Provisional Report

Twenty eight volunteers returned stag beetle road-casualty data, with returns coming from seven different counties and London. 20 returns were from Suffolk, two from Sussex and one each from Berkshire, Essex, Hampshire, London, Surrey and Somerset.

Stag beetle road casualties				Live stag beetles observed on roads
Male	Female	Unident.	Total	Male	Female	Unident.	Total
66	106	54	226	38	48	2	88
Female:male ratio = 1.6:1				Female:male ratio = 1.25:1

Table 1 Numbers of dead and living stag beetles counted in the 2006 survey

A total of 314 stag beetles (or their remains) was observed on the roads and the number of times a route was surveyed varied from 3 to 68, the average being 22. Thirteen volunteers surveyed throughout the ‘stag beetle season’.

The total number of road casualty and live stag beetles observed along an individual transect over the ‘stag beetle season’ varied from 0 to 90.

Excluding the beetles whose sex was not identifiable (Unident.), female beetles killed on the roads outnumbered males in a ratio of 1.6: 1. Previous stag beetle road casualty surveys (Hawes) show female to male ratios of 3.5, 2.4, 3.4 and 2.2: 1.

The mean ratio of female to male stag beetle road casualties for the years 2000, 2003, 2004 and 2005 (excluding those where sex was unidentifiable) is 2.6: 1. Of the 54 stag beetles whose sex could not be identified (corpses too damaged) the proportion of females to males is unknown.

Comments and discussion

One Suffolk respondent who had recorded beetles along his road transect in the years prior to 2003, reported that no stag beetles were observed there in 2006, a repeat of the results he obtained in 2003, 2004 and 2005. The colonies along this route are probably extinct.

Four transects gave zero sightings.

One surveyor collected and recorded 26 stag beetles of unidentified sex. These had parts missing vital to sex identification (examination of the corpses, where sex was not able to be determined, has yet to be carried out).

Surveys carried out several times a week gave better results than those carried out once a week. Surveying throughout the adult season is essential if this method is to be used to calculate the sex ratio. The sex ratio changes as the season progresses. Males are more abundant early in the season, emerging approximately one week before the females. As the season moves on females become more abundant than the males, the latter dying and declining in number before the females.

Surveying throughout the adult season is essential if this method is used to calculate an annual index of abundance.

To date, seven surveyors have submitted the stag beetle remains and corpses that they collected. The dead beetle remains were useful in (1) confirming the species (2) confirming the sex (3) attempting to determine the sex of specimens (by examining the genitalia) where this had presented difficulty for the surveyor and (4) providing material for DNA analysis and body measurements at Royal Holloway University of London.

Conclusions

Annual road casualty surveys

These are easily repeatable road, track or footpath belt transects (collectively called road casualty transects), which are designed to give an indication of trends in stag beetle abundance. The method is not suitable for calculating stag beetle population size.

The method has proved reliable both in local and national surveys, is easily repeatable and can be carried out quickly. It is a good indicator of stag beetle presence or absence, requires no special equipment or chemicals and can be used along footpaths, pavements, tracks and roads of all types . .

Surveyors found no difficulty in distinguishing stag beetles from other species, which suggests that annual road casualty belt transect surveying to monitor these insects can be undertaken by volunteers from the general public.

The results indicate that road casualty surveying for Lucanus cervus provides a suitable method of monitoring the species presence or absence. To date it has proved to be more effective than parallel studies carried out by the author where pitfall and cross-vaned flight interception traps were used. However, it is not intended that the road casualty belt transect method should replace trapping, but be used to complement it. Stag beetle road casualty numbers could be used to calculate an annual index of abundance for specified transects, thus providing a monitoring system for the species, much in the same way as transects are used to monitor butterfly numbers.

Road belt transect monitoring of stag beetle flight

This method has also been used over a set period of time in the evening to count stag beetles along roads. Stag beetles are crepuscular. The results will be used to calcu April 23, 2007 15:39 y are most active.

No of road transects	Stag beetle road casualties				Live stag beetles on road			Total stag beetles observed
	Female	Male	Unident	Total	Female	Male	Total
82	447	193	199	839	205	111	316	1155

Table 2
Cumulative totals of living and dead stag beetles counted in the surveys in 2000, 2003, 2004, 2005 and 2006

The mean ratio of dead females to dead males counted in 2000, 2003, 2004, 2005 and 2006 (excluding those where sex could not be determined) was 2.3 : 1 (Table 2). Stag beetles produce roughly equal numbers of female and male offspring. However, female stag beetle road casualties, on average, outnumber those of males by more than 2 : 1. A possible explanation for this difference lies in the behaviour of the two sexes. Although both sexes can fly, females spend most of their active time on the ground searching for a suitable place to lay eggs, whereas males spend the greater part of their active time flying in search of females with which to mate. Thus females are more likely to be found crawling on footways and highways than males, where they are vulnerable to passing pedestrian and vehicular traffic.

Acknowledgements

I am indebted to all the volunteer surveyors who took part, and especially to those* who have contributed to all five surveys referred to above. Suffolk: Guy Ackers*, Janet Baker, Janet & Jim Buis, Bob Deex, Marion Finbow, John Glazebrook, Doug Harper*, Sarah Hill, Rosemary Milner*, Nicola Moxey*, Gill & Chris Pink, John Tombs*, Mark Usher, David Walker*. Berkshire: A. Pickford. Essex: Maria Fremlin. Hampshire: M. & J. Willbourne. London: Mark Wagstaff, A. N. Other. Somerset: Nicolas Freeland. Sussex: F. N. Allen, Pauline Griffiths.
Any errors and omissions in the above are the responsibility of the author, for which he apologises.

Reference
Hawes, C. (2006). Stag Beetles 2003-2005. White Admiral 63.