Ocean Mist

8 Apr 2017

Brimming with Light and Life

Posted by Jes

The uninterrupted sunshine forecast for today promised the ideal conditions to visit a favourite patch so we set off for Lullybeg.

The work party in February 2017 was dedicated to removing heavy scrub that shaded the small tree species used by the Brimstone for breeding (see Facebook for details). It was hoped that opening the area to light and warmth would create the conditions needed for the butterfly to breed in this particular spot, chosen for scrub control because it contains a significant concentration of Common/Purging Buckthorn and Alder Buckthorn. These are the only plants used by the Brimstone in Ireland for breeding.

When we worked our way in from the edge of the clearing to tackle the taller scrub we discovered other very heavily shaded food plants present. We now had the chance to free not just the plants at the edge of the clearing but also several more buckthorn plants in the interior of the scrub.

Today we were able to see how our work succeeded. At one time, four female Brimstones were observed, fluttering around the food plants and laying eggs. We watched this activity for over two hours and was still in progress at the time of our departure, highlighting how suitable the habitat is now. The habitat is still sheltered by tall trees but shade has been greatly reduced. The heat created by the continuing shelter and direct sun meant that the females were able to maintain activity levels for a prolonged period, with only very brief basking breaks to recover heat lost during flight. A good deal of heat is radiated by the dry Moor-grass present around the buckthorns that are located at the edge of the original scrub and this is where basking took place. The presence of this leaf litter creates warmth around the food plant and we observed that most laying took place on these plants, with less attention given to plants that grow where the dense scrub was located. This might be due to the cooler conditions as there is less Moor-grass present where scrub was thickest, owing to the lack of light. However, as the spring advances, air temperatures increase and there may be more eggs laid on these plants then.

Thanks to all our conservation volunteers; your management work is achieving success.

Click on the image for enlargement.

Brimstone lays an egg on unshaded Alder Buckthorn. ©JHarding.

Freshly laid Brimstone ovum on Alder Buckthorn, Lullybeg.©J.Harding.

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