INTRODUCTION
This summary is based upon a PowerPoint presentation given at the Stag Beetle Conference at Holly Lodge in Richmond Park. It briefly reviews stag beetle habitat issues in Richmond Park highlighted by their Stag Beetle Project to which I have contributed and my work as part of my third year undergraduate research project for BSc Hons Natural History at Kingston University, Surrey.
There are four parts to my presentation: the factors I will be investigating, their relevance towards stag beetle habitat, the proposed methodologies and finally a general review of possible outcomes, potential flaws or errors in recent and future results and/or research methods.
Any figures referred to are based upon test results presented so far by Project Volunteer Coordinator John Hatto, and Community Ecologist Nigel Reeve. Results from my own project research will be completed by May of 2005.
The aim of my work is to contribute to future research by providing more rigorous definitions and analysis of criterion for surveying, data collection and monitoring methods of stag beetle habitats in Richmond Park.
ISSUES OF HABITAT
1. Importance of investigating stag beetle (Lucanus cervus) habitat
The causes of the decline in stag beetles in southern England during the recent decades are still being investigated. Richmond Park is an SSSI site and National Reserve and cSAC site for stag beetles so Staff want to take appropriate measures towards long-term monitoring and conservation of the areas and feature that benefit beetles as well as identifying their vulnerability to predators and human activity.
2. What we don’t know about habitat
It is already known that stag beetles prefer to inhabit areas rich in dead wood debris, including dead trees or dead tree stumps, and that while females are often found lurking beneath the bark of dead trees, males may select taller dead trees as posts for taking flight in the evenings during mating periods.
However, while most sites recommended on the survey walks included that of dead trees or stumps, it is inconclusive whether half-dead or dying trees are not also used.
While tree species in Richmond Park is predominantly Quercus robur (oak), there have been from 1 up to 5 sightings or finds at a time around other tree species, including Fagus sylvetica, hawthorn, hornbeam, horse chestnut, and sycamore. However it may not be possible to determine whether stag beetles are species-particular towards tree habitat within Richmond Park itself.
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Other factors affecting the selection and use of the habitat by beetles and predators include the levels of ground and general vegetative cover and physical characteristics of targeted trees/stumps including girth and height and their general surrounding, such as the aspect (e.g. South facing) and relative altitude – all of which will affect the microclimate (extra warmth to enable a beetle to take to the air). Survey results so far revealed that all finds and sightings were around that of relatively mature trees. |
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METHODOLOGY
In addition to data already processed from results, I shall be collecting data which takes into account the above factors, including altitude and aspect, trunk girth and height if applicable, presence/absence of mammal-size burrows, and soils and pH with geology and drainage. Data will be collected from both - all sites with findings, and a random selection taken from those without, as illustrated in the designated survey walks, e.g. using discriminant function analysis, and possibly principal components, similarity coefficients and cluster analysis.
Statistical analyses of the data will be taken in order to deduce any relationships between groups of measurements; relative to live/dead beetle specimens found; and relative to weeks when numbers of findings peaked during summer.
Some data will also be compared with findings taken in 2003 by volunteers Mark and Jean Wagstaff. However comparisons will be limited, as the Stag Beetle Project is the first coordinated survey of its kind in Richmond Park
Richmond Park has already found recent analyses to be inconclusive. My objective is to further determine this, using statistical analysis and to quantify inconsistencies within the results. This will be used to ultimately evaluate the quality of the survey: taking into account e.g. the volunteers, their timing, and design of the walks.
POSSIBLE OUTCOMES – Why results may be inconclusive
Results may also be inconclusive due to the fact that there is very little comparison to be made due to lack of data from previous years.
Results show that most finds occurred within 200m of park boundaries and within around 50m roads within the park. Other finds were noted just beyond park boundaries. If stag beetles are migrating to or from beyond Richmond Park this may affect my results? It is possible that these effects are due to most walks starting by roadsides and along park boundaries; or the relative lack of finds further within the park may be due to a larger number of predators in the area?
The population distribution of stag beetles may be limited and/or ‘kept in check’ by increasing numbers of predators, e.g. mammals, birds, and human activity. Thus, if stag beetles were not declining and a wide number were found, it would be easier to specify the types of habitat they prefer. Plus, if higher predation affects the selectivity of stag beetles this may force them to migrate between park boundaries: explaining the lack of findings further within the park.
Any recommendations for monitoring or conservation may also be given, e.g. loggeries for stag beetles, such as that at Kew gardens, provide excellent stag beetle habitat, but may also be obvious ‘beacons’ to predators like crows and magpies.
CONCLUSION
It is most important to currently monitor and conserve sites of stag beetle emergence and reproduction in order to sustain and, ideally, increase their population.
This therefore makes the case for continued surveying within Richmond Park and possibly the local community to find any migrating beetles.
It is hoped that my own research will contribute to future habitat research in Richmond Park.
