RAUK - Archived Forum - reasons to explain adders absence

on the south Wales coast there are two dune systems, one at Methyr Mawr and the other at Kenfig, at kenfig there are common lizards and grass snakes but no adders, at Methyr Mawr there are adders and i imagine both other species. trying to think of a possible reason why adders havent choosen to or been able to settle at kenfig, there very close to each other being on the same stretch of coast, any one have any ideas?

Hi Mike,

I've seen the same a couple of times before, adjacent habitats one with adder, the other without. Taking it to individual site level I find adder will use specific areas and be totally abscent from the rest of the site that looks at first to be equally as good. Factors such as basking opportunity, cover and food source play a part in this and though difficult to measure in the field, may give clues as to why one area of habitat has been colonised and another apparently similar, has not. Also consider that adder can be very 'traditional' with regard to hibernacula, basking areas and foraging grounds.

I agree with Lee though that it could just be down to chance. I'm currently surveying a site that looks ideal for slow-worm, plenty of vivi lizards are showing and grass snake are known to be present, so far not one single slow-worm and none have ever been reported.. if they are abscent I can see no good reason other than slow-worm have not reached the site in sufficient number to establish a viable/detectable population.

M Mawr does have more dense veg on a wider area but i still think kenfig has enough suitable to allow for adders, certainly other factors should all be favourable. Kenfig is being left to natural succession if i remember correctly and there are areas of good scrub and woodland, especially by the lake which i would guess would be excellent summer hunting grounds. Chance may be the key or habitat choice, i dont think that there there in such a small number as not to be found as the site is too widely walked etc mmmmm good question this :) thanks for ya ideas 

yeah i know Dave,  due to do some work exp next month when i hand my MSc dis in next week, if grazing is their approach then yes i'd agree with the loss of site suitability there, how much high ground is there, not a great deal for hibernation sites? 2/3rds floods in winter if i remember correctly could have a good reason here, not to sure on n natrix hiberntion whether its similar?

Mike,

berus and natrix will share the same hibernacula, so one could presume requirements are broadly similar. (adder hibernaculum are known to range from grass tussocks to the more obvious rotten tree stumps, banks and mounds). I would place hibernation opportunity very high on a list of criteria if making an assessment of a sites suitability for adder.

Mike,

I'll back Lee up on this 100%, I surveyed a site in 2003 intensively for adder. It took 12 visits to record the first individual, a neo, using both refugia and visual techniques. It was only returning this year in the early spring that I caught up with the main group emerging form hibernation and established that a good population was present. This was only possible by focusing visual survey around the immediate area where the neo was recorded the previous autumn.

Having said this, I also managed to find 3 gravid females within 60 seconds of stumbling out of the car at a 'new to me' site this year, as Lee said it's often easy to establish presence, absence is a whole different ball game!

thats interesting, i have survyed the site only one day and it is a huge site, nice pic of a common lizard, but was told no we dont get adders here only grassies by the warden, hes done the job for years and is there everyday seemed very certain of the lack of adders. brings up more questions and uncertainties hehe dam this disertation :P

is there any idea on mortality on females when they give birth? imagine must put them through some stress taking that they need a year off to recouperate before breeding again.

the thing that still amazes me is the paper infront on me now 'beyond hypothesis a long term study of british snakes' Phelps T, June 2004 British Wildlife, where tony found the same adder and smooth snake making them over 30years old!  did you see them between 1976 and 2003 or were there good at hide n seek?