Bat box check at Wilson Reserve, 18 April 2015

Written by – Robert Bender

1A beautiful day for outdoor work, Steve and Jessica had been vigorously recruiting among Latrobe Conservation Biology and Melbourne Uni. Vet Science students so a big team turned up to help. We split into two groups, Steve doing the meadow boxes, my group the woodland boxes. Jessica was keen to get some practice using the harness, so did most of the climbing for my team.2

Steve arrived just as my group was finishing – he had 38 bats and we had none – they had all been out in the meadow boxes, which is normal in autumn. He finished up checking the last remaining bat detector, and found three Gould’s had sneaked in through the plastic tube underneath and were roosting around the handset – first time this has happened!3

Steve had earlier been to the Burke Rd. tubes with me and extracted 7 Gould’s from tube 6.

One of the Vet Sci students, Irina Ternovskaya, had her maiden effort at bat handling, assisted by Steve.

Helen Reilly has finished her vaccinations so I helped her get started on handling bats.4

And one of them was Whitespot, 84596, captured for the 41st time.5

The back deck was very crowded, with bat handlers, scribes and onlookers, cups of water and nibbles.

6

Jessica helped Ashley Mooney get started on bat handling.7

Steve got some help labeling vials for genetic samples, and had 10 new bats to band, 5 male, 5 female.

Work continued until it was almost dark, with 7 bats from Burke Rd tubes and 35 from Wilson Reserve boxes. All the novice bat assessors are keen to return for more practice.

I hurried down to release the Wilson Reserve bats just after dark, then we went off to see some Buster Keaton films with Blue Grassy Knoll at Southbank. By the time we returned it was raining fairly steadily, so I took a step-ladder and put the Burke Rd. bats back into tube 6.

We had a small number of anomalies: two bats recorded originally as males had become females, and two bats from different boxes had the same band number.

As usual, the post-lactating bats, older and more experienced than the young adolescents, were heavier, being more successful hunters and better at fattening up for winter. And females are markedly heavier on average than males. But forearms are all in the same length range. So bone growth comes before weight gain.8 9

Analysing how long this month’s bats have been in our colony shows obvious recruitment each year to join the long-term members of the group. Some have been with us 3½ years, some for 2½, some for 1½, and this year’s adolescents for under half a year. So each year, most of that year’s young emigrate and a few from elsewhere immigrate, as well as a few young females staying with their mother’s colony.

Over 11 years there has been a strong preference in April for the boxes out in the open meadow, so the ones in the shadier woodland are avoided. This month all 38 bats were in the meadow boxes, true to form, which is why my woodland team didn’t find any.

 

Wilson reserve box tally:

Box Bats Species Adult
M F
B06 18 Gould’s 5 13
B01 12 Gould’s 1 11
B02 3 Gould’s 2 1
Det 3 Gould’s 1 2
B05 2 Gould’s 2
  38 Total 11 27

Burke Rd tube tally:

Tube Bats Species Adult
M F
T06 7 Gould’s 3 4
  45 Total 14 31
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About Pia Lentini

Pia Lentini is a Postdoctoral Research Fellow with the University of Melbourne's Quantitative and Applied Ecology group.
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