Wildlife conference: The "red-arsed" bumblebee has gone missing from Irish farms. Other species of important bumblebee pollinators are also in decline right across Europe, largely because of intensive agricultural practices.
The difficult future of the red- arsed bumblebee and a host of other species from birds and spiders to plants, provided the focus for a one-day conference in Dublin yesterday on the subject of biodiversity in the farmed landscape.
One presentation detailed how the shape, size and plant species in a hedgerow can influence the numbers and species of birds using it as a winter refuge or nesting site. It showed that for most common Irish birds, high, wide hedges are the preferred option.
UCD hosted the conference, which was organised by Ag-Biota, a €1.3 million agri-environmental research project funded by the Environmental Protection Agency and involving researchers from the University of Limerick and Teagasc.
UL's Veronica Santorum explained a study done in conjunction with Prof John Breen on the biodiversity of bumblebees on Irish farms. Bumblebee numbers have been falling across Europe since the 1970s, she said. "Agricultural intensification is seen as the greatest problem for bumblebee decline." The loss of walls and hedges, the increased use of insecticides and a reduction in plant diversity generally have put bumblebee numbers and species diversity under pressure.
Ms Santorum and Prof Breen conducted a survey on 37 typical Irish farms and 11 farms in the Burren, Co Clare. Bumblebee numbers and species variety were both higher in the Burren, she said. More than 70 bees were spotted per hour there compared to just over 18 bees per hour on conventional farms.
She puts the much lower figures seen on typical farms down to a lack of food supplies. "There are a lot more flowers in the Burren," she said. The "red-arsed" bumblebee, Bombus lapidaries, is well known by older farmers but virtually non-existent on typical farms. It was spotted in the Burren, she added.
Birds are also under pressure due to intensive farming, UCD's Barry McMahon told delegates. Working with Prof John Whelan, Mr McMahon conducted a study of bird species and numbers in hedgerows at various locations.
He studied nine hedgerow sites, assessing the nature of the hedgerow and measuring richness and abundance of bird species in each. There was a "significant relationship" between the hedge and the species variety and abundance, Mr McMahon said.
He catalogued 34 over-wintering bird species and 30 breeding species in the hedges which contained 45 shrub and tree species. Pheasants favoured wide hedges, while the wrens, robins and chaffinch preferred high, long hedges.