RAUK - Archived Forum - Reptile Habitat Management

Well you know my views on bracken Lee, but to start the discussion off I will post a few pictures to illustrate why I believe on some sites bracken is very good and should be preserved at all costs.

Firstly a general view of part of Hindhead Common Surrey in early spring

Not hard to imagine emerging adders and mate searching males here is it.

A view of the same area in mid summer

(imagine visual survey in this lot, impossible there can't be any reptiles here I hear you all say... but)

A shot taken at the base of the trees in the mid ground of the picture above on the same day

...  adder, slow worms, vivi lizards and grass snakes in abundance

The key to this site is that the lying bracken has built up over many years giving superb structure. Also it has piled up high enough in some places that even in the height of summer when it looks like a forest of green bracken, many basking spots are still open and sunny.

~Rating "totally superb do not disturb"~

Based on VEGETATION STRUCTURE

(Sorry to any botanists out there)

Anthills, grassy tussocks, all indicators of lack of management such as mowing, heavy grazing - The anthills are used by Lizards for basking and of course they also use them for overwintering (i suspect) adult and juvenile lizards have been found in the 'inactive' parts of anthills in a site in Essex.

Adders are often found at the base of birch trees along a tree line with bracken, bramble, molinia - these trees provide underground cavities for shelter. All the things that land managers want to get rid of -

I would agree that habitat structure is vital for reptiles, invertebrates and mammals - even some ground nesting birds need some structure otherwise they are sitting ducks excuse the pun

Sadly this habitat structure is a threat to flora diversity - so in comes the bovine mowers, mechanical mowers, tree clearance, soil stripping etc etc just to increase the flowers!

I will be very interested in helping with determining the habitat index for reptiles - as the majority of their habitat is not lowland heathland in the UK! and so we need to look outside the superior habitat and into others

JC

Right as lot of the land managers i deal with are mainly concerned with flora, oddly enough 'habitat' aswell when i mention reptiles and their needs on sites. We need to link 'positive' benefits that features which are often overlooked or are not considered to be important - say anthills within a rough grassland or molinia tussocks both are very important to biodiversity - invertebrates, mammals etc

Measuring the 'structure' of a particular feature using a simple scale as the one used on the GCN HSI - Poor, below average, average, good and exceptional? -

An example

Anthills are good features when they exist within reasonably rough long grass - the anthils provide good basking opportunities while the cover provided within the grassland can allow for foraging - In some grazed fields the anthills are leaft in very short swards -the mown lawn effect - the anthills become unsuitable, inaccessible to animals like reptiles - of course if old anthills are surrounded by heavy scrub - th eanthills will eventually cease to exist but the shading would also make the habitat feature unsuitable.

it is going to be very difficult to measure HSI for reptiles - maybe if the habitat is broken down into smaller units - say for adder we look at the population's hibernation areas,  foraging areas which can be assessed using habitat structure measurments - percentage of shading (scrub/trees) level of protection (bramble/gorse etc), height of grass sward (low to high).

fixed point photography can be used to measure changes in vegetation - just like Gemmas pictures at Hindhead - with proofing on the ground using other measuring devices? 

The essential features of good vegetation structure be it primroses, bracken or grasslands with brambles and lots of ant hills comes down to one factor.. lack of interference by land managers.

Possibly this is a factor that can be used for an HSI index, managed in last 5, 10, 15 years? I would think it is almost impossible to describe how to spot such areas in any other way apart from listing the sort of features given as examples so far.

Of course this exactly constitutes the sort of area that many land management teams will want to 'tidy up'.

Then it might be asked if any area become fantastic reptile habitat if it isn't managed, well maybe not all (woodland), but look to brownfield sites and perhaps the answer is very often yes for the four widespread species.

Yes

 I would say that there are habitat features which may have more benefit towards a particular species. It seems to me that all the widespread reptiles are lumped together in their requirements - especially in mitigation schemes. I have seen measures undertaken for viviparous lizards are considered acceptable for grass snakes! - the two species have very different ecology and habitat requirements that operate on two very differen scales but these species are often translocated without thought to the possible consequences for conservation.

It is something that the habitat suitability indexes can draw out the discrete differences in ecology between the reptiles - I made this suggestion at the reptile mitigation guidelines meeting in Dorset last year that the Snakes need to be considered separately from the lizard species - highlighting this ecology and the different approaches needed in mitigation and compensation schemes. This was for development relarted schemes and so it needs to be applied to habitat management schemes

I know that the invertebrate conservation agenda (if you will) is coming up higher onto the agenda and in the minds of land managers thanks to Buglife - They have recently published a guide on invertebrates in 30+ UK Biodiversity Action Plans - Habitats in relation to invertebrates and their management for invertebrates we need something for Reptiles. The HSI is a good first step - would this be an HGBI report - could be good to help revitalise the HGBI advisory panel -  

How would we go about testing the indices in the field? At Epping Forest our reptile survey will be looking at habitat changes throughout the seasons and the effects of management - Gemma' ssurveys at Essex sites can look at unfavourable management and I hope remedial action which we will be able to push soon. I am looking at agri environment schemes - countryside stewardship, set aside in several places in Essex, Hampshire and Surrey - how can we pull all this together?

JC

Sorry I didnt mean to confuse things with the mitigation angle - I thought that the HSI would eventually help consultants (hmmmm) to provide conservation gains rather than errrr fulfiling legal obligations to avoid 'killing or injury'.

Anyhow I have been thinking about the vegetation on my reptile sites in Hampshire and Essex - the areas where high levels of grazing or disturbance by machinery is in my mind the least favourable habitat - grass blades less than 1cm even - Reptiles are found in little islands of bramble in short grassland - the brambles provides protection - limited habitat which in turn limits food abundance.

In other parts large areas of grassy tussocks with bracken, small amounts of heather with tree boundaries provides an abundance of food and cover to which the reptiles can bask and move around in -

The interface between scrub/tree lines, bracken, rough grassland and grazed areas provide the best opportunities for reptiles - During the year the bracken grows very high - even higher if it is bashed by the land managers - yet you still get slowworms, grass snakes etc under tins in amongst the bracken -

Maybe percentage of cover at different heights - 1 to 10cm, 10 to 30cm 30 to 50cm 50 to 90cm and then above 90cm - You could either measure the heights with rulers etc - or estimate heights - There is a drop disc - known as a boorman Drop Disc (Smith et al 1993) - Percentage cover estimates by eye in quadrats? Conversion to the Domin Scale (Kent & Coker 1992)

Can this be applied to Reptile habitats? You would measure habitat over reptile suitable and non suitable areas and then match up with survey data - over the season -

Fixed Point Photography would help with points along transects with a suitable scale in photograph the height can be determined?

References

Kent M & Coker P (1992) Vegetation description and analysis, a practical approach John Wiley and Sons Chichester

Smith H Et al (1993) the conservation management of arable field margins English Nature Science No18 Peterborough

Separate indices for the four widespread species would be desirable - its only four species - unlike invertebrates which would run into Hundreds!

JC

I hope you don't mind me keep gatecrashing your conversations, if it is something you'd like to keep between yourselves please feel free to say 0:).

I can only comment on the habitat structure that I have become familiar with over EF. Jon probably knows these areas too, but may have slightly different observations.

Basically. Regular piles of sawn up birch logs placed in a pile may attract the odd Adder but does not attract Grass Snakes and from what I have noticed, Viv lizards don't seem to care for them much either. However. A naturally fallen birch tree where bracken, bramble and grass has grown up around it is great. Conc. Let them rot where they fall.

Birch up to about 1.5M great for ground cover for grass snakes. Once it grows above that, the land around becomes too shaded and dark and the species seeks a sunnier aspect. Bracken banks - essential (if nasty). Why can't managers ensure that instead of scrub clearance, the bracken is piled in banks?

I would agree with Jon that Purple Moor grass (Jon said tussocks) may be where Viv liz hibernates? The managers in EF hate this stuff but like it or loathe it, its where the action is for reptiles. I know it takes over the Heather but even in the autumn its literally covered with garden spiders webs. I'm yet to get a photo of a lizard taking a garden spider but they definitely love the wolf spiders so i would think its a natural follow on. The two other major insect species in that grass; obviously, grass hoppers and also rousels bush cricket. Jon. ask yourself this question. Why is it that the adders are not found on some of the plains? Its not to do with the Heather, there is some of that to be found. What about slow worms? Common where the adders are found - usually in bracken banks! But scarce in those other places. Sorry to say it, but Bracken also has a key role. And again, most managers hate the stuff.

R   

Dont worry about the gate crashing - as this is meant for everyone to have a say. It is always interesting to hear other people's views.

At EF there are other agendas relating to heather and its restoration - The log piles do attract adders as they are often the only places left for the animals to bask on or hibernate in - as the grassland has been grazed and has not left real shelter -

Log piles do attract grass snakes when they are located with habitat around them - Larger linear log piles would also pick up the larger ranging grass snake especially if they follow linear features such as woodland edges, river banks and hedgerows.

The main culprits to degrading diverse 'grassland' 'heathland' and 'woodland' to these nature conservation managers are bracken, bramble, molinia, birch, all have been 'demonised' and they sort have the same feelings about these features as say the general public do about the thought of snakes. You can imagine these people asleep at night worrying about those bracken patches and the need to get rid of them - You can see that in the eyes of the warden at the BW where Gemma has found a good population of adders -

I went there on Saturday and I saw 8 male adders on the two sites where Gemma had shown me last year - it was great! then you see the clearance of the bracken, bramble etc which is close to where the adders are. I have reckonised the adder in the pictures that Gemma posted recently - there are adders with distinct inverted 'V' which joins with the Apex of the zig zag (Sheldon & Bradley 1989) to one side - The males are grouping up basking together -

There is stacks of scrub which can be cleared without much effect on the adder population - by hand of course - but still the top soil is being stripped and piled up in big piles and the bracken is being cleared -

I am trying to get in touch with the owners and the managers over this but we have come up against being ignored - I did have a chat with the Reserves Manager and the Conservation Manager - I tried to reason with them but they are getting pressured from the owners which are unhappy with the SSSI status report from EN so they are trying to get the SSSI to a higher level - unfavourable but recovering rather than declining.

It pretty much the same at EF but there has been a reptile survey project which has been running over last year and it will be running again this year - last year was a pilot and so Rob you could help with this survey if you like - contact the conservators - the ecologist is Imogen Wilde -

The conservators have undertaken restoration works with the help of the reptile survey and a person who is very familar with the reptile population at the site. the follow up surveys will be an important part of assessing the management outcomes. 

Regards

JC

Reference

Sheldon S & Bradley C (1989) Identification of individual adders (Vipera berus) by their head markings Herpetological Journal Vol 1 pp392 396

Jon,

1st three adders in EF today. All similar in size and colour. Further points cont.... For Adders and slow worms, it would appear that birch reaching a height of above 2meters (say) should be thinned to one trunk every 3-4 metres. At EF I am reliably informed that the heavy undualtions are down to the fact that returning bombers in the war used to jetison their payloads before touch down. Whatever. But the undulations seem to be a major attraction to v.berus. the higher banks are up to 1.5 m above regular ground level with the dips as far down as that again. With piles of dead bracken, fallen birch and bramble the undulations create wind break sun traps (south and west facing), collect water in some, and provide safe hibernation as the level would always be above ground water table. The difference in ground temp between sun and shade is more marked than out in the heather banks. good for vb in summer.

If managers are serious about reptile conservation for v.berus, one suggestion could be that any major birch removal/scrub clearance have some digger work included so that these undulations are built in. They could be deliberately located with a southerly orientation.

As far as natrix is concerned, egg laying sites are to be found in very unlikely places in the forest, but, Lee, Jon, Gemma, if you would like to know how a manager can provide these I dont mind emailing you direct with the observations.

Ok Rob