More amphib adventures as promised.
This Easter I was at Malham Tarn Field Studies Centre with two fellow MSc students. The aim of the trip was to survey the many ponds on the fen for amphibians. The first step was to check NBN Gateway for any existing records. There were not many amphibian records for the site and as far as we knew there had not been any systematic surveys carried out so it was quite exciting to be part of establishing the site records.
The Field Studies Centre very kindly agreed to accommodate and feed us for the weekend so on Friday morning we set off, and despite getting embroiled in the bank holiday traffic we got to Malham in the early afternoon ready to make the initial site assessment and measure variables to calculate the great crested newt Habitat Suitability Index (HSI).
When we got there, we found that there were many more ponds than we had anticipated from a preliminary search based on satellite images. Most of them appeared to be deliberately cut into the peat on the fen, although we have no idea what the purpose of these holes was – it’s on the list to ask the National Trust ecologist when we meet him next time! Many of the ponds were very deep with vertical sides, or even overhanging banks, so we were very careful not to fall in! Several were alive with frogs as we approached, although we only recorded two clumps of spawn. The adult frogs themselves were difficult to count as they tended to hide themselves away as soon as we approached.
For the habitat survey, we recorded a number of variables including size and permanence of the ponds, vegetation, presence of fish and waterfowl, water turbidity, pH and conductivity, underlying geology and surrounding habitat. For the GCN HSI a few other factors allowed calculation of an index using the system developed by Oldham et al. (2000) which is used nationally to assess sites for GCN potential.
After the initial site assessment, and some well earned tea and cake, we headed out to set the bottle traps for the evening. This was a completely new technique to two of us so it was fascinating to see them. There’s nothing complex about a bottle trap, it’s just a 2l soft drink bottle with the top cut off and inverted to make a funnel. This is attached to the body of the bottle and a bamboo cane passed through the sides of the bottle to allow it to be fixed in place in the ponds. We distributed the traps among the ponds, a few metres apart, spaced around the edge with a bubble of air caught inside… adult newts aren’t able to breathe under water and must come to the surface for air.
After setting out the traps (and meticulously recording what we’d placed where!) we had dinner, and once it was dark we set out to do some torching. We saw several more frogs, mostly in amplexus (mating pairs) and our first glimpse of a possible newt turning and diving into the dense spagnum vegetation lining the sides of the pond.
In the morning, excited, we headed down to the ponds to collect in the bottle traps and see if we had caught anything. Sadly there were no newts in our traps, although we had caught several frogs… a first for our resident expert!
After breakfast we headed out to the ponds again to assess the vegetation surrounding the ponds to describe the general area and to do some netting for invertebrates. The invertebrate diversity of ponds is a good indicator of the pond quality and a factor used to assess GCN habitat suitability. We did not find a huge number of inverts in any of the ponds, although it is possible that there is seasonal variation in invert activity and we were simply too early. There were plenty of caddis fly larvae and lesser water boatman though.
This is also when we found our first newts! Sarah, an expert after a childhood spent fishing for newts in her grandmother’s pond, managed to find both an adult male palmate newt and an eft (juvenile). These were in the same pond that we caught a glimpse of a newt the previous night and the presence of the eft showed there was a breeding population present, exciting stuff!
A wet day was spent indoors trying to identify our vegetation and invertebrate samples before heading out into the rain to set the nights bottle traps. This time we decided to concentrate our efforts on the cluster of ponds where the ‘newt pond’ was located. A bit more experienced this time, we set the traps around the pond edges, this time facing into the submerged vegetation at the sides rather than into the open water at the edges of the ponds. Newts like to walk along the bottom of ponds, and generally it is best to set bottle traps so that they are on the bottom. Since these ponds are so deep with vertical edges, this is impossible . The newts we had found earlier and seen on the previous torching attempt appeared to be hidden in the sphagnum lined sides of the pond so we hoped that by setting the traps this way we might have more success.
Since the weather was not good and the results from torching previously had been limited, we decided not to go out torching on Saturday evening and instead had a lovely pub meal at the Lister Arms in Malham before heading to bed.
Early on Sunday morning (still in the rain) we checked and collected the traps. From the first few ponds still nothing but frogs. Then, excitement building, came the ‘newt pond’. This time we had three newts! Two adult male and one pregnant female palmate newt.
Palmate newts (Lissotriton helveticus) can be distinguished from smooth newts (Lissotriton vulgaris) by the absence of colour in the skin on the underside of their head. Both can have orange spotty bellies but palmate newts have a pink chin, this is the only way to distinguish between females of each species. Male palmate newts in breeding season have frilly webbed toes on their hind feet and a thin filament on the end of their tails. In the individuals we caught these are not very distinct, possible because it is still early in the season, so on our next visits these should be more pronounced.
There will be two more visits to Malham this year, I will be going on the next one at the end of April and it’ll be exciting to see if we see more newts. The presence of lots of mating frogs and little spawn shows that it is still early in the season up at Malham. Being higher and colder than down in Leeds, it is likely that things are a bit behind there. Newts tend to get going a few months behind frogs and toads, peak time being April-May so hopefully we’ll get a lot more activity next time!
It’ll also be interesting to see if we can find newts in any of the other ponds. In the ‘newt pond’ area there are 12 other ponds that we surveyed, all within an area about 25 x 50m with some very similar to the ‘newt pond’ so it seems odd if none of the others are home to a newt population.