output, we investigated relationships between characteristics and location of nesting sites within a breeding colony, age structure, and short- and long-term reproductive output of breeders.
Our results are consistent with studies conducted on other colonially breeding seabirds, in that peripheral breeders perform considerably less well than do core breeders, but differ in that nest position was not found to be related to adult age. The timing of failure was affected by nest
position, with peripheral nests significantly more likely than core nests to fail during chick rearing. The results suggest that predation is the cause, acting in a non-uniform fashion, because Brown Skuas Catharacta [antarctica] lonnbergi and Giant Petrels Macronectes spp. both appear to target more accessible nests on the periphery of colonies. This behaviour could potentially expose a greater proportion of birds to predation if colony sizes diminish in tandem with the decline in albatross populations currently being observed worldwide.