Evaluation of the interest of southern Patagonian ranchers toward selective and efficient predator control methods

Elaboramos una encuesta con el fin de evaluar el interés de los productores ganaderos por incorporar prácticas selectivas de control basándonos en la caracterización del sistema de producción ganadera de Santa Cruz y su relación con la predación por el zorro colorado (Lycalopex culpaeus). Para los encuestados (n = 90) la carga ovina actual está por debajo de la óptima, lo que es consistente con el hecho de que para la mayoría (73%) la ganadería solo representa una parte de sus ingresos. El nivel de pérdida de corderos por predación de zorros colorados varía entre el 5% y el 50% de la producción anual y esta tasa se ha mantenido en los últimos años, a pesar de que el 56% de los encuestados percibe un aumento en la abundancia de zorros en sus campos en los últimos 10 años. Las actitudes negativas de los productores hacia el zorro colorado se reflejaron en el hecho de que su control continúa siendo una práctica habitual para el 73% de los encuestados incluso en establecimientos sin producción. El uso de veneno es o ha sido utilizado por la mayoría de los productores (74%) a pesar de su prohibición. Sin embargo, el 91% de los encuestados estaría dispuesto a reemplazar sus prácticas por métodos de control selectivos y eficientes. Este es un punto importante para incentivar el uso de métodos alternativos de control, como cebos tóxicos administrados selectivamente, lo que permitiría el abandono de las prácticas tradicionales tan nocivas para la conservación de la biodiversidad.Sheep ranchers (n = 90) were surveyed to evaluate their interest in the incorporation of  predator selective control methods. We based our survey on the characterization of the sheep ranching system of Santa Cruz province and its relationship with culpeo fox predation. For a large percentage of producers (73%), the carrying capacity at present is under the optimal, which is consistent with the fact that sheep ranching represent only a part of their income. Lamb losses due to culpeo foxes (Lycalopex culpaeus) predation vary between 5% and 50% of the annual lamb production, and these percentages did not vary during the last years in spite of 53% of ranchers perceived an increment in foxes abundances. Ranchers tend to exaggerate real losses of their lambs due to predation, although they recognize that there are other causes that could facilitate it. Nevertheless, fox control, including poisoning as a method, is still a current practice even in those ranches without sheep. The 90% of the sheep ranchers showed a good predisposition to replace their current practices by selective and efficient control methods. This is an important point to incentive the use of selective control methods, like toxic baits delivered in a selective way, which would allow the abandonment of the traditional practices so dangerous to biodiversity conservation.Fil: García Brea, Aranxa. Universidad Nacional de la Patagonia Austral; ArgentinaFil: Zapata, Sonia Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral; ArgentinaFil: Procopio, Diego Esteban. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Martínez Peck, Rolando. Universidad Nacional de la Patagonia Austral; ArgentinaFil: Travaini, Alejandro. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Evaluación del interés de productores ganaderos en el control selectivo y eficiente de predadores en la Patagonia austral

Sheep ranchers (n = 90) were surveyed to evaluate their interest in the incorporation of predator selective control methods. We based our survey on the characterization of the sheep ranching system of Santa Cruz province and its relationship with culpeo fox (Lycalopex culpaeus) predation. For a large percentage of producers (73%), the carrying capacity at present is under the optimal, which is consistent with the fact that sheep ranching represents only a part of their income. Lamb losses due to culpeo foxes predation vary between 5% and 50% of the annual lamb production, and these percentages did not vary during the last years in spite of the perceiving, by 53% of ranchers, of an increment in foxes abundance. Ranchers tend to exaggerate real losses of their lambs due to predation, although they recognize that there are other causes that could facilitate it. Nevertheless, fox control, including poisoning as a method, is still a current practice even in those ranches without sheep. The 90% of the sheep ranchers showed a good willingness to replace their current practices by selective and efficient control methods. This is an important point to encourage the use of selective control methods, like toxic baits delivered in a selective way, which would allow the abandonment of the traditional practices so dangerous to biodiversity conservationElaboramos una encuesta con el fin de evaluar el interés de los productores ganaderos por incorporar prácticas selectivas de control basándonos en la caracterización del sistema de producción ganadera de Santa Cruz y su relación con la predación por el zorro colorado (Lycalopex culpaeus). Para los encuestados (n = 90) la carga ovina actual está por debajo de la óptima, lo que es consistente con el hecho de que para la mayoría (73%) la ganadería solo representa una parte de sus ingresos. El nivel de pérdida de corderos por predación de zorros colorados varía entre el 5% y el 50% de la producción anual y esta tasa se ha mantenido en los últimos años, a pesar de que el 56% de los encuestados percibe un aumento en la abundancia de zorros en sus campos en los últimos 10 años. Las actitudes negativas de los productores hacia el zorro colorado se reflejaron en el hecho de que su control continúa siendo una práctica habitual para el 73% de los encuestados incluso en establecimientos sin producción. El uso de veneno es o ha sido utilizado por la mayoría de los productores (74%) a pesar de su prohibición. Sin embargo, el 91% de los encuestados estaría dispuesto a reemplazar sus prácticas por métodos de control selectivos y eficientes. Este es un punto importante para incentivar el uso de métodos alternativos de control, como cebos tóxicos administrados selectivamente, lo que permitiría el abandono de las prácticas tradicionales tan nocivas para la conservación de la biodiversidad

Evaluation of the interest of southern Patagonian ranchers toward selective and efficient predator control methods

Elaboramos una encuesta con el fin de evaluar el interés de los productores ganaderos por incorporar prácticas selectivas de control basándonos en la caracterización del sistema de producción ganadera de Santa Cruz y su relación con la predación por el zorro colorado (Lycalopex culpaeus). Para los encuestados (n = 90) la carga ovina actual está por debajo de la óptima, lo que es consistente con el hecho de que para la mayoría (73%) la ganadería solo representa una parte de sus ingresos. El nivel de pérdida de corderos por predación de zorros colorados varía entre el 5% y el 50% de la producción anual y esta tasa se ha mantenido en los últimos años, a pesar de que el 56% de los encuestados percibe un aumento en la abundancia de zorros en sus campos en los últimos 10 años. Las actitudes negativas de los productores hacia el zorro colorado se reflejaron en el hecho de que su control continúa siendo una práctica habitual para el 73% de los encuestados incluso en establecimientos sin producción. El uso de veneno es o ha sido utilizado por la mayoría de los productores (74%) a pesar de su prohibición. Sin embargo, el 91% de los encuestados estaría dispuesto a reemplazar sus prácticas por métodos de control selectivos y eficientes. Este es un punto importante para incentivar el uso de métodos alternativos de control, como cebos tóxicos administrados selectivamente, lo que permitiría el abandono de las prácticas tradicionales tan nocivas para la conservación de la biodiversidad.Sheep ranchers (n = 90) were surveyed to evaluate their interest in the incorporation of  predator selective control methods. We based our survey on the characterization of the sheep ranching system of Santa Cruz province and its relationship with culpeo fox predation. For a large percentage of producers (73%), the carrying capacity at present is under the optimal, which is consistent with the fact that sheep ranching represent only a part of their income. Lamb losses due to culpeo foxes (Lycalopex culpaeus) predation vary between 5% and 50% of the annual lamb production, and these percentages did not vary during the last years in spite of 53% of ranchers perceived an increment in foxes abundances. Ranchers tend to exaggerate real losses of their lambs due to predation, although they recognize that there are other causes that could facilitate it. Nevertheless, fox control, including poisoning as a method, is still a current practice even in those ranches without sheep. The 90% of the sheep ranchers showed a good predisposition to replace their current practices by selective and efficient control methods. This is an important point to incentive the use of selective control methods, like toxic baits delivered in a selective way, which would allow the abandonment of the traditional practices so dangerous to biodiversity conservation.Fil: García Brea, Aranxa. Universidad Nacional de la Patagonia Austral; ArgentinaFil: Zapata, Sonia Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral; ArgentinaFil: Procopio, Diego Esteban. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Martínez Peck, Rolando. Universidad Nacional de la Patagonia Austral; ArgentinaFil: Travaini, Alejandro. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Morphoguilds identification as an approach to the study of resource partitioning in assemblages of terrestrial carnivores | Identificación de morfogremios como aproximación al estudio de reparto de recursos en ensambles de carnívoros terrestres

We used an ecomorphological approach to examine trophic diversity in two terrestrial carnivore assemblages: one from NE Santa Cruz province (Argentinean Patagonia), and the other from Doñana National Park (SO Spain). We selected 16 measures related with the shape and size of carnivore mandibles and teeth. Measures were used deriving morphometric (dental and mandible) ratios which allowed us to quantify the proportion of dental structures related with grinding function as opposed to slicing function, and different aspects of mandibular shape related with the moment arm of muscles responsible to the biting and chewing strength. Ratios were used as axes of three dimensional graphs (morphospaces) where the potential diet diversity of the different predators could be inferred (morphoguilds). Carnivore species from Santa Cruz and Doñana were grouped in the morphospace in 4 and 3 morphoguilds respectively, following a carnivory-omnivory-insectivory/herbivory gradient. In general, the morphological pattern was similar in both assemblages. Felids and mustelids with a specialized dental pattern for consumption of meat, cluster in one of the extremes of the morphospace; mustelids with specialized dental patterns for grinding invertebrates and vegetal materials, score in the opposite side; and the rest of species, with generalized dental patterns, scatter in the center. The last group of species belongs to different families of the Order such as canids, viverrids and herpestids. The relative position of each species in the morphospace and previous information of their diets were used to infer resource partitioning among them. ©SAREM, 2008.Peer Reviewe

Food habits and resource partitioning between grey and culpeo foxes in southeastern Argentine Patagonia

We studied the annual and seasonal food habits of sympatric grey fox (Lycalopex griseus) and culpeo fox (Lycalopex culpaeus) in a protected area, in southeastern Argentine Patagonia, to test the hypothesis that both foxes partition prey. Grey foxes consumed a larger proportion of rodents than culpeos (66.1% versus 37. % of occurrences in feces, respectively), and culpeos consumed a larger proportion of the introduced European hare (Lepus europaeus) (32.8% versus 7.1%, respectively). Additionally, arthropods made up a significant portion of the diet of the grey fox, and occurred in the 95.5% of the analyzed feces. Despite the great differences in size of culpeo and grey foxes, the former being significantly larger, both species consumed the same type of prey, and no significant differences in the mean weight of vertebrate prey were detected in their diets. Culpeo and grey foxes diets differed during spring – summer with low values of mean diet overlap (31%). But in autumn – winter, when prey diversity is lower in Patagonia, diet was more similar and diet overlap (73%) increased. An exploratory analysis of habitat use by culpeo and grey foxes suggested that both species utilize habitat in a similar way. Our data agree with generalizations about competitive interactions between the large and the small canid in an assemblage. Although both foxes can potentially consume the same type of prey, through interference the larger culpeo would exclude the smaller grey fox from habitats with high-quality prey, resulting in prey partitioning. The possibility that both foxes partition habitat at a finer scale in our study area should be explored.Peer reviewe

Annual food habits of the lesser grison (Galictis cuja) at the southern limit of its range

Peer reviewe

A monitoring program for Patagonian foxes based on power analysis

Culpeo fox (Pseudalopex culpaeus) and gray fox (Pseudalopex griseus) are heavily culled in Patagonia. Fox populations seem to persist thanks to spatial refuges from which hunted areas are repopulated, following a source¨C sink dynamics. Sustainable use of Patagonian foxes warrants the design of a monitoring program in nature reserves and areas subjected to predator control. During 7 years, we used visitation indices to bait stations in a national park and neighboring sheep ranches of southern Argentina. We operated bait stations during three consecutive nights and calculated seven indices of relative abundance. For each fox species, we compared the power of different monitoring designs and scenarios that combined visitation indices, effort (number of bait station lines and survey frequency) while controlling for type I error, and magnitude of population change during a given period. We looked at the combinations that produced high power (¦Â¡Ü0.24). The operation of bait stations during several nights markedly increased statistical power. Index 7 (recording visits 72 h after activation) exhibited the lowest variation and improved expected power to detect a population trend. Both fox species could be monitored simultaneously, with power >0.76 in the short term (5 years), activating 24 bait station lines. We conclude that monitoring programs for culpeo fox and gray fox based on bait stations are able to detect marked declines but are less useful to reliably detect moderate increases in abundance, especially in sheep ranches.Fil: Travaini, Alejandro. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; EspañaFil: Zapata, Sonia Cristina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; ArgentinaFil: Zanón Martínez, Juan Ignacio. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; EspañaFil: Martinez Peck, Rolando. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentin

New records indicate that Austral Pygmy Owl Glaucidium nanum breeds in eastern Patagonia

El Caburé Grande Glaucidium nanum se distribuye ampliamente en Argentina y Chile, siendo la Cordillera de los Andes su lugar de residencia conocido para todo el año. Presentamos nuevos registros y datos preliminares de la biología reproductiva del Caburé Grande para la Patagonia Argentina. Nuestras observaciones expanden su presencia permanente 300 km al este de su distribución conocida. Encontramos que G. nanum es un residente anual en la estepa patagónica, y consideramos que no posee movimientos migratorios, solo de dispersión. Creemos que es importante conocer cuáles son los factores ecológicos que intervienen en la residencia de la especie en la estepa patagónica.Fil: Santillán, Miguel Ángel. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Universidad Nacional de La Pampa. Facultad de Ciencia Exactas y Naturales. Departamento de Recursos Naturales. Centro para el Estudio y Conservación de Aves Rapaces; ArgentinaFil: Travaini, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; ArgentinaFil: Procopio, Diego Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; ArgentinaFil: Zanón Martínez, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Universidad Nacional de La Pampa. Facultad de Ciencia Exactas y Naturales. Departamento de Recursos Naturales. Centro para el Estudio y Conservación de Aves Rapaces; ArgentinaFil: Yaya, Martín. Parque Nacional Los Glaciares; ArgentinaFil: Martínez Ayala, Juan de la Cruz. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; ArgentinaFil: Martinez Peck, Rolando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentin

A monitoring program for Patagonian foxes based on power analysis

Culpeo fox (Pseudalopex culpaeus) and gray fox (Pseudalopex griseus) are heavily culled in Patagonia. Fox populations seem to persist thanks to spatial refuges from which hunted areas are repopulated, following a source– sink dynamics. Sustainable use of Patagonian foxes warrants the design of a monitoring program in nature reserves and areas subjected to predator control. During 7 years, we used visitation indices to bait stations in a national park and neighboring sheep ranches of southern Argentina. We operated bait stations during three consec- utive nights and calculated seven indices of relative abundance. For each fox species, we compared the power of different monitoring designs and scenarios that combined visitation indices, effort (number of bait station lines and survey frequency) while controlling for type I error, and magnitude of population change during a given period. We looked at the combinations that produced high power (β ≤ 0.24). The operation of bait stations during several nights markedly increased statistical power. Index 7 (recording visits 72 h after activation) exhibited the lowest variation and improved expected power to detect a population trend. Both fox species could be monitored simultaneously, with power >0.76 in the short term (5 years), activating 24 bait station lines. We conclude that monitoring programs for culpeo fox and gray fox based on bait stations are able to detect marked declines but are less useful to reliably detect moderate increases in abundance, especially in sheep ranches.Peer reviewe