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    Ecology of the Endemic Mearns's Squirrel (Tamiasciurus Mearnsi) in Baja California, Mexico

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    Author
    Ramos-Lara, Nicolas
    Issue Date
    2012
    Keywords
    Mearns's squirrel
    Mexico
    Sierra de San Pedro Martir
    Tamiasciurus mearnsi
    Natural Resources
    Baja California
    Endemic
    Advisor
    Koprowski, John L.
    
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    Show full item record
    Publisher
    The University of Arizona.
    Rights
    Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
    Abstract
    One of the major environmental concerns in the world is the loss of biological diversity due to anthropogenic activities. Of special concern is the conservation of endemic species that are particularly vulnerable to extinction. The Mearns's squirrel (Tamiasciurus mearnsi) is endemic to the Sierra de San Pedro Mártir, Baja California. Federally listed as threatened in Mexico and as endangered by the International Union for Conservation of Nature (IUCN), little is known about the ecology of this southernmost Tamiasciurus. Interestingly, Mearns's squirrels exhibit deviations from common behaviors observed in other congeners such as lack of leaf nests (dreys) and larderhoards (middens), suggesting potentially unique adaptations. Herein, I reviewed the diversity and conservation status of the arboreal squirrels of Mexico. Using radio-telemetry and satellite imagery, I examined if the lack of dreys and middens may be associated with differences observed in nesting behavior, home-range dynamics, and life-history and behavioral tactics between Mearns's squirrels and other arboreal squirrels.Mexico harbors 14 species of arboreal squirrels, of which four are endemic, with the states of Chiapas and San Luis Potosí possessing the greatest diversity. Unfortunately, high deforestation rates in Mexico, and a dearth of information on their ecology, pose serious threats to the persistence of this squirrel diversity. Mearns's squirrels apparently are obligate secondary cavity-nesters with specific nesting requirements and their population possibly limited by the low occurrence of tree cavities in their habitat. The species seems to have lost the territorial behavior that is characteristic of the genus Tamiasciurus. Home-range dynamics of Mearns's squirrels are similar to nonterritorial Sciurus squirrels. Although reproduction and survival are similar to other Tamiasciurus, the species is heavier and apparently larger while exhibiting important variations in their behavior compared to other congeners. The lack of dreys and middens appears to be associated with the unique tactics adopted by Mearns's squirrels to persist in the Sierra de San Pedro Mártir. The species provides an important opportunity to learn more about geographic variation in nesting behavior and the evolution of territoriality. Large trees and snags that facilitate cavity formation are critical for the conservation of this species.
    Type
    text
    Electronic Dissertation
    Degree Name
    Ph.D.
    Degree Level
    doctoral
    Degree Program
    Graduate College
    Natural Resources
    Degree Grantor
    University of Arizona
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