an experiment...

Hi Will

That is an an excellent result, more than we have managed to achieve in Merseyside in that amount of time with a group of observers in different places!

Nonetheless, it proves the value of walking round the same area several times. It is surprising how many extra lizards are recorded with this method. The problem is that the weather rarely remains suitable for a whole five hour period. It either becomes too hot or clouds over!

That turquoise male is really attractive!

Cheers

Mike

Thanks for your comments Mike; it only goes to show that your Merseyside lizards are much more thinly spread (even at foci) I guess, than Dorset lizards.  I was also lucky with the weather, which was ideal for the whole 5 hrs, not common as you say !

Jon - yes, I was careful not to re-count individuals and used photography whenever possible (long lens, no disturbance).  I agree also that reptile surveying is season-dependent for each species.  We all tend to focus on different species as the spring warms up.  Adders are perhaps similar to sand lizards in the importance of finding foci (eg hibernacula for adders, and core areas for sand lizards) at certain times of year.  I would agree with Steve that for population estimates concentrating on hibernacula at the start and end of the active season is best, but that establishing areas of summer occupancy and migration routes where applicable is also vital.

I think you are both right, Jon from the consultancy aspect where detection can be very low for adder unless 'foci' are targeted, Steve on a longer term survey without time constraints or covering a wider area of habitat than a potential development site.

Adder have a generally low population density, it takes time for them to intercept ACO and many consultancy based surveys just simply 'miss' the bulk of the population and so only detect presence at low numbers if at all. It isn't a good picture of the real situation. It takes far more effort than the usual 7 visits to achieve anything like a population estimate.

Steve with longer-term survey or more widespread targeting will see a completely different picture of adder populations. I certainly find the dispersal and the migration to the summer feeding grounds a great time for seeing adder, but particularly when I already know where to target my effort. That tends to mean there was a lot of 'down time' trudging around for days seeing nothing at all in past seasons until I stumbled across where everyone had got to!

Hence once you know an adder population(s) you can find animals at any time during the active season. If you don't know the population there isn't usually the time available in the world of consultancy in my opinion to really formulate a picture and check all suitable habitat over a wide off-site range.

For such work at a new site, I agree with Jon that I can't make an assessment just from summer sightings or un-targeted spring survey, in such cases I've relied on past knowledge to locate suitable 'foci' and likely important areas and base assessments for capture effort etc from that. So far I've not got it wrong, on two projects I detected adder presence on the extends of the site yet felt the works would not impact the adder populations and that is exactly how it turned out with not a single adder showing up during the mitigation works, yet I knew exactly where to find them each day just a few meters behind the exclusion fence. I guess that is the pay off for spending half my childhood working out where I did and didn't see adders.

Interestingly I now know of 4 populations where the summer feeding grounds and the hibernation area are within a few meters of each other. I agree therefore with Jon that they act as generalists, given suitable habitat, they don't actually migrate at all as they simply don't have to, though if needed they will and those habitats can be variable.