40 research outputs found

    Habitat and abundance of the Neotropical otter (Lontra longicaudis annectens) in Pueblo Nuevo, Durango, Mexico

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    La nutria neotropical es un depredador ubicado en el nivel trófico superior, su distribución geográfica abarca desde el norte de México hasta la zona central de Argentin

    New records of non-resident pinnipeds from the Gulf of California, Mexico Registros nuevos de pinnípedos no-residentes en el golfo de California, México

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    Abstract. Although the California sea lion (Zalophus californianus) is the only pinniped resident in the Gulf of California, there are occasional records of 3 additional species; here we report 4 recent records of the Guadalupe fur seal (Artocephalus townsendi), 6 of the northern elephant seal (Mirounga angustirostris) and 2 of the harbor seal (Phoca vitulina). Harbor seals have been observed mostly during the winter-spring months of El Niño years, before water temperature warms in the summer. It is possible that juveniles and subadult and adult males of A. townsendi and M. angustirostris are using the Gulf as an alternative feeding area during the season of intensive feeding as individuals disperse more and more widely as their populations grow. Key words: Guadalupe fur seal, harbor seal, northern elephant seal, Gulf of California. Resumen. Aunque en el golfo de California, el único pinnípedo residente es el lobo marino de California (Zalophus californianus), existen registros ocasionales de otras 3 especies; en la presente nota se proporcionan 4 registros recientes de lobo fi no de Guadalupe (Arctocephalus townsendi), 6 de elefante marino del norte (Mirounga angustirostris) y 2 de foca común (Phoca vitulina). La foca común se ha observado principalmente durante los meses de invierno-primavera en años de El Niño, antes del calentamiento anual del agua en verano. Es posible que los juveniles y los machos sub-adultos y adultos tanto de A. townsendi como de M. angustirostris hagan uso del golfo como un sitio alternativo durante la temporada de alimentación intensiva como de su expansión geográfi ca debido a su incremento poblacional. Palabras clave: lobo fi no de Guadalupe, foca común, elefante marino del norte, golfo de California

    Dieta de la nutria neotropical (Lontra longicaudis annectens) en Pueblo Nuevo, Durango, México

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    El objetivo del presente trabajo fue determinar la dieta de la nutria neotropical en la parte alta del río San Diego. Esta especie es un depredador considerado como indicador de la calidad de los ecosistemas acuáticos, además de estar catalogada como amenazada en México, por lo que es indispensable realizar estudios para conocer su biología y ecología. El monitoreo se realizó durante 2 años (2012-2013), se muestrearon 8 km sobre el río, los cuales se dividieron en 3 segmentos de igual tamaño, se recolectaron 266 heces y se identificaron los distintos ítems alimenticios encontrados en las mismas. La dieta se separó en 7 categorías, siendo los invertebrados y los peces los de mayor porcentaje de aparición (39.45 y 34.86%, respectivamente) y en menor presencia plantas, anfibios, mamíferos, reptiles y un 4.95% corresponde a elementos no identificados. Se encontraron elementos de todas las categorías en el periodo de primavera. Gila conspersa, Corydalus texanus y Abedus sp. se observaron con mayor frecuencia en la dieta. No existieron diferencias significativas en la dieta entre estaciones del año ni entre los segmentos del río muestreados, solo entre temporada de secas y lluvias para el año 2012. ABSTRAC The aim of this study was to determine the diet of the neotropical otter in the upper San Diego River. Neotropical otters are predator considered as an indicator of the quality of the aquatic ecosystems, the species is listed as threatened in Mexico; therefore it is essential to conduct studies to understand their biology and ecology. The monitoring was carried out for 2 consecutive years (2012-2013), a longitudinal section of the river of 8 km was surveyed, it was divided into 3 equal sections. A total of 266 scats were collected, food items found in them were identified. Diet was conformed by 7 categories of prey, invertebrates and fish representing the highest percentage (39.45% and 34.86%, respectively), with a smaller presence plants, amphibians, mammals, birds, reptiles and 4.95% of unidentified items. Itemsin all categories were found in spring. Gila conspersa, Corydalus texanus and Abedus sp., were the most often species found in the diet. There were no significant differences in diet between seasons, or segments of the river (only between dry and rainy season for the year 2012)

    文献レビューに基づく路上犯罪の都市環境的ハザード抽出

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    Social interest in "Planning for Crime Prevention", for the purpose of improving urban crime prevention, is increasing. The previous studies that elucidated the urban environmental factors that affected the crime played a major part in Planning for Crime Prevention, and, furthermore, these findings from the previous studies have been used when we discovered a potentially dangerous area. However, in fact, the urban environmental factors affecting the crime do not cause a crime, and these factors are only hazard of the crimes. Therefore a purpose of this study is to extract crime hazards through literature review to investigate urban environmental indexes that are capable of helping a risk evaluation or analysis. Specifically, the following were conducted. 1) From among domestic journals published from 1980 through 2011, the articles on the relationship between urban environment and crime were sorted; 2) The crime hazards regarding street crimes were extracted from these articles

    Foraging Behavior and Success of a Mesopelagic Predator in the Northeast Pacific Ocean: Insights from a Data-Rich Species, the Northern Elephant Seal

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    The mesopelagic zone of the northeast Pacific Ocean is an important foraging habitat for many predators, yet few studies have addressed the factors driving basin-scale predator distributions or inter-annual variability in foraging and breeding success. Understanding these processes is critical to reveal how conditions at sea cascade to population-level effects. To begin addressing these challenging questions, we collected diving, tracking, foraging success, and natality data for 297 adult female northern elephant seal migrations from 2004 to 2010. During the longer post-molting migration, individual energy gain rates were significant predictors of pregnancy. At sea, seals focused their foraging effort along a narrow band corresponding to the boundary between the sub-arctic and sub-tropical gyres. In contrast to shallow-diving predators, elephant seals target the gyre-gyre boundary throughout the year rather than follow the southward winter migration of surface features, such as the Transition Zone Chlorophyll Front. We also assessed the impact of added transit costs by studying seals at a colony near the southern extent of the species’ range, 1,150 km to the south. A much larger proportion of seals foraged locally, implying plasticity in foraging strategies and possibly prey type. While these findings are derived from a single species, the results may provide insight to the foraging patterns of many other meso-pelagic predators in the northeast Pacific Ocean

    Therya E-ISSN: 2007-3364 [email protected] Asociación Mexicana de Mastozoología

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    Feral cats steal milk from northern. Elephant Seals Therya, vol. 1, núm. 3, diciembre, 2010, pp. 207-211 Asociación Mexicana de Mastozoología Baja California Sur, Méxic

    Diet composition of the Guadalupe fur seal (Arctocephalus townsendi). Where and what do they eat?

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    The Guadalupe fur seal (Arctocephalus townsendi) is a specialist predator feeding on prey present in one trophic level. Data related to the diet of the Guadalupe fur seal are few. It is still unknown where most of the individuals forage or the composition of their diet. On Isla Guadalupe, the San Benito Archipelago and the Farallon Islands, fur seals primarily feed on pelagic and coastal squids. However, differences between colonies were found probably caused by differences in diversity and abundance of prey species over the continental shelf and the pelagic environment, and maybe due to the plasticity of the species in their foraging behavior. Diet composition of the Guadalupe fur seal might reflect adaptations to local and temporal environmental conditions. The aim of this work was to consider historical information, add new information, identify main prey species, and determine where in the marine regions the Guadalupe fur seals feed.13 page(s

    Unusual record of Pacific harbor seal (Phoca vitulina richardii) feeding on anchovy (Engraulis mordax) in the fishery of small pelagic fishes in the Gulf of California

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    Abstract: Pacific harbor seals (Phoca vitulina richardii) range in North America from Japan to Mexico. Here we report the first record of a Pacific harbor seal feeding on Northern anchovy (Engraulis mordax) inside a purse-seine net of a sardine fishing boat in the Gulf of California. This event was recorded on video on January 11th, 2010, near Estero Tortuga, Guasimas, Sonora (27°50’N, 110°39’W). Sea conditions were of El Niño Southern Oscillation; this record was likely due to El Niño, forcing seals to travel beyond their distribution range in search of alternate foraging areas
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