The beginning of June always holds a nice fieldtrip in store for us in one of the most beautiful parts of the Netherlands – Drenthe. This area is patch work of heath lands, grasslands, swamps and beautiful woodlands. All full of creeks, small rivers and important for amphibian lovers like us: ponds! For three consecutive years now we have been supervising a group of five students (Environmental studies – Van Hall Larenstein University of Applied Sciences) in this area. The study area is also very patchy with heath land, moist grass lands and peat lands with several ponds and a creek. For their module they are measuring all natural aspects of the area, abiotic and biotic. Every year one group does a small study on the local herpetofauna. We help them setting up this study at school and more importantly in the field. The study its focus is species determination, which species is associated with which (micro-) habitat, which species may be used as bio indicators and what their place is in the ecosystem. But the most important lesson of all is that herps are an amazing group of animals, amphibians especially! We hope to convey our enthusiasm and love for these animals to the students and we are pleased to say that we had an awesome group of aspiring naturalists!!
The morning is always used to find reptiles, before they heat up. We found quite a few and large adders (Vipera berus) and loads of common lizards (Zootoca vivipara). The slow worm (Anguis fragilis) remained elusive that morning but we have found them in previous years. We were very pleased to find that the adders could now also be found in the grass lands adjacent to the heath and not only on the heath. A change in management, from farmers that mowed the grasslands for hay to State Forestry, brought that to be as well as some other actions like making the area more wet. The same was true for the common lizards. Our search for reptiles was accompanied by the chorus of many pool frogs (Pelophylax lessonae) and edible frogs (Pelophylax klepton esculentus) in nearby ponds. A wonderful opportunity for the students to recognize the species of water frog just by listening to their call. Most of them got it really fast.
After a lunch break it was time to go frogging! We went netting in the ponds! Lots of larvae were scooped up and examined from close by. The ponds were full of common newt larvae (Lissotriton vulgaris) and water frog larvae (Pelophylax). The adult water frogs did not seem to mind our presence and disturbance and kept singing their happy songs! By closer examination of one water frog larvae of one pond we found some possible disturbing features. A dead larvae with a reddish colour in the tail section, a possible sign of Ranavirus. In nearby areas there have been outbreaks of this nasty virus. Luckily no other frogs and larvae showed signs. However, it gave the students an idea what to look for and why these animals can be used as bio indicators in some circumstances. After netting the ponds we headed out in the grass lands to find moor frogs (Rana arvalis), common frogs (Rana temporaria), Water frogs sub adults and the odd common toad (Bufo bufo). And find them we did! Large numbers of common frogs and water frogs happily hopped about in the grass lands.
After a long day in the field the students gathered their data and took a well deserved rest. The next day “our” herp group had to give a presentation about what they learned the day before. They gave an excellent presentation about the local herpetofauna! After the presentation the whole class had to take a test on species identification. We are happy to report they all past this test!
That wrapped up another great field period in Drenthe – 2014. On to next year!
By: Tariq Stark