Monday 24 September 2012

Naval top brass in drunken spree with goat...

Don't you just loathe sensationalist tabloid headlines? Those that twist the merest thread of truth into a preposterous yarn of such outrageous colours that your eyes hurt? Vastly exaggerated tales that promise much and deliver less than nothing? Hmmm, I know what you mean.

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
Skirting around the Pine, we found a Red Admiral butterfly roosting in the sun. OK, that answered the 'what', but not the 'why'. Looking around the adjacent Gorse bushes, there were several more butterflies, mostly Red Admirals, lazily having a bit of a siesta in the heat of the day. This was actually a big clue, if only we'd thought about it in those terms!

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
Recourse to that hit-and-miss solver of mysteries, the internet, revealed that this was a phenomenon with a fairly rational, if a little bizarre, explanation.

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.

Lepidopteran contentment
We had not seen this particular interaction between species before, indeed we had not known of its existence. I was so amazed that when, later in the day, a Hobby flew passed with a dragonfly in its talons, I didn't even mind that much.



holdingmoments said...

Wildlife never ceases to amaze does it.

As for that Hobby; oh dear. ;-)

Imperfect and Tense said...

Very true on both counts!

Colin D said...

Sitting in a flat in Good old Vienna a nice read.A usual I enjoyed it !!!!

Imperfect and Tense said...

Your postcard arrived today! We're glad you're having a good time :o)