Occupancy of the American Three-Toed Woodpecker in a Heavily-Managed Boreal Forest of Eastern Canada

Vincent Lamarre,Junior A Tremblay

doi:10.3390/d13010035

Vincent Lamarre, Junior A Tremblay

Open Access

https://doi.org/10.3390/d13010035

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Abstract

The southern extent of the boreal forest in North America has experienced intensive human disturbance in recent decades. Among these, forest harvesting leads to the substantial loss of late-successional stands that include key habitat attributes for several avian species. The American Three-toed Woodpecker, Picoides dorsalis, is associated with continuous old spruce forests in the eastern part of its range. In this study, we assessed the influence of habitat characteristics at different scales on the occupancy of American Three-toed Woodpecker in a heavily-managed boreal landscape of northeastern Canada, and we inferred species occupancy at the regional scale. We conducted 185 playback stations over two breeding seasons and modelled the occupancy of the species while taking into account the probability of detection. American Three-toed Woodpecker occupancy was lower in stands with large areas recently clear-cut, and higher in landscapes with large extents of old-growth forest dominated by black spruce. At the regional scale, areas with high probability of occupancy were scarce and mostly within protected areas. Habitat requirements of the American Three-toed Woodpecker during the breeding season, coupled with overall low occupancy rate in our study area, challenge its long-term sustainability in such heavily managed landscapes. Additionally, the scarcity of areas of high probability of occupancy in the region suggests that the ecological role of old forest outside protected areas could be compromised.

Highlights

The boreal forest represents about 48% of the world’s forested biomes [1]
We investigated the influence of habitat characteristics that were likely to affect the occupancy of American Three-toed Woodpecker by calculating vegetation covariates within buffers of 250 and 750 m-radii centered on each surveyed station, representing respectively the stand and landscape scales
In the black spruce moss domain of eastern Canada, recent clear-cuts have a lower density of snags, and the American Three-toed Woodpecker is solely found in old-growth forest [19]

Summary

Introduction

The boreal forest represents about 48% of the world’s forested biomes [1]. Boreal landscapes are shaped by natural disturbances such as windthrows, forest fires and insect outbreaks that generate a complex mosaic in vegetation structure and composition [2,3]. Old-growth boreal forests are characterized, among several attributes, by irregular vertical and horizontal structures, large volumes of deadwood either standing (snags) or fallen (coarse woody debris) and in different decaying stages [7]. These attributes are considered key for hundreds of species that depend upon dead or decaying woody material during some part of their life cycle and that are found disproportionately in old-growth forests [8,9]. A recent study highlights the continuous supply of large slightly decayed snags in specific old-growth forest type as a key element to provide temporal stability in the foraging habitat of the Black-backed Woodpecker, Picoides arcticus [12]

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