RAUK - Archived Forum - surveying grass snakes

hi, i'm currently surveying most reptiles and such at merrist wood college, guilford, as i am a student. any way we have a few tins next a small water pit ( about 10m X 10M). i would have thought that there would have been grass snakes here, but to my urprise i have only found 2 adders and a slow worm on a different time.

so does anyone know of any secure ways of seeing grass snakes or any survey techniques . would it be better to use roofing felt instead of tins?

anything is of help.

mark jacobs

Grass snakes will use tin, though the majority of my Natrix sightings are visual.

Pick a day that is overcast but not too cool and start early. Grass snakes will start the day openly basking, but their isn't much of a window before they become active and more difficult to locate on warm days.

Don't assume that they will bask directly next to a pond either, look for cover nearby that catches the early morning sun.

(Comments invited on whether or not visual survey is a forgotten art)

Hi Danial,

It's getting late in the season to pick up adder visually, though you may still find some gravid females lying out, best time is mid February and through March, good counts are possible.

Though I agree the effort put in is often greater for visual, just as a comparison IÔÇÖve surveyed a site just outside of the M25 for the last 2 seasons, I think it was around 12 visits before we picked up a single neo berus under tin. Returning in the spring I recorded 6 adults in 45 minutes visually. So targetted visual survey can actually be more effective. I also think visual techniques often give a better feel for the ecology of the animals at a given site.

I've yet to record a single adult adder under refugia at this site, though they are in the right place and adder are often sat around in the grass inbetween refugia. However, tin can be good when placed in foraging grounds and for picking up neo's to establish presence.

I really do think that visual survey techniques are underestimated and largely ignored in favour of refugia, which may appear quick and efficient, but may also fail to pick up some species at a site which could be located by simply 'looking'.

PS good luck with the adders in Greater London, I'm still looking without much luck so far around the Kent border. (I own up to giving up with visual at one site in favour of refugia, both methods have their merits)

Hi Al,

I just did a total of my adder sightings this year over 4 counties, over 40, all visual.

The rub is all were at survey sites with tin and felt refugia in place. Still can't beat refugia for slow-worm sightings though, 2 visual all season 50 billion refugia :0)

I was out with a consultant a few years back whilst they 'taught' me how to survey for reptiles. Whilst stomping from one refugia to another as quickly as possible she asked if I had seen anything visually, laughed, I could have cried.

i was surprised when a friend of mine ,who works for GPM & EPR, told me how much refugia needs to be placed out. what is the best refugia to put out tin or roofing felt? or something completely different?

mark 

I would go for a mix of tin and felt as both can be good and one is sometimes better than the other on any given day depending on the weather conditions.

Dr. Lee Brady is currently studying if reptile species favour one or the other, so most survey sites I visit have both tin and felt in pairs. I'm sure Lee won't mind me mentioning that preliminary results show a preference for tin by adder and a preference for felt by slow-worm.

Density is often a balance between possible public disturbance, ability to lug refugia across the countryside and consideration as to what you are trying to achieve, i.e. to establish presence/likely abscence or relative population size. The Froglife guidelines give a maximum of 10 per hectare for example for establishing relative population size, but as Tony states if your pulling animals out as part of a mitigation as many as possible would be placed. Something in the region of 25 paired refugia might be convenient for a preliminary presence/abscence study.

Mark,

here are some times and materials that produced Grass snake records today, timing visits can be crucial, most of these refugia were meadium shaded by vegetation and begining to feel cool to the touch (note time is GMT not BST).

i went out today with my surveyor friend, at about 12. although it is the hottest part of the day i found an adult female adder , i sub adult male grass snake and 1 huge grass snake female all under tin.

very pleased.

my friend has advised me about the best places to place tins. i found another 4 tins, 1 very large egg laying site and what looked like a very large old hibernaculum. there seemed to be many natural basking sites over it .

is it advisable to cover these with tins like my friend advised? or is it best to just leave this well alone and allow for natural basking.

what do you all think?  i will post photos soon. mark

Hi Mark,

be careful with 12 being the hottest part of the day, if you ment 12 British Summer Time, it was only 11 GMT, still within the morning 'window' when you can expect to record animals under refugia. Roughly from 8.30 - 11 GMT in the morning 2-4.30 GMT afternoons - though it varies with the weather, the site, placement of refugia etc etc etc, you'll find though that visiting around these times can optimise sightings.

I wouldn't place refugia on an area which I knew was used by an individual for basking, it's usually more important to go for a good vegetation layer under the refugia than anything else. But do make use of features such a brambles, placing the tins on the south side is often good.