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This paper presents observations of Houbara Bustard Chlamydotis undulata undulata homerange, in the semi-desert steppe of eastern Morocco. Home-ranges were calculated from radiotagged birds using the fixed kernel method (LSCV). The mean annual home-range of males (17 km 2 ) was smaller than that of females (146 km 2 ; P < 0.001). The majority of male home-ranges had a unimodal distribution (86%), whereas 67% of female home-ranges were multimodal. Consequently, the amplitude of female movements was larger (mean: 44 km/13 km; P < 0.002). In spring, male home-ranges decreased in size around display sites (8 km 2 ) and many of them overlapped considerably. Display sites show an aggregative distribution ( P < 0.001) and a single female reproductive range may contain the display sites of several males. The data fulfil the definition of an exploded lek social structure. In our study, C. u. undulata appears to be sedentary with relatively limited home-ranges. Successive years of fidelity to home-ranges indicate that adults are not nomadic.

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International audienc

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Aim To assess the exposure of 10 spider species to two drivers of global change (climate and land use), the suitability of the current network of protected areas with respect to this exposure, and the implications for a national conservation programme.Location The western Palearctic and France.Methods We predicted the current and future potential distributions of 10 spider species using species distribution models (SDMs). We explicitly quantified uncertainties in the models and estimated the future environmental suitability with discounted uncertainty. We analysed the predicted future suitability for protected versus unprotected occurrence cells. ResultsIn this first forecast of the future of multiple spider species in the face of environmental changes, we showed that environmental changes could be confidently predicted to have serious impacts on all the studied species, with significant range contractions and expansions within a relatively short timescale (up to 2050). We predicted that for seven of the 10 species, the current network of protected areas will conserve at least one occurrence cell in suitable conditions in the future. However, we showed that there is considerable room for improvement.Main conclusions This study illustrated how SDMs could be applied to a conservation programme for an understudied taxon such as spiders, in spite of significant uncertainties in their predictions. In addition, the uncertainties raised here compel us to emphasize the pressing need to improve our knowledge on understudied taxa such as spiders. We advocate the necessity of increasing monitoring schemes, experiments and forecasts of environmental change effects on a larger and more diversified range of species than is currently the case in the literature.

Studies of the movements and home-ranges of houbara bustards (Chlamydotis undulata undulata) showed sexual and seasonal differences in the use of space, with a polygynous mating system similar to an 'exploded-lek' or a 'resource-defence-polygyny', that remains undefined. We used the arthropod biomass as an index of the trophic quality of six defined habitats and we radio-tracked 7 females and 13 males to test whether sexual and seasonal variations in habitat use were related to resource availability, and to verify if critical resources for breeding females were monopolised by males. We analysed habitat selection in both sexes separately. We used the habitat type composition of buffer zones around radio-locations to study annual and seasonal habitat selection and to identify preferred habitats, using the chi-square goodness-of-fit test. Habitat use between sexes and between seasons were compared using MANOVA based on log-ratios of habitat proportions. During the year, and in each season, both sexes appeared to be significantly selective for habitats in comparison to their availability. But males avoided esparto grass, while females used all habitats. Habitat use differed between sexes in the breeding season, but not in the non-breeding season. In spring, when food resources were abundant and uniformly distributed in space, males preferred 'temporarily flooded areas' and females preferred 'reg with tall perennials' that offered both food and cover for brooding. Critical resources were not monopolised by males and the mating system fulfilled the definition of the 'exploded-lek'. Leks are key sites for reproduction and should be considered as priority areas in further conservation plans.

Aim To provide a procedure for measuring the rarity of both invertebrate species and assemblages of species from multiple scales without the need for fineresolution datasets over broad areas.Location The western Palearctic (WP) and western France.Methods On the basis of different datasets from different geographical extents, we applied a multiscale rarity weight to species occurrence from multiple scales. Multiscale rarity weights were then averaged at an assemblage level in a multiscale index of relative rarity (I RR ). These rarity weights were calculated using a flexible, scale-dependent method that ensures equitable contributions of each scale to the final index. We provided a simple two-scale example of the application, on spiders of western France, for which we obtained occurrence information from a regional-extent dataset (regional scale) and a western Palearctic-extent dataset (WP scale). Thus, we showed the necessity of a two-scale approach by successively analysing species occurrence, multiscale rarity weights of species and multiscale indices of species assemblage. Finally, we presented a case study within a nature reserve.Results Species occurrences are not predictable from one scale to another, and rarity indices of assemblages are poorly congruent among scales, which supports the necessity of a two-scale approach. Multiscale rarity weights accurately showed information on species rarity from both scales. Multiscale indices of assemblages were congruent but with additional information over each onescale index.Main conclusions The novelty of the multiscale method developed here is to accurately combine different datasets of varying extents and resolutions to provide multiscale rarity weights for species and indices for assemblages. Given the increasing availability of datasets for invertebrate taxa, this method represents a significant improvement for rarity and conservation studies on invertebrates.