Bat Counts at the John Guilday Caves Nature Preserve
(Trout Rock)
Pendleton County, West Virginia

The National Speleological Society purchased 40 acres containing the entrances to Trout, Hamilton, and New Trout caves in 1983.  Since that time there has been an annual bat count in each cave to document the change in populations over time.

Several bat counts were also done before the NSS purchased the caves.  Finding the actual records of those old counts is difficult, but as they are uncovered they will be posted on this page.

Some Modern (1980 and newer) Bat Count Reports

Reports for the bat counts done since 1999 have been published in various caving newsletters.  These reports are available below.  Reports of some of the earlier counts were also published, but they are not available in electronic format.

During the annual counts no attempt is made to count in the entire cave, but the same area in each cave is counted each year.  This methodology should provide comparable statistics each year.

You can see the recent counts by clicking the link to each year's count.  The files are all PDF files. (There was no count in 2021).
1999   2000   2001   2002   2003   2004   2005   2006   2007   2008   2009   2010   2011   2012   2013   2014   2015   2016   2017   2018   2019   2020   2022   2023   2024

  2019 White-Nose Syndrome found in Hamilton Cave (2009) (detailed report about finding WNS in Hamilton Cave in January, 2009).

The 2010 Trout Rock Bat Count (Report on the 2010 bat count when Hamilton Cave's population crashed to 30 bats.  Includes graphs showing historical counts in all three caves).

Raw Data for Recent Bat Counts

The raw data for the "modern era" of bat counts is available below.  The data is in PDF files, but the raw data is also available in Excel format if desired.  Contact Bob Hoke for more information or to get the Excel files.

   Trout Cave raw data 1983-2023
   Hamilton Cave raw data 1984-2024
   New Trout Cave raw data 1982-2024

Historical Bat Counts

This section contains documentation about historical (pre-1980) bat counts in the Trout Rock caves.   There are many  sources that refer to several early counts, but the intent is to provide the actual data here rather than merely references to it  All of the links below are to PDF files.

Fowler-1941 (scanned document and text file)
A copy of an article in the May, 1941, issue of the Bulletin of the National Speleological Society by James Fowler.  The article covers many topics, but page 38 briefly describes counting 1,600-2,400 Myotis sodalis bats in one room in Trout’s [sic] Cave on February 23, 1941.  [Article was supplied by the NSS Library in Huntsville, AL].

Hall-1962 (scanned document only)
A very poor scanned image of Life History and Taxonomic Study of the Indiana Bat, Myotis sodalis, by John S. Hall (Reading, Pennsylvania, Reading Public Museum and Art Gallery Scientific Publication Number 12, 1962, 59 pages)  [Scanned image was supplied by Barbara Douglas of the U.S. Fish & Wildlife Service].

Davis-1983 (scanned document and text file)
A letter from Wayne Davis (Univ. of Kentucky, Lexington, KY) to Dr. Virginia Tipton (Radford University, Radford, VA) saying that he did not have his notebook with banding statistics from the 1950s.  He did provide some estimates of the number pf bats banded in Trout and several other caves in the 1950s.  [Letter was supplied by Barbara Douglas of the U.S. Fish & Wildlife Service].

Sullivan-1984 (scanned document and text file)
A 1984 letter from Brother Nicolas Sullivan (Manhattan College, Riverdale, NY) to Janet McCormick (National Speleological Society) saying that he had seen an estimated 1,000 Myotis Sodalis bats in Trout on several winter visits from 1955-1957.  These bats were located in what he called “the roost”, but he doesn’t specify where it is.  He also reported seeing six clusters of 10-20 bats in the main passage toward the entrance from the roost passage.  [Letter was supplied by Barbara Douglas of the U.S. Fish & Wildlife Service].

Hall-1984 (scanned document and text file)
A 1984 letter from John Hall (Albright College, Reading, PA) to Leonard Walker (U.S. Fish and Wildlife Service, Elkins, WV) giving detailed statistics of counts done in Trout Cave in 1951-53 by Wayne Davis.  Davis banded 238 Myotis sodalis in Trout in 1951, 232 in 1952, and 565 in 1953.  The letter also reports finding 5 Myotis sodalis bats in Trout in 1960, 13 in 1961, and none in 1965 and later. [Letter was in correspondence file supplied by Paul Stevens].

Miles-1984 (scanned document and text file)
A 1984 letter from Robert Miles (WV Department of Natural Resources, Charleston, WV) to Paul Stevens (NSS President) reiterating Fowler’s 1941 Trout Cave count and stating that it is encouraging that a small colony of Myotis sodalis bats again find Trout a suitable hibernation site.  [Letter was in correspondence file supplied by Paul Stevens].

Fowler-1984 (scanned document and text file)
A 1984 letter to Rane Curl (NSS Board of Governors member) from James Fowler (Cranbrook Institute of Science, Bloomfield Hills, MI) giving information about the counts that Fowler did in Trout cave in 1941.  [Letter was in correspondence file supplied by Paul Stevens].

Questions and comments about this page are welcome.  Send them to Bob Hoke at

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This page last updated or verified on February 14, 2024