Literaturdatenbank
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Martin, B. E., & van Devender, T. R. (2003). Seasonal diet changes of gopherus agassizii (desert tortoise) in desert grassland of southern arizona and its behavioral implications. Herpetological Natural History, 9(1), 31–42.
Added by: Admin (14 Aug 2008 20:36:24 UTC) |
| Resource type: Journal Article BibTeX citation key: Martin2003 View all bibliographic details  |
Categories: General Keywords: Ernährung = nutrition, Gopherus, Gopherus agassizii, Habitat = habitat, Nordamerika = North America, Schildkröten = turtles + tortoises, Testudinidae Creators: van Devender, Martin Collection: Herpetological Natural History |
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| Abstract |
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Testudinidae We studied the diet of a Gopherus agassizii (desert tortoise) population in desert grassland of Arizona, a high-elevation peripheral habitat for this species. We analyzed diet by fragment and microhistological analyses of seasonally fresh scat collected in 1990, and feeding observations of free-ranging tortoises during 1990-91. Tortoises primarily fed on a variety of grasses and annuals, in part tracking seasonal species availability in response to winter or summer precipitation. Tortoises consumed lesser amounts of shrubs, subshrubs, herbaceous perennials, and succulent fruit, although these life forms are widespread and diverse (68 taxa) in the study area. The peak feeding period was mid-summer to early fall (July-October), when tortoises fed primarily on grasses (especially Aristida and Bouteloua spp.) and lesser amounts of summer annuals (Boerhavia intermedia, Euphorbia spp., Mollugo verticillata, Portulaca oleracea), prickly pear cactus (Opuntia engelmannii) fruit, and herbaceous perennials (Sida abutifolia, etc.). Fresh scat and foraging were not observed until May. The limited spring diet was dominated by annuals (Astragalus nuttallianus, Lotus humistratus, Lupinus spp., Plantago patagonica) and perennial grasses (Aristida spp., Bouteloua spp.). However, dried spring annuals were important supplements during the summer-fall peak feeding period. Two exotics (Bromus rubens, Erodium cicutarium) and one shrub (Calliandra eriophylla) were important in the diet. Fragment analysis detected far more taxa (50) in the diet than the other methods. Seasonal behavior of Sonoran G. agassizii affects the utilization of and perceived availability of food resources. Tortoises at the study area acquired most, if not all, of their annual dietary intake, from mid-summer through early fall, suggesting that even with recurrent abundant fresh spring forage there has been little selection for spring activity in this subpopulation.
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