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Animal movements at large spatial scales are of great importance in population ecology, yet little is known due to practical problems following individuals across landscapes. We studied the whole Norwegian population of a small songbird (ortolan bunting, Emberiza hortulana) occupying habitat patches dispersed over nearly 500 km2. Movements of colour‐ringed males were monitored during ten years, and extensive long‐distance dispersal was recorded. More than half of all cases of breeding dispersal took place within one breeding season, and males moved up to 43 km between singing territories, using 1–22 d. Natal dispersal was usually to a habitat patch close to the natal patch, or within the natal patch if it was large. Breeding dispersal movements were often long‐distance, beyond neighbouring patches, and up to 11–19 patches were overflown. Movements of at least 6–9 km across areas of unsuitable habitat occurred regularly. The number of patches visited was low (1–4) even though search costs in terms of time spent moving from one site to another were relatively low (often only a few days even for distances >10 km). Most males seemed to use a threshold tactic when choosing a patch, but returns to previously visited patches were recorded, including some cases of commuting. In conclusion, male ortolan buntings have a surprising ability to move quickly at the landscape level, and this resulted in a high connectivity of patches. We discuss our results in relation to optimal searching strategies, in particular the use of within‐breeding season versus post‐breeding season search, conspecific attraction and adaptive late arrival of young birds.

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Geographic isolation is one of several models that has been proposed to explain the evolutionary course of speciation. In this study, we examined how geographical isolation may affect subspecies discrimination in the freeranging Scandinavian beaver (Castor fiber fiber L., 1758) by simulating a territorial intrusion by using scent (castoreum and anal gland secretion) from a con-subspecific (N = 8 for castoreum and N = 7 for anal gland secretion) and a hetero-subspecific (Castor fiber albicus Matschie, 1907; N = 2 for both castoreum and anal gland secretion). Direct observations of 33 families during evenings showed that beavers (i) sniffed castoreum but not anal gland secretion from C. f. fiber significantly longer than from C. f. albicus and (ii) responded aggressively (i.e., stood on the mound on their hind feet, pawing and (or) overmarking) significantly longer to castoreum but not anal gland secretion from C. f. fiber than from C. f. albicus. When experimental scent mounds were allowed to remain overnight, the response was significantly stronger to castoreum but not to anal gland secretion from C. f. fiber than from C. f. albicus. Gas chromatographic comparisons of castoreum and anal gland secretion from the two subspecies supported our behavioral observations for castoreum but not for anal gland secretion. These findings suggest that geographical isolation has developed discriminatory abilities in C. f. fiber. We further suggest that the proximate factors involved are of environmental origin.Résumé : L'isolement géographique est l'un de plusieurs modèles proposés pour expliquer le développement de la spé-ciation au cours de l'évolution. Notre étude examine comment l'isolement géographique peut affecter la reconnaissance des sous-espèces chez le castor de Scandinavie (Castor fiber fiber L., 1758) sauvage par la simulation d'une intrusion territoriale au moyen d'odeurs (castoréum et sécrétions de la glande anale) provenant d'animaux la même sous-espèce (castoréum, N = 8, sécrétions de la glande anale, N = 7) et d'une autre sous-espèce (Castor fiber albicus Matschie, 1907; N = 2 pour le castoréum et les sécrétions de la glande anale). Des observations directes de 33 familles en soirée indiquent que les castors (i) reniflent le castoréum, mais pas les sécrétions des glandes anales, de C. f. fiber significativement plus longtemps que les mêmes substances provenant de C. f. albicus et (ii) qu'ils réagissent agressivement (position debout sur les pattes arrières sur les monticules, coups de pattes et (ou) marquage excessif) significativement plus longtemps au castoréum, mais non aux sécrétions des glandes anales, de C. f. fiber, qu'aux mêmes substances provenant de C. f. albicus. Si les monticules portant les odeurs sont laissés toute la nuit, la réaction est significativement plus forte au castoréum, mais non aux sécrétions de la glande anale, de C. f. fiber qu'aux mêmes substances provenant de C. f. albicus. Des analyses comparatives par chromatographie en phase gazeuse du castoréum et des sécrétions d...

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