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Open Access Publications from the University of California

Scholarly Works (2 results)

  • Article
  • Peer Reviewed
Journal of California and Great Basin Anthropology, Volume 24, Issue 1 (2002)

Archaic Period subsistence data recovered from two temporally distinct features at the Scripps Poway Parkway site (CA-SDI-4608) were assessed in an analysis of differences between Middle and Late Archaic Period subsistence practices at inland sites along the Los Penasquitos watershed. The Late Archaic sample was hypothesized to show evidence of a more intensive terrestrial focus, exhibiting greater proportions of deer and Leporid species, and greater species diversity, due to more intensified exploitation of terrestrial resources in response to degradation of the coastal habitat at Los Penasquitos Lagoon following increased sediment flux ca. 3,500 B.P. Although species diversity measures were essentially equal between the samples, indicating cultural continuity rather than cultural change between Middle and Late Archaic Periods, species proportions by bone weight indicated a higher reliance on Leporid species during the Late Archaic Period, which may have been in response to an overharvest of deer, indicating intensification on terrestrial resources. Los Penasquitos Lagoon, which remained open and tidally flushed throughout the Late Holocene, was nonetheless affected by sediment flux and habitat degradation, which necessitated an intensification on terrestrial resources.

    Cover page: Middle to Late Archaic Period Changes in Terrestrial Resource Exploitation Along the Los Peñasquitos Creek Watershed in Western San Diego County: Vertebrate Faunal Evidence from the Scripps Poway Parkway Site (CA-SDI-4608)
    • Article
    • Peer Reviewed
    UCLA Previously Published Works (2015)
    We released and monitored 53 juvenile Agassiz’s Desert Tortoises (Gopherus agassizii), aged two to 15 y, that were hatched and head-started inside predator-resistant field enclosures. We set free these tortoises under a variety of conditions to evaluate effects of release distance, season of release, and age/body size on homing behavior and survivorship. Some juveniles moved large distances following release, but homing itself was undetectable. The lack of homing behaviors was likely due to release distance and selection of release sites out of the line-of-sight of natal enclosures. The use of small halfway-house enclosures to accustom some relocated juveniles to release sites for four months before release (i.e. “soft release”) had no effect on subsequent movements or survivorship during the first year following release. Survivorship was not affected by distance of release from natal enclosures, which ranged from 546 m to 1.4 km. Survivorship through one year was similar for juveniles released in spring or autumn. After two years, most small juveniles had been killed by predators, but survivorship increased with body size and age. Juveniles over approximately 100 mm MCL (midline carapace length) and nine years of age when released exhibited high survivorship. However, following a long drought the previous two years, predation by Coyotes (Canis latrans) was heavy on these larger juveniles in the third year after release. Thus, survivorship after three years was relatively low (34%) with the youngest, smallest cohort (two years old when released) exhibiting the lowest survivorship (4%). We recommend releasing headstarted tortoises after they attain a body size of larger than 100 mm MCL and selecting release sites at least 546 m from enclosures.
      Cover page: HEAD-STARTED DESERT TORTOISES (GOPHERUS AGASSIZII): MOVEMENTS, SURVIVORSHIP AND MORTALITY CAUSES FOLLOWING THEIR RELEASE
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