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1 December 2003 Azorean Bats Nyctalus azoreum, Cluster as they Emerge from Roosts, Despite the Lack of Avian Predators
Nancy R. Irwin, John R. Speakman
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Abstract

We tested the hypothesis that clustering in the behaviour of emerging bats is a response to the risk of avian predation. We hypothesised that if avian predation was the cause of clustering, bats in the prolonged absence of avian predators, would not cluster or would cluster less during their emergences. We studied the Azorean bat (Nyctalus azoreum) in the Azores Archipelago. The Azores have a depauperate fauna with no raptorial birds likely to predate bats. The Azorean bat is an endemic mammal to the archipelago, which has an unusually extensive degree of diurnal activity that has been hypothesised to reflect release from the risk of diurnal predation by raptors. Contrary to our prediction Azorean bats clustered during emergence to the same extent as bat species which occur where there are raptors. Two interpretations of these data are possible. First, the hypothesis that the behaviour is anti-predatory may be incorrect. Most of the variation in clustering was explained by variation in ambient temperature possibly suggesting the bats emerged in groups to aid exploitation of sparsely distributed food. Alternatively, the behaviour may be anti-predatory, but the key factor precipitating clustering may not be the risk from aerial predators, but terrestrial predators, such as rats (Rattus norvegicus) and cats (Felis cattus), both of which were common around the roost sites.

LITERATURE CITED

1.

M. I. Avery , P. A. Racey , and M. B. Fenton . 1984. Short distance location of hibernaculum by little brown bats (Myotis lucifugus). Journal of Zoology (London), 204: 588–590. Google Scholar

2.

Y. Barak , and Y. Yom-Tov . 1989. The advantage of group hunting in Kuhl's bat (Pipistrellus kuhli) (Microchiroptera). Journal of Zoology (London), 219: 670–675. Google Scholar

3.

D. A. Bannerman , and W. M. Bannerman . 1966. Birds of the Atlantic islands. 3. A history of birds of the Azores. Oliver and Boyd, Edinburgh, 262 pp. Google Scholar

4.

D. J. Bullock , B. A. Combes , L. A. Eales , and J. S. Pritchard . 1987. Analysis of the timing and pattern of emergence of the pipistrelle bat (Pipistrellus pipistrellus). Journal of Zoology (London), 211:267–274. Google Scholar

5.

M. B. Fenton , I. L. Rautenbach , S. E. Smith , C. M. Swanepoel , J. Grosell , and J. Van Jaarsveld . 1994. Raptors and bats: threats and opportunities. Animal Behaviour, 48: 9–18. Google Scholar

6.

M. B. Fenton 1995. Constraint and flexibility — bats as predators, bats as prey. Symposia of the Zoological Society of London, 67: 277–289. Google Scholar

7.

D. D. Gillette , and J. D. Kimbourgh . 1970. Chiropteran mortality. Pp. 262–281, in About bats ( B. H. Slaughter and D. W. Walton , eds.). Dallas Southern Methodist University Press, Dallas, 339 pp. Google Scholar

8.

G. Jones , P. L. Duverge , and R. D. Ransome . 1995. Conservation biology of an endangered species: Field studies of greater horseshoe bats. Symposia of the Zoological Society of London, 67: 309–324. Google Scholar

9.

W. D. Hamilton 1964. Geometry of the selfish herd. Journal of Theoretical Biology, 31: 295–311. Google Scholar

10.

M. C. Kalcounis , and R. M. Brigham . 1994. Impact of predation risk on emergence by little brown bats, Myotis lucifugus (Chiroptera: Vespertilionidae), from a maternity colony. Ethology, 98: 201–209. Google Scholar

11.

C. McAney , and J. Fairley . 1990. Activity of Leisler's bat Nyctalus leisleri (Kuhl, 1818) at a summer roost in Ireland. Myotis, 23: 83–92. Google Scholar

12.

N. W. Moore 1975. The diurnal flight of the Azorean bat (Nyctalus azoreum) and the avifauna of the Azores. Journal of Zoology (London), 177: 483–506. Google Scholar

13.

J. J. Negro , C. Ibañez , J. L. Perez Jorda , and M. J. Delaviro . 1992 Winter predation by common kestrel Falco tinnunculus on pipistrelle bats (Pipistrellus pipistrellus) in southern Spain. Bird Study, 39: 195–199. Google Scholar

14.

J. M. Palmeirim 1991. A morphometric assessment of the systematic position of the Nyctalus from the Azores and Maderia (Mammalia: Chiroptera). Mammalia, 55: 381–387. Google Scholar

15.

K. J. Petrželkova , and J. Zukal . 2001. Emergence behaviour of the serotine bat (Eptesicus serotinus) under predation risk. Netherlands Journal of Zoology, 51:395–414. Google Scholar

16.

K. J. Petrželkova , and J. Zukal . 2003. Does a live barn owl (Tyto alba) affect emergence behavior of serotine bats (Eptesicus serotinus)? Acta Chiropterologica, 5: 177–184. Google Scholar

17.

J. Rydell , A. C. Entwistle , and P. A. Racey . 1996. Timing of foraging flights of three species of bats in relation to insect activity and predation risk. Oikos, 76: 243–252. Google Scholar

18.

J. R. Speakman 1990. The function of daylight flying in British bats. Journal of Zoology (London), 220: 101–113. Google Scholar

19.

J. R. Speakman 1991. Why do insectivorous bats in Britain not fly in daylight more frequently? Functional Ecology, 5: 518–524. Google Scholar

20.

J. R. Speakman 1993. Clustering in the emergence behavior of bats: Some pitfalls in analysis and how to overcome them. Bat Research News, 34: 49–54. Google Scholar

21.

J. R. Speakman 1995. Chiropteran nocturnality. Symposia of the Zoological Society of London, 67: 187–201. Google Scholar

22.

J. R. Speakman , and P. I. Webb . 1993. Taxonomy, status and distribution of the Azorean bat (Nyctalus azoreum). Journal of Zoology (London), 231:27–38. Google Scholar

23.

J. R. Speakman , D. J. Bullock , L. A. Eales , and P. A. Racey . 1992. A problem defining temporal pattern in animal behaviour: clustering in the emergence behaviour of bats from maternity roosts. Animal Behaviour, 43: 491–500. Google Scholar

24.

J. R. Speakman , L. F. Lumsden , and G. C. Hays . 1994. Predation rates on bats released to fly during daylight in south-eastern Australia. Journal of Zoology (London), 233: 318–321. Google Scholar

25.

J. R. Speakman , R. E. Stone , and J. E. Kerslake . 1995. Temporal patterns in the emergence behaviour of pipistrelle bats, Pipistrellus pipistrellus, from maternity colonies are consistent with an anti-predator response. Animal Behaviour, 50: 1147–1156. Google Scholar

26.

J. R. Speakman , N. R. Irwin , N. Tallach and R. Stone . 1999. Effect of colony size on the emergence behaviour of pipistrelle bats (Pipistrellus pipistrellus): intra- and inter roost effects. Animal Behaviour, 58: 787–795. Google Scholar

27.

S. M. Swift 1980. Activity patterns of pipistrelle bats (Pipistrellus pipistrellus) in north-east Scotland. Journal of Zoology (London), 190: 285–295. Google Scholar

28.

S. Ulfstrand 1961. On the vertebrate fauna of the Azores. Biological Bulletin of the Municipal Museum at Funchal, 14: 75–86. Google Scholar

29.

P. Ward , and A. Zahavi . 1973. The importance of certain assemblages of birds as ‘Information centers’ for food-finding. Ibis, 115: 517–534. Google Scholar

30.

G. S. Wilkinson 1992. Information transfer at evening bat colonies. Animal Behaviour, 44: 501–518. Google Scholar

31.

G. S. Wilkinson 1995. Information transfer in bats. Symposia of the Zoological Society of London, 67: 345–360. Google Scholar

32.

G. S. Wilkinson , and J. W. Boughman . 1998. Social calls coordinate foraging in greater spear-nosed bats. Animal Behaviour, 55: 337–350. Google Scholar
© Museum and Institute of Zoology PAS
Nancy R. Irwin and John R. Speakman "Azorean Bats Nyctalus azoreum, Cluster as they Emerge from Roosts, Despite the Lack of Avian Predators," Acta Chiropterologica 5(2), 185-192, (1 December 2003). https://doi.org/10.3161/001.005.0203
Received: 26 May 2003; Accepted: 12 September 2003; Published: 1 December 2003
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KEYWORDS
bats
behaviour
clustering
emergence
group-feeding
predation
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