Tuesday, 14 October 2014

How Productive Can a Survey Be...

Every so often, and particularly around now, when numbers are peaking and concentrated at Strangford Lough, we try and sample the flocks, to determine how good a breeding season it has been.
Today has been one of those days, and Kerry Mackie, Alex Portig and myself have been out attempting to sample the proportion of juveniles, and trying to determine the average family brood size.
Now, hot off the press, I can tell you (thanks, Kerry for collating the data) that, between us, we managed to age a very respectable 8,827 geese. Of these, 3.1% were juveniles from this summer's breeding in Canada ( VERY noticeable at this stage of the winter by the white lines down their back feathers (adults are uniform black), or, less importantly, by their absent or less pronounced neck mark). This percentage young figure is likely to be higher than actual, as many of the unsurveyed flocks present were massed way out at the edge of the mud-flats beyond the definition of our scopes (such flocks are known historically to include very few young). In the sample, 96 families averaged a brood of 2.2 juveniles.
The increase in larger families has been noticeable over the past week, which, as already reported, as seen the arrival of some of our larger Canadian-ringed families.
Given that we were recording very small families earlier, these results are a bit of a relief, particularly as the 2013/2014 year was, to all intents and purposes, a near total wash-out for breeding.

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