Rude daytime awakening for nocturnal bats

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By Hanna Eriksson
     
      Leaning her ladder against a tree, Silva Sallamaa quickly clatters up the rungs. She is agile with the ladder, which is no wonder, considering that she gets to climb it least 30 times a week.
      Sallamaa looks cautiously into the nesting box. The swarm of flies indicates that it contains fresh bat droppings, if nothing else.
      "There’s bats here too", Sallamaa says excitedly, as she detaches the box from the trunk of the tree.
     
Sallamaa, who is working on her master’s thesis in biology, and Eeva-Maria Kyheröinen of the Finnish Museum of Natural History are both bat researchers.
      For a second year running, they are busy tagging the winged mammals that they find in nesting boxes in Kirkkonummi, Siuntio, and Inkoo.
      Last summer the two tagged 90 bats. Already 28 bands have been placed on bats’ legs so far this summer.
      This time six bats, all Myotis daubentoni, are resting their muscles in the box. Last week there were four bats in the same box, and in the previous week there were 18.
      "It is a warm location, with great sources of food nearby", Kyheröinen says, describing the nest in the way that a real estate agent might present a house.
     
There has not been much bat research in Finland. The task of these experts is to ascertain the kinds of groups that bats form, and whether or not they return to the same groups and nesting boxes each year. Judging from last year’s findings, they do not.
      "They do not keep nearly to the same bat gangs as we thought they would", Kyheröinen observes.
     
The tagging process began in May this year, and it is to be continued into October.
      Silva Sallamaa puts on a pair of leather gloves, and begins to carefully move the bats in the nesting box into a cloth bag.
      "My mother’s old gloves are being used for something better now", Sallamaa grins, as one of the bats tries to gnaw away at the gloves with its short, sharp teeth.
      "Sometimes they bite when we move them. It is their nature", Kyheröinen says.
     
The bats are picked out of the bag one by one to be weighed and measured. One Myotis daubentoni weights about ten grammes - about the same as a single serving of butter.
      The researchers also ascertain the bats’ gender, and check the teats of the females.
      "If the teat is small and furry, the bat probably has not yet given birth. A large teat without fur suggests that the female has suckled", Kyheröinen says, as she blows at the bat’s thick fur.
      In addition to weighing, measuring, and tagging the bats, Sallamaa and Kyheröinen check their overall condition and possible injuries.
      "There are often holes in the wings. The claws of other bats might scrape against the wings as they all crowd into the nesting box", Kyheröinen points out.
     
The uncomfortable process is soon over, and the bat can go back to sleep. A pause in the tagging process began on Wednesday, and continues through mid-July. The researchers do not want to interfere with the bats when the females are in the later stages of pregnancy, or when the newborn bats are still vary small.
      Sallamaa and Kyheröinen hope that the summer will be warm, and that there will be many insects for the bats to feed on.
     
Helsingin Sanomat / First published in print 15.6.2005

More on this subject:
 FACTFILE: Bats: the world's only flying mammals

Links:
  Finnish Museum of Natural History

HANNA ERIKSSON / Helsingin Sanomat
hanna.eriksson@hs.fi