The road to opportunities: landscape change promotes body-size divergence in a highly mobile species

Abstract

Landscape change provides a suitable framework for investigating population-level responses to novel ecological pressures. However, relatively little attention has been paid to examine the potential influence of landscape change on the geographic scale of population differentiation. Here, we tested for morphological differentiation of red-necked nightjars Caprimulgus ruficollis breeding in a managed property and a natural reserve situated less than 10 km apart. At both sites, we also estimated site fidelity over 5 years and quantified the potential foraging opportunities for nightjars. Breeding birds in the managed habitat were significantly larger in size—as indexed by keel length—than those in the natural one. However, there were no significant differences in wing or tail length. Immigration from neighboring areas was almost negligible and, furthermore, no individual (out of 1130 captures overall) exchanged habitats between years, indicating strong site fidelity. Food supply for nightjars was equally abundant in both habitats, but the availability of foraging sites was remarkably higher in the managed property. As a result, nightjars—particularly fledglings—in the latter habitat benefited from increased foraging opportunities in relation to those in the natural site. It seems likely that the fine-scale variation in nightjar morphology reflects a phenotypic response to unequal local conditions, since non-random dispersal or differential mortality had been determined not to be influential. High site fidelity appears to contribute to the maintenance of body-size differences between the two habitats. Results from this nightjar population highlight the potential of human-induced landscape change to promote population-level responses at exceedingly small geographic scales.

Natal habitat imprinting counteracts the diversifying effects of phenotype-dependent dispersal in a spatially structured population

“…Likewise, we observed qualitatively similar differences between cross-fostered individuals moving from the coniferous to the deciduous forest and those moving the other way round (respectively, 19.52 ± 0.08 mm and 19.28 ± 0.15 mm; mean ± SE). Even though this difference (1.1 %) might seem modest, it is well within the range reported in other studies made at small spatial scales (5–10 km; 0.9–1.2 % difference; [ 33 , 64 , 65 ]. Nevertheless, in contrast to the large sample of unmanipulated individuals, the effect of the interaction between body size and rearing patch on the propensity to change habitats did not reach significance in our experimental birds (see ‘results’), possibly because the sample size of ‘non-philopatric’ recruits stemming from the experiment is very limited compared with the observational study (29 vs. 115).…”

WITHDRAWN—Administrative Duplicate Publication: Influence of habitat composition features on nestling physiological condition and breeding success in Pied Flycatchers, Ficedula hypoleuca

“…1,2 Temporal and spatial variation in habitat quality influences reproduction, body condition and survival of birds. [3][4][5] Factors affecting the breeding distribution of birds are macro-habitat differences related to habitat quality such as urban versus forest, deciduous forest versus coniferous forest; on the other hand, there are also habitat composition differences occurring between nesting territories within one habitat, for example, deciduous forests. 6,7 One of the most often used indicators of habitat composition features for territorial avian insectivores is the vegetation structure around each nesting site.…”

Taxonomy as tyranny

“…), Red‐necked Nightjars Caprimulgus ruficollis are larger in one breeding habitat than another (Camacho et al . ) – and the ‘implications for conservation’ (a subheading that is becoming standard at the ends of modern taxonomic papers) are, collectively, enormous.…”