Habitat use by Pileated Woodpeckers at two spatial scales in eastern Canada

To study the multiple spatial scale pattern of habitat use by Pileated Woodpeckers (Dryocopus pileatus L.), we compared the vegetation characteristics at used sites with those at unused sites at macrohabitat (154 ha radius plots) and microhabitat (ca. 0.04 ha radius plots) scales in the La Mauricie region of Quebec. Used macrohabitats were those in which woodpeckers were detected at playback stations. Used microhabitats corresponded to sites showing signs of foraging (i.e., excavated cavities). Pileated Woodpeckers responded to vegetation structure at both scales sampled. Macrohabitats used by woodpeckers had relatively low percentages of mixed shade-intolerant hardwood stands, conifer- ous stands, and stands of relatively low stem density and tree height, but included high percentages of 51- to 90-year- old stands. Microhabitats used by woodpeckers were characterized most strongly by a high density of large snags but also by a high density of small-diameter snags and a low density of shade-intolerant hardwood trees and coniferous trees ≤30 cm diameter at breast height. The concordance between the observed and predicted use of micro- and macro- habitat plots was independent of spatial scale (logistic regression, χ 00 5 1 2 ., = 1.8, P = 0.18, n = 429), suggesting that habitats use by woodpeckers was influenced to a similar extent by habitat features measured at both spatial scales. Be - cause Pileated Woodpeckers are likely to require specific habitat features at different spatial scales, forest-management guidelines intended to conserve this umbrella species should consider a multiple spatial scales approach. Resume : Nous avons etudie la variation spatiale de l'utilisation de l'habitat par le Grand Pic ( Dryocopus pileatus L.) dans une foret mixte-decidue de la Mauricie, au Quebec, en comparant les caracteristiques vegetales de sites utilises et non utilises a l'echelle du macrohabitat (parcelles de 154 ha) et du microhabitat (parcelles de 0.04 ha). Les macrohabi- tats utilises correspondaient a des stations d'appel ou des pics ont ete reperes. Les microhabitats utilises correspon- daient a des sites avec signes d'alimentation (c.-a-d. cavites). A chacune des echelles, les pics utilisaient l'habitat principalement en fonction de variables structurales de la vegetation. Les macrohabitats utilises par les pics avaient de faibles pourcentages de peuplements mixtes a dominance de feuillus intolerants a l'ombre, de peuplements coniferiens et de peuplements de densite 〈 hauteur moyenne. Ils avaient toutefois de forts pourcentages de peuplements matures (c.-a-d. 51-90 ans). D'autre part, les microhabitats utilises etaient caracterises surtout par une densite elevee de chicots de grand diametre, mais aussi par de faibles densites de feuillus intolerants a l'ombre de diametre a hauteur de poitrine (dhp) ≤30 cm et d'essences coniferiennes de dhp ≤30 cm ainsi que par une densute elevee de chicots ≤30 cm. La concordance entre l'utilisation observee et l'utilisation predite des parcelles de macro et microhabitats etait indepen - dante de l'echelle spatiale (regression logistique, χ 00 5 1 2 ., =1 .8,P = 0.18, n = 419), ce qui suggere un degre d'influence similaire des caracteristiques vegetales aux deux echelles spatiales. Etant donne que le Grand Pic peut repondre a cer - taines composantes vegetales a differentes echelles spatiales, les amenagements forestiers pour cette espece parapluie devraient tenir compte de plusieurs echelles spatiales.