Amphibian Surveying & Bottle Traps

Another successful trip out with NEW Yorks ARG last night, and a visit to a local outdoor centre to investigate their raised ponds and a more naturalised area. Arriving at 8pm, it was still light so we had a walk around the ponds looking for newt eggs.  We also put together and laid out some bottle traps.

A bottle trap is a simple device made out of a 2 litre drinks bottle and a bamboo cane. The top of the bottle is cut off and the cap removed. This is inverted into the rest of the bottle. A cane pierces the bottle, which has the dual purpose of holding the two parts together, and fixing the bottle into the bank or base of the pond. The bottle has to be set so that it is firmly fixed, the entrance is under water, and there is an air bubble in the bottom of the bottle.  It also has to be clearly marked (we used a 'flag' made from hazard tape on top of the cane) to ensure that all bottles are retrieved the following morning and any captured animals are released. For the same reason, its important to note how many bottle traps have been deployed and in which ponds. 

In practice, it was quite hard to get the angle of the bottle right, so that there was sufficient air in the bottle but this did not make it unstable and too floaty.  The bottle traps did capture some newts in the short time we were there though, so there will undoubtably be more in them when they are retrieved in the morning. The raised ponds had an artificially liner, so we had to be careful not be pierce the bottom of the pond and instead had to use the stone flags along the side to hold the bottle in place. The natural pond was quite shallow, so it was easier to stake into the bank rather than the bottom of the pond.

After retrieving torches from the car, armed with my new Clulite CB2 mega torch, we took a second sweep of the ponds to count the newts.  The raised ponds revealed numerous palmate newts - male, female and juvenile. The webbed feet and tail filament were obvious (even from the slightly dodgy underwater photo) and some were obviously pregnant females with swollen bellies.

There were also several alpine newts. The females were larger than the males and the palmates. They also had a blue-grey appearance from the top, and a bright orange underneath (our native newts are also orange underneath but have speckled bellies). The alpines are non-native and can spread chytrid disease - they were humanely removed and will take part in a university project.

In the natural pond, there were more tadpoles than in the raised ponds - both frog and toad. There were also unfortunately a number of dead toads in the water; there were no clear signs of predation, though their babies were starting to make use of the extra protein ...  We also saw several fleeting glimpses of great crested newts - at least half a dozen, with some juveniles. We were unable to catch one for a definite ID, but they were obviously larger than the palmates, and had a silver flash on the bottom of their tail.

A very successful ARG outing, with five amphibian species identified on the site.

Closer to home, my own pond is also thriving. My frog spawn has now hatched, and I have thousands of colourful tadpoles. We also have some newly laid frog spawn, a few weeks behind the initial batch - perhaps a more cautious adult frog unwilling to be caught out by a sudden cold spell like last year.

We have been blessed with good weather over the last few weeks. Last week I carried out a torch survey at my local nature reserve. I was disappointed with the number of toads: given there were hundreds there last year, we could count on one hand the number seen this year. Perhaps our timing was just a little late; we did see toad spawn though not much.  Though the weather was good, the water was very murky in places.  However, we did see a number of smooth newts in ponds that we hadn't seen them in last year, and there were some still making their way to the ponds (like this female).

Apart from amphibian surveys, I have also been getting involved in activities with Yorkshire Wildlife Trust.  On Sunday, I ran a stall at the Wildlife Discovery Day at Roundhay Park in Leeds with another of our volunteers. We had information on invasive species for adults, and some fun invasive games for the kids, as well as some 'mini beast' invertebrates for 'pond' dipping using containers, which always goes down well. Unfortunately we had to fnish early as it got rather windy and the gazebo took off(!), but we had 325 visitors through the door so every little helps.

Yesterday I also took a trip out to look at the first invasive plant report received directly from a member of the public. The message is obviously starting to get out. I was able to confirm the sighting of American Skunk Cabbage. Luckily, it looks like a small and isolated incidence - the chap that reported it believes it was deliberately planted, and it does not appear to be spreading yet. It should be relatively easy to dig out, once I have figured out who owns the land and can get their permission to do so.