Biology subjects

Olivier Gimenez

Publications and source records attributed to Olivier Gimenez.

3 recordsLinked to original sources

bioRxiv2016

Shrinking of the endangered brown bear Ursus arctos distribution in the French Pyrenees revealed by dynamic occupancy modeling

The Pyrenean brown bear (Ursus arctos) in the mountainous border between France and Spain is one of the smallest and most endangered populations of large carnivores in Europe. Here, we aimed at assessing trends in brown bear habitat use in the Pyrenees and determining the underlying environmental and anthropogenic drivers. Using detection/non-detection data collected between 2008 and 2014 through non-invasive methods, we developed occupancy models to investigate the dynamic of brown bear habitat use in the Pyrenees accounting for local colonization and extinction processes. First, we found two non-connected occupancy cores, one located in the West and another in the Center of the Pyrenees, with an overall significant decrease in habitat use between 2008 and 2014. Second, we showed a negative correlation between human density and bear occupancy in agreement with previous studies on brown bear habitat suitability. Our results confirm the critically endangered status of the Pyrenean population of brown bears.

Ecology↗

bioRxiv2016

Better together: a transboundary approach to brown bear monitoring in the Pyrenees

Human administrative borders have no effect on wild animals, and the vast home ranges of large carnivores often cause them to live simultaneously on the territory of two or more countries or jurisdictions with different management policies. Here, we investigate the importance of transboundary population monitoring using as a case study the Pyrenean brown bear population (Ursus arctos) that lives in France, Andorra and Spain. Using capture-recapture models and the Pollocks robust design, we estimated abundance and demographic parameters using data collected separately in France and Spain and a dataset gathered from joint monitoring on both sides of the border. As expected, the abundance estimates from French (from 11 bears in 2008 to 13 in 2014) or Spanish (from 4 bears in 2008 to 9 in 2014) data only were lower than abundance obtained from both sides of the border (from 11 in 2008 to 18 in 2014). The joint monitoring dataset also highlighted the importance of individual detection heterogeneity that, if ignored, would lead to underestimation. Our results reinforce the importance of transboundary cooperation when dealing with animal populations with territory spanning two or more administrative jurisdictions for collecting reliable scientific data and providing relevant abundance estimation to take sound management decisions.

Ecology↗

bioRxiv2014

Meteorological conditions influence short-term survival and dispersal in a reinforced long-lived bird population.

O_LIA high immediate mortality rate of released animals is an important cause of translocation failure (\"release cost\"). Post-release dispersal (i.e. the movements from the release site to the first breeding site) has recently been identified as another source of local translocation failure. In spite of their potential effects on conservation program outcomes, little is known about the quantitative effects of these two sources of translocation failure and their interactions with environmental factors and management designs.\nC_LIO_LIBased on long-term monitoring data of captive-bred North African houbara bustards (hereafter, houbaras) over large spatial scales, we investigated the relative effects of release (e.g., release group size, period of release), individual (e.g., sex and body condition) and meteorological (e.g., temperature and rainfall) conditions on post-release survival (N = 957 houbaras) and dispersal (N = 436 houbaras).\nC_LIO_LIWe found that (i) rainfall and ambient air temperature had respectively a negative and a positive effect on houbara post-release dispersal distance, (ii) in interaction with the release period, harsh meteorological conditions had negative impact on the survival of houbaras, (iii) density dependent processes influenced the pattern of departure from the release site and (iv) post-release dispersal distance was male-biased, as natal dispersal of wild birds (although the dispersal patterns and movements may be influenced by different processes in captive-bred and in wild birds).\nC_LIO_LISynthesis and applications. Overall, our results demonstrate that post-release dispersal and mortality costs in translocated species may be mediated by meteorological factors, which in turn can be buffered by the release method. As the consequences of translocation programs on population dynamics depend primarily upon release costs and colonisation process, we suggest that their potential interactions with meteorological conditions be carefully addressed in future programs.\nC_LI

Ecology↗