Monday, 26 November 2012

Tawny Frogmouth fledging dates

There has been some discussion between members of the local Canberra Ornithologists' Group on the apparent synchronisation of the Tawny Frogmouth fledging dates in the Canberra area this year. So I have plotted these and those of the previous years on the graph below and ran some simple statistical tests on the figures. As not all birds have fledged in 2012 yet, the expected dates have been calculated for use now as some people have been asking for these figures. These dates will be corrected when possible and more precise analyses published at a later date.

The mean fledging date has been in mid-November every year, ranging from the 13th in 2009 and 2011, to 22nd November in 2010, although that year the mean date was late due to the influence of several late fledgings from re-lays after first breeding attempts failed. The median dates, from each year in order from 2009-2012 were 12th, 16th, 10th and 15th November. A simple ANOVA test for differences between years, not using any birds fledged from re-lays, showed no difference (P = 0.217, F = 1.51, n = 29,30,25,24).

The earliest fledging was on 14th October 2011 and the latest was 7th February 2010. 

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