Summary of results of stag beetle road casualty survey

19 volunteers returned results

Returns were received from 5 different counties.

15 returns were from Suffolk, and one from each of Essex, Hampshire, Surrey and Sussex.   

Returns were all from stag beetle hotspots (except Pakefield, near Lowestoft, Suffolk).

168 stag beetles (or their remains) were observed on the roads.

The number of times a route was surveyed varied from 5 to 80+, the average being 20.

Excluding the beetles whose sex was not identifiable, female beetles killed on the roads outnumbered males in a ratio of 3.4: 1. Previous stag beetle road casualty surveys (Hawes (1998; 2000; 2003) show a minimum female to male ratio of 2.8:1.  The mean ratio of female to male stag beetle road casualties for the years 2000, 2003 and 2004 (excluding those where sex was unidentifiable) is 3.0:1.0.

Of the 40 stag beetles whose sex was not identified the proportion of females to males is unknown.

1 volunteer surveyed her chosen route on too few occasions (route surveyed 3 times).

One surveyor did not carry out a road casualty survey but submitted stag beetle records from her garden.

Comments and discussion

One Suffolk respondent cycled his hotspot route on 80+ separate days (which in the years prior to 2003 revealed a number of stag beetle road casualties) but no stag beetles were observed in 2003 or 2004. The colonies along this route may be extinct.

Another Suffolk surveyor also recorded nil sightings (road casualties, or live beetles on the road or elsewhere), even though stag beetles had been seen in her garden and on the road in 2002 and previously.

Two other survey routes produced zero sightings: (1) Pakefield, near Lowestoft, Suffolk (TM 59),

(2) Worthing. Only two stag beetles have ever been recorded (to my knowledge) from north   Suffolk, one in 1899 (Lowestoft TM 59) and one in 1980 (Reydon, near Southwold TM47).

Worthing is a noted hotspot for stag beetles, where the species appeared to be doing relatively well (PTES 1998 National Survey).

One surveyor collected and recorded 24 stag beetles of unidentified sex. These had parts missing vital to sex identification.

The two surveys carried out throughout the period 01 June to 14 August in one case, and 04 June to 07 August in the other (the adult stag beetle season) gave the best results.

Surveys that were made several times a week gave better results than those carried out once a week.

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

Eight surveyors submitted the stag beetle corpses and remains that they had collected. The dead beetle remains were useful in: (1) confirming the species, (2) confirming the sex, (3) attempting to determine the sex of specimens where this had presented difficulty for the surveyor and (4) providing material for size comparison and DNA analysis at Royal Holloway University of London  (RHUL).

Stag beetle sex ratios

Of the total number of sightings where sex was distinguished (1,270 individuals) in the stag beetle survey of northeast Essex, 52% were of males and 48% of females (Bowdrey, 1997). An analysis of the number of stag beetle sightings made in the two national surveys of stag beetles of 1998 and 2002 where sex was recorded showed a total of 8,334 (54.3% males: 45.7 females) and 3,189 (51.9% males: 48.1% females) respectively. The average male to female sex ratio for all three surveys is 1.1: 1  (Hawes, in press).

Monitoring stag beetle flight

The road casualty method of surveying stag beetles has been adapted for monitoring stag beetle flight.  (see volunteers required).

Recording stag beetles in 2005

Records of all stag beetle sightings are required. Please send them to me and include the date and location of the sightings, a grid reference is also helpful. If beetles are recorded from your garden, please include your postcode. I will pass the records to the Suffolk Biological Records Centre and the People’s Trust for Endangered Species (PTES).

Volunteers urgently required for 2005

By the time you receive this 2005 Spring Newsletter the stag beetle season will be almost upon us, with the first beetles emerging mid to late May, if the weather is warm. Volunteers are needed to take part in stag beetle road casualty and flight surveys in Suffolk (and other counties), especially at sites that are stag beetle hotspots, and at locations on the edge of the beetle’s range. The surveys require the volunteer to walk the same route (500 metres) regularly and count the beetles that have become the victims of pedestrians or vehicles. Several volunteers in previous years have combined their regular dog walking with the surveying. 

Further details can be obtained by contacting
Colin Hawes
at 3 Silver Leys, Bentley, Ipswich, Suffolk IP9 2BS
by telephoning 01473 310678
or via e-mail: colinjhawes@btopenworld.com

Thank you to all who were kind enough to send me records of your stag beetle sightings made in 2004. A special thank you to the stag beetle road casualty survey volunteers (Guy Ackers, Angela Bamford, Janet and Jim Buis, Maria Fremlin, Richard Gant, Dr Douglas Harper, Moray Henderson, Sue Medcalf, Rosemary Milner, Nicola Moxey, Elaine Sinclair, Mrs F. Strang, Duncan Sweeting, John Tombs, Mark Usher, Mark Wagstaff, David Walker and Peter Winter), who provided valuable monitoring data for 2004 and stag beetle corpses for the studies taking place at RHUL.

Colin Hawes

Suffolk lead partner for the stag beetle biodiversity action plan
PTES steering group for the UK biodiversity action plan.

© 2005   Suffolk Naturalists' Society

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