Habitat Quality
Daubenton's bats require clear and unobstructed water to trawl over the surface (which is the feeding strategy of this species). The water surface at the Filter Beds is currently > 40% cluttered with emergent vegetation and there are many studies that show that Benton's will not feed under these conditions.
It is estimated the average distance at which this species can detect their prey to be only 128 cm. The water surface, therefore, seems to have an important influence on the acoustic environment. For this reason clutter on the water surface, such as plant cover, could exert a negative effect on the hunting behaviour of any trawling bat species. This is one of the reasons why so many local foraging sites have been lost, as the surface of the water has been covered in algal blooms during the summer through nutrient enrichment.
It is estimated the average distance at which this species can detect their prey to be only 128 cm. The water surface, therefore, seems to have an important influence on the acoustic environment. For this reason clutter on the water surface, such as plant cover, could exert a negative effect on the hunting behaviour of any trawling bat species. This is one of the reasons why so many local foraging sites have been lost, as the surface of the water has been covered in algal blooms during the summer through nutrient enrichment.
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| Scum, 2012 |
Monitoring 2012 has shown that the low activity at the barge tunnel roost has been unprecedented this year. Bats were late to arrive at the tunnel and were observed in reduced numbers. It is possible that the maternity colony did not even form.
One of the highlights of the annual London Bat Group Batty Boat Trip (BBT) is to watch Daubenton's bats light sampling from within the barge tunnel at a respectful distance (sunset + 35 minutes). No bats were seen during any of this year’s BBT’s (the first time since 2006). Usually bats return after 30 minutes to feed their young . The small size of the colony, its late arrival, and late emergence, may indicate a perturbation. This may arise out of the current state of the FB’s or from the poor weather in the early part of the year.
One of the highlights of the annual London Bat Group Batty Boat Trip (BBT) is to watch Daubenton's bats light sampling from within the barge tunnel at a respectful distance (sunset + 35 minutes). No bats were seen during any of this year’s BBT’s (the first time since 2006). Usually bats return after 30 minutes to feed their young . The small size of the colony, its late arrival, and late emergence, may indicate a perturbation. This may arise out of the current state of the FB’s or from the poor weather in the early part of the year.
Female Daubenton's bats have a relatively strong social structure and the roosting areas used by female groups is very small, perhaps 17 hectares. The foraging areas are much wider. The researchers from the Centre for Ecology and Hydrology at Wallingford and the Universities of Oxford and Exeter concluded that as groups use very small areas for their roosting needs, this species is vulnerable to even minor habitat changes.
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