Forest birds inventory

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Forest birds inventory

FALARDEAU, G. ET J.P.L. SAVARD. (En prép.) Inventaire des oiseaux terrestres de la réserve de parc national du Canada de l'Archipel-de Mingan, 1998-1999 . Rapport du Service canadien de la faune, région du Québec, pour Parcs Canada, Unité de gestion de Mingan.

ABSTRACT(Preliminary version)

Black-throated Green Warbler
© Parks Canada / É. Le Bel / L 63 07 01,1992

We conducted 231 point count bird surveys (75m radius) distributed among the main islands of Mingan Archipelago National Park Reserve in the summers of 1998 and 1999 to document the composition and structure of bird communities in eight major habitat types. We also surveyed 47 point counts on the mainland to compare mainland and island bird communities. Overall, we recorded 47 species of terrestrial birds on the islands. Island bird communities were poorly diversified which reflects the boreal character of these islands and their northern latitude. The five most abundant species on the islands were the White-throated sparrow, Ruby-crowned Kinglet, Fox Sparrow, Yellow-rumped Warbler and Swainson's Thrush. The most common species in forested habitats were the Ruby-crowned Kinglet, Black-throated Green Warbler, Yellow-rumped Warbler and Swainson's Thrush. The White-throated Sparrow was by far the most abundant species in bogs and moors followed by the Tennessee Warbler and Fox Sparrow in bogs, and the Savannah Sparrow and Lincoln Sparrow in moors. The White-throated Sparrow was the most ubiquitous species of the archipelago, being abundant in nearly all habitats.

Species richness and bird density were greatest in both minerotrophic and ombrotrophic treed bogs. Stands of short and tall Balsam-Fir (with both low and high stem densities) came second in terms of both species richness and bird density. Minerotrophic herbaceous and shrubby bogs had lower values than Balsam-Fir forests but higher than moors. The ombrotrophic shrubby bogs were last in terms of both species richness and bird density and thus constituted the poorest habitat of the archipelago.

With the exception of Île Nue de Mingan , which is mostly covered by moors where bird species richness and density were low, we did not find marked differences between the bird communities of the different islands. Most habitats found in the archipelago were present on each island and the differences observed in the abundance of some species can be related, for each island, to habitat availability, forest stand age, level of forest disturbance (windfalls) and distance from the mainland. Several species typical of mature forests such as the Ruby-crowned Kinglet, Swainson's Thrush and Black-throated Green Warbler reached peak abundance on Île du Fantôme . Species associated with shrubbery bogs such as the Alder Flycatcher, Common Yellowthroat and Lincoln Sparrow were most common on Île du Havre . Species that were more abundant on the mainland (Alder Flycatcher, Hermit Thrush, American Robin, Yellow Warbler, Common Yellowthroat, Dark-eyed Junco, American Goldfinch) were more frequent and abundant on islands closest to the mainland. Species associated with human habitations (Tree Swallow, European Starling) were recorded mainly on Île du Havre and on Petite île au Marteau located near the mainland village of Havre-Saint-Pierre .

Differences in bird communities between the mainland and the islands were greater than differences among the islands. Coastal forests were mostly open spruce forests compared to the closed Balsam-Fir forests of the islands. However, few species known to be typical of Balsam-Fir forests more abundant on the islands than on the mainland, because the archipelago lies outside the breeding range of many of those species. We suspect that the observed differences were mostly related to forest structure as species associated with dense forest cover such as the Yellow-billed Flycatcher, Golden-crowned Kinglet, Ruby-crowned Kinglet, Swainson's Thrush and Yellow-rumped Warbler were more common on the islands than on the mainland where forests were more open. Large, poorly diversified ombrotrophic bogs are common on the mainland whereas on the islands, bogs are smaller and more diverse in types (minerotrophic and ombrotrophic) and structure (various vegetation height). Species associated with shrubby bogs such as the Alder Flycatcher and the Savannah Sparrow were more numerous on the mainland whereas species associated with treed bogs such as the Tennessee Warbler and the Nashville Warbler were more abundant on the islands. We only observed the Greater Yellowlegs and Palm Warbler once on the islands although both were common on the mainland and suitable habitat was present on the islands.

The most common species recorded in this study of the Mingan Archipelago were quite similar to those observed on several other islands of the St. Lawrence estuary and gulf. The insular character coupled with the marine climate favors similar vegetation types and structures (mainly coniferous forests) and thus attract similar species even though they may be several hundred kilometers apart. However, due to the northern latitude of the Mingan Archipelago, several meridional species recorded on other islands of the St. Lawrence estuary were rare or absent and few of the more boreal species were more abundant.

A study report is forthcoming.