Primary predators or dispersers such as birds and rodents cache acorns of northern red oak (Quercus rubra L.). A proportion of these acorns are not retrieved, and thus, animals may favour oak regeneration by placing acorns in microsites suitable for recruitment. We experimentally investigated the effects of acorn burial and litter cover on red oak recruitment at two sites at the northern limit of the species' range in North America. Laboratory experiments also tested the effects of acorn burial and litter cover on desiccation and germinability and the influence of soil moisture on germination. Burial and litter protected acorns against predation by deer in the field. Germination was promoted by burial both in field and laboratory experiments. Germination was proportional to acorn water content and to soil moisture. Seedling emergence in the field was enhanced by burial but reduced by litter cover. Acorns buried but uncovered by litter had the highest probability of recruiting a seedling. A potential effect of seed predators or dispersers on red oak regeneration and expansion is suggested, as acorn caching by birds and rodents may actually enhance population recruitment, despite high mortality through acorn consumption.

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Counting rare and elusive animals and evaluating their demographic status, are fundamental yet challenging aspects of population ecology and conservation biology. We set out to estimate population size (Nc), genetic effective population size (Ne gen), sex ratio, and movements based on genetic tagging for the threatened Cantabrian capercaillie. We used 9 microsatellite loci to genotype 134 droppings collected at 34 display areas during the breeding season. Using genetic capture-mark-recapture, we estimated 93 individuals (Nc, 95% CI: 70–116) in an area of about 500 km2, with sex ratio biased towards males (1∶1.6). Estimated Ne gen (35.5) was 38% of Nc, notably higher than the published average in wild populations. This capercaillie population is small and well within concern in terms of population viability. By genetic tagging, we detected mostly short movements; just a few males were recaptured between contiguous display areas. Non-invasive surveys of endangered populations have a great potential, yet adequate sample size and location are key to obtain reliable information on conservation status.

The endangered Cantabrian capercaillie (Tetrao urogallus cantabricus) lives at the southern edge of tetraonids' distribution range, in entirely deciduous forests. Its conservation planning has been always lek-centred. There is very little information about the specific habitat requirements of hens and broods, even though reproductive success appears to be a limiting factor. We analysed summer surveys from 1997 to 2004, carried out to estimate the reproductive success of the population. We compared the habitat characteristics at different spatial scales of hens with broods, broodless hens, and cocks in summer, with the better known spring habitat in display areas. Summer habitat showed higher proportion of open areas and was associated with more rugged zones at moderate spatial scales (78 ha) than spring habitat at display areas. Cocks and hens showed summer habitat partitioning; hens were associated with higher proportions of open and shrubby habitats. Furthermore, broodless hens preferred areas with higher slope variability than the display and summer areas preferred by cocks. These differences may reflect the sexual dimorphism of the species in reproductive role, energetic demands and conspicuousness. At larger spatial scales a previously developed habitat suitability model performed well to predict good brood-rearing areas. Hens with broods were located in the best-preserved areas in the range, mainly characterized by higher proportion of forest cover at a large (50 km 2 ) scale. We suggest that these characteristics indicate refuge habitats where Cantabrian capercaillie can still breed successfully.