Northern Gannet

At 6-7 pounds, the Northern Gannet is by far the largest seabird that occurs in New Hampshire, weighing in at twice the size of the more familiar Great Black-backed Gull. They are strictly a non-breeding visitor to our waters, with all North American gannets nesting in large colonies in Quebec or Newfoundland. However, because gannets take up to five years to mature, young birds in a variety of plumages can be seen offshore during summer and fall when the adults are nesting farther north. As winter approaches, younger birds tend to shift farther south (some as far as Florida) while adults are concentrated between Massachusetts and North Carolina. Timing and abundance vary among years, and some winters see more gannets than others in the Gulf of Maine.

Gannets feed by plunge-diving, sometimes in large congregations when fish are schooling. A hunting gannet will take up a position facing into the wind, and when prey are sighted it will tilt forward, fold back its wings, and drop almost vertically into the water at 60 mph or more. The combination of the bird’s size, speed, and aerodynamic shape allow it to reach depths or over 60 feet in such dives, although the average is closer to 10-15. Watching such a large bird crashing into the water is one of the more impressive things you can experience while watching seabirds offshore.

North American gannet colonies were severely depleted during the nineteenth century due to overharvest for eggs and bait by fishermen. As top marine predators, gannets have also suffered from impaired reproduction stemming from DDT and other contaminants (e.g., mercury). With both these major threats now removed, and nesting colonies in Canada protected, gannets have made a significant recovery. Populations continue to grow, and the main remaining risk is uncertainty about the potential effects of climate change on this species adapted to cold water habitats, at least during the breeding season.