| Publication Type: | Journal Article |
| Year of Publication: | 1989 |
| Authors: | Rendell, WB, Robertson, RJ |
| Journal: | The Condor |
| Volume: | 91 |
| Issue: | 4 |
| Date Published: | 1989 |
| ISBN Number: | 00105422 |
| Keywords: | Hirundinidae, Hirundo, Hirundo rustica, Iridoprocne, Iridoprocne bicolor, Tachycineta, Tachycineta bicolor |
| Abstract: | We examined 10 characteristics of natural cavities and their influence on reproductive success of Tree Swallows (Tachycineta bicolor) nesting in dead trees in beaver ponds. Large ranges were found for entrance height and area, cavity volume, and nearness to shore of nest sites. Other characteristics were less variable: 46% of cavities were less than 2 m above the pond surface, and 48% had entrance widths of 4-5 cm. Tree Swallow nest sites were uniformly dispersed in the ponds. Two cavity characteristics, cavity height and floor area, influenced reproductive success. Lower nest sites were more frequently preyed on and females laid larger clutches in cavities with a large floor area. Five species larger than Tree Swallows used cavities during the study. Girth of the snag at the base and at the cavity, entrance width, and cavity volume were significantly greater at sites used by these species than those used by Tree Swallows. Nest sites suitable for breeding did not appear to be limiting to Tree Swallows, because characteristics of unused cavities did not differ from those used by Tree Swallows and other species. Intraspecific territoriality was likely responsible for the large number of unused cavities in our populations. Other factors influencing cavity availability in our sites include interspecific competition, predation, snag fall, and continuing woodpecker excavation. |
| URL: | http://www.jstor.org/stable/1368072 |
| Short Title: | The Condor |
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