Florida Key deer (Odocoileus virginianus clavium) were listed as endangered by
the U.S. Fish and Wildlife Service (USFWS) in 1967. A variety of survey methods have
been used in estimating deer density and/or changes in population trends for this species
since 1968; however, a need to evaluate the precision of existing and alternative survey
methods (i.e., road counts, mark-recapture, infrared-triggered cameras [ITC]) was
desired by USFWS.
I evaluated density estimates from unbaited ITCs and road surveys. Road
surveys (n = 253) were conducted along a standardized 4-km route each week between
January 1999ÂDecember 2000 (total deer observed, n = 4,078). During this same period,
11 ITC stations (1 camera/42 ha) collected 5,511 deer exposures. Study results found a
difference (P < 0.001) between methods with road survey estimates lower (76 deer) than
ITC estimates (166 deer). Comparing the proportion of marked deer, I observed a higher
(P < 0.001) proportion from road surveys (0.266) than from ITC estimates (0.146).
Lower road survey estimates are attributed to (1) urban deer behavior resulting in a high
proportion of marked deer observations, and (2) inadequate sample area coverage. I suggest that ITC estimates are a reliable and precise alternative to road surveys for
estimating Key deer densities on outer islands.
I also evaluated density estimates from 3 road survey methods. Road survey
methods (n = 100) were conducted along a standardized 31-km route where markresight,
strip-transect, and distance sampling data were collected between June 2003Â
May 2004. I found mark-resight estimates to be lower ( x = 384, 95% CI = 346Â421)
than strip-transect estimates ( x = 854, 95% CI = 806Â902) and distance estimates ( x =
523, 95% CI = 488Â557). I attribute low mark-resight estimates to urban deer behavior
resulting in a higher proportion of marked deer observations along roadways. High
strip-transect estimates also are attributed to urban deer behavior and a reduced effective
strip width due to dense vegetation. I propose that estimates using distance sampling
eliminate some of these biases, and recommend their use in the future.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/3812 |
| Date | 16 August 2006 |
| Creators | Roberts, Clay Walton |
| Contributors | Lopez, Roel R. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 1214203 bytes, electronic, application/pdf, born digital |
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