Rare Wood Ants in the Upper Dearne Woodlands
Formica rufa Research Project 2003-04
Upper Dearne Woodlands Conservation Group & Sheffield University
If you visited the Upper Dearne Woodlands in the summer and noticed someone looking closely, with intense concentration, at one of the trees, we may have the explanation for this strange behaviour.
1. Background
A research project is under way into the foraging behaviour of red wood ants (formica rufa). The project has been commissioned by the Upper Dearne Woodlands Conservation Group and will be carried out by Sheffield University (Laboratory of Apiculture and Social Insects) under the direction of Dr. Francis L. W. Ratnieks.
The Upper Dearne Woodlands, where the field work is taking place, are near Denby Dale in West Yorkshire (SE 210082). The woods are owned by Hepworth Building Products and there is a public access agreement in place between the company and Kirklees Metropolitan Council. The conservation group manages the woodlands on behalf of Hepworth’s and with the support of Kirklees Environment Unit and the Denby Dale Parish Environment Trust.
This is a mixed woodland, consisting of about 5% semi-natural, about 70% beech with some oak and about 25% conifers, again mixed with oak. There is also a significant sycamore content throughout the woods.
2. The Need
Within the woods is a colony of the Southern Wood Ant (Formica Rufa). This is a priority species in the UK Biodiversity Action Plan (BAP). The Species Statement for f. rufa in the BAP can be found at:
www.ukbap.org.uk/asp/UKPlans.asp?UKListID=311
Formica rufa is normally found in southern Britain and its existence in this location and at this altitude (230 metres) is unusual. It is the only known colony in the Yorkshire and Humberside Region.
Clearly this colony needs to be protected and encouraged.
The ants appear to be flourishing at present. A comprehensive invertebrate survey commissioned by the Group in 1998 located 73 nest mounds. This survey was carried out during the summer when bracken cover impeded the task. A nest count in April, 2002, with less ground cover and on a sunny weekend, found 153 active nests.
Thus there would appear to be no urgent problems. However, the woodland trees themselves have been identified as requiring active management for their long-term health. (The trees are generally over-crowded, with limited light reaching the woodland floor and little regeneration. The regeneration that is occurring is mostly of invasive species such as sycamore.)
The threats to Formica rufa identified in the UK BAP are loss of suitable habitat and inappropriate woodland management. The recommended action plan for the species in the Kirklees MC BAP is to initiate appropriate woodland management practices. The problem the Group faces is in defining “appropriate woodland management”. There is little of help to be found in the literature.
There seems to be something the ants like about this northern location, but what is it?
The nests are principally located in two areas of the woods that are dominated by conifers (mostly larch, scots pine and spruce). There are also a few isolated nests that, in every case, are adjacent to individual scots pine trees. This is in contrast to colonies in the south of England, which are mostly in broad-leaved woodlands.
A superficial amateur conclusion links the success of the ants in this location to the conifer content of the woods, hence perhaps we should encourage the growth of conifers. However, this is in conflict with general woodland management protocols for the area, which would encourage native broad-leaved species at the expense of the conifers.
As a result of the above factors the Group has concluded that there is a need to investigate further the relationship between Formica rufa and the variety of tree species in this location. Following discussions with Professor Ratnieks and colleagues from the Laboratory of Apiculture and Social Insects at Sheffield University, this research project has been devised.
3. The Research Project
Given the above, it is clear that the most useful information necessary for making decisions about tree management in relation to ant conservation is to obtain data on the use of different tree species by the ants. This will be carried out as follows.
a. The project will study several large ant nests or groups of nearby ant nests. These will be nests in different parts of the wood such that within the foraging range of the nest (c. 10-20m) there is a variety of tree species. We will determine the number of ants climbing the trunks of trees of all species. Because not all tree species are found together near an ant nest, studying several nests will enable us to compare across all the major tree species. Because the available prey and honey-dew secreting aphids will almost certainly change across the seasons, we will gather data during the main months when the ants are actively foraging in the trees (May-October). Because trees vary in size we will also obtain data on the sizes of the trees studied, so that we do not bias the conclusions in favour of large trees.
b. We will observe the ants descending the trees and determine the proportions carrying prey and building materials (visible, held in mandibles) and honey dew (distended abdomen; analysis of crop contents).
c. We will identify the main prey and honeydew-secreting aphid species.
The project will be carried out by graduate students from Sheffield University, supervised by a post-doctoral research student specialising in wood ants and by Professor Ratnieks.
The University will report their results to the Conservation Group.
4. The View of English Nature
The project has been discussed with English Nature who have made the following comment:
“Following our telephone conversation, I read your email and can confirm that the results of your proposed research will be of significant use to woodland managers across England. Formica rufa has been declining in Wales and in parts of north-west England. Elsewhere its populations are misunderstood because of the abundance of the worker caste. Woodland managers are becoming increasingly aware that wood ants are becoming less widespread but are at a loss to put any positive actions in place. If your research can identify some of the features of a woodland which wood ants require for their survival, this will enable others to re-assess their own properties and to implement appropriate management, albeit still experimental.”
5. Future Work
Future continuation will/may come in 3 areas:
- The results of the research will guide our tree management activities. These will be funded by a Woodland Management Grant from the Forestry Commission, which has already been approved and a contract is in place.
- Informing the community about the project. As noted above this will be achieved by using the local press and by public meetings (which have little cost implication) and by information display in our woodlands. This application includes a small sum to fund the latter.
- Further research. Until this project is complete we will not know whether or what future research may be of value. Funding for any future work will be addressed at that time. The current project and its results stand alone and are not dependent on any future work.