Harp Trapping Wimbledon Park
Photos Dr. D. Dawson.
London Bat Group was invited to take part in the National Nathusius Project in early 2016. Four 3-bank harp traps and lures were purchased in May 2016 and licences and training events were organised.
Note the 'harp' strings
Trapping surveys occur between May and end of October with a pause in surveys between mid-June and mid-Late July to avoid trapping heavily pregnant females or bats with suckling young. Surveys commence in late May 2016 through to early October.
Sites near water bodies are chosen as prime foraging habitat, where bats will travel to from offsite locations to spend a substantial part of the early evening. Several sites in Kingston, Richmond and Merton have been covered accruing some interesting data.
Last night, five participants attended a harp trapping session at Wimbledon Park. Two traps were positioned at the lake at locations 150m apart, as part of the National Nathusius' pipistrelle project.
We caught four soprano pipistrelle bats, one common pipistrelle and a juvenile Daubentons's bat. The Nathusius' pipistrelle eluded us, arriving later in the evening and remaining >10m from the bank side. A lure playing a loop of the call of this species was insufficient to tempt it's investigation.
Animals fly into the 'harp' strings and fall into the white bag where they are collected at regular intervals.
They are placed into smaller bags and identified to species.Information on the sex, breeding condition, weight, forearm and 5th finger measurements are taken during the processing of any Nathusius’ pipistrelle captured.
As a identification validation the cell structure of the wing patterns - or veination - is checked. Hair samples can be taken for isotope analysis which should reveal more insight into where the bat has travelled from. As the project has advanced the animals are more likely to be ringed.
So far >141 Nathusius' pipistrelle bats have been caught and 100 ringed. This August 25 Nathusius' pipistrelle were caught of which one was a recap from Surrey Bat Group (Molesey Reservoir to Kempton Park Nature Reserve - 1.7km) and another a London recap (Walthamstow to Woodberry Wetlands - 2.8km).
In addition, three bats have been controlled wearing rings that are registered in Latvia giving us valuable information about the movements of this animal.Last week a bat that was ringed in Latvia was controlled at Kempton Park.
Table: To show the number of passes per bat species at Wimbledon Park 2.9.17 (M. Wagstaffe).