EFFECT OF RAINFALL. ON BREEDING OF GREY SHRIKE-THRUSHES Colluricincla harmonica
| Posted: |
12/04/2021 |
| Author(s): |
David M. Watson, Helen C. Stevens |
Observational data from 24 nests in a single area in central New South Wales over eight years were used to
determine whether the reproductive output (eggs laid, chicks fledged, number of broods) in a breeding season
was related to rainfall before and during the breeding season in an endemic passerine, the Grey Shrike-thrush
Colluricincla harmonica. In a species where clutch size is low and relatively fixed, annual rainfall nevertheless
influenced both clutch size (correlation coefficient r = 0.62) and number of successful nests (r = 0.94). There was
a strong relationship (r = 0.98) between annual rainfall and number of chicks fledged over the breeding season. It
appears that the Grey Shrike-thrush can fine tune reproductive output in response to rainfall (presumably
mediated via food availability) an ability that would assist adult survival while maximizing reproductive output
where climate and resources fluctuate markedly.
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