Lullybeg Reserve Update

Lullybeg Reserve, also known as Crabtree Butterfly Reserve, is located in Lullybeg, County Kildare. The reserve contains a range of habitats that have developed on the cutaway bog. These include open water, marsh, heath, wet and dry grassland, scrub, and woodland. The soil chemistry is variable, allowing a wide range of plants to occur. The diverse vegetation and intimate proximity of habitats mean that invertebrate diversity is high, and butterflies are a salient representation of this biodiverse reserve.

Key butterflies present on the wing now are the Dark Green Fritillary, Marsh Fritillary, and the Small Heath. All three are carefully monitored, with site and transect counts compiled from 2011 to date. Two of these species are on the rise, one is in decline. The declining species is the Small Heath, which number 231 in 2013. By 2020 it had plummeted to 44. Up to June 29th this year (2021), 45 Small Heaths have been recorded. This figure should rise, but the future for the species is insecure. Better grazing management may help, but grazing regimes are hard to secure, especially for conservation organisations.

Small Heath, Lullybeg, in decline. Grazing is needed to prevent the loss of breeding habitat.
Dark Green Fritillary, female, on Lullybeg Reserve.

In better news, the Marsh Fritillary, an endangered species, is thriving on the reserve. Between 2011 and 2020, the average number of adult Marsh Fritillaries is 61. This year to date, 285 adults have been counted, a remarkable increase.

Marsh Fritillary (underside) on Rough Hawkbit, on Lullybeg Reserve.

It is too early in the flight period of the Dark Green Fritillary to make assess its progress, as its flight period on the reserve begins in late June. The highest total recorded was in 2018 when 35 were counted. This declined to 27 and 21 in 2019 and 2020 respectively, but a good year is a strong possibility, given the presence of good habitat patches on the reserve. The foodplant for the larva is mainly Common Dog-violet, which is now appearing in well-developed clumps as well as in smaller, scattered plants in the grassland. We look forward to bringing you an update on this powerful butterfly’s progress next month. For now, it is great to see it beginning to emerge on the reserve. We are hoping to have good news to report.

Dark Green Fritillary (underside), Lullybeg, County Kildare.

Post Update: July 15th, 2021

Some good news…

71 Small Heaths counted to July 15th, 2021, an increase on the 45 counted in 2020.