When the LGV from Tours
to Bordeaux was being constructed there
were a large number of environmental impacts that had to be considered as a
matter of law these days and I will go into them at a later date. Here I only
want to touch upon one site, Le bocage humide de Chaunay a wetland site site in
the south west of the Vienne departement of some
importance.
All in all at this site some 120 hectares were purchased by Réseau
ferré de France, (RFF), which is the company that owns and maintains the French
national railway network. The land is
comprised of moderately managed small copses and hedged fields that have been
cut for hay. It’s something of an exception among the wetlands of the
department. With no connection to any river an alluvial aquifer feeds directly
into the pools and ditches creating large area of seasonal surface water. With
a handful of man made ponds left in existence another 7 have or are being
created on the 45 hectares that have been contracted to CREN, (Conservatoire
d’Espaces Naturels de Poitou-Charente), for 25 years. CREN in turn are
establishing a management plan with farmers that use the land regarding types
and timing of any hay cutting that will take into account the various species
present.
The site is particularly rich and includes some of the rarer
and endangered amphibian species that have been lost in huge numbers due to the
vast destruction of ponds and habitat throughout the region over the last 50
years or so. I bet like me you must get
sick of hearing this, everywhere we look it’s the same old story and sadly not
getting any better.
Anyway, on a positive note this particular site is
relatively safe although there are some issues that will be difficult to
resolve as we shall see.
When observing or compiling records for amphibian species at
any given site it’s necessary to do this at night essentially combining two
different means. The first is to listen and identify any of the frog or toad
species present. To do this, having approached the pond, we then turn off all
lights and wait 5 minutes as little by little they settle down and get back
into their calling. As with most other creatures each species has its own
unique call and for some it may be the only way we can determine their
presence.
Next it’s light and time for a careful search in the shallow
margins. The water will be slightly warmer here and it’s where mating takes
place for most amphibians. For many species there is no need to actually
capture them, simple observation is enough, indeed strictly speaking it’s
illegal to capture them without being authorised and absolutely illegal to deliberately
harm or move one.
Of particular interest is the Triton de Blasius a hybrid
newt that results from the mating between a male Great Crested Newt, (Triturus
cristatus), and a female Marbled Newt, (Triturus marmoratus), which obviously
requires the prescence of both species. Biologically the males are sterile and females
only partly fertile. There is no typical Blasius but the essential features are
the back with the markings of a Marbled Newt and the belly of a Great Crested
Newt.
Click on photos to enlarge.
Photos below of Triton de Blasius.
Photo below of Male Common tree frog
Photo below of an Agile frog
Photo below of Female Palmate Newt
Photo below of Female Great Crested Newt
Other species are also present at the same site - Marbled Newt, Common toad and Parsley Frog.
There remains as I mentioned one not so small issue and that is the presence of Procambarus clarkii, Red Swamp Crayfish an introduced species from the USA. This species can reach 85-90mm total length and are aggressive in behaviour presenting a threat to the native amphibian species that are there. Due to the protected nature of this site only authorised trapping can take place but as it is a species that will move through ditches and indeed overland in wet conditions total eradication is unlikely.
Photo below Procambarus clarkii, Red Swamp Crayfish
