Michael Walter's latest update:

It’s the time of year when graphs get brought out of the cupboard, dusted down and re-examined.  The bird survey data has all been analysed, with the result that for some species emerging trends look even stronger than a year ago.  Two examples are given below, and the good news is that jackdaws are enjoying a bit of a renaissance.  The first thing I should say about this graph is that the flatlining apparent from 1991 to 2003 is simply due to this species not being monitored then, but it is obvious that in the early years of this century the population was quite small, whereas for the past three years numbers have been soaring.  Of particular interest is a colony close to the stream that thrived in the 1980s, but then was abandoned in the 1990s.  Is there a parallel with medieval villages that disappeared off the map, a decline usually inaccurately attributed to the Black Death but, as often as not, due to some other impact of the rural economy?  Jackdaws are colonial, nesting in tree holes, but clusters of suitable sites are at a premium in the wood, hence the tendency for the colonies to be fixed in defined areas of the wood for years.  But perhaps there comes a point when a build-up of parasites in the old, soiled nests affects the health of the chicks, reducing productivity, and causing the adults to decamp, only returning when the hollows are safe once more.  Whatever the reason, the jackdaw population is certainly thriving at present, something that cannot be said of the willow warbler.  This season I was able to locate a mere four territories, and I am resigned to the conclusion that this lovely little migrant, with its sweetly melancholy song, may soon be just a memory on the reserve.  Like a rather scaled-down version of the woeful American passenger pigeon tale, the willow warbler was so common in Blean Woods in the 1980s as to be almost uncountable, and its subsequent fortunes serve as a sobering reminder that when humans alter the environment on a planetary scale we have to expect wholesale changes to wild populations.  Nationally, numbers are relatively stable, and even increasing in Scotland, but in the south east and south west of England the species has been sliding downhill for at least 25 years.

 

I don’t record amphibians that often, so it was good to see a tiny, but perfectly-formed toad, and later an equally diminutive frog, laboriously traversing the short grass of one of the ride paths recently.

 

Michael Walter

michaelwalter434@gmail.com

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