First Records of Brazilian Free-Tailed Bats (Tadarida Brasiliensis) in the Willamette Valley,OregonAuthor(s): Gregory M. Smith and David L. WaldienSource: Northwestern Naturalist, Vol. 80, No. 3 (Winter, 1999), pp. 113-114Published by: Society for Northwestern Vertebrate BiologyStable URL: http://www.jstor.org/stable/3536658 .

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WINTER 1999 GENERAL NOTES 113

survey at a trough. We know nothing about in- terannual variation in abundance of Umpqua chub. Scheerer and Apke (undated. Oregon chub research: Middle Fork Willamette and Santiam drainages. Oregon Department of Fish and Wildlife Progress Report, contract E96970022. 1 October 1996-30 September 1997. 79 p) have documented interannual variation in Oregon chub populations, and found popula- tions declining, increasing, or staying relative- ly stable. They have observed maximum fluc- tuations of an order of magnitude over 5 yr (1993 to 1997), including populations driven close to extinction, but they have not seen any disappear. Our data suggest Umpqua chub have disappeared from half the sites surveyed 11 years ago, a survey which had documented an expansion of the known range of the species at that time. Further, the apparent pattern of displacement, whereby smallmouth bass may

have "replaced" Umpqua chub in mainstem sections and restricted them to lower order tributaries, has resulted in fragmentation and isolation with unknown demographic and ge- netic consequences.

ACKNOWLEDGMENTS

Financial support was provided by the Willamette National Forest, U.S. Fish and Wildlife Service, Oregon Department of Fish and Wildlife's Nongame Program, and Oregon State University Agricultural Experiment Station. S. Litrakis and C. Lorion assist- ed with field collections and data compilation. This is technical paper number 11534 of the Oregon State University Agricultural Experiment Station.

Department of Fisheries and Wildlife, Oregon State University, Corvallis, Oregon 97331 USA. Sub- mitted 11 January 1999, accepted 6 June 1999. Cor- responding Editor: D. H. Olson.

NORTHWESTERN NATURALIST 80:113-114 WINTER 1999

FIRST RECORDS OF BRAZILIAN FREE-TAILED BATS (TADARIDA BRASILIENSIS) IN THE WILLAMETTE VALLEY, OREGON

GREGORY M. SMITH AND DAVID L. WALDIEN

Key Words: Tadarida brasiliensis, Brazilian free-tailed bat, Willamette Valley, Oregon

Brazilian free-tailed bats (Tadarida brasilien- sis) are distributed widely throughout North and South America. In western North America, their range extends from Baja California north- ward to southwestern Oregon (Verts and Car- raway 1998). Distribution in Oregon is known from specimens collected in Douglas, Jackson, and Klamath counties (Maser and Cross 1981; Verts and Carraway 1998), although Csuti and others (1997) include part of Josephine County based on habitat similarities. Douglas County has been considered the northernmost extent of their range in North America (Verts and Car- raway 1998). Here we report a range extension for the species into the Willamette Valley, Lane County, Oregon.

During September and October 1998, we captured solitary T. brasiliensis day roosting on the top of Lookout Point Dam (elevation 287 m; T19S, R1W, SE 1/4 Sec. 13) on 4 separate oc- casions. Two bats were roosting in expansion joints of west-facing parapet walls (76.2 cm X 38.1 cm x 1.3 cm) and 2 were in single-chamber bat boxes (61 cm X 61 cm, crevice width taper- ing from 2.5 cm at the bottom to 1.3 cm at top) placed on the east side of the dam. We deter- mined age class (adult or juvenile) of bats based on epiphyseal closure (Anthony 1988) and reproductive status (Racey 1988). Refer- ence photographs of 2 of these bats are on file at Oregon State University (FW 09493 and FW 09494). These 4 observations comprised at least 3 separate individuals based on differences in sex and age.

The 1st bat was a post-reproductive female

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114 NORTHWESTERN NATURALIST 80(3)

that appeared old based on severe incisor wear; the 2nd was an adult male with swollen testes. The 3rd bat was an adult female of undeter- mined reproductive status; this individual ap- peared younger than the 1st female based on in- cisor wear. The final bat was a female of un- known age. These are the 1st reported obser- vations of T brasiliensis in the Willamette Valley and represent a northerly range extension of approximately 90 km.

It is unclear whether the T brasiliensis ob- served in the Willamette Valley in autumn were individuals dispersing from distant locales or were part of a resident population. The nearest known colonies are found in Roseburg (T. Fer- rel, Oregon Department of Fish and Wildlife, pers. comm.). However, given the number of in- dividuals identified and the propensity of the species to over-winter in Oregon (Verts and Carraway 1998), these observations suggest that a colony may exist within the Willamette Valley. It is also unclear if these bats are ex- panding their range northward, or if they have been overlooked because of a lack of surveys for bats in the Willamette Valley. Further study is required to determine the status of T brasi- liensis in the Willamette Valley.

ACKNOWLEDGMENTS R. Magne, S. Richardson, and P. Severns provided

field assistance. We thank the U.S. Army Corps of En-

gineers, particularly K. Beal for providing the op- portunities that lead to this finding. E. Fritzell, J. Hayes, L. Hennings, R. Magne, and C. Starck provid- ed insightful comments on early drafts.

LITERATURE CITED

ANTHONY ELP. 1988. Age determination in bats. In: Kunz TH, editor. Ecological and behavioral meth- ods for the study of bats. Washington DC: Smith- sonian Institution Press. p 47-57.

CSUTI B, KIMERLING AJ, O'NEIL TA, SHAUGHNESSY MM, GAINES EP, Huso MMP. 1997. Atlas of Oregon wildlife. Corvallis, OR: Oregon State Uni- versity Press. 352 p.

MASER C, CROSS SP. 1981. Notes on the distribution of Oregon bats. Portland, OR: Research Note PNW-379. 31 p.

RACEY PA. 1988. Reproductive assessment in bats. In: Kunz TH, editor. Ecological and behavioral meth- ods for the study of bats. Washington DC: Smith- sonian Institution Press. p 31-46.

VERTS BJ, CARRAWAY LN. 1998. Land mammals of

Oregon. Berkeley, CA: University of California Press. 668 p.

Resource Section, U.S. Army Corps of Engineers, Lookout Point Dam, Lowell, Oregon 97452 USA (GMS); Department of Forest Science, Oregon State University, Corvallis, Oregon 97330 USA (DLW). Submitted 16 April 1999, accepted 3 June 1999. Corresponding Editor: E. Muths.

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