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Accueil du site → Doctorat → États-Unis → 1982 → BEHAVIORAL ECOLOGY OF REINTRODUCED DESERT BIGHORNS, ZION NATIONAL PARK, UTAH

Colorado State University (1982)

BEHAVIORAL ECOLOGY OF REINTRODUCED DESERT BIGHORNS, ZION NATIONAL PARK, UTAH

Mccutchen, Henry

Titre : BEHAVIORAL ECOLOGY OF REINTRODUCED DESERT BIGHORNS, ZION NATIONAL PARK, UTAH

Auteur : Mccutchen, Henry

Université de soutenance : Colorado State University

Grade : Doctor of Philosophy (PhD) 1982

Résumé
Desert bighorns (Ovis canadensis nelsoni) were propagated in an enclosure in Zion National Park and released in two phases in 1977 and 1978. Bighorn behavior and population dynamics were monitored by a combination of radiotelemetry and observation until 1979. In the first phase 13 bighorns were translocated 5 km from the rearing area and released. Only four were believed to be alive in the wild a year later. This group exhibited persistent social disintegration and home range divergence. Factors contributing to these effects included timing the release just prior to lambing, social segregation during home range exploration, mortalities, and ewes homing to the rearing enclosure. Mortalities occurred from disease, transplanting injuries, and mountain lion (Felis concolor) predation. In the second phase 20 bighorns were released directly from the Zion rearing enclosure following the lambing season in 1978. After this release there was a period of social disintegration which lasted for about 2 months followed by a reestablishment of social ties and social organization. Social segregation of the bighorns during home range exploration was related to differences in sex, age, reproductive status and prior home range experience. A main factor facilitating later socialization was bighorn philopatry to rearing enclosure. By the end of the study period only 11 of the original bighorns from this release were present in the population. The stimuli and barriers affecting bighorn movement and home range sizes are discussed. A major cause of mortality was mountain lion predation. The bighorns were vulnerable to lion predation at high elevations in dense habitats, where visibility was low and when group sizes were three or less. There was evidence that the bighorns adapted to the predation by maintaining large group sizes and shifting their use to the more open habitats at lower elevations. The subsequent development of a familiar area (home range) through exploration and the influence of sociality and tradition were believed to have played important roles in bighorn antipredator strategies and resource exploitation. Pre-release and post-release dominance hierarchies and leadership behavior are described. The management implications of the project are discussed

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