Food Habits and Selective Foraging by the Texas Tortoise (Gopherus berlandieri)
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The Texas tortoise (Gopherus berlandieri) is a state threatened species occurring in southern Texas. Dietary specifics for this species are not known and are needed for appropriate management and conservation. I collected 51 Texas tortoise fecal samples from 5 different sites from across the distribution during summers of 2007 and 2008. Vegetative analysis was performed at each site using the Daubenmire method (Daubenmire, 1959) to estimate percent cover of each plant species. Later, each species was categorized by forage class (cactus, forb, grass, or woody vegetation) and percent cover estimates were summed for each forage class. Dietary analysis was performed on fecal material using a microhistological approach. My results varied by study site, but some trends were evident. Forb fragments were identified from 100% of fecal samples, cactus in 98.0 %, grass in 96.0 %, woody vegetation in 92.2%, and animal fragments in 56.9 %. Analysis of data from all sites suggests Texas tortoises forage selectively (χ23 = 875.8, p < 0.001) and consume cacti more than expected and grasses less than expected. Male tortoise diets differed significantly (χ24 = 42.1, p < 0.001) from female tortoises as males consumed more cacti than females. Adult and juvenile tortoise diets also differed significantly (χ24 = 30.3, p < 0.001) where juveniles consumed less grass and more forbs than adults. This information is very valuable as invasive grass species could potentially out-compete native flora. Land management practices by landowners providing forage for Texas tortoises should be considered.