Bats fly high and DNA techniques are classy

By Paul Robinson - 12 Jan 2015 19:51:1 GMT
Bats fly high and DNA techniques are classy

This is a splendid image of the bat concerned, ears akimbo, ready for action high in the mountains. You have to love the flying mammal for its sheer life style, very different from the other Orders.

Long-eared alpine bat image; Credit: © A Alberdi

We owe the bats a favour as they have previously starred for us in several accounts of communication and evolution. Before, we have noted effects such as social networking and flight changes on the life of bats. This time, a paper on a relatively new species, the alpine long-eared bat, Plecotus macrobullaris explores its diverse habitat. Its discovery in 2002 was followed by surprising sightings far away around the Mediterranean coasts, where the climate is far from alpine.

This species is the only bat to feed above the tree line, but it uses its foraging ability there at lower altitude too. Any animal has to shelter in crevices or among rocks if there ae no trees. The bat follows suit with its feeding discovered by using novel molecular techniques of analysis using DNA barcodes, found in the bat faeces. For the first time the prey are identified in this paper down to species level, which is great news for ecologists. The authors, Antton Alberdi, Inazio Garin, Ostaizka Aizpurua, Joxerra Aihartza of the University of the Basque Country publish in Plos One

The hunting strategy of the animal as it flies the alpine meadows is known now to involve 44 moth species that hide in narrow spaces, particularly in 6 named types of habitat. They were mainly noctuids but light relief for the researchers was provided by “daddy-long-legs” (tipulids) and the small elephant hawk moth. These occurred at many heights, indicating a broad range of elevations for their habitat (in 42.8% of the bats.)

Most of the moths inhabited subalpine meadows and the habitats bordering those, all of them open in character. The plants hosts for moths were grassland species while the wingspan of those caught averaged 3.8cm (almost 1.5”.) Obviously this is a moth specialist, as recorded from Turkey to Spain and Austria. Other long-ears (genus Plecotus) eat a greater variety of moths, probably because of the limited high-mountain environment. Techniques could affect results by missing less abundant moths however.

So how alpine is the bat? In summer, they can be found between 1500 and 2500m. Half of the samples reflected this, showing that meadows in flower enable the alpine bat to exploit a different food source from those hunting lower down the mountain. Great scientific interest lies in the co-evolution of moth ears to hear the bat and the bats echolocation to combat this. Plecotus spp. use low-intensity calls to avoid detection while hawking. -- until it is too late!

As the first use of a highly-advanced technique this study advertises the utility of DNA bar coding. More species need to be added, especially as 4.3% of samples failed to match any known bar code. New species anybody? (This is unlikely as many species are still to be coded.) Also, the bat only visits the high pastures in June, so assumptions about spring habitat are on hold. The rest of the bat’s life history are due to be worked out, now we know what happens during the feeding and breeding season.