|
The species that make up the breeding avifauna of the St. Lawrence can be divided into different groups based on their morphology and specific ecological requirements. These groups vary according to their number of species as well as their relative abundance along the entire St. Lawrence, according to the availability and quality of ecosystems along the river.
Taxonomic groups
Species groups based on taxonomic classification shows the numerical importance of passerines within the breeding avifauna of the St. Lawrence. Representing half of the species, passerines are roughly five times more abundant than other groups such as colonial waterbirds, waterfowl and raptors.
Although passerines dominate the breeding avifauna of all the natural provinces, their number decreases by 50% from the estuary to the Gulf, explaining in large part the significant decrease in species richness observed in this part of the St. Lawrence. Raptors, though less numerous, also contribute to this phenomenon; shorebirds, waterfowl and colonial waterbirds do not. In the last group, an increase in the number of breeding species from the estuary to the Gulf is observed, particularly in the Magdalen Islands.
| Richest squares in confirmed breeding birds for passerines, raptors, waterfowl and colonial waterbirds |
Square
No. |
Location |
Region |
Number of breeding species |
Attribute |
| Passerines |
Waterfowl |
Raptors |
Colonial
waterbirds |
| 1 |
Cap Tourmente |
C8 |
65 |
6 |
7 |
0 |
Passerines and raptors |
| 2 |
Sainte-Foy |
B2 |
57 |
2 |
8 |
0 |
Passerines and raptors |
| 3 |
Sainte-Brigitte-de-Laval |
C8 |
46 |
1 |
6 |
0 |
Passerines and raptors |
| 4 |
Vaudreuil |
B1 |
45 |
4 |
6 |
1 |
Passerines and raptors |
| 5 |
Sorel Islands |
B1 |
26 |
12 |
5 |
5 |
Waterfowl and raptors |
| 6 |
Beauharnois |
B1 |
19 |
9 |
5 |
3 |
Waterfowl and raptors |
| 7 |
Pointe-au-Père |
A3 |
54 |
7 |
2 |
3 |
Passerines |
| 8 |
Beauport Bay |
B2 |
49 |
3 |
1 |
0 |
Passerines |
| 9 |
Donnacona |
B2 |
47 |
3 |
2 |
0 |
Passerines |
| 10 |
Sorel |
B1 |
46 |
0 |
3 |
0 |
Passerines |
| 11 |
Saint-Fulgence |
D1 |
46 |
1 |
1 |
0 |
Passerines |
| 12 |
Pointe-Claire |
B1 |
44 |
4 |
4 |
0 |
Passerines |
| 13 |
Carleton |
A4 |
44 |
4 |
1 |
3 |
Passerines |
| 14 |
Charlesbourg |
B2 |
44 |
1 |
1 |
0 |
Passerines |
| 15 |
Baie-du-Febvre (north) |
B1 |
12 |
13 |
4 |
3 |
Waterfowl |
| 16 |
Dundee |
B1 |
31 |
11 |
4 |
1 |
Waterfowl |
| 17 |
Pierreville |
B1 |
33 |
10 |
1 |
1 |
Waterfowl |
| 18 |
Yamachiche |
B1 |
17 |
10 |
2 |
3 |
Waterfowl |
| 19 |
Maskinongé |
B1 |
17 |
10 |
2 |
2 |
Waterfowl |
| 20 |
Lake Saint-François |
B1 |
13 |
10 |
2 |
4 |
Waterfowl |
| 21 |
Laval (north) |
B1 |
40 |
9 |
4 |
2 |
Waterfowl |
| 22 |
Cap-aux-Meules |
IMA |
24 |
9 |
4 |
6 |
Waterfowl |
| 23 |
Sainte-Anne-de-la-Pocatière |
A3 |
43 |
3 |
6 |
0 |
Raptors |
| 24 |
Perrot Island |
B1 |
40 |
2 |
5 |
1 |
Raptors |
| 25 |
Bois-des-Filion |
B1 |
36 |
7 |
5 |
1 |
Raptors |
| 26 |
Hudson |
B1 |
34 |
3 |
5 |
0 |
Raptors |
| 27 |
Roxboro |
B1 |
33 |
4 |
5 |
0 |
Raptors |
| 28 |
Saint-Clet |
B1 |
14 |
1 |
5 |
0 |
Raptors |
| 29 |
Sainte-Marie Islands (east) |
E3 |
4 |
1 |
0 |
13 |
Colonial waterbirds |
| 30 |
Brion Island |
IMA |
5 |
4 |
1 |
12 |
Colonial waterbirds |
| 31 |
Sainte-Marie Islands (west) |
E3 |
3 |
2 |
1 |
12 |
Colonial waterbirds |
| 32 |
Percé |
A4 |
21 |
1 |
0 |
10 |
Colonial waterbirds |
| 33 |
Niapiskau Island (Mingan) |
E2 |
15 |
1 |
1 |
10 |
Colonial waterbirds |
| 34 |
Forillon Peninsula |
A4 |
18 |
0 |
2 |
9 |
Colonial waterbirds |
| 35 |
Île aux Lièvres |
A3 |
9 |
2 |
1 |
9 |
Colonial waterbirds |
| 36 |
Île aux Perroquets (Mingan) |
E2 |
6 |
1 |
0 |
9 |
Colonial waterbirds |
| 37 |
Betchouane |
E2 |
5 |
3 |
1 |
9 |
Colonial waterbirds |
| 38 |
Falaise aux Goélands |
X4 |
5 |
1 |
0 |
9 |
Colonial waterbirds |
| 39 |
Manowin Island |
D10 |
4 |
2 |
0 |
9 |
Colonial waterbirds |
| 40 |
Baie des Loups (west) |
E3 |
2 |
1 |
0 |
9 |
Colonial waterbirds |
| 41 |
Baie des Loups |
E3 |
0 |
1 |
0 |
9 |
Colonial waterbirds |
Although some squares are not particularly rich in breeding birds, they are of great importance in terms of breeding by certain groups of birds. This is particularly true of colonial waterbirds and of coastal birds in general. Some of these species depend mainly on marine resources for their diet and often breed within multispecies colonies to avoid predation. Such colonies are generally located on offshore islands that do not usually have a great diversity of habitats and therefore have few species of the other types. The squares with the greatest diversity of colonial birds are almost all located in the Gulf of St. Lawrence, while the squares in Lake St. Pierre are crucial to breeding waterfowl and the squares in the St. Lawrence Lowlands contain squares rich in breeding raptors. Only two squares contained more than five species of breeding shorebirds (Laval-North: six species; Sainte-Anne-de-la-Pocatière: six species), while two squares, both on the Magdalen Islands, contained five species of shorebirds (Dune du Nord, Cap-aux-Meules).
Breeding habitats
Breeding birds were also classified according to their primary breeding habitat. The analysis revealed a fairly even distribution of species in the different groups. Roughly 41% of species preferred aquatic habitats, while 36% preferred forested habitats, and 23%, agricultural and urban habitats.
Given the importance of passerines in the groups of birds frequenting terrestrial habitats, the decrease in species richness observed from upstream to downstream in the St. Lawrence in these habitats is to be expected. The decrease is particularly accentuated in the case of species that frequent hardwood-dominated forests and, to a lesser extent, agricultural, urban and wetland habitats. Species favouring coniferous forests have a more uniform geographic distribution, although they are more abundant in the Appalachians and Laurentians. Inversely, coastal species, many of which are colonial, increase from upstream to downstream.
According to the distribution of the major bioclimatic domains, the squares richest in breeding bird species favouring urban-agricultural habitats, deciduous forests, wetlands and freshwater habitats are located in the St. Lawrence Lowlands. Species for which the preferred breeding habitat is coniferous forest and coastal habitats are concentrated in the squares east of Quebec City.
Jean-Luc DesGranges and Benoît Jobin
|
|
