Conservation in Carmarthen: Rhos Cefn Bryn and Cors Goch Updates

Conservation in Carmarthen: Rhos Cefn Bryn and Cors Goch Updates

Our Reserve Officer and volunteers have been busy over winter working to improve the habitat at Rhos Cefn Bryn and Cors Goch for some of our rarest species.

Boosting Black Bog Ant Numbers at Cors Goch

Following recommendation from an ecological report work has been carried out at Cors Goch to improve the habitat for Black Bog Ants. They are one of our rarest species of ants, with a very localised distribution. They are only 3 known populations in Wales: in the Gwaun Valley in Pembrokeshire, Rhossilli Down on Gower and at Cors Goch, our lowland raised bog near Carmarthen. It is important that we do our best to safeguard this rare species and work to improve the habitat to encourage them to extend their range on site.

The report assessed population size, distribution and extent across the bog. It compared survey data from 2024 with historical data to gauge how the population was faring. The report showed that the population was within the limits of what was expected, with 150 nests across the site. However, some of the areas where bog ants had been found previously had become degraded through lack of management. It was also noted that the highest concentration of ants were found along a mown strip of vegetation, where the vegetation was less uniform and more diverse.

As such, work was carried out over winter to create more of the ant's preferred habitat. A number of narrow strips have been mowed to break up the sward. The area identified as having lost it’s attractiveness for Black Bog Ants has been fenced. We aim to get ponies on the managed parts of reserve next year to maintain the habitat works that have been carried out.

Helping Hazel Dormice and Marsh Fritillary at Rhos Cefn Bryn

At Rhos Cefn Bryn in Carmarthenshire, volunteers have been working to improve the habitat for Dormice and Marsh Fritillary. Both are iconic species but often management favours one over the other. With careful planning we have hopefully improved habitat conditions for both species.

Marsh Fritillaries are notorious weak flyers and can struggle to recolonize areas when the habitat is fragmented. To better connect our reserve and surrounding fields owned and managed by Carmarthenshire County Council, we have created flight lines on two hedges through a combination of coppicing and hedge laying.

The hedges were becoming over mature and consequently had lost a lot of the dense growth near the base of the trees through shading. This is where dormice will often chose to build their maternity nests and so the hedges were becoming less favourable nesting sites. We have coppiced the willow, which was becoming very dominant, and laid the remaining hazel and oak to encourage them to spread. In the gaps, we planted a variety of fruiting trees and shrubs to increase feeding opportunities for dormice. Species planted included oak and hazel, and also crab apple, elder, hawthorn, blackthorn, rowan and dog rose. Next year we will continue this work on other sections of hedge, working our way up the fields.

We also planted some trees on the Carmarthenshire County Council site next door to try and create a wind break on a large exposed field. Whilst Marsh Fritillaries need marshy grassland for their life cycle, the butterfly and its larvae do prefer sheltered places where they can bask and absorb the sun. The new trees we hope will in time, provide more opportunities for basking. Thanks to The Woodland Trust for providing the trees to enhance the existing hedgerows and in creating the wind break.

Our volunteers also helped us to replace the holding pen needed for safe loading and unloading of grazing animals. This will help to support conservation grazing needed on the site. A special thanks to the Carmarthenshire Volunteers who have turned up rain or shine throughout the winter.