versión On-line ISSN 1519-6984
Braz. J. Biol. v.66 n.1a São Carlos feb. 2006
NOTES AND COMMENTS
Esbérard, C. E. L.I; Moreira, S. C.II
IDepartamento de Ecologia, IBRAG, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524, CEP 20559-900, Rio de Janeiro, RJ, Brasil
IIEverest Tecnologia em Serviços Ltda., Av. Nossa Senhora Navegantes, 671/1201, CEP 29056-900, Vitória, ES
Lasiurus ega (Gervais, 1856) occurs from the southwestern United States to northern Argentina and Uruguay, with the most austral record being Buenos Aires province, Argentina, at 40° S (Baker et al., 1971; Barquez et al., 1993; Eisenberg, 1989; Redford & Eisenberg, 1992). This species was recorded over the open south Atlantic Ocean on March 15, 1960, 335 Km from the cost of Argentina (Van Deusen, 1961). Lasiurus ega most often roosts in trees, generally hanging by its feet from the midrib of a leaf and occasionally by its thumbs as well (Nowak, 1994). This species commonly roosts among dead fronds of palm trees and the use of ornamental palms in the southwestern United States may have helped the bat to extend its range northward (Spencer et al., 1988).
On April 9, 2002, an adult male with a forearm length of 47.05 mm and weighing 11.2 g landed at night on the seismic vessel Ramform Explorer, which was on the open seas 145 Km from Brazil's southeastern coast (Fig. 1).
Both Lasiurus borealis (Muller, 1776) and L. cinereus (Beauvois, 1796) are migratory, moving southward during the fall, and eventually landing on ships or oceanic islands (Baker, 1956; Findley et al., 1975; Griffin, 1940; Nowak, 1994). Populations of Lasiurus seminolus (Rhoads, 1895) can move south or enter torpor in colder months (Barbour & Davis, 1969). In the northern hemisphere, males of L. ega become scarce between April and June, while females are present year-round, suggesting a migratory strategy (see Kurta & Lehr, 1995). Lasiurus ega shows a tendency to migrate toward the Equator, as described for other species of the genus (Kurta & Lehr, 1995).
Bats that migrate along coastlines take shortcuts over water. Many North American migrant bats can be found at a distance of several kilometers from their normal destination during fall and spring migrations, probably having been blown there by wind (Constantine, 2003). Both records of L. ega in the Southern Hemisphere indicate movements at the end of summer and beginning of fall, supporting the theory that at least some animals migrate to avoid cold temperatures. With this second sighting, the probability that both records of this species over the South Atlantic were the result of wind has become less likely.
Acknowledgments The bat is deposited as a voucher in the reference collection of the Projeto Morcegos Urbanos (License Process 1456/95-46 Ac-SUPES/DF/IBAMA) and is identified with the number PMU3555. We are indebted to Everest Tecnologia em Serviços Ltda and PGS Investigação Petrolífera Ltda for welcoming Brazilian researchers aboard their vessels and for encouraging the scientific publication of the data collected. We wish to thank Tatiana Fernandes reviewing this manuscript. Carlos E. L. Esbérard received a grant (151029/2004-0) from CNPq (Brazil).
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Carlos Eduardo Lustosa Esbérard
Departamento de Ecologia, IBRAG
Universidade do Estado do Rio de Janeiro
Rua São Francisco Xavier, 524
CEP 20559-900, Rio de Janeiro, RJ, Brasil
Received November 8, 2004 Accepted December 27, 2004 Distributed February 28, 2006