Research team from the Basque Country investigates species of bat that traps fish for food

(Press-News.org) There are 27 species of bats identified in the Basque Country today. Twenty years ago there were hardly any records. This data reflects the fruitful work on the ecology and behavioural development of bats by the University of the Basque Country (UPV/EHU) research team since the 90s. The director of the team, Mr Joxerra Aihartza, took the first steps when he began drawing up a complete atlas of the distribution of bat species in the Autonomous Community of the Basque Country (CAV-EAE). There are now nine biologists on the team.

As Mr Egoitz Salsamendi, member of the team, explained, they took Mr Aihartza's research as the starting point and, "from then on, the group specialised in analysing the choice of habitat and diet". To this end, they mainly used radio-telemetry. "We have highly specialised radio transmitters – they have to be very small in order to attach them to the animals. When the transmitters are attached, we release the bats back into the cave and, when the next night they begin feeding, we can monitor them. In this way we know when and to what extent they move and what they feed on".

Long-fingered bats partial to fish

They undertook the study within the CAV-EAE but also outside its boundaries. In fact their relation with certain researchers in Valencia gave the team members the opportunity to participate in a surprising discovery: the curious eating habits of a Mediterranean species known as the long-fingered bat (Myotis capaccini). According to Mr Salsamendi, "it was thought that in Europe all bats were insectivores but, on analysing the diet of this bat, we discovered in their faeces the vertebrae and scales of fish".

They thus showed that this species of bat eat fish but, as Joxerra Aihartza himself explained, it was needed to show that it was the bats themselves who were catching the fish: "We controlled their movements for a number of days using a tent where we had left fish and we observed that they did, in fact, catch live fish". Their staple diet are the insects inhabiting the surface of the water, "but there is an ecological reason that explains this fishing behaviour: when the pools of water in a cave start drying up, the fish concentrate at their surface and they are easy to catch", added Mr Salsamendi. Ostaizka Aizpurua, member of the team, has begun to write a PhD thesis on the species.

Necessity for caves and suitable habitats

Thanks to the great quantity of work undertaken abroad, but above all at home, in order to get to know the ecology of bats, the team were also able to identify the risk factors that put their existence at risk. For example, they know that at least two species of bat, of the 27 identified in the Basque Country, are endangered. They observed that, amongst those species inhabiting caves, one of the principal risk factors is the loss of refuges. "Bats require places with very special microclimatic conditions. Some choose a cave for their litter for its characteristics, but use another to hibernate in. Some bats are very exigent with these conditions and create very large colonies in such caves. These places have to be cared for – there is no replacement for them", stated Mr Aihartza. He added that humans are doing precisely the opposite.

The biologist also underlined that the habitat is a fundamental factor, given that bats need a great variety and quantity of insects. In this sense, Mr Aihartza pointed out that pine tree management and the use of pesticides such as Dimilin cause considerable damage, and not only affect the conservation of the bats: "Bats are very good indicators of the state of health of habitats. A prosperous habitat provides refuge to a prosperous community of bats. The protection of bats guarantees the protection of the habitat - each needs the other".

In relation to this, and as requested by government bodies, the team carried out a number of management plans, but Mr Aihartza states that no notice has been taken of them: "The species continue as bad as before, or even worse, and this is our main concern".

Investigating virology

Leaving the questions of protection to one side, the research team has continued to be involved in a number of projects. For example, they are carrying out an in-depth study of the ecology of the three long-eared species dwelling in the Pyrenees and their cohabitation.

Mr Aihartza also mentioned "a large-scale project" for the coming years: "According to data revealed in recent years, a number of diseases have appeared in bats that substantially affect humans. For example, bats could be carriers of the African Ebola virus". Thus, they are also studying, in conjunction with other teams, the virology of bats.

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