delawarensis Ring-billed Gull

(last update: 10-03-2014 )

Coordinators:
Keith Mueller
Amar Ayyash
Mars Muusse

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1cy June
1cy July
1cy Aug
1cy Sept
1cy Oct
1cy Nov
1cy Dec

2cy Jan
2cy Feb
2cy March
2cy April
2cy May
2cy June
2cy July
2cy Aug
2cy Sept
2cy Oct
2cy Nov
2cy Dec

3cy Jan
3cy Feb
3cy March
3cy April
3cy May
3cy June
3cy July
3cy Aug
3cy Sept

adult Jan
adult Feb
adult March
adult April
adult May
adult June
adult July
adult Aug
adult Sept
adult Oct
adult Nov
adult Dec

adult: May

Île Deslauriers, Varennes, Québec (45.713° N, 73.441° W)

Elevation 20m, Size 0.96 km²
Habitats: native grassland, abandoned & fallow farmland/disturbed ground

Flying over the colony of Île Deslauriers. © M. Tremblay

Site Description

Île Deslauriers is part of the Varennes Archipelago in the St. Lawrence River, just east of Montréal and directly north of the town of Varennes. The western part of the island contains mounds of sediment from dredging of the river. In spring, about 30% of the island becomes submerged. Vegetation on the island consists of short grasses, and Black Mustard and dandelions grow on the spoil piles. Aquatic vegetation is composed of arrowhead, Sago Pondweed and Spiked Water-milfoil.

Colony on Île Deslauriers near the St.Lawrence Seaway. Picture: J-F Giroux.

Birds

An extremely large Ring-billed Gull colony is located on Île Deslauriers. Over the past two decades, the colony has substantially increased in size. At last count in 2000, 51,667 pairs (5% of the global Ring-billed Gull population) nested on the island, which makes this colony the largest in Québec as well as one of the largest in Canada, and represents over 5% of the world’s population.
A population of Black-crowned Night-Herons has recently become established on the island and has shown a large increase in recent years. In 1994, 28 pairs nested on the island, and in 1997 there were 49 pairs. Compared to other nearby islands, Île Deslauriers hosts large numbers of breeding Gadwall and other waterfowl species. A Bank Swallow colony is also located on the northeast part of the island.

Conservation Issues

Accidental or purposeful human disturbance and red fox predation could both potentially affect the health of this colony.

Complete Bird records for Île Deslauriers

Colony on Île Deslauriers. © M. Tremblay

Nesting adults on Île Deslauriers. © M. Tremblay

Capturing gulls with net launcher. © F. St Pierre

Nest monitoring on Île Deslauriers. © F. Racine

Hatching. ©  C. Girault

Chicks in the nest. © M. Tremblay

Two chicks with a parent on Île Deslauriers. © C. Girault

Roof nesting at Ville St-Laurent. © C. Girault

Roof nesting at Ville St-Laurent. © C. Girault

After breeding: winter plumage adult in Florida. © E. Landa