Foraging in the Woods
by Nick Hope, Upper Dearne Woodlands Conservation Group
A research project has recently been completed into the foraging behaviour of wood ants in the Upper Dearne Woodlands, between Birdsedge and Upper Cumberworth. The woodlands are well known locally for the abundance of these ants that can be seen in the summer months, busily foraging on the woodland floor and up and down the trunks of the trees. These rare creatures are in decline nationally and hence are listed in both the UK and the Kirklees Biodiversity Action Plans. Their wellbeing is a high priority for the conservation group that manages the woodlands.
The group has previously developed a management strategy for the woodlands, after wide consultation to discover how best to ensure the long-term health of the trees themselves as well as all the wildlife that can be found there. However, we were surprised to find how little was known about the specific behaviour of wood ants. Why do the ants thrive here, when they are found nowhere else in Kirklees and in very few places in the entire region? How could we be sure that in our efforts to ‘improve’ the woodlands we don’t inadvertently harm the habitats for the ants?
As a result we decided 2 years ago to commission specific research into the foraging behaviour of ‘our’ ants in ‘our’ woods. Which trees are most and which less important? The study has been carried out by LASI (Laboratory of Social Insects) in the Department of Animal and Plant Sciences at the University of Sheffield, under the direction of Professor Francis Ratnieks, with funding obtained from the Esmée Fairbairn Foundation.
So what are the results of the study? The first, unexpected, result was the re-identification of the species of wood ants present. These had previously been identified as Formica rufa, the so-called southern wood ant and very unusual this far north. The wood ants here have now been identified (and confirmed by the leading UK taxonomist) as Formica lugubris, a different and more northern species. Whilst it is considered less unusual to find F. lugubris here than F. rufa both species are equally threatened, both are in equal need of conservation and both have similar habitat needs. Hence the importance of the colony is unaffected on either a local or a national scale.
The ants have been found to forage on a wide range of tree species, with oak being the most important, but also pine and spruce being utilised to a high degree, out of proportion to the low numbers of these trees found in the woods. The proposed tree management strategy would involve reducing the numbers of sycamore (an invasive non-native species) and thinning of larch (believed to have been introduced to these woods about 80 years ago). The results of the study have shown that neither of these steps will themselves be detrimental to the ants; moreover the anticipated longer term effects will be beneficial, in allowing more light to reach the woodland floor and encouraging regeneration of more favourable species.
As a result of this project the group will be able to implement our plans with a greater degree of confidence for the future of our most unusual inhabitants. Ensuring the regeneration of oak trees and the continued presence of pine and spruce trees are high on our list of priorities.
