Saturday, July 25, 2015

Disaster in Savernake

Today I conducted my annual 'peak season count' of males in territories along Three Oak Hill Drive at the southern end of Savernake Forest, N Wilts.  Weather conditions were good, with only a light - moderate breeze, for a change, and plenty of sunshine.  Note that this is a late site for iris, though today's visit may have taken place a few days past actual peak season.  I think they started here around July 10th (and would welcome clarification on this), possibly a little later. 

A thorough search revealed only five males, all in reasonable condition (looking quite dark).  This compares to six seen along the same route in rather cloudy conditions on Thursday, and a par for the course of eight or nine.  Last year's peak count was a dismal five.  

My guess is that either yesterday's rain (25mm or 1") has depleted numbers or the butterfly has again emerged here in poor numbers, or both.  Usually, the adults are quite adept at surviving rain (with the exception of the great deluge of 20/7/2007), providing it isn't accompanied by strong winds.  As they roost high in the tree canopy they are extremely vulnerable to gales.  Yesterday's winds were light.  They do, though, tend to be quiet after a very wet day - drying out perhaps.

What worries me is that if numbers here have been depleted by heavy rain relatively early in the season - before many eggs have been laid, then what will the egg lay be like?  The relatively good news is that two females were seen around Three Oak Hill Drive today, though not by me.  But more rain is forecast for tomorrow, and then more windy weather...

Here's one of today's males, framed by beech branches - 

In the early 2000s the FC opened sections of Three Oak Hill Drive, generating a much-needed new generation of sallows.  Many of these sallows were used, for the first time, in 2013.  However, squirrels have recently stripped bark from a great many of them.  Most affected trees will now die.  Here's an example - 

Next time I'm taking my cats...

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