Trapping and sampling
Trapping animals, humanely might I add, is a source of debate within ecology circles. Whether its bird ringing or insect pitfalls, is it right to interfere with an animal’s ‘business’ in order to learn a little more about it?
If done well, and by that I mean carried out with little or no stress to the creatures involved, I think it can be an invaluable source of information.
I have been laying out reptile traps on a couple of East Devon District Council’s Local Nature Reserves recently, and it might come as a surprise to you what this entails. Reptile trapping is possibly the least intrusive form of surveying reptiles. Far from physically trapping an adder, slow worm or common lizard within ensnaring clutches, a reptile trap is merely a sheet or mat put out to entice reptiles to sunbathe!
This form of ‘trapping’ uses the animal’s own behaviour to lure it into a specific spot. Corrugated tin is widely used but can become discoloured or dangerous, so we use simple sheets of roofing felt. The felt is laid out in sunny positions and acts as a solar sink, warming in sunlight more quickly than the surrounding landscape. Reptiles, with their inherent desire for warmth will seek out such sunny spots and warm their bodies beneath or on top of the heat trap.
When surveying the traps each is inspected from a distance using binoculars to see if a reptile is on top of the sheet and therefore easy to survey without causing disturbance. This is the easiest method and it is often adders which adopt this position, so there’s another good reason for not venturing close!
If the sheet is clear, I will then gently make my way up to the trap and quietly lift from a corner to see if anything is taking refuge beneath. I tend to lift towards my body, so that if a well-warmed reptile lies beneath and wants to shoot off, they can do so without bumping into my bodily obstruction. If one lifts the sheet carefully the reptile beneath will often sit quietly, giving you a chance to identify its species – well, there’s only 6 possibilities to choose from and two of those aren’t found on any of the Council’s reserves, more’s the pity. In some cases, such as slow worms, adders and grass snakes its possible to tell the sex of the individual if its an adult, and number of occupancy is also noted.
So far this spring there have been plenty of common lizards and slow worms under the traps, but I have yet to find any serious numbers of adders, something which other reptile ramblers have noted too. There’s a regular basking spot for adders on Beer Head and the guys up there have had some luck, but on the heathland reserves I have only had a single sighting. Could this be because of the sudden cold snap we suffered in early April? Or because of the really wet weather we have endured since then? Does this represent the current situation or is it just a surveying blip – are my traps in the wrong places for adders? They weren’t last year!
These are questions that might be answered through continued surveying, or it might pass and be an previous curiosity to be pondered over a pint. Whatever comes, I will continue to keep an eye on the reptilian life on the reserves, trying to build up a picture of their heath and wellbeing through familiarity.
Birds are sometimes a much easier quarry for the surveyor. By their very nature they are identifiable either by eye or ear, and most of them are active at a convenient time of the day. Birdwatching is undoubtedly the form of surveying with the highest participation in the UK, with initiatives such as the Big Garden Birdwatch, bringing it to people’s attention how important their sightings can be.
Down on the Axe Estuary, records noted in the bird hide log books, combined with local birdwatcher’s private records, provide a wealth of information about bird numbers and seasonality. This is collated into a fabulous yearly report. This tome is put together by a few local birding stalwarts, with a bit of help from Fraser and me at the District Council, and what is produced is, in my opinion, a wonderful reference for local interest.
The Axe Estuary and Seaton Bay Bird Report, should be a feature of anyone’s reference library, and I don’t just say that because I helped write it – honest! Not only does a report such as this give you an insight into where and when birds were seen over the previous 12 months, but it is a complete guide of how to see birds within this location. Where to go, when to go and what to look out for, is the sort of insider’s knowledge I am constantly being asked for – well here it is in one publication. Get in touch with Diane at the Countryside Service on 01395 517557 to reserve your copy now!
Yuck, that was in danger of becoming a sales pitch, so I will quickly move on…
The final form of surveying is one which courts most controversy and therefore has the highest degree of licensing. Bird ringing involves trapping a bird in one of a number of different nets, removing them unharmed and recording a number of statistics before setting them free with a lightweight ring on their leg for future identification.
The number of times the same reed warbler, or kingfisher has got stuck in a mist net at Colyford Common has lead me to the conclusion that the process has little or no ill effect on the birds involved. Also, the data collected is so valuable that a few minutes inelegance on the birds’ behalf is worth it in the long run. From recaptures we have records of bird longevity, health and even breeding status in our patch. As easy as it is to recognise species of bird, it is very difficult to tell one from another, and so ringing birds gives us the potential to identify individuals and therefore understand more about them.
Over the winter more than 100 shelduck were ringed on the estuary, as the years pass, we will be able to recognise whether the population of these impressive ducks is a local one, or are we a staging post for European birds?
The more you dig beneath the surface of the local ecology scene, the more individuals and initiatives you find going on. The people involved are often volunteers and all give a considerable amount of their time in the quest for knowledge. As changes to our climate loom on the horizon, this knowledge base will prove invaluable in guiding our responses and dealing with that change.