Browsing by Author "Villavicencio, Camila P."

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    BREEDING BIOLOGY OF THE SOUTHERN HOUSE WREN ON CHILOE ISLAND, SOUTHERN CHILE
    (2012) Ippi, Silvina; Vasquez, Rodrigo A.; Moreno, Juan; Merino, Santiago; Villavicencio, Camila P.
    We studied the breeding biology of a Southern House Wren (Troglodytes aedon chilensis) population using nest boxes on Chiloe Island, southern Chile (41 degrees S) to make latitudinal comparisons at the intraspecific level. There were no significant differences in body size between adult males and females, although wings were significantly longer in males. Clutch size averaged 4.3 eggs per nest, and brood size was 3.9 nestlings. Egg size averaged 17.3 mm in length and 13.2 mm in width. Incubation and nestling periods averaged 16 days each. The Southern House Wren on Chiloe Island has a larger clutch size than in the tropics, but a smaller clutch size than populations at the same latitude in the Northern Hemisphere. The Southern House Wren has larger eggs and a longer incubation period but a similar nestling period as House Wrens in the Northern Hemisphere. Received 23 August 2011. Accepted 29 January 2012.
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    Ecological drivers of group living in two populations of the communally rearing rodent, Octodon degus
    (2012) Ebensperger, Luis A.; Sobrero, Raul; Quirici, Veronica; Castro, Rodrigo A.; Ortiz Tolhuysen, Liliana; Vargas, Francisco; Burger, Joseph Robert; Quispe, Rene; Villavicencio, Camila P.; Vasquez, Rodrigo A.; Hayes, Loren D.
    Intraspecific variation in sociality is thought to reflect a trade-off between current fitness benefits and costs that emerge from individuals' decision to join or leave groups. Since those benefits and costs may be influenced by ecological conditions, ecological variation remains a major, ultimate cause of intraspecific variation in sociality. Intraspecific comparisons of mammalian sociality across populations facing different environmental conditions have not provided a consistent relationship between ecological variation and group-living. Thus, we studied two populations of the communally rearing rodent Octodon degus to determine how co-variation between sociality and ecology supports alternative ecological causes of group living. In particular, we examined how variables linked to predation risk, thermal conditions, burrowing costs, and food avail-ability predicted temporal and population variation in sociality. Our study revealed population and temporal variation in total group size and group composition that covaried with population and yearly differences in ecology. In particular, predation risk and burrowing costs are supported as drivers of this social variation in degus. Thermal differences, food quantity and quality were not significant predictors of social group size. In contrast to between populations, social variation within populations was largely uncoupled from ecological differences.