Well……what an eventful and exciting last few
weeks it’s been in the world of the West Midlands Brown Hairstreak!
The last six months had continued the
fairly quiet trend that we had been experiencing since Summer 2015 with adult
sightings in Grafton Wood, in 2016, well down on that previous summer. Once
this winter’s egg searches then got underway in November, the similar theme
continued. Counts at most sites that are monitored every year, were either down
or about the same as the previous winter (which was, in itself, a disappointing
one). Some sites bucked the trend though such as the National Grid site at
Feckenham, which had the best count we’ve ever recorded there, responding to
the great management work done by the Worcs Wildlife Trust and National Grid.
Plus a long stretch of footpath hedgerow near Bishampton that we’re now using
for the new BC Head Office monitoring methodology and where eggs were only
found for the first time, a few years ago. Large numbers of eggs were found
here this winter, easily surpassing last years’ total and seemingly indicating
the build-up of a colony right at the southern edge of the known distribution
of the butterfly in Worcs.
Events really started to take off though just
before Christmas, with the discovery of what were the most southerly eggs ever found for this current-day Worcs population.
These eggs were actually in an already recorded 1Km grid square but later that
same day, after moving on to a nearby (previously unrecorded) square and
searching there, Jenny Tonry discovered an egg on the northern outskirts of the
village of Pinvin, in square SO9549.
A few weeks later, one of our regular
Thursday searches had to be cancelled because of a bad weather forecast.
Undeterred, two of us then went out searching (independently) the following
day, in better weather, with the result that three more previously unrecorded
squares were ticked off the list. These three squares were the ones flanking
Tibberton village (SO9056/57/58) and were significant in that they’ve all been
searched many times before in previous winters, to no avail. These squares were
also out near the extreme western edge of the butterfly’s Worcs distribution. So
again, these egg records provide compelling evidence of distribution expansion
of the butterfly.
It was becoming increasingly clear, from all
these ‘new square records’, that the Brown Hairstreak had experienced a flight
season characterized by ‘dispersal’ and it was therefore going to be worth
putting in a bit of extra effort to try and find other new square territories.
Cue a couple of weeks ago and the discovery
of another new square record in yet another location that had been unsuccessfully
searched in many previous winters. This one being on Pumphouse Lane, close to
Redditch, in SP0166, and these discoveries marked the most northerly eggs so far found. This was then followed, just a week
ago, by the discovery of an egg over the border in Warks, east of Astwood Bank plus
egg records in another new ‘Redditch’ square:
SP0364 at Hunt End.
We had therefore, in just a single winter, recorded
the most northerly and southerly eggs in the distribution, whilst also finding them
out very close to both the western and eastern extremes!
With all this ‘edge of distribution’
exploration going on it might seem like there wouldn’t have been much time left
to devote to our core area searches at Grafton Wood however, sandwiched in
between all these new range discoveries, have been some incredible recent finds
within the wood itself. Following a rather abortive attempt at searching some
excellent areas of Blackthorn coppice and re-growth, in a much hampered heavy
hoar frost search a few weeks previously, we decided to return to carry out a more
systematic and painstaking search of some key areas within the wood. The result
of these searches was that the in-wood total number of eggs found this winter
at Grafton was a staggering 555. One particularly favourable ride corner
revealing 186 eggs!
These searches within Grafton Wood itself have only
been carried out over the last three winters, and are done to provide a
monitoring and planning tool to aid the huge amount of excellent management
work that has taken place within Grafton over the last few years to open up the
wood and cut down old blackthorn thickets. The egg totals have proved beyond
all doubt, how fantastically well the butterfly has responded to all this
management work.
This brings the news of an exciting Brown
Hairstreak season, right up-to-date although, at the time of writing, there’s
still a few more weeks left for egg searching. So who knows what we may yet
turn up, before the Blackthorn comes into flower and the 2017 egg searching
season draws to a close?