Introduction
 The
following methodology is based on survey work normally required in the
Northwest of England and north Midlands, i.e. Cheshire, Lancashire, Staffordshire
and Shropshire – our main areas of employment. As such it deals
with the species encountered in the region: common lizard, slow worm,
grass snake and adder.
Survey Period
The key time periods for the survey of reptiles is April, May and September – these
are the months when are temperature is low, but the sun is still shining,
thereby encouraging reptiles to bask. April and May are the preferred
months, being the reptile mating months, when animals are more obvious
and less wary of observers.
Surveys are best undertaken between 0900 and 1100 hours and between 1600
and 1900 hours. Surveys in the middle of the day tend to be less effective
as most reptiles will have warmed up and become active.
Survey Methodology
The survey site is to be walked and key areas for basking be mapped
and targeted for subsequent survey. Prime basking areas include sunny
spots is dense vegetation, pools of sunlight deep in wooded areas and
south facing banks such as those along raised hedgerows or ditch sides.
Once suitable basking sites are identified, refugia will be set down
in the areas. Refugia will consist of sheets of tin, roofing felt, wood
or black plastic not more than 0.5m square in area and should be hidden
in vegetation to avoid unwanted disturbance. The location of all refugia
is to be mapped and each refugia numbered to aid recovery at the end
of the project.
Once established, the refugia are to be left in position for a period
of approximately 10 days and then monitoring should commence for a
minimum of five days. All monitoring should be done on suitable sunny
warm days
and be within the time periods stated earlier.
Species Requirements
Common Lizard
Common Lizards will bask between temperatures of 9° C and 18°
C. Surveys in late August and September may reveal young lizards. The
hatchling lizards are more numerous and active than the adults and hence
easier to find. They also provide evidence of breeding within, or close
to, the survey site. The common lizard does not hibernate communally,
so individuals can be found dotted around the survey site.
Slow-worm
 Slow-worms
are found by turning over debris / refugia and are rarely seen in the
open. However they do bask and the timing and temperatures are similar
to the conditions favoured by common lizards. Hatchlings, born in September
rarely bask. Slow-worms are frequently found in urban and suburban situations
– along disused railways and in allotments for example.
Grass Snake
 Grass
snakes use a variety of habitats, but tend to be associated with fresh
water bodies due to their (the grass snake’s) diet. The grass snake
is more nervous than the other British reptiles so surveying needs to
be undertaken with care; grass snakes may bask partially concealed by
vegetation. The grass snake basks in temperatures of between 12° C
and 20° C
The need of grass snakes to incubate their eggs provides additional
monitoring opportunities. Suitable egg-laying sites (compost heaps,
stable manure,
grass cuttings etc) can be checked by surveying for basking adults
close by, or by searching for entrance holes in well consolidated
piles of
sawdust or cuttings. Young can be found in September.
Adder
 Surveying
for adders is best undertaken in the spring as they leave their hibernation
sites. Several snakes can be found basking close to the hibernation sites
together. Hibernation sites can also be detected by looking for collections
of sloughs (cast skins). Adders cast their skin for the first time in
early April soon after emerging from hibernation. Adders bask in temperatures
of between 8° C and 16° C: they are less tolerant of higher temperatures.
Adders are less nervous than grass snakes and therefore easier to approach,
often basking in the open and moving away slowly. Young adders are born
live during August, but are secretive and hard to detect.
Summary
Reptiles are best surveyed for on warm sunny days in April, May and
September. Different species have slightly different basking requirements,
mainly governed by their temperature requirements and breeding biology.
Refugia are set to provide artificial basking sites and these are monitored
on a regular basis over a given period.
Further information on survey and recording of all amphibians (and reptiles)
can be found in The Herpetofauna Workers’ Manual published by JNCC.
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