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1 August 2018 Foraging ecology of the Williamson's Sapsucker: Implications for forest management
Julien St-Amand, Junior A. Tremblay, Kathy Martin
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Williamson's Sapsuckers (Sphyrapicus thyroideus) are montane woodpeckers threatened by widespread tree removal activities and climate change. Current forest management plans focus on nesting trees, but the incorporation of foraging trees would lead to a more effective management strategy to mitigate habitat loss for this species. We investigated the selection of foraging trees in forests managed for timber extraction and maintenance of wildlife values using foraging observations of 27 radio-tagged adult Williamson's Sapsuckers during the breeding season in 2 regions (Okanagan and Western) of their limited Canadian range. Characteristics of foraging trees (88% of observations on live trees, 11% on dead trees) differed with foraging mode. Large, live Douglas-firs (Pseudotsuga menziesii; ≥22.5 cm dbh) were used for gleaning and sap feeding on tree trunks in both regions, whereas trees used for trunk pecking were mostly large, senescent western larches (Larix occidentalis) in the Okanagan region and large, dead ponderosa pines (Pinus ponderosa) in the Western region (average dbh = 46 cm). For overall foraging activities, Williamson's Sapsuckers selected large, live Douglas-firs with signs of resin exudation and blistering (pitching), and avoided live lodgepole pines (Pinus contorta), quaking aspens (Populus tremuloides), and ponderosa pines. Larger trees and standing dead conifer trees were reused more often for foraging than smaller and live trees. The quality of Williamson's Sapsucker habitat could decrease over the long term if forest management practices reduce the overall size of trees or alter tree species composition to promote lodgepole pine. Forest management should focus on retaining and promoting large live Douglas-fir trees and large senescent or standing dead conifers (also used for nesting), which can be achieved by using thinning, prescribed fire, partial harvesting, and tree retention strategies.

© 2018 American Ornithological Society.
Julien St-Amand, Junior A. Tremblay, and Kathy Martin "Foraging ecology of the Williamson's Sapsucker: Implications for forest management," The Condor 120(3), 680-702, (1 August 2018).
Received: 14 November 2017; Accepted: 22 May 2018; Published: 1 August 2018

foraging habitat
large trees
Montane forest
Pseudotsuga menziesii var. glauca
resource selection function
Sphyrapicus thyroideus
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