Boreal forest migrants mark special day
International Migratory Bird Day (IMBD) celebrates the incredible journeys of migratory birds between their breeding grounds in North America and their wintering grounds in Mexico, Central, and South America. It is held each year on the second saturday in May. The focus of the 2006 IMBD was the North American Boreal Forest.
Covering an area equivalent to 75% of the contiguous United States, the North American Boreal Forest is of immense global importance to landbirds, especially during the spring and summer when millions of individual birds rely on boreal nesting grounds. Of the 325 species that regularly occur in this region, an estimated 94% of all individuals migrate out of the Boreal Forest region after breeding. Many of these individuals migrate as far as the Tropical Andes of Bolivia, Peru, Ecuador, Colombia and Venezuela.
A total of 96 Boreal Forest breeding migrants have been documented to regularly occur in the Tropical Andes. These include 37 species for which 50% or more of their breeding distribution lies within the Boreal Forest. Nine of these species have breeding distributions primarily restricted to the Boreal Forest and wintering ranges restricted to the Tropical Andes. These are: Olive-sided Flycatcher Contopus cooperi, Alder Flycatcher Empidonax alnorum, Gray-cheeked Thrush Catharus minimus, Swainson's Thrush Catharus ustulatus, Canada Warbler Wilsonia canadensis, Blackburnian Warbler Dendroica fusca, Bay-breasted Warbler Dendroica castanea, Blackpoll Warbler Dendroica striata and Mourning Warbler Oporornis philadelphia.
The Tropical Andes region is one of the biologically richest yet most threatened areas in the planet. Covering just 3% of the world it nevertheless holds 28% of the world’s bird species, many of them endemic, and 130 in imminent danger of extinction. To expedite the conservation of the unique biodiversity of the Tropical Andes, BirdLife International and Conservation International together with partner organizations in each country have identified a network of 455 Important Bird Areas (IBAs) – sites of global significance for the conservation of birds. However, it is not just the endemic species which are threatened with extinction. The populations of many migratory species are also undergoing marked population declines. At least 40 species of landbirds are experiencing population declines in the boreal forest and range-wide, according to long-term Breeding Bird Survey trends, and 30 species of migrants that occur in the Tropical Andes are considered as “Birds of Conservation Concern” (17 species of landbirds and 13 waterbirds). Among the species of conservation concern that depend on both the Boreal Forest and forests in the Tropical Andes are Canada Warbler and the globally near-threatened Olive-sided Flycatcher. With support from USFWS, BirdLife has recently completed an analysis of the importance of these IBAs for the conservation of Neotropical migrants.
The information compiled shows that 39 IBAs in the Tropical Andes regularly maintain wintering populations of Olive-sided Flycatcher and Canada Warbler. These IBAs are located primarily on the east slope of the Andes in Colombia and Ecuador.
While the breeding habitat of many Boreal Forest migrants is still relatively intact, the same is not true for their wintering range in the Tropical Andes. The altitudinal range which is the center of abundance for many migratory species, from 500 to 2000 m, is also one of the most threatened by habitat destruction. Of the IBAs found in this area, 51% are threatened by agricultural expansion and intensification, 37% by too frequent burning, and 32% by selective logging. Four of the thirty-nine key IBAs are totally unprotected, and a further ten are only partially protected.
Therefore, the long-term conservation of many Boreal Forest breeding migrants will depend on site-based conservation actions within the Tropical Andes, where many species depend on the forests of the eastern and western flanks of the Andes, habitats which are under massive threat from unsustainable logging and clearing for cattle- ranching. A focus on actions at key IBAs will bring benefits for both migratory and endemic species.
More detailed information on Neotropical migrants can be found in: http://www.birdlife.org/action/science/sites/neotrops/andes/index.html