Age Structure Differences in American Mink , Mustela vison , Populations under Varying Harvest Regimes
Two American Mink populations were examined using canine tooth cementum annuli to assess age structure of harvested segments of the populations. Trapping mortality was different between these two populations. Comparisons are made with a Montana Mink population. I propose that forbearer managers can readily assess relative harvest pressures by analyzing the age structure of a Mink population, and offer management recommendations for populations displaying various age structures.
Demographic structure of three riparian mustelid species in Spain
Age estimation of three mustelid species with similar body size was performed in Northern Spain. Canine samples of 1766 carcasses from 1661 American mink (Neovison vison), 54 European mink (Mustela lutreola), and 51 European polecats (Mustela putorius) were sectioned, and cementum annuli counts in tooth sections were used for age estimation. American mink samples consisted primarily of trap-captured animals from governmental control campaigns, whereas road casualties were the principal origin of European mink and European polecat carcasses. Individuals prior to their first breeding season (class 0+) represented approximately half of all animals, with no significant differences between species or causes of death. Differences in sub-adult percentages were observed between the pre- and post-reproductive period, with a high mortality during the dispersal-winter period in all three species. Frequencies of mortality of the sub-adult age class were 0.46, 0.50, and 0.55 for American mink, European mink, and European polecat, respectively. Survival rates of the American mink were higher than those of the native species. The oldest animals detected were 7+, 5+, and 3+ years old for the American mink, European mink, and European polecat, respectively. No differences were observed in mean age of animals found dead as road casualties in all three species or between captured American mink and road casualties. The information obtained is of high value for understanding the demographic processes of the populations and particularly for conservation and management decisions for these species.
Geographic And Environmental Influence On Maya Settlement Patterns Of The Northwest Yucatan: An Explanation For The Sparsely Settled Western Cenote Zone
Most settlement pattern research and GIS analysis of the ancient Maya of the Northern Yucatan have focused on water availability in a dry landscape where cenotes are often the only water source. While water is of paramount importance, permanent settlement secondarily requires farmable soil, a resource often as precious as water in many parts of the Yucatan. The dynamics between these resources reveal areas of ideal settlement and more challenging landscapes for which the Maya developed strategies to overcome environmental conditions. A region of the southwest "Cenote Zone", however, appears to have presented the ancient Maya with insurmountably poor environmental conditions despite abundant water resources. The lack of dense population and stone architecture in this area emphasizes the lack of a simple correlation between cenotes and settlement. This thesis uses GIS analysis to identify and explore such problematic settlement areas to better understand the factors and complexities involved in the more successful settlements of neighboring regions. iv This work is dedicated to my late father, who first introduced me to the Mundo Maya through a visit to the ruins of Tikal at the age of nine, and who instilled in me strength, curiosity, and a love for exploring the world. v ACKLOWLEDGEMENTS I'd like to acknowledge Dr. Arlen Chase and Dr. Diane Chase for providing such outstanding opportunities and instruction, and for leading by example both in the field and in the classroom. Dr. John Walker for his eye-opening perspectives, GIS instruction, inspiring hard-working attitude, and patience in the field. Dr. Clifford Brown and Dr. Walter Witschey for their invaluable correspondence and for their contributions to mapping and GIS data of Maya sites.