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Gières, France

Jakob C.,FRC LR | Ponce-Boutin F.,CNERA PFSP | Besnard A.,CNRS Center of Evolutionary and Functional Ecology | Eraud C.,ONCFS
European Journal of Wildlife Research | Year: 2010

Successful management practices for declining bird species depend often on long-term surveys acquired by point counts. Despite high standardization of field protocols, uncertain detection probability remains an important source of variability and bias in point-count data. This effect is of main importance in low-responsive species as the Red-legged partridge (Alectoris rufa), but it can be counterbalanced, increasing detection probability. In this 2-year study, we sampled using traditional point-count methods, followed by playback sessions for each repetition. We measured detection probability and the efficiency of playback for detectability in the context of a feasibility study on long-term point-count surveys for a harvested game bird, the Red-legged partridge. The results for both study years show a distinct increase in detection probability (23% and 45%, respectively) when using playback vs. the traditional point-count method. We also tested our results for heterogeneity, trap dependence, and time dependence, and no effect was detected. Thus, we suggest that the future design of long-term surveys on Red-legged partridges should consider abundance indices using playback sessions. © 2010 Springer-Verlag.

Searching for the Eagle Owl in non-rocky areas has shown the occurrence of breeding birds which were far to be expected in such areas. Three nesting sites are described : 1) ground nest at the foot of a tree in a formerly grazed grassland, 2) ground nest on a small rocky outcrop in an open oak woodland close to cultivations and to a road, 3) open wooded lowland near an inhabited farm. This area is further occupied by other ground nesting pairs using wood-lands or small rocky outcrops. The population is probably in a phase of recolonization of deserted habitats following persecutions in former time. Owing to their ecological plasticity, cryptic plumage and nocturnal life, Eagle Owls are able to find suitable nesting sites and accessible food resources in areas where they are not expected. Bird observers are invited to search for this species in such unexplored areas. The monitoring of these birds should allow a better understanding of their more or less regular reproduction, their dispersal and finally their survival rate.

Breeding biology of 29 radio-tracked Hazel Grouse hens was investigated from 1999 to 2008 in the south-eastern part of French Alps. Spring home range of females up to incubation sized from 7.6 to 31.1 ha (50% activity range covered 2.5-9.4 ha, Kernel method). First clutches were 7.3 (range: 6-9) eggs and second clutches were 3.7 (range: 3-4) eggs in average. Hatching period extended from 23 May to 4 July, the median date for first clutches was 4 June and that for second clutches was 25 June. Nesting success was estimated by the Mark software capture-recapture method. Breeding success from the beginning of laying to hatching was 0.34 for all nests (first and second clutches together) and 0.46 during the incubation period. Nest loss was mainly, if not entirely, due to predation, probably by carnivores. 15% of the hens did not initiate a clutch but this rate was probably biased by undetected early destroyed clutches. If these hens were taken into account, breeding success was 0.28. Nest loss was not influenced by hen's age, nest visibility, distance to roads and laying date. Breeding success was significantly higher in the first study years (0.55 in 1999-02) than subsequently (0.22 in 2004-08). Reproduction traits (clutch size, nesting success) of this population appeared relatively low when compared to other studies on Hazel Grouse. Results are discussed in relation to the adaptive value of clutch size and to the role of environmental factors on breeding success.

Bonnot N.,French National Institute for Agricultural Research | Morellet N.,French National Institute for Agricultural Research | Verheyden H.,French National Institute for Agricultural Research | Cargnelutti B.,French National Institute for Agricultural Research | And 3 more authors.
European Journal of Wildlife Research | Year: 2013

Wildlife populations are subjected to increasing pressure linked to human activities, which introduce multiple stressors. Recently, in addition to direct effects, it has been shown that indirect (non-lethal) effects of predation risk are predominant in many populations. Predation risk is often structured in space and time, generating a heterogeneous "landscape of fear" within which animals can minimize risks by modifying their habitat use. Furthermore, for ungulates, resource quality seems to be positively correlated with human-related sources of risk. We studied the trade-off between access to resources of high-quality and risk-taking by contrasting habitat use of roe deer during daytime with that during nighttime for 94 roe deer in a hunted population. Our first hypothesis was that roe deer should avoid human disturbance by modifying their habitat use during daytime compared to nighttime. Our results supported this, as roe deer mainly used open fields during nighttime, but used more forested habitats during daytime, when human disturbance is higher. Moreover, we found that diel patterns in habitat use were influenced by hunting disturbance. Indeed, the roe deer decreased their use of high-crops during daytime, an important source of cover and food, during the hunting season. The proximity of roads and dwellings also affected habitat use, since roe deer used open fields during daytime to a greater extent when the distance to these sources of disturbance was higher. Hence, our results suggest that roe deer resolve the trade-off between the acquisition of high-quality resources and risk avoidance by modifying their habitat use between day and night. © 2012 Springer-Verlag Berlin Heidelberg.

Distribution and population status of the Capercaillie were updated in 2010 in the French Jura mountains (Northeast France). In comparison with a first regional overview in 1995, distribution range covers 21 585 ha in 2010, thus showing a decrease of 21% of the range regularly occupied. Total population is estimated to amount 340 adults in 2010 indicating a decrease of 27%. Population trend was assessed by counts of displaying cocks at 20 leks and was analysed with log linear model between 1991 and 2012. Only 3 out of 20 leks remained stable at a low level. Ten leks showed marked decline between 1991 and 2004 leading to complete disappearance of 6 leks. Seven leks steadily decreased until 2004 and subsequently showed marked increase. Overall cock numbers decreased by 73% between 1991 and 2004 and then was multiplied by 3 from 2004 to 2012. Despite this increase displaying cock numbers are still 13% lowerthanin 1991. The marked instability of this population associated with a complete isolation represents a serious threat for its long term survival. Several small populations in that region have vanished during the last 30 years and only those occupying large tracks of forest at higher altitude seem to be able restoring after a steep decline. Local trends can hardly be associated with evident change in habitat quality or human disturbance. They can rather be related with change in breeding success which remained low in general (0.34 juvenile/hen in July on 3 sites) but seems to have increased since 2003 explaining the observed partial recovery. However, without a comprehensive knowledge of the role played by environment on the demographic parameters it is difficult to promote specific and efficient conservation measures.

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