Thanks to the Environment Wales Ponds and People project we had a chance to collect data on ponds which would allow us to look at how the Great Crested Newt (GCN) Habitat Suitability Index (HSI) works in this part of Wales.

A special thanks to Eleanor Jones for helping with the data inputting and all the other volunteers who helped survey ponds.

The Habitat Suitability Index was developed by Oldham et al (2000) and is not a substitute for newt surveys but ponds with a higher score are more likely to contain great crested newts (GCN) then one with a lower score (so they say). The index takes into account ten factors, these are: location, pond area, frequency of drying out, water quality, shade, presence of waterfowl and fish, terrestrial habitat quality, number of nearby ponds and summer macrophyte cover. Some of the measures are subjective and depend on the surveyor's judgement and experience, but this can be a useful tool for assessing ponds.

In our small sample the HSI for ponds with GCN was on average in the 'good' category, but so were a lot of ponds in the uplands and we felt that altitude is not properly compensated for in this index. Using the Biodiversity Information Service for Powys and BBNP (BIS), we found the average altitude at which GCN are recorded and created a new multiplier to make local HSI more relevant and accurate in predicting the presence of GCN.

However there is probably a bias in recording against higher altitude sites. Also ponds in uplands, even if not ideal GCN for breeding in terms of temperatures, macrophytes, terrestrial habitat and invertebrate abundance, could still be important when the low level ponds suffer more from isolation through poor terrestrial habitat, linking habitat and loss of suitable ponds.

How important are these high scoring upland ponds to GCN breeding and can we identify which are important?

Are they important for breeding, connecting populations or just where dispersing newts turn up occasionally?

A juvenile great crested newt found at Pant y Llyn SO0346 420m asl., under some material by Keith Noble.

We can answer this question by looking for breeding evidence at suitable upland ponds, i.e through egg searches, torching at night and (fine mesh) netting for larvae perhaps.