Joe LeMonnier 



Bonaventure Island 



For visitor information write: 



Bonaventure Island Park 



Quebec Department of Recreation, 



Game, and Fish 



C. P. 310, Perce, Quebec GOC 2L0 Canada 



(418) 782-2240 



showing between adjacent nests. The park 

 service permits visitors to come to a fence 

 not more than six feet from the nearest 

 nesting birds. There is also a sturdy, forty- 

 foot-tall observation platform that pro- 

 vides an overall view of the spectacle. 



Gannets are large, soft-looking birds 

 with dark bills and legs. A patch of yellow- 

 brown on the back of the head is all that 

 marks the otherwise white, downy 

 plumage. An adult gannet weighs about 

 seven pounds. When spread, its wings 

 span a little more than five feet. The birds 

 I saw nesting were at least five or six years 

 old, the age of sexual maturity for a gan- 

 net. Younger gannets congregate on the 

 rocks at the base of the cliffs, practicing 

 their diving and fishing skills and learning 

 the techniques of social behavior that they 

 will need when they are sexually mature. 



The adults, which pair for life, arrive in 

 early April from their wintering grounds 

 in Florida and Mexico. They soon begin 







Pointe-Saint-Pierre 



Cap-d'Espoir 



Perce Rock 



Bonaventure 

 Island 



5 Miles 

 1 



Unlike most flowering plants, Indian pipe 

 lacks green leaves for photosynthesis. 



building their nests of grass on the bare 

 rock. Each site is about twenty-nine and a 

 half inches in diameter, separated from ad- 

 jacent nests by no more than two inches. 

 Mid- April is the mating season, and it be- 

 gins with the art of fencing, in which a 

 male and female carry out a ritual of cross- 

 ing beaks. 



The female lays a single white egg in 

 early May, and incubation lasts for forty- 

 three days, with the female and the male 

 alternating shifts every thirty to thirty-six 

 hours. When the parent that is incubating 

 the egg wants to leave the nest, it signals 

 its partner to return by pointing its beak 

 straight up. 



The egg hatches about the third week in 

 June. The hatchling is black, naked, and 

 blind, but within three weeks, it weighs 

 two-thirds as much as the adult. At seven 

 weeks, the chick actually outweighs the 

 adult by two pounds. After exercising its 

 wings, it takes its first flight from the cUff, 

 landing in the sea. This action is so ex- 

 hausting, and the young bird is so heavy, 

 that it is unable to take off again for a few 

 days. Instead, it swims away from the is- 

 land, surviving on its excess fat and some 

 fish. During this time some 60 percent of 

 the fledglings perish. 



Young gannets that survive the fledg- 

 Ung stage usually start on their migration 

 south in September, before stormy 

 weather sets in. Adults stay longer, feed- 

 ing on the abundant fish and perhaps lin- 

 gering over the late-hatching chicks (most 

 of which are doomed to perish). The adults 

 begin the long journey southward about 

 the middle of October, and the last ones 

 are gone a few weeks later. Interestingly, 

 the adults leave Bonaventure Island as 



Thomas A. Schneider 



pairs, but the males overwinter on the Gulf 

 Coast of Mexico, while the females gener- 

 ally go to the Atlantic coast of Florida. 



The gannets' breeding cycle meshes 

 with the seasonal distribution of the fish 

 on which the birds feed. Gannets arrive at 

 Bonaventure Island in the spring, pre- 

 cisely when large numbers of herring are 

 spawning in the nearby waters. The hatch- 

 ing of the gannet eggs coincides with the 

 spawning of another fish, the capulin. 

 Adult gannets feed upon the capulin, then 

 regurgitate some of the food for their 

 young. They continue by feeding them on 

 mackerel, which subsequently appear in 

 abundance. Then, just as the young are 

 fledging, a second large population of her- 

 ring arrives. 



During the late 1960s, the hatching suc- 

 cess rate for gannets, normally 75 percent, 

 fell to half that. Scientists from the Cana- 

 dian Wildlife Service discovered that 

 DDT, ingested by birds from contami- 

 nated fish, was being stored in the bird's 

 fat and ultimately causing a calcium defi- 

 ciency in the eggshells. Thus weakened, 

 many of the shells would break. When 

 DDT was eventually eliminated, the 

 hatching rate returned to normal. Nonethe- 

 less, the large gannet colony at Bonaven- 

 ture Island must always be monitored for 

 oil spills, PCB contamination, and other 

 environmental pollutants. A major disaster 

 here could wipe out up to one-fifth of the 

 birds' total population. 



This month, Robert H. Mohlenbrock, pro- 

 fessor emeritus of plant biology at South- 

 em Illinois University, Carbondale, takes 

 a northern holiday from his usual beat, the 

 156 U.S. national forests. 



70 Natural History 5/94 



