Biodiversity Portrait of the St. Lawrence - Biological diversity: Birds - Population trends among the birds of the St. Lawrence

Birds
Birds of the St. Lawrence [Total species richness] [Geographical distribution] [Seasonal status] [Relative occurence of species] [Richness of accidental species] Breeding birds [Species richness] [Avifaunal regions] [Types of breeding birds] [Colony-nesting birds]	Priority species [Genetic diversity] [St. Lawrence species] [High conservation priority] [Rare bird species] [Population trends] Relational analyses [Relationships between bird species and terrestrial physiographic units]

Priority species:
population trends

For a number of years, both professional and amateur ornithologists have been gathering data that have allowed population trends in most species breeding along the St. Lawrence to be determined. In the case of 40 species (close to 20% of species breeding along the St. Lawrence), particularly reliable data revealed a significant decrease (n = 21) or increase (n = 19) in their Quebec populations (CDPNQ 1999).

Species with changing populations can be found throughout the St. Lawrence system. Close to 40% of the squares where one of these species has bred (98 out of 251 squares) support species with populations that are decreasing and increasing.

Species with increasing populations are much more evenly distributed and many breed in various locations around the Gulf of St. Lawrence.

Breeding species with increasing populations in Quebec
(n = 19 species)

Species Suscep-
tibility¹ Nesting habitat Priority rank

Queb. Contin.

Northern Gannet Coastal S4 G5

Double-crested Cormorant Coastal S5 G5

Great Egret Wetlands S3 G5

Black-crowned Night-Heron Wetlands S5 G5

Snow Goose Wetlands S4 G5

Redhead Freshwater S3 G5

Ruddy Duck Freshwater S3 G5

Bald Eagle x Wetlands S3 G3

Cooper's Hawk x Deciduous Forest S4 G4

Peregrine Falcon x Agricultural-urban S4 G3

Gray Partridge Agricultural-urban S4 G5

Ring-billed Gull Agricultural-urban S5 G5

Black Tern Wetlands S5 G4

Common Murre Coastal S4 G5

Razorbill Coastal S5 G5

Atlantic Puffin Coastal S4 G5

Mourning Dove Agricultural-urban S5 G5

Carolina Wren Agricultural-urban S4 G5

Nelson's Sharp-tailed Sparrow x Wetlands S3 G5

¹ Species likely to be designated as threatened or vulnerable in Quebec (Beaulieu 1992)

Squares with more than two breeding species increasing in Quebec

Square
No. Location Region Number of species

Increase Decline

1 Sorel Islands B1 7 8

2 Laval (north) B1 4 10

3 Baie-du-Febvre (north) B1 4 4

4 Pointe-Claire B1 4 4

5 Lake Saint-François B1 4 4

6 Sainte-Marie Islands (west) E3 4 2

7 Percé A4 4 1

8 Sainte-Marie Islands (east) E3 4 1

9 Baie du Renard (south) X4 4 1

10 Île aux Lièvres D1 4 0

11 Forillon Peninsula A4 4 0

12 Falaise aux Goélands X4 4 0

13 Rocher aux Oiseaux IMA 4 0

14 Varennes B1 3 8

15 Îles de la Paix B1 3 5

16 Bois-des-Filion B1 3 5

17 Dupas Island B1 3 4

18 Mount Royal B1 3 4

19 Beauharnois B1 3 4

20 Pierreville B1 3 3

21 Gentilly B2 3 2

22 Chandler A4 3 2

23 Brion Island IMA 3 2

24 Le Pilier de Pierre B2 3 1

25 Manowin Island D10 3 1

26 Baie des Loups (west) E3 3 1

27 Saint-Ours Island B1 3 0

28 Sainte-Catherine Bay (south) D1 3 0

29 Les Pèlerins A3 3 0

30 Forillon (west) A4 3 0

31 Île aux Perroquets (Mingan) E1 3 0

32 Betchouane E2 3 0

33 Matchiatic Island E3 3 0

34 Baie des Loups E3 3 0

35 Étamamiou Island E3 3 0

Most of these squares are found in the freshwater section, particularly squares with the greatest number of species with a declining population in Quebec.

Breeding species with decreasing populations in Quebec
(n = 21 species)

Species Suscep-
tibility¹ Nesting
habitat Priority rank

Queb. Contin.

Pied-billed Grebe Wetlands S4 G5

Horned Grebe x Wetlands S1 G5

Leach's Storm-Petrel Coastal S3 G5

Least Bittern x Wetlands S3 G5

Blue-winged Teal Wetlands S5 G5

Common Goldeneye Wetlands S5 G5

Red-shouldered Hawk x Deciduous Forest S4 G5

Wilson's Phalarope Freshwater S3 G5

Caspian Tern x Coastal S1 G5

Short-eared Owl Wetlands S4 G5

Common Nighthawk Agricultural-urban S5 G5

Chimney Swift Agricultural-urban S5 G5

Red-headed Woodpecker x Agricultural-urban S2 G5

Purple Martin Agricultural-urban S5 G5

Sedge Wren x Wetlands S2 G5

Wood Thrush Deciduous Forest S5 G5

Brown Thrasher Agricultural-urban S5 G5

Loggerhead Shrike x Agricultural-urban S1 G4

Indigo Bunting Agricultural-urban S4 G5

Vesper Sparrow Agricultural-urban S4 G5

Grasshopper Sparrow x Agricultural-urban S2 G5

¹ Species likely to be designated as threatened or vulnerable in Quebec (Beaulieu 1992)

Squares with more than two breeding species decreasing in Quebec

Square
No. Location Region Number of species

Increase Decline

1 Laval (north) B1 10 4

2 Sorel Island B1 8 7

3 Varennes B1 8 3

4 Cap Tourmente C8 8 2

5 Dundee B1 7 2

6 Hudson B1 7 1

7 Senneville B1 6 2

8 Vaudreuil B1 6 2

9 Lachine B1 6 1

10 Sainte-Anne-de-la-Pocatière A3 6 1

11 Îles de la Paix B1 5 3

12 Bois-des-Filion B1 5 3

13 Longueuil B1 5 2

14 Baie-du-Febvre (north) B1 4 4

15 Pointe-Claire B1 4 4

16 Lake Saint-François B1 4 4

17 Dupas Island B1 4 3

18 Mount Royal B1 4 3

19 Beauharnois B1 4 3

20 Yamachiche B1 4 2

21 Verchères B1 4 2

22 Sainte-Foy B2 4 2

23 Sorel B1 4 1

24 Deschambault B2 4 1

25 Île Perrot B1 4 0

26 Rimouski A3 4 0

27 Pierreville B1 3 3

28 Lavallière Bay B1 3 1

29 Oka B1 3 1

30 Laval B1 3 1

31 Maple Grove B1 3 1

32 Saint-Antoine-sur-Richelieu B1 3 0

33 Saint-Clet B1 3 0

34 Saint-Placide (Oka) B1 3 0

35 Saint-Damase-de-L'Islet B2 3 0

36 Saint-Anaclet-de-Lessard A3 3 0

Two thirds of the species with decreasing or increasing populations frequent aquatic habitats in the St. Lawrence, while the remaining one third breed in various habitats associated with agricultural and urban landscapes in southern Quebec. Species that are either increasing or declining are found in most types of habitats. However, there is a strong downward trend in the populations of solitary aquatic species frequenting freshwater marsh habitats, such as the Horned Grebe, Pied-billed Grebe, Least Bittern, Blue-winged Teal and Wilson's Phalarope (but not the Redhead or Ruddy Duck). Inversely, colonial waterbirds, many of which are marine species, show a clear upward trend, such as the Northern Gannet, Double-crested Cormorant, Great Egret, Ring-billed Gull, Black Tern and several species of alcids. The gradual disappearance of mature deciduous forests and shrubland from the agricultural landscape of the St. Lawrence Lowlands may have contributed to the decline of species such as the Red-shouldered Hawk, Wood Thrush, Indigo Bunting, Loggerhead Shrike, Brown Thrasher, and Vesper Sparrow. Declines recorded in three species that feed on the wing over cities, the Common Nighthawk, Chimney Swift and Purple Martin, suggest that their urban habitat is deteriorating. On the other hand, the increased vegetation cover in the suburbs may have improved the lot of the Mourning Dove and Carolina Wren.

The populations of most species at risk are currently showing signs of decline. Fortunately, the populations of some of these species, and the numbers of other species that have been the subject of concern recently (Beaulieu 1992), seem to have stabilized or even recovered. This is the case for three species of raptors, the Bald Eagle, Cooper's Hawk and Peregrine Falcon, whose reproductive performance has improved significantly since the banning of several organochlorines, particularly DDT (Dykstra et al. 1998; Millsap et al. 1998).

Jean-Luc DesGranges and Benoît Jobin

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