Spring‐summer movements of male capercaillie Tetrao urogallus: A test of the ‘landscape mosaic’ hypothesis

Abstract

The 'landscape mosaic' hypothesis predicts that adult male capercaillie Tetrao urogallus track available habitat when making distinct seasonal migrations. We tested this hypothesis by comparing movement from leks to summer range in three geographical regions, viz. northwest Russia (Pechora), southwest Russia (Tver) and southeast Norway (Varaldskogen). All radio-collared males dispersed out of their daytime lek territories to an average distance of 2.3 km (±0.37) from lek centres (N = 52). In Russia, three birds, which were not included in this estimate, moved beyond the 6-7 km detection distance, but returned the fol lowing year. Due to large variation among birds at each lek, the only signifi cant difference in movement was found between the birds at the lek in Pechora ( x = 1.3 km) and those at one of the two leks in Tver (x = 3.6 km) and at one of the three leks in Norway (x = 3.2 km). At all leks except the one in Tver, the amount of suitable summer habitat, e.g. old Norway spruce Picea abies forest on rich soil, was smaller within a 1-km radius of leks centres than in the outer two 1-km zones. Despite a large proportion of old spruce forest at and near the lek site in Tver, the males at this site moved >2 km from the lek centre in late May/early June. When data were pooled, the dispersal distance did not correlate with the amount of old spruce forest nor with the size of patch es (e.g. grain size) with increasing distance from leks. However, at the Nor wegian study area, which is highly fragmented with a fine-grained habitat mosa ic due to commercial forestry, variation in topography and soil quality, birds tended to move farther away from the leks with increasing patch size and with increasing proportion of old spruce forest. When fitting a second polynomi al regression function to the pooled data, there was only a weak relationship between dispersal distance and grain size for leks (P = 0.19). When includ ing all birds, the relationship was highly significant (P = 0.002). The Pechora lek in northwest Russia contributed mainly to the lack of a clear relationship between movement pattern and distribution of old spruce forest. Here large, contiguous bands of old spruce forest were located along the main river courses in a coarse-grained fashion within 2 km of lek sites. Thus, local con figuration of preferred summer habitat at the landscape scale probably affects both direction and movement to a larger extent than predicted from the 'land scape mosaic' hypothesis.

Capercaillie (Tetrao urogallus) habitat characteristics in north-boreal Finland

“…The home ranges are large, about 100 hectares or more (Rolstad 1988, Rolstad et al 1988, and the area used by a lekking population covers several thousands of hectares (Hjorth 1994, Hjeljord et al 2000. There are also differences, for instance, in habitat use between the sexes (Rolstad and Wegge 1990).…”

Integrating landscape connectivity in broad-scale forest planning through a new graph-based habitat availability methodology: application to capercaillie (Tetrao urogallus) in Catalonia (NE Spain)

“…This means that, according to movement abilities of capercaillie (Hjeljord et al 2000), dispersal of this species across the Catalan landscape appears to be seriously hindered due to the very low chances of effective connections between forest habitat components. However, 35% of the total habitat area corresponds to one single connected region (with 183 nodes out of 522), and the class coincidence probability (CCP) (Pascual-Hortal and Saura 2006) equals 0.18 for the capercaillie habitat, where CCP is defined as the probability that two individuals randomly placed within the habitat are able to find each other (Jaeger 2000;Pascual-Hortal and Saura 2006), which occurs if they are placed within the same component.…”

“…Capercaillie average dispersal distance, obtained as a result of a spring-summer movements study with 52 radio-collared males (Hjeljord et al 2000), was found to be 2.3 km (±0.37).…”

“…A graph component disconnects when a part of it, after a change in the landscape, becomes not reachable from some other part, causing an increase in the number of components in the landscape. In this study, links are considered symmetric and are obtained by comparing the edge-to-edge Euclidean distance between nodes (d ij ) with the 2.3 km average dispersal distance of capercaillie (Hjeljord et al 2000). If d ij < 2.3 km, a link was assigned between nodes i and j; otherwise, nodes i and j had no direct functional connection (no link).…”

Ranging behaviour of male capercaillie Tetrao urogallus outside the lekking ground in spring

“…Several authors have described seasonal range use patterns of capercaillie resulting from large-scale movements and changes in seasonally based resources , Storch 1995, Menoni et al 1997, Hjeljord et al 2000. Smaller-scale changes may occur on a daily and weekly basis as resources such as food plants fluctuate in availability (Odden et al 2003).…”