Comparisons with the other breeding colonies of NZ sea lions are presented and data are discussed in the context of the recolonization of the NZ mainland. Overall, the most suitable terrestrial habitat configuration for a breeding aggregation of NZ sea lions appears to be a sandy beach, with a wide area above high tide and moderate intertidal zone (for breeding), backed with vegetated
sand dunes and forest on primarily flat terrain (for later dispersion). “
“Toothed whales (crown Odontoceti) are unique among mammals in their ability to echolocate underwater, using specialized tissue structures. The melon, a structure composed of fat and connective tissue, is an important MK0683 mw component in the production of an echolocation beam; it is known to focus high frequency, short duration echolocation clicks. Here, we report on the morphology of the odontocete melon to provide a comprehensive understanding of melon structure across odontocete taxa. This study examined nine odontocete species (12 individual specimens), from five of the ten extant odontocete families. We established standardized definitions using computed tomography scans of the melon to investigate structure without losing geometric integrity. The morphological features that relate to the focusing capacity of the melon include internal density
topography, melon size and shape, and relationship to other forehead structures. The potential for melon structure to act as a Selleckchem LDK378 filter is discussed: establishing a lower limit
to the frequency of sounds that can be propagated through the head. Collectively, the results of triclocarban this study provide a robust, quantitative and comparative framework for evaluating tissue structures that form a key component of the echolocation apparatus. “
“Many pinniped populations precipitously declined during the 19th and 20th centuries due to overharvesting. In Uruguay, the South American sea lion (SASL) was harvested until 1986. Birth rates in two nearby breeding colonies have had opposite trends for at least 20 yr. We assessed different mechanisms that could explain opposite trends in birth rates in the two SASL colonies. We compared feeding habits (δ15N and δ13C) of breeding females, birth mass, individual growth rate and early survival of pups and the social structure between colonies. Breeding females from the two colonies did not differ in their feeding habits. However, male and female pups grew faster but had a lower survival in the second month in the smallest colony. We found differences in the social structures, with a higher proportion of males in the smallest colony. The latter is important because peripheral SASL males may abduct and kill pups, which may explain the lower survival of pups in smaller colonies.