Habitat partitioning in endangered Cantabrian capercaillie Tetrao urogallus cantabricus

Abstract

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.

Habitat partitioning and molting site fidelity in Tetrao urogallus cantabricus revealed through stable isotopes analysis

“…Our results suggest distinct trophic variability for each gender, which may be related to spatial separation in foraging; females use the more diverse and less homogeneous treeline forests, while males mainly use the inner areas of the forests during molting (Rolstad et al 1988;Ménoni 1990;Bañuelos et al 2008). Our main contribution to previous knowledge of Capercaillie feeding ecology (Storch et al 1991;Odden et al 2003;Borchtchevski 2009) is to reveal sex-related trophic variability in Capercaillie by means of stable isotope analysis, and trophic differences likely driven by habitat segregation.…”

“…In the Cantabrian Mountains, Capercaillie reproduction appears to occur 3-4 weeks later than in northern populations (Martínez 1993;Moss et al 2001;Wegge et al 2005), and, thus, molting is also delayed. See Bañuelos et al (2008) for details on those surveys.…”

“…We studied the Cantabrian population of Western Capercaillie (Tetrao urogallus cantabricus), the only population that inhabits all year round purely deciduous forests (Quevedo et al 2006a, b). Previous studies on Cantabrian Capercaillie showed that habitat partitioning exists during summer in this population, related to sex and reproductive status, and associated with the females' stronger reliance on more heterogeneous treeline habitats while males remain in more homogeneous inner areas of the forests (Bañuelos et al 2008). These previous studies on the Cantabrian range, altogether with studies on northern Capercaillie populations that report more generalized diets for females (Storch et al 1991;Odden et al 2003;Borchtchevski 2009), are hinting at possible sexual dimorphism in the diet and feeding behaviors.…”

“…Our hypothesis is that Capercaillie's marked sexual dimorphism would imply distinct dietary variation of each sex. Therefore, based on previous studies on habitat partitioning for this population (Bañuelos et al 2008), we predict broader trophic niche in females.…”

Diet and habitat selection in Cantabrian Capercaillie (Tetrao urogallus cantabricus): ecological differentiation of a rear-edge population

“…We considered that visual discrimination of sex from capercaillie droppings may be hampered by individual diet variation and seasonal diet shifts, which may be particularly important in our finegrained study area. Nonetheless, sexual dimorphism and individual variation are potential sources of variability that could affect understanding of capercaillie ecology and management plans (Bañuelos et al 2008). Intrapopulation variability in the use of resources should be addressed by specific studies that assign diet unequivocally to individuals, perhaps combining microhistological and molecular techniques.…”