Management of forage ofer in the National Park Campos del Tuyú and neighbouring cattle farms for Pampas's deer conservation. Campos del Tuyú National Park, located at the southern part of the Samborombón Bay, is a protected area created to promote the recovery of an endangered species, the pampas deer (Ozotoceros bezoarticus celer). Previous studies suggest that deer protection is related to the availability and nutritive value of forage provided by Celtis tala and Spartina densifora communities, both preferred as feeding habitat. With the aim of enhace forage ofer for pampa deer, specifc management practices were designed: a) high intensity biomass defoliation in late summer followed by cattle exclusion from March to August in the Celtis community of the neighbor cattle farm, and b) periodic biomass defoliation of the Spartina densifora Brongn community in the protected area. Defoliation in late summer followed by cattle exclusion from March to August in the Celtis community promoted the establishment or increased the contribution of the native cool-season grasses Bromus catharticus, Bromus auleticus and Elymus scabrifolius and warm-season grasses Bothriochloa laguroides and Paspalum dilatatum, and the legume Melilotus ofcinalis. Periodic defoliation of the Spartina densifora community during its growing period increased the contribution of the native cool-season grasses Elymus scabrifolius, Chaetotropis elongata and Phalaris angusta and of the legume Melilotus ofcinalis, while decrease basal cover of the cordgrass Cortaderia selloana. Forage value increased in both communties because grasses and legumes species of high nutritive value increased their contribution, while herbaceous species of low nutritive value decrease their proportion.

El Parque Nacional Campos del Tuyú, ubicado en el extremo sur de la Bahía de Samborombón, es un área protegida creada para conservar el venado de las pampas (Ozotoceros bezoarticus celer). Los antecedentes sugieren que la protección del venado de las pampas dependería, entre otros factores, de la disponibilidad y calidad de la oferta forrajera provista por las dos comunidades preferidas como hábitat de alimentación: el monte de tala y el espartillar. Con el fn de mejorar la oferta de forraje se diseñaron y evaluaron prácticas de manejo específcas para las dos comunidades: a) exclusión del ganado en los montes de tala del establecimiento ganadero aledaño, luego de una defoliación intensa a fn de verano, y b) defoliaciones mecánicas periódicas en los espartillares. La defoliación intensa a fn del verano seguida por la exclusión al pastoreo del ganado entre marzo y agosto en los montes de tala del establecimiento vecino promovió la aparición o aumentó la contribución de los pastos nativos invernales Bromus catharticus, Bromus auleticus y Elymus scabrifolius, de los estivales Bothriochloa laguroides y Paspalum dilatatum y de la leguminosa Melilotus ofcinalis. La defoliación periódica del espartillar durante el período de crecimiento de la especie dominante, Spartina densifora, incrementó la contribución de los pastos invernales nativos Elymus scabrifolius, Chaetotropis elongata y Phalaris augusta, y de la leguminosa Melilotus ofcinalis, y disminuyó la cobertura de la paja Cortaderia selloana. En ambas comunidades se registró un aumento del valor zootécnico ya que las especies que elevaron su contribución fueron pastos y leguminosas de alto valor nutritivo, mientras que las especies que disminuyeron su cobertura fueron herbáceas de escaso valor nutritivo.

Ozotoceros bezoarticus celer, the southernmost subspecies of pampas deer and endemic to the Argentine Pampas, is seriously endangered. In Buenos Aires Province, the last Pampas deer population is located in the Bahía Samborombón region. Poaching and the increase in exotic species such as feral dogs and feral pigs have been suggested as the most important causes affecting the recovery of the deer population. Thus, the aim of this study was to analyze the spatial and temporal variations in distribution and abundance of the Pampas deer and the feral pig in the Bahía Samborombón Wildlife Refuge and to discuss the possible consequences of the interaction between these species. Six aerial surveys were conducted during 2002-2005. A total of 747 deer and 2690 feral pigs were counted, with a slight decrease in the deer sightings and an important increase in pig sightings during the sampling period. Estimated density ranged between 0.63-1.56 individuals/km² for deer and from 0.91 to 7.78 individuals/km² for pigs. A negative correlation was found between densities of the two species (r s=-0.83; P=0.04), and the distributions are not mutually independent. A progressive change in distribution has been detected in the Pampas deer population during the last three decades. This study provides evidence of the potential existence of negative interactions between Pampas deer and pigs. Due to the critical situation of the Pampas deer population, a control plan for feral pigs should be developed and urgently implemented to prevent the increase and expansion of this population to the south of the Samborombón bay, and consequently, to reduce the potential competition and predation on the existing deer population.

Ozotoceros bezoarticus celer es la subespecie más austral del venado de las pampas; es endémica de la eco-región pampeana y se encuentra seriamente amenazada de extinción. En Buenos Aires, el último núcleo poblacional existente se localiza en la Bahía Samborombón. El objetivo del presente trabajo fue determinar las variaciones en la distribución y abundancia de venados y chanchos cimarrones en el Refugio de Vida Silvestre Bahía Samborombón, y discutir la interacción potencial entre ambas especies. Se realizaron seis muestreos aéreos durante el período 2002-2005, en los que se contabilizaron 747 venados y 2690 chanchos, y se registró una leve disminución del número de venados y un notable incremento del de chanchos. Se halló una correlación negativa entre la densidad de ambas especies (r s=-0.83; P=0.04) y se detectó que su distribución no es independiente entre sí. En las últimas tres décadas se observó un cambio en la distribución de venados, posiblemente asociado al incremento de chanchos. Este trabajo aporta evidencias indirectas de la existencia potencial de interacciones negativas entre las dos especies que se reflejan en relaciones numéricas y espaciales inversas.

A prevalência de Trichinella spiralis, Leptospira spp. e Salmonella spp. foi estudada em ratos e gambás que habitam granjas avícolas da região de Exaltación de la Cruz, Buenos Aires, Argentina, com o objetivo de determinar o potencial risco sanitário para pessoas que ficam em contato com esses animais. O estudo foi realizado entre a primavera de 1999 e o inverno de 2001 em 48 granjas avícolas. O estudo em gambás iniciou-se no inverno de 2000. Foram capturados 152 Rattus norvegicus, 3 Rattus rattus, 16 Didelphis albiventris e 1 Lutreolina crassicaudata. Registrou-se a presença de ratos e de gambás em 70% e 27% das granjas estudadas, respectivamente. A percentagem de granjas com ratos foi independente da presença ou da ausência de suínos. Não foi detectada a presença de Leptospira spp. e de Trichinella spiralis em nenhum animal avaliado. Foi detectada, porém, a presença de Salmonella Enteritidis em um Rattus norvegicus e em um Didelphis albiventris. Nas condições em que esse estudo foi realizado, os nossos resultados indicam que ratos e gambás que habitam granjas avícolas não constituem um fator de risco na transmissão de Trichinella e de Leptospira. A detecção de Salmonella Enteritidis tanto em ratos quanto em gambás, porém, sugere a necessidade de aplicar medidas profiláticas em granjas avícolas para maior controle desse agente.

We have studied the prevalence of Trichinella spiralis, Leptospira spp. and Salmonella spp. in rats and opossums that inhabit poultry farms of Exaltación de la Cruz, Buenos Aires, Argentina, to determine the potential sanitary risk for humans that are in contact with these animals. The study was carried out on 48 poultry farms between spring 1999 and winter 2001. The study of opossums began in winter 2000. During the study period we captured 152 Rattus norvegicus, 3 Rattus rattus, 16 Didelphis albiventris and 1 Lutreolina crassicaudata. We have registered the presence of rats and opossums in 70% and 27% of the studied farms, respectively. The percentage of farms with rats was independent of the presence or absence of pigs. We did not detect the presence of Leptospira spp. and Trichinella spiralis in any individual. We detected the presence of Salmonella Enteritidis in one Rattus norvegicus and one Didelphis albiventris. According to our results, the rats and opossums of poultry farms may not report a risk factor in the transmission of Trichinella and Leptospira under the present conditions; but the detection of Salmonella Enteritidis in rats as well as in opossums suggests the idea of applying prophylactics measurements on poultry farms.