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Centro de Investigaciones Biológicas del Noroeste (CIBNOR) 2014

Dieta y densidad estacional de Lepus Insularis (bryant, 1891) en distintos ambientes del complejo insular Espíritu Santo, Baja California Sur, México

Torres García, Flor Marleny

Titre : Dieta y densidad estacional de Lepus Insularis (bryant, 1891) en distintos ambientes del complejo insular Espíritu Santo, Baja California Sur, México

Auteur : Torres García, Flor Marleny

Etablissement de soutenance : Centro de Investigaciones Biológicas del Noroeste (CIBNOR)

Grade : Maestría en Ciencias en el Uso, Manejo y Preservación de los Recursos Naturales 2014

Résumé
Mexico is well known for its richness in hares. However, many of them are found in different risk categories due to different human activities as excessive hunting and loss of habitat. In northwestern Mexico the genus Lepus is represented by three species (L. californicus, L. alleni, L. insularis) that include five taxa distributed in the islands. One of these species, Lepus insularis, is endemic to the Espiritu Santo Island Complex that forms part of the Gulf of California Areas of Faunal and Floristic Protection. Because of the lack of biological and ecological information about many of the species with distribution in the islands, the main objective of this research is to identify the diet of the Black jackrabbit (L. insularis) and estimate its population density in the different environments of the island complex during two study seasons (rainy and dry). For this purpose the environments were characterized as : mountain tops, slopes, lowlands and dune association with halophyte areas ; variables were estimated such as : type of vegetation, slope, and exposure. Scat was collected from 1m2 land areas, used as indirect method to estimate population, and used at the same time to identify diet to know food preferences of the species by using a microhistological technique made up with a previous reference collection of island plants. For samplings, transects distributed in the four different environments were used. The results of the characterization showed as dominant species herbaceous plants, followed by shrubs, succulent plants, and stones (elements > 25 cm) as the main components of the superficial layer of the soil dominating over bare, gravel, and pebbles. A conglomerate analysis grouped dunes and dune association with halophyte areas as a separate set form the rest of the environments (mountain tops, slopes, lowlands). General density averaged 2.48 hares/km2 and 1.71 hares/km2 in rainy and dry environments, respectively. By environments, the highest average density was estimated in mountain tops (3.44 hares/km2) and the lowest one for dune association with halophytes (1.11 hares/km2). These densities agree with those that can be found in island ecosystems. Diet was estimated in 52 species consumed besides grasses. These last ones were identified only at family level but constituted 55.38 % of the botanical composition of the Black jackrabbit’s diet. The rest of the species of major consumption corresponded to the families Fabaceae and Cactaceae with eight and six species, respectively. The results show that the Black jackrabbit is a generalist selective species.

Mots Clés : Lepus insularis ; islas ; densidad ; dieta ; Espíritu Santo.

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Page publiée le 26 décembre 2019