Do covers used for surveying benefit reptiles?

Sorry if this question or subject has been discussed before. I don't remember it, so here goes...
In placing tins of felt or other materials as covers to enable surveying, is the habitat being made more beneficial to the reptiles? In raising the body temps do we help them to digest their food quicker, shed their skins more speedily, reach breeding condition more quickly after hibernation etc?
Have any comparisons been made of the health of a population at a site with covers against one with no covers? To help avoid variables it would seem best for maybe a site to be split in half, with one having no covers. Would the half with no covers show a movement to the half with covers? Maybe this is already researched and written up somewhere.
I notice on this site that high saturation of covers is mentioned at times. Again is this even better than 6 sets of five tins widely scattered?
Overall I'm wondering are covers beneficial for reptiles or just spreadsheets?

Interesting Gemma. Thanks for replying. So I guess in seeking to monitor populations we are in fact having some effect and it can't be considered a neutral action.

Any home range and local population undergoing study should not be monitored in such a way so as to draw attention to the area (such as grid referencing using stakes and marker tape, or high numbers of ground sheet refugia!). Anything that encourages attention to the animals such as the prominent and obvious installation of Artificial Covered Objects (ACO’s), inevitably leads to disturbance and which is likely to be detrimental in the long term.

 

In these studies, “Tins” (ACO’s) were not used as in the opinion of the author they can often provide a disproportionate population indicator in that snakes using such refugia were not then inclined to move as freely as at sites where no such cover existed. “Tins” placed at locations known to contain reptiles could simply encourage reptiles to remain and encourage indolence in species which are supposed to travel and / or migrate!

 

Fallen logs and more natural field cover which can take years to provide suitable day-time refugia will help build a natural course by which many generations of snakes will follow by scent trail and indeed, the ditches, and similar passages provide the normal migration corridors which may not be used if man-made refugia is placed, especially if they become attractive to toads and newts. The whole home range mapping can then become an unnatural falsification of local population numbers.

 

 

                        Figure 12: Basking area 2010 prior to the installation of Artificial Covered Objects

                                           Note the natural migration movement across site during summer.

 

Three study sites included an enclosed farm site without public access and surveys were undertaken in the summer of 2010 and which showed regular basking areas for Grass Snakes to be beside a hibernacula beneath tree roots in a raised south facing bank and adjacent to natural ‘obstacles’ such as fallen logs, stumps etc, which had appeared over the course of time, to be utilised by different members of the group in a circular migration movement around the site. In the autumn, tins were placed at strategic positions around

 

                        Plate 67: Overhead shot from balloon which sets out the details of the farm site.

 

the pond and from there along the migration ditch and stream which also included many of the natural refugia sites back to the vicinity of the hibernacula used by most of the group.

            Figure 13: Comparative study of sightings in 2011 – note the reduction in sightings generally

 

In the Spring, surveying of the site was again instituted and it was found that upon emergence from hibernation although the snakes appeared as expected close to the hibernacula, during the following weeks they began to ignore the more natural refugia in favour of the tins and individual snakes could then be found under the same tin repeatedly, until hibernation again drew close in October / November when most of the group could be found again in the vicinity of the hibernacula. The most striking aspect of this preliminary study is not only how the preference changed from natural refugia to the Artificial Covered Objects, but also how the previously recorded migration around the site was not observed in 2011, but instead the individuals maintained a presence under tins much closer to the hibernacula and for all year round.

            Figure 14: Recorded observations under tins in 2011 compared to more natural refugia

 

Observation point numbers 3 and 5 for instance, which in 2010 recorded a steady level of sightings in summer suddenly ceased in 2011 to have anything like the same number and whereby the mid point on the site was seemingly abandoned in favour of ACO’s close to the hibernacula and point 2.

 

To the Author’s knowledge no other study has been set up to show if snakes begin to show a preference in similar situations, or if the impact as a result of installing or removing ACO’s from any given site is detrimental to site observations generally. Nor is there any alternative detailed data of the impact that the presence of ACO’s might present to the movement and seasonal migration of snakes. Until such studies are undertaken and the results fully understood, any national reptile survey protocol which includes ACO’s as the primary source of statistical data, as opposed to the repeated transects of criss-cross site monitoring will be based upon the possibility of skewed information, the results of which should not necessarily be relied upon as being accurate or representative of a wider distribution.

Thanks Robert. All very interesting. 

I don't think anyone would mind Rob if you self promoted on the forum in any case, we might have pulled your leg about it in the past but it was just banter.