Trends in Rio Grande wild turkey (Meleagris gallopavo intermedia) abundance on the Edwards Plateau (EP), Texas, have been either stable or in decline since the 1970s. Four study areas, 2 each within stable (Stable Area A, SAA; Stable Area B, SAB) and declining regions (Declining Area A, DAA; Declining Area B, DAB), were delineated to examine (1) both annual and seasonal survival, (2) relative mammalian predator mean abundance (RMA), and (3) potential effects of lunar phase on scent-station visitation.
During February 2001-March 2003, 257 turkeys were captured and instrumented with radio transmitters. Survival probabilities were generated using a Kaplan-Meier product limit estimator; a log-rank test tested for differences among sites. Annual survival was statistically different between regions (stable 0.566 ± 0.081; declining 0.737 ± 0.094; X2 = 3.68, P = 0.055) in 2002. Seasonal survival differed between regions (stable 0.812 ± 0.103; declining 0.718 ± 0.130; X2 = 3.88, P = 0.049) in spring 2003. Annual survival results during 2002 were counterintuitive with turkey trend data. Scent-station transects were established on non-paved ranch roads within study regions. Scent-station indices revealed higher (H = 19.653, P ≤ 0.001) RMA of opossum (Didelphis virginiana) and skunk (eastern spotted [Spilogale putorius], striped [Mephitis mephitis], or western spotted [S. gracilis]) (SAA, x⎯ = 0.0148; SAB, x⎯ = 0.0151; DAA, x⎯ = 0.0042; DAB, x⎯ = 0.0065) on stable areas. Higher RMA of coyotes (Canis latrans) on declining areas (SAA, x⎯ = 0.0067; SAB, x⎯ = 0.0022; DAA x⎯ = 0.0234; DAB x⎯ = 0.0434) suggested a possible causative factor of the decline, but abundance indices were not verified by empirical data though. Lunar phase was not a significant (T = -0.225, P = 0.822) covariate in scent-station visits by raccoons, opossums (new, x⎯ = 0.0111; full, x⎯ = 0.0324), or unidentified tracks (new, x⎯ = 0.0649; full, x⎯ = 0.0375). Nightly precipitation and wind speed probably influence mammalian use of scent stations more so than lunar illumination.
Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/419 |
Date | 30 September 2004 |
Creators | Willsey, Beau Judson |
Contributors | Silvy, Nova J., Peterson, Markus J. |
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 | 571130 bytes, 76115 bytes, electronic, application/pdf, text/plain, born digital |
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