Îles de la Madeleine: more than half of the northern gannet colony has disappeared

The Rocher aux Oiseaux is difficult to access, hence the importance of carrying out aerial inventories of the northern gannet colony. Located 32 km north of Grosse-Île, in the Madelinot archipelago, the rocky islet is only accessible by helicopter. (File photo)

Canadian Wildlife Service biologists estimate that the northern gannet population on Rocher aux Oiseaux, in the Magdalen Islands has decreased by 58%.

The biologists made this observation after having completed the count of nesting pairs of northern gannets at Rocher aux Oiseaux from aerial photographs taken last July.

More than 5,000 bird carcasses were picked up on the beaches of the Islands due to avian flu last summer, but the impact of the virus in the bird population of the protected area of Rocher aux Oiseaux had not been assessed.

The Rocher aux Oiseaux colony is the second largest in North America after that of Bonaventure Island.

 It is significant and when the second largest colony decreases by more than half, yes, it's worrying,” says Jean-François Rail, seabird population biologist for the Canadian Wildlife Service.

The Rocher aux Oiseaux is a protected area located about thirty kilometers off the Magdalen Islands.

According to data provided by Mr. Rail, just over 11,000 breeding pairs were still on the rock at the time of the count. Biologists averaged about 25,000 in the past decade.

Aerial photos were also taken at Bonaventure Island last summer. Biologists observe a decline of 13% for the colony on the island. What is special is that Bonaventure Island was affected in a much more marginal way , indicates the biologist.

Biologist Jean-François Rail has been monitoring the evolution of northern gannet colonies since 1994. (File photo)

The population of breeding pairs on Bonaventure Island in 2022 is estimated at around 46,500, according to the latest inventory carried out last summer by the Canadian Wildlife Service. Previously, before the last count, it was around 50,000 pairs.

However, Jean-François Rail cannot explain why one colony was more affected than another. It doesn't seem random, because sometimes these are islands that are very close to each other and on some there have been hundreds of deaths and on others there is no sign”, explains he.

He gives the example of the common guillemot colony, which numbers thousands of individuals that nest in great density at the Rocher aux Oiseaux. According to aerial photos, this species does not appear to be affected by avian flu, says Mr. Rail.

Jean-François Rail believes that a new wave of avian flu remains possible. This strain appeared in Europe before us and they didn't get rid of it after just one year, so chances are it will continue here too , he says.

While desired, the immunity that birds might develop against the virus is also uncertain.

According to Jean-François Rail, gannets were the species most affected by avian flu in North America so far. (File photo)

 It would be interesting to see resistance to this flu in gannets and that the repercussions not be as deadly as what we have seen so far 'now, but at the moment, we can't know , adds Mr. Rail.

Otherwise, the biologist still sees potential for the repopulation of colonies. There is a part of the population that may not have started nesting yet, but there is a pool of individuals that could recruit into the breeding population in the coming years, he believes.

The Canadian Wildlife Service will conduct further aerial surveys next July to reassess colony sizes.

• Several cases of bird flu confirmed in gannets in the Magdalen Islands

• Bird flu: 5,000 bird carcasses collected from Îles-de-la-Madeleine

• Avian flu has not harmed the reproduction of gannets on Bonaventure Island