Department of Biological Sciences, Cameron University, Lawton, Oklahoma 73505; U. S. Fish and Wildlife Service, 222 S. Houston, Tulsa, Oklahoma 74127
The hoary bat (Lasiurus cinereus) is a wide-ranging, often migratory bat that probably occurs in all 50 of the United States (1). Blair (2) provided the first published record of the hoary bat in Oklahoma and believed that the species rarely occurred in the state. According to Glass and Halloran (3) L. cinereus is found throughout Oklahoma in summer. In Kansas, the species is widely distributed but more numerous in the eastern part of the state (4). Findley and Jones (5) found that hoary bats exhibit a distinct seasonal, sexual, and geographic distribution in North and South America.
Museum and reliable sight records were compiled to determine the status of L. cinereus in Oklahoma. Figure 1 shows the distribution based on these records, the majority of which are from central and extreme western Oklahoma. Of particular interest is the distribution of the sexes. Females have been taken primarily in the central and eastern portions of the state and constitute 63 percent of the specimens for which the sex is known, whereas the less common males were found most often in the Panhandle. This sexual segregation in Oklahoma agrees with the findings of Findley and Jones (5) which indicated that females occupied an eastern summering ground but that males were more prevalent in the montane West. They theorized that the more eastern areas of parturition were unoccupied by adult males and that most males recorded in these localities would be young-of-the-year. This theory is supported by the fact that one of only two males from central Oklahoma is a newly fledged juvenile (see Table 1).
Records of occurrence by season for the hoary bat in Oklahoma are presented in Table 1. Thirty-five percent of the specimens were taken in June or July, with scattered records from earlier in spring and in autumn. Findley and Jones (5) also found L. cinereus to be most abundant in New Mexico in June and July. The late summer and autumn (August, September, and October) and spring (April and May) records probably represent migrating individuals. Except for one, all records from the Panhandle occurred between August and October. This could suggest that L. cinereus does not reside there during summer, or merely that little collecting takes place then.
The hoary bat in Oklahoma is seemingly a migrant statewide. Summer residents are dominated by females in central and eastern Oklahoma. Females, pregnant prior to beginning their northward spring migration, probably bear young in Oklahoma in May and June. Our present understanding of the distribution of Lasiurus cinereus in the state may be biased by times and locations of sampling and by lack of adequate collection.
1. R. W. BARBOUR and W. H. DAVIS, Bats of America, Univ. Kentucky Press, Lexington, 1969, pp. 143-149.
2. W. F. BLAIR, Am. Midl. Nat. 22: 101-102 (1939).
3. B. P. GLASS and A. F. HALLORAN, J. Mammal. 42: 236 (1961).
4. J. K. JONES, E. D. FLEHARTY, and P. B. DUNNIGAN, Misc. Publ. Mus. Nat. Hist., Univ. Kansas 46: 20-21 (1967).
5. J. S. FINDLEY and C. JONES, J. Mammal. 45: 461-470 (1964).
6. S. BASS, letter of 7 December 1976 to C. M. Scott, on file in CUMZ.
7. B. P. GLASS, Proc. Oklahoma Acad. Sci. 39: 83-84 (1959).