| Citation: | Aitken KEH, Martin K. The importance of excavators in hole-nesting communities: Availability and use of natural tree holes in old mixed forests of western Canada. Journal of Ornithology. 2007;148 (S2) :S425-S434. |
Abstract:
Nest-holes created by woodpeckers or natural decay processes are an essential commodity for secondary hole-nesting species. Hole-making agents may strongly influence the richness and abundance of species in hole-nester communities. However, few studies have examined the characteristics and relative importance of naturally occurring holes for hole-nesters. Between 1995 and 2006, we examined 1371 excavated and non-excavated holes used by 29 bird and mammal species in central British Columbia, Canada. Excavated holes were much more abundant (85%) than non-excavated holes (15%). Red-naped sapsucker (Sphyrapicus nuchalis) and northern flicker (Colaptes auratus) excavated 52% of the holes monitored. At the community level, non-excavated holes were used for nesting less than expected based on their availability (6% of total nests), particularly among woodpeckers (2% of nests). However, secondary hole-nesters used non-excavated holes roughly in proportion to their availability (10% of nests), and some excavators used non-excavated holes for nesting (flicker and red-breasted nuthatch, Sitta canadensis, 4% of nests each; black-capped chickadee, Poecile atricapillus, 13% of nests). Although nests in non-excavated holes tended to be lower on the tree, larger internally and with larger entrances, only European starling (Sturnus vulgaris) appeared to select non-excavated holes with characteristics most similar to their preferred excavated holes. Non-excavated holes may be an alternate nesting resource for secondary hole-nesters that cannot acquire an excavated hole and, occasionally, for excavators. The use of non-excavated holes may provide an advantage for secondary hole-nesters by releasing them from the constraints of excavator nest-site preferences.
Last updated on 01/28/2019