10 research outputs found
Comportament territorial de les marmotes, la teoria "dear enemy" a prova
En etologia animal, la teoria del "dear enemy" postula que els individus territorials responen de manera més agressiva cap als desconeguts que entren al seu espai que cap als veïns. La del "nasty enemy" suggereix tot el contrari. En aquest article, investigadores del CREAF i de la UAB en col·laboració amb altres universitats, resumeixen els resultats del seu treball en el qual, tenint en compte diversos factors, han posat a prova el comportament territorial d'una població de marmota alpina (Marmota marmota). Els resultats obtinguts indiquen que l'amenaça que senten aquests animals és independent del grau de proximitat en el qual habiten, de la seva jerarquia social i de l'estació de l'any.En etología animal, la teoría del "dear enemy" postula que los individuos territoriales responden de manera más agresiva hacia los desconocidos que entran en su espacio que hacia los vecinos. La del "nasty enemy" sugiere todo lo contrario. En este artículo, investigadoras del CREAF y de la UAB en colaboración con otras universidades, resumen los resultados de su trabajo en el que, tomando en cuenta diversos factores, han puesto a prueba el comportamiento territorial de una población de marmota alpina (Marmota marmota). Los resultados obtenidos indican que la amenaza que sienten estos animales es independiente del grado de proximidad en el que habitan, de su jerarquía social y de la estación del año
Minimising trapping effort without affecting population density estimations for small mammals
Improving species community diversity studies needs population abundances to be calculated. Micromammal population densities are highly variable at small spatial scales. Mark-recapture methods based on grid trapping is the most reliable technique to study density in small rodents, albeit it is time-consuming because it necessitates increasing the number of spatial replicates. Here, we evaluated a live-trapping grid strategy to minimise field effort without decreasing the accuracy of small rodent population density estimations. We first computed spatially explicit estimates of population density using CMR histories from a large grid made by 100 traps set over 4 consecutive days and nights trapped twice per year between 2012 and 2015, and compared these estimates with those obtained from reduced session time and grid extent for two common rodent species: the wood mouse (Apodemus sylvaticus) and the bank vole (Myodes glareolus). We then compared density estimates to simpler catch-effort indexes of abundance for these rodents. Spatially explicit density estimates from capture-mark-recapture over 4 consecutive days from grids set with a single trap interspaced 5 m on a 10 × 10 square were highly correlated (R² = 0.945) with density estimates after 4 consecutive days on a 7 × 7 square arrangement. The best performance of catch-effort indexes relative to 4 days on 10 × 10 square grid spatial density estimates for these two rodents was found when using total trapping events recorded on 8 × 8 grids over 4 days or 9 × 9 over 3 days (R² = 0.947 and 0.945 respectively). Our results support the use of a reduced grid design over 4 days to obtain reliable spatially explicit density estimates. We also obtained a reduced duration of trapping at the expense of keeping larger grids when using catch-effort indexes.This paper is based on a study financed by the Conseil Général Hauts de Seine (CG92). The PhD student, leader of this paper I. Castañeda is funded by Region Ile de France, project R2DS 2014-02
Socially mediated effects of climate change decrease survival of hibernating Alpine marmots
International audienc
A Viable Population of the European Red Squirrel in an Urban Park
<div><p>Whether urban parks can maintain viable and self-sustaining populations over the long term is questionable. In highly urbanized landscapes, urban parks could play a role in biodiversity conservation by providing habitat and resources to native species. However, populations inhabiting urban parks are usually small and isolated, leading to increased demographic stochasticity and genetic drift, with expected negative consequences on their viability. Here, we investigated a European red squirrel population located in an urban park close to Paris, France (Parc de Sceaux; 184 ha) to assess its viability. Using mitochondrial D-loop sequences and 13 microsatellite loci, we showed that the population presented high levels of genetic variation and no evidence of inbreeding. The size of the population was estimated at 100–120 individuals based on the comparison of two census techniques, Distance Sampling and Capture-Mark-Recapture. The estimated heterozygosity level and population size were integrated in a Population Viability Analysis to project the likelihood of the population's persistence over time. Results indicate that the red squirrel population of this urban park can be viable on the long term (i.e. 20 years) for a range of realistic demographic parameters (juvenile survival at least >40%) and immigration rates (at least one immigration event every two years). This study highlights that urban parks can be potential suitable refuges for the red squirrel, a locally threatened species across western European countries, provided that ecological corridors are maintained.</p></div
Results of simulations run for the population viability analysis of red squirrels population of the Parc de Sceaux.
<p>Results of simulations run for the population viability analysis of red squirrels population of the Parc de Sceaux.</p
Map of the Parc de Sceaux showing the distribution of line transects, traps, and woody areas suitable to red squirrels.
<p>Map of the Parc de Sceaux showing the distribution of line transects, traps, and woody areas suitable to red squirrels.</p
Results of the genetic diversity analyses obtained per locus for the red squirrel populations.
<p>Results of the genetic diversity analyses obtained per locus for the red squirrel populations.</p
Relationships between the deterministic growth rate of the population, the rate of juvenile survival and the age at which females have their first litter.
<p>Relationships between the deterministic growth rate of the population, the rate of juvenile survival and the age at which females have their first litter.</p