dominated by habitat that had been logged 40 years previously, but residual trees left in logged areas were abundant. Large territory sizes that related to lower habitat quality did not reduce fitness. I found no effect of any habitat characteristics on clutch size, fledged young, nesting success, and adult survival. I did not radiotag pairs in very low quality habitat (eg large areas of non-forest or young forest) where low habitat quality that would affect fitness response could be expected. However, I recorded successful reproduction in habitat with <10% forest cover, which suggests that pileated woodpeckers are able to maintain fitness across a wide gradient of habitat quality. In Sweden, black woodpeckers living in forest habitat fragmented by agriculture adjusted territory size to secure approximately the same amount of forest habitat as pairs living in continuous forest, with no effect on reproduction and survival (Tjernberg et al. 1993). In Norway, black woodpeckers nesting in open areas had higher nesting success than birds in denser forests, possibly because the main nest predator, the pine marten (Martes martes), was less abundant in open habitats (Rolstad et al. in review). Further work on pileated woodpeckers living in low quality forest habitat is needed to determine if pileated woodpeckers show similar behaviour. Although pairs living in large territories did not have lower fitness, territory size does affect pileated woodpecker population density. Pairs defend territories year-around against other territorial pileated woodpeckers (Kilham 1979) so the main effect of lower habitat quality (increased territory size) is to reduce population density (Schoener 1968). Pileated woodpecker density may increase (reduced territory size) during periods of temporary food abundance such as bark beetle epidemics (Bull 1980). If food availability is a primary factor, territory size should change after major forest disturbances, including fire and logging. However, the short-term response of pileated woodpeckers to disturbance may not be a direct function of changes to the availability of foraging substrates unless there is a direct relationship between foraging substrate availability and the density of wood-dwelling ants, especially carpenter ants. Further work to document responses of both pileated woodpeckers and carpenter ants to disturbances would provide information to improve understanding of the effects of disturbances on pileated woodpecker territory size and stability. LITERATURE CITED AUBRY, K. B., AND C. M. RALEY. 1992. Landscape-level responses of pileated woodpeckers to forest management and fragmentation: a pilot study. Progress Report: 1990 and 1991. U.S. Forest Service, Pacific Northwest Research Station, Olympia, Washington, USA. BECKINGHAM, J. D., I. G. W. CORNS, AND J. H. ARCHIBALD. 1996. Field guide to ecosites of westcentral Alberta. Special Report 9, Canadian Forest Service, Edmonton, Alberta, Canada. BONAR, R., R. QUINLAN, T. SIKORA, D. WALKER, AND J. BECK. 1990. Integrated management of timber and wildlife resources on the Weldwood Hinton Forest Management Agreement area. Weldwood of Canada Ltd. and Alberta Forestry, Lands, and Wildlife, Hinton, Alberta, Canada. BULL, E. L. 1980. Resource partitioning among woodpeckers in northeastern Oregon. Dissertation, University of Idaho, Moscow, Idaho, USA. _____, AND R. J. PEDERSEN. 1978. Two methods of trapping adult pileated woodpeckers at their nest cavities. North American Bird Bander 3:95–99. _____. 1987. Ecology of the pileated woodpecker in northeastern Oregon. Journal of Wildlife Management 51:472–48l. _____, AND E. C. MESLOW. 1988. Breeding biology of the pileated woodpecker – management implications. U.S. Forest Service Research Note PNW-474. _____, R. S. HOLTHAUSEN, AND M. G. HENJUM. 1992. Roost trees used by pileated woodpeckers in northeastern Oregon. Journal of Wildlife Management 56:786–793. _____, AND R. S. HOLTHAUSEN. 1993. Habitat use and management of pileated woodpeckers in northeastern Oregon. Journal of Wildlife Management 57:335–345.
Published on Feb 9, 2014