There was plenty of activity yesterday morning at a brand new Brown Hairstreak site discovered just last year near Shurnock in Worcestershire. Despite arriving at the known master tree at around 9:30am, it was still quite chilly and the sun was rather hazy. No doubt all the Brownies were hiding at the top of the ash, trying to warm up! I was there for a good 45 minutes before I saw the first one take flight. Between 10:15am – 11:30am, I estimate I saw between 4-5 individuals (most likely males), with 10+ sightings. As soon as the sun started warming up at around 11am, the males were literally buzzing around the top of the ash. Amusingly, 1 male spiralled quite low down to bask for a few minutes before deciding to have a little fly at head height along the treeline. He then changed his mind, flew way out into the field, skipped over my head and zoomed back into an apple tree just below the favoured ash. Strangely enough, 1 male and 1 female Brown Hairstreak have been observed in this apple tree previously (by Simon Primrose on 28th August), and 2-3 males were also seen in an alder tree which is situated right next to another master ash, roughly 50m from the favourite. I had 2 Brownies in this 2nd ash yesterday, plus 1 male in the very same alder tree. It was clearly turning its nose up at the attractive ash next door, preferring to explore the alder top to bottom instead. I must also mention that most of the sightings yesterday were of quite worn/faded looking specimens.
I also had a look at the other ash trees in the same field and managed to spot a definite hairstreak that descended out of an ash and landed high up in a hawthorn bush. However, I wasn’t able to confirm if this was a Purple or Brown Hairstreak. Still, it requires some further observation, as do other trees in the area that I have on my ever growing list.
Despite multiple searches of the main hedgerows, no females were to be seen anywhere.
So, at this point, we have 3 confirmed master trees bordering the same field. Ash 1 and 2 are roughly 50m apart, and ash 2 and 3 are roughly 300m apart. Considering the concentration of eggs that were found in these locations, all 3 trees are clearly within the main colony boundary. Does anyone know how many males can occupy a moderate-large sized ash before others start being used?
3 comments:
Went with Simon Primrose to Shurnock yesterday but both us and the Brownies were lost in the fog. Reports from elsewhere in Worcs, however, suggests that there is still considerable activity around assembly trees which is very unusual for us in September by which time most males have normally disappeared. Gill's question about the carrying capacity of each assembly tree is an interesting one and something we need more information on. The area around Shurnock clearly has a very healthy population of Brown Hairstreaks and it may be that a higher number of males leads to greater displacement to other nearby trees than would typically be the case. West Midlands Butterfly Conservation are running their Big Ash Bash again this year and are keen to hear of any observations of Brown Hairstreak behaviour on and around ash trees. Please post any sightings or comments here or email me at mike@stagborough.fsnet.co,uk
Like Mike and others I am also very surprised at the presence of male BrH into September. This has been the case too here in my home area of Bucks/Oxon. A friend Alan Wingrove had two males in an ash in Sussex last week. This raises the question as to the likely emergence of these individuals so late in the flight season? Do all males emerge early on or is it protracted? I have always assumed the latter never having had evidence to the contrary. How late in the flight season do others find fresh males?
Will successive batches of eggs laid by a female be fertile with only one mating prior to the outset of her egglaying cycle? Mike's point re the 'normal' absence in September might indicate so? We have so much to learn!
I think "generally", the males emerge before the females but not always. This year has been a strange one. Not only has the season been late but because of the constantly changing weather, i believe we are having a much longer emergence period, hence the reason we are still seeing the males. Im unsure if a female can mate more than once but id be interested to hear if anyone has any further theories on this.
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