Summer bat surveys

The bat survey season is well and truly underway and at NWS surveys are taking place almost every day of the week. Initial surveys are undertaken to look for evidence of bats and if found then a minimum of three nocturnal surveys (dawn and dusk) may be required during the main survey season, i.e. May to September.

During a dusk survey, surveyors watch the building from 15 minutes before dusk and 2 hours after dusk to watch for any bats emerging from the building. A bat detector and a recording device are used to record any bat calls which are then analysed to confirm the sightings and to identify species. Target notes are also recorded on a map so any points of entry can be identified.

During a dawn survey, surveyors watch the building for the 2 hours before dawn (which means a very early start!). The same method is used as in a dusk survey but the surveyors are mainly watching for bats to return to roost.

These surveys can be really interesting and exciting if there is lots of activity at the site but they can also be a bit boring if there isn’t much going on (you are essentially staring at a building for 2 hours…. potentially at 2.30am!). It can be worth getting up super early though if you get a close encounter with a bat like at a recent site where Brown Long-eared bats were roosting just above our heads in a barn.

Brown long-eared bat

Brown long-eared bat

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