But it ain't gonna get in the way of a story...
Early in the month, and in the company of JD, Our Lass and I ventured over to RSPB Lakenheath Fen for a wildlifey day midst the wetland habitat beside the River Little Ouse. It was a gloriously warm day with plenty of sunshine that guaranteed some dragonfly activity, if not much in the way of ornithological interest. But more of that in due course.
However, the most fascinating part of the day was completely off the wall, off the radar, and very left field, as the sayings go. In fact, to be exact, it was very left carrot field, this being the reserve's former life before habitat recreation was begun.
After walking around a footpath loop in the north east corner of the site, we were returning to the car for a much-anticipated picnic, when a movement at the base of a tree caught my eye. To be honest, I wasn't sure that I had seen anything concrete, it was more likely a shadow from a branch moving in the breeze. But the old Nature neurones were firing like crazy, so I stopped to have a second look. I mentioned to JD that something small and dark had flown from the base of a Birch tree and disappeared behind a nearby Pine tree. Probably too small to be a bird, but what else would fly out from the shade, low down a tree trunk?
|Exhibit A: a Birch tree
As we photographed the butterflies, it became apparent that more were arriving all the time. And all from downwind. What the heck was pulling them in? Then we noticed that the Gorse bushes weren't the centre of attraction, that honour went to the base of the Birch tree. Good old Nature neurones, they'd been right all along.
The lower part of the trunk was surrounded by chicken wire (as were most of the Birches in the area) but whether this was significant we couldn't be certain. However, there was no doubting that there were several holes in the tree, though they seemed too low down to be caused by a Woodpecker. Despite the wire, several Red Admiral butterflies were gathered in the crevices of the gnarled and holed bark, so we assumed that Birch sap was oozing out and the insects were drinking this. However this did not offer sufficient explanation for the holes in the trunk.
|There's at least 3 butterflies here
The larvae of the Goat Moth feed and grow inside tree trunks. Due to the poor nutritional value of the wood, it can take up to 5 years for the larvae to become fully grown and exit the tree to pupate. Along with their bodily output, the larvae create runs of fermented sap on the exterior of the trunk and many insects will seek this out to feed upon.
In this instance, this had resulted in not only plenty of 'happy' Red Admirals, but also three happy naturalists.