Proximity of breeding and foraging areas affects foraging effort of a crepuscular, insectivorous bird
(2018) Scientific Reports — Vol. 8, n° 1, p. 1-11 (2018)
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- (en) When complementary resources are required for an optimal life cycle, most animals need to move between different habitats. However, the level of connectivity between resources can vary and, hence, influence individuals' behaviour. We show that landscape composition and configuration affect the connectivity between breeding (heathlands) and foraging habitats (extensively-grazed grasslands) of the European Nightjar (Caprimulgus europaeus), a crepuscular insectivorous bird. On a daily basis, nightjars connect breeding and foraging sites by rapidly crossing unsuitable habitats in order to exploit a higher prey biomass in foraging sites. However, low availability of foraging habitat near breeding sites and clustered landscapes greatly increase foraging distance. Birds occupying these sub-optimal breeding areas compensate for longer travels by increasing foraging duration, and their physiology shows increased stress levels. All findings suggest that landscape heterogeneity can affect population dynamics of nightjars. Therefore, we recommend an integrated management approach for this EU-protected bird species. Movement is essential for almost all animals on earth and influences processes ranging from the individual to the ecosystem level 1,2. In order to link vital resources, such as nesting and feeding sites, many species undertake daily movements between complementary habitats 3-5. However, the quality of, and accessibility to these resources can vary 6-10. Human pressures on natural habitats cause rapid changes in landscape composition and configuration 11,12. Recent studies have shown that some species, such as Red-necked Nightjars Caprimulgus ruficollis and Marsh Harrier Circus aeruginosus, benefit from anthropogenic landscape modification 13,14. However, more often, these modifications reduce the availability of resources and/or decrease the connectivity between complementary habitats 15. Consequently, bird species can experience increased energy expenditure 16 , lower foraging efficiency 6,17 , higher predation risk 18 and increased physiological costs 19 , which all can lead to changes in population dynamics 20,21. Understanding how animals move in heterogeneous environments is, therefore, critical in the framework of the conservation of species and the sustainable management of altered landscapes 1,2,12,22. The European Nightjar Caprimulgus europaeus, a crepuscular, insectivorous, EU-protected bird species (European Birds Directive 2009/147/EC) uses complementary habitats within its home range for different resources 5. In Flanders (Northern Belgium), breeding areas of this sub-Saharan migratory bird are mainly found on open semi-natural, low-nutrient habitats, such as heathlands and inland dunes (hereafter together referred to as heathlands) 23. Whereas nightjars rely on their camouflage to stay well-hidden from predators during daytime, at night they use complementary habitats, such as extensively-cultivated grasslands and wet grasslands, to forage for aerial insects 5. The nightjar's typical breeding habitat has decreased by 95% due to anthropogenic activities over the last 150 years 24. Consequently, breeding habitats now only occur in fragmented landscapes dominated by woodland, agricultural, urban and industrial areas. There is ample evidence for many animal groups, including nightjars 5 , that home range size and foraging distance are influenced by habitat composition 21,25-28. When foraging distances increase and animals invest more
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Evens, R., Beenaerts, N., Neyens, T., Witters, N., Smeets, K., & Artois, T. (2018). Proximity of breeding and foraging areas affects foraging effort of a crepuscular, insectivorous bird. Scientific Reports, 8(1), 1-11. https://doi.org/10.1038/s41598-018-21321-0 (Original work published 2018)