Geoscience Reference
In-Depth Information
oms during the summer, which in turn are fed upon by large species of zooplankton, such as Calanus species
and euphausiids. This biological productivity moves up the food chain through fish and seabirds, in particular
to mackerel and gannets.
A quarter of the 400,000 seabirds breeding in the gulf do so on the cliffs and islands off the eastern Gaspé
Peninsula. The most important site is Bonaventure Island, adjacent to the iconic Percé Rock, the 100-meter-
high (300-foot) limestone island whose soft sediments have been dramatically pierced by tidal action.
Bonaventure is the largest colony of northern gannets in the North Atlantic, now boasting 122,000 pairs. It is
also the most accessible, as visitors can approach within feet of the seabirds as they court and nest on the
80-meter-high (260-foot) cliffs. There are few spectacles in nature as impressive as the massing of these mag-
nificent white birds on their nesting grounds. As biologist Bryan Nelson observed in The Gannet: “A seabird
colony is, in a sense, a supra-organism . . . not just a homogenous mass of birds.”
Gannets are large seabirds with wingspans of almost 2 meters (6.5 feet). Their rudimentary nests are made
from a random collection of seaweed, sticks, and moss and are occupied year after year, with accumulated
droppings, fish skeletons, and feathers adding to their bulk. Gannets always nest in very dense colonies, even,
it seems, where there is a surplus of nesting space. Nests are packed as closely together as possible, perhaps as
an anti-predator device, but more likely to provide social stimulation, which leads to reproductive success.
The timing of breeding appears to be especially important to gannets breeding in the northwest Atlantic.
Gannets arrive en masse at Bonaven-ture, and there is fierce competition—fighting—for a site among, or near,
established birds. The courtship antics of pairs are elaborate, even comical, involving much head bobbing, sky-
pointing, and fencing with their bills, but the fighting and wooing are thought to stimulate neighboring birds to
breed. The earlier the better seems to be the rule, as young grow more rapidly early in the season and early
fledgers are more likely to survive. In northern climes, such as on the Gaspé, it is also important that the breed-
ing cycle be completed before late September, when the weather usually deteriorates rapidly. Gannets lay a
single egg beginning in late April or early May, and by the first week of July the young gannets begin to hatch.
Parents will feed the young with regurgitated fish until they fledge in September.
