SILVER-HAIRED BAT
Lasionycteris noctivagans
(Le Conte, 1831)


laz-E-O-nic-ter-us noc-ti-vA-gans




An adult Silver-haired Bat. Photo by John MacGregor
Image © by Greg Sievert.
Image © by Greg Sievert.
Image © by Greg Sievert.

Description:
Lasionycteris noctivagans is a medium-sized bat with black wings, face, ears, and interfemoral membrane. The ears are short, rounded, and naked, with a broad, blunt tragus. The pelage is dark brown or black with silvfery-white tips on individual hairs, giving a silvery appearance. No other species of bat in Kansas has blackish pelage with silver tips. The hoary bat has a frosted appearance but is not likely to be confused with the silver-haired bat. 

External measurements of adults are as follows: total length 92-115 mm; length of tail 35-45 mm; length of hind foot 7-10 mm; length of ear 12-17 mm; weight 8.1-11.0 g. 

The dental formula is incisors 2/2, canine 1/1, premolars 2/3, molars 3/3.



Distribution:
The silver-haired bat can be found throughout most of temperate North America from southern Alaska and Canada south to northern Mexico. It inhabits the upper slopes of mountains and northern latitudes during summer and migrates to southern North America in autumn. The species has been documented throughout Kansas, albeit more commonly in western counties. Most specimens have been taken in the months of May and September, suggesting that this bat migrates twice annually across the state.
Fossils of Lasionycteris have been found in Pleistocene sites in Texas and Wyoming.

(, Museum Voucher) (, Observation) (, Literature Record)
Open icons are questionable records; Click on a marker to view details.
  • Occurrence Summary:  
  • 41 Total Records 
  • 39 Museum Vouchers 
  • 2 Other Observations 
Some county occurrences indicated below may be too imprecise to map above.
County Breakdown: County Name (# occurrences):
Decatur (2); Douglas (2); Ellis (4); Finney (1); Geary (1); Grant (2); Meade (4); Morton (14); Norton (1); Rooks (2); Sedgwick (1); Sherman (2); Thomas (3); Trego (1); Wallace (1);

Natural History:
The silver-haired bat is one of the least-known species of bat in North America, probably because it is not especially gregarious or abundant. The species seems to be rare mainly because individual silver-haired bats are solitary for much of the year and roost in trees (often beneath loose bark) where they are difficult to find. Individuals of this species also have been found in abandoned swallow nests. The flight of this bat is often slow, low, and leisurely, and appears less erratic than that of myotis. 

This species begins feeding early in the evening, and prefers openings among trees (especially areas bordering forests) and open fields where it searches for nocturnal insects. Sometimes an audible chirping call of this bat can be heard. Foraging activity exhibits two peaks, with a lull around midnight. The first peak occurs 2 to 4 hours after sunset, and the second, 2 to 6 hours later. Insects evidently are consumed based on their abundance, as most orders of insects are represented in the diet.
 
Owls seem to be the principal predators on silver-haired bats when they are foraging, but skunks have been reported to eat them also. Hoary bats have been reported to attack silver-haired bats. Another cause of mortality is collision with structures during migration. This species accululates organochlorine residues in areas where chemicals are sprayed. The strain of rabies associated with silver-haired bats has been the cause of 15 human deaths in the United States since 1983.

This bat is not known to produce young in Kansas although one pregnant female has been found in the state during migration. Mating evidently occurs in autumn, and sperm are stored in the uterus during winter. Ovulation and fertilization occur in late April or early May, followed by a gestation period of 50 to 60 days. Females give birth to 1 or (usually) 2 black and wrinkled young in June or early July. Only one litter is produced each year. The young bats nurse for approximately 36 days and can fly by the end of July.


Occurrence Activity:
Remarks:
This species is monotypic in that no subspecies have been recognized.

Bibliography:
1952 Cockrum, E. L. Mammals of Kansas. Univ. Kansas Publ. Mus. Nat. Hist. 7:1-303. ():
1967 Jones, J. K. Jr., E. D. Fleharty, and P. B. Dunnigan The distributional status of bats in Kansas. Univ. Kansas Mus. Nat. Hist. Misc. Publ., 46:1-33. ():
1982 Kunz, T. H. Lasionycteris noctivagans Mammalian Species 172():1-5
1983 Jones, J. K., Jr., D. M. Armstrong, R. S. Hoffmann, and C. Jones University of Nebraska Press, Lincoln, NE. 1-379pp.
1994 Fitzgerald, J. F., C. A. Meaney, and D. M. Armstrong University Press of Colorado, Niwot, CO. 1-467pp.
2000 Sparks, D. W., and J. R. Choate Distribution, natural history, conservation status, and biogeography of bats in Kansas Pages 173-228 in Reflections of a Naturalist: Papers Honoring Professor Eugene D. Fleharty Fort Hays State University, Hays, KS. pp.
2000 Sparks, D. W., K. J. Roberts, and C. Jones Vertebrate predators on bats in North America north of Mexico. Pages 229-241 in Reflections of a naturalist: Papers honoring Professor Eugene D. Fleharty. Fort Hays Studies, Special Issue 1, Hays, Kansas. pp.
2003 Cryan, P. M. Seasonal distribution of migratory tree bats (Lasiurus and Lasionycteris) in North America Journal of Mammalogy 84(2):579-593
2008 Timm, R. M., G. R. Pisani, J. R. Choate, N. A. Slade, G. A. Kaufman, and D. W. Kaufman http://www.ku.edu/~mammals, . pp.
Account Last Updated:
8/21/2018 7:54:02 PM


TWT © 2023 — Sternberg Museum of Natural History, Fort Hays State University