Watching the Water bats

It has been our privilege this summer to takeover a Bat Conservation Trust waterway survey route. We learned of the opportunity when we met Anne and Chris at an early meeting of Friends of the River Rib back in May who for a number of years have conducted the Standon Daubenton’s Bat survey, amongst a number of others that record and research the various species of bats present in this part of north-east Hertfordshire. Anne was also kind enough to accompany us on our second survey in late August to make sure we were on the right track.

Our particular route took us along the River Rib through Standon and followed a set methodology. On two separate visits, one in the first and the other in the second-half of August, starting 40 minutes after sunset we were to visit each of 10 specified spots approximately 100 metres apart. At each spot our detector was switched on and set to a frequency of 35khz* for a period of 3 minutes, during which time each bat pass identified by the detector and confirmed by torch-light as flying low and straight over the water and therefore a Daubenton is noted. Sound passes also heard but not visually identified are also recorded (as possibles in the recording form) and at the end of each time period you move to the next spot. Temperature and weather conditions are also recorded and the results added to the national survey through an internet portal. According to the graph showing data from the Standon survey route, our average count score for 2019 doesn’t appear to show a radical diversion from the range and certainly confirms a continued presence of the species on the River Rib in Standon.

Average counts for Daubenton’s bats at Standon, Hertfordshire

 

Talking with Anne as we walked between survey spots we learned that from her experience the Daubenton’s appeared to favour open areas of water with some tree cover in the vicinity, which was also indicated in our own results this year; survey spots with significant river reed vegetation and smaller water channels had no Daubenton activity, whilst areas with more open water – for instance close to the Standon A120 bridge – had high pass counts.

Now equipped with reasonable confidence in our identification skills for this species and the survey now completed, our attention turned to Barwick Ford, where for a number of years we have watched bats skimming the surface in torchlight on summers evenings. A couple of visits both proved fruitful with at least three individuals working the river up and down from the ford, occasionally chasing and interacting. This knowledge brings an interesting perspective to the recording and sonogram below, where a second bat can be heard and seen at a slightly higher pitch.

 

Video shot by torchlight also shows the amount of activity and the occasional snatched view of a Daubenton’s bat passing by and makes an interesting comparison from earlier in the year of Pipistrelles working trees earlier in the year at a location not far from the ford.

It has been absolutely fascinating to learn about the Daubenton’s bat this summer. Myotis daubentonii to give it it’s scientific name is a small to medium sized bat belonging to the Vespertilionidae group, meaning evening flying (think evening vespers). Myotis refers to their mouse-like ears and the name daubentonii given by the first to describe the species, Heinrich Kuhl in honour of the French naturalist Louis-Jean-Marie Daubenton. For me, the German common name of Wasserfleidermaus or Water Bat seems the most appropriate and endearing.

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