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COSEWIC Assessment and Status Report on the Red Crossbill (Percna) in Canada

Special Significance of the Species

Ecological Role

Crossbills are the quintessential birds of the boreal forests of the world. Within the boreal forest, crossbills are distributed where conifer seed resources are sufficient, and their presence is thus a crude indicator of cone availability within an area. Uncut or mature forest is important habitat for crossbills because it offers the largest and most stable cone crops (Newton 1972; Benkman 1993b; Holimon et al. 1998). In Newfoundland, the Red Crossbill has suffered from the effects of habitat degradations that have reduced seed availability. A return to historic population levels, when Red Crossbills were common, would indicate a healthy, functioning native forest ecosystem.

 

Endemism and Speciation

Red Crossbill percna subspecies, is endemic to Canada. Available evidence suggests that its breeding range is restricted to insular Newfoundland. Given that recent work has concluded that the North American Red Crossbill group be considered sibling species and not a group of subspecies (Groth 1993b), the threat to the percna taxonomic unit is considerable. Were the taxon to be lost, a likely species, and not subspecies, would be extinct. 

While the Red Crossbill as a species is generally secure in North America (NatureServe 2002), there are other Red Crossbill forms that are also declining. A Red Crossbill population in the Cypress Hills on the border of Alberta and Saskatchewan might be extinct (Benkman et al. 2001; Parchman and Benkman 2002). Red Crossbill populations in New England (Dickerman 1987)and Canada’s Maritime Provinces (Erskine 1992)declined significantly in the early 20th century as a result of extensive logging of Eastern White Pine. Red Crossbills in Ontario have also demonstrated a decline based on CBC data (E. Dunn, pers. comm., 2004). Other Loxia forms that are at risk are the Hispaniolan Crossbill (L. megaplaga), which is threatened by forestry and fragmentation of the native West Indian Pine (Pinus occidentalis) forest on which it depends (Benkman 1994; Smith 1997), and the Scottish Crossbill which may depend at least partly on native pine stands in Britain (Summers et al. 2002). Both of these species are large-billed, island endemic, pine foraging crossbills.