Breeding ecology of Welcome Swallows Hirundo neoxena in the Yarra Valley, Victoria: the nestling stage
| Posted: |
12/12/2014 |
| Author(s): |
Alan Lill |
Breeding ecology studies encompassing multiple seasons, sites and breeding attempts help in determining which aspects of a species’ breeding ecology are widespread, which vary temporally and spatially, and the reasons for such variation. The nestling stage of Welcome Swallows Hirundo neoxena breeding in eleven sites less than or equal to 12 kilometres apart in the Yarra Valley, southern Victoria was studied over three successive seasons. The seasonal timing of the nestling stage (late Sept. –early Jan.), degree of hatching synchrony (53%) and the length of the nestling period (20–24 days) were similar to findings of other Welcome Swallow studies in SE Australia and suggested that these features may be genetically regulated. In contrast, values for features likely to be more proximally influenced by environmental variation were more at variance with values reported in some other investigations, e.g. absolute hatching success (68%), fl edging success and, to some extent, the causes of nestling mortality. There was some variation among years in the seasonal timing of hatching, and among years and colonies in the causes of nestling losses. The role of predation in nestling mortality was equivocal; there was little direct evidence for it, but it may have contributed to the high frequency of nestling disappearance.
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