The Essex Naturalist
85
Mortality
By far the majority of dead stag beetles found appear to have been the victims of
traffic, either pedestrian or vehicular.
Several respondents reported numerous dead individuals along footpaths,
particularly where these ran adjacent to mature hedges, presumably breeding
sites. Whether the beetles were accidentally or deliberately stepped on is
difficult to ascertain. The number of crushed bodies on the roads leads to the
conclusion that road traffic doubtless accounts for countless stag beetle deaths
and, indeed, many observers mention this in their reports. Direct observations
are limited to a couple of reports of flying beetles striking moving vehicles. The
insects seem to be especially vulnerable when walking on the carriageway, it
may be that the warmth of the road surface is attractive to them as it can be to
other wildlife (Slater, 1994).
One observer monitored stag beetle numbers on a regular cycle journey
through suburban Colchester of about 2.5 miles. He made an attempt to count
each individual beetle once only. Between 1st June and 24th July 1996, 70 stag
beetles were seen along the route, of which 63 (90%) were dead.
Accidental drowning appears to be another hazard to adult beetles. Eleven
observers reported ponds, drains, buckets and even a bird bath as hazards. In
several cases the beetles revived after being placed on dry land.
Instances of people deliberately killing stag beetles are fortunately few and are
usually the result of fear or ignorance such as in the case of a stag beetle being
doused with a proprietary ant powder.
Several observers noted beetles with missing appendages or cracked
exoskeletons, presumably the result of accident or attempted predation. Two
instances of mites attached to beetles were noted. It was not possible to
determine whether these were ectopatasitic or phoretic species.
Predation
Thirty-six instances of interactions between stag beetles and other animals were
recorded, including many actual or attempted cases of predation.
Amongst the mammals a hedgehog (Erinaceus europaeus) was observed eating a
stag beetle. Hedgehog predation is also mentioned by Hodge (1995) and Steggall
(1996). Ten reports of domestic cats catching stag beetles were received. The
insects were either taken on the ground or caught in flight. One cat was observed
to actually eat the beetle whilst others gave up after receiving retaliatory nips.
Birds also figure highly among predators of the stag beetle. One beetle was
seen to be eaten by jackdaws (Corvus monedula) after it flew into a lilac tree.
This bird is known to include a high proportion of insects in its diet and has
previously been seen to prey on Lucanidae (Cramp et al, 1994).
The magpie (Pica pica) appears to be a significant predator on stag beetles in
north-east Essex, behaviour which has also been recorded in Suffolk (Hawes,