This bank holiday weekend I spent another day at Malham Tarn FSC, surveying the ponds on the moss for amphibians.
Last time we were there we saw lots of frogs and found newts in one of the many ponds near the boardwalk. Since frogs are the earliest amphibians to get going in the spring generally, we had been hoping that this visit would see lots more newt activity being warmer and later in the season. However, given the recent cold snap and overnight temperatures of below zero we were not too optimistic!
Newts are much less active at low temperatures, and the general advice is that at temperatures below 5°C, the survey effort required is much greater and detectability falls dramatically.
This time, as well as the ponds we knew of, we had two more to survey which had been newly dug two years ago. We were told about these by the National Trust ranger who said that they had been dug to improve the breeding habitat for dragonflies.
On Saturday morning we scoped out the new ponds and did the pond habitat and environmental surveys, we also did some netting for inverts to give a water quality assessment. The seasonal difference really showed here as the water in the ponds was alive with midge larvae this time. We were also excited by the number and diversity of the case caddis fly larvae we found!
We also did a quick visual and netting survey of the other ponds for frogspawn and tadpoles. In most of the ponds, the spawn had hatched already although the tadpoles we did see were still relatively small. In many of the ponds the spawn appeared to have been degraded to some degree and many unhatched eggs remained with clouded brown/grey/white centres. A possible reason for this is the acidity of the water which was generally between pH 4.5 and 5.0.
Since the temperature was forecast to be so cold, we did not have many traps this time, and intended only to put a few in the ‘newt pond’ and the new ponds. After setting the traps and waiting for dark, we started torching the ponds. In the cluster including the newt pond, we saw only one frog although he torchlight did make it easier to spot frogspawn below the surface too.
Moving onto a larger pond, we saw lots of fish and a couple of times “ooh, I saw something!…ah, it was probably just a fish.”
Then: “There’s a newt! Definitely as newt! Female!” we watched a definite newt swim across the bottom of the pond and thought “Oh, bother! Why didn’t we bottle trap this one?!”
After the initial sighting we saw 6 more newts, mostly appearing female although we saw one probable male with dark webbed back feet. Unusually for females at this time of year they all appeared quite slim and small rather than swollen with eggs so the ID we gave was by no means positive… Were they juveniles? Why were they not breeding? Were there not enough males?
After the unexpected success of the night, we ventured out in the morning to collect in the bottle traps. In the ‘newt pond’ cluster, we had no luck, only catching a few tadpoles. Moving onto the new ponds we had no expectations, after all these ponds were only two years old and we hadn’t detected any newts in the ponds out on the fen last time.
Once again we were surprised. In the first bottle trap was a female palmate newt and an eft!
The next planned visit to Malham is in 3 weeks and instead of narrowing down the survey field in any way we’ve managed to extend it. Despite the cold weather we found newts in places we weren’t expecting and next time with warmer weather and more active newts there might be even more to see!
Sadly I’m not booked to go on the third trip due to other commitments but I hope I might be able to pop up just for a day, I don’t want to miss out!