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Versluijs, M., S. Eggers, G. Mikusiński, J.-M. Roberge, and J. Hjältén. 2020. Foraging behavior of the Eurasian Three-toed Woodpecker (Picoides tridactylus) and its implications for ecological restoration and sustainable boreal forest management. Avian Conservation and Ecology 15(1):6. https:// ABSTRACT. Several studies have shown that the Three-toed Woodpecker (Picoides tridactylus) is strongly favored by large-scale disturbances, including forest fires. However, natural disturbances have largely disappeared from European boreal forests because of modern forestry practices and fire suppression. We currently lack knowledge on the foraging activity and resource use of the Eurasian Three-toed Woodpecker, especially in burned forests, and this restricts our ability to develop strategies for sustainable forest management and ecological restoration aiming at improving the situation of this woodpecker and associated species. In order to fill this knowledge gap, we studied the characteristics of selected foraging substrates and the foraging behavior of the Three-toed Woodpecker during the breeding season in unburned forests and forests that have been subjected to prescribed burning. We used instantaneous sampling during two consecutive springs (2016-2017), where we observed the woodpeckers' foraging behavior during a total of 977 minutes in burned forest and 962 minutes in unburned forests. The preferred foraging substrate for Three-toed Woodpeckers in both burned and unburned forests can be characterized as freshly dead trees with a DBH > 15 cm. However, data on time spent foraging on different substrates suggest that also substrates in the 5-15 DBH range and living trees are important. Additionally, prescribed burnings led to less pronounced selection of tree species, which suggest that fire may reduce differences in abundance of saproxylic insect prey between tree species. This information on substrate selection and foraging time provide complementary knowledge and thus should be used simultaneously when management strategies for improved woodpecker habitat are developed. Our results suggest that both prescribed burning and protecting forests with high density and diversity of dead wood provides habitat opportunities for Three-toed Woodpeckers and using both in management may maximize conservation outcome. Comportement d'alimentation du Pic tridactyle (Picoides tridactylus) et ses implications pour la restauration écologique et les pratiques durables d'aménagement de la forêt boréaleRÉSUMÉ. Plusieurs études ont montré que le Pic tridactyle (Picoides tridactylus) profite des perturbations survenant sur de vastes étendues, dont les incendies de forêt. Toutefois, les perturbations naturelles n'existent presque plus dans les forêts boréales d'Europe en raison des pratiques forestières modernes et de la suppression des incendies de forêt. Le manque actuel de connaissances sur l'alimentation et l'utilisation des ressources par le Pic tridactyle, spécialement dans les forêts brûlées, restreint notre habilité à élaborer des ...

Species’ range shifts and local extinctions caused by global change lead to community composition changes. At large spatial scales, ecological barriers, such as biome boundaries, coastlines, elevation, and temperature gradients, can influence a community's ability to shift. Yet, ecological barriers are rarely considered in global change studies, potentially hindering predictions of biodiversity shifts. We used data from two consecutive European breeding bird atlases to calculate the geographic distance and direction between communities in the 1980's and their nearest compositional equivalent in the 2010’s and modelled their response to barriers. The ecological barriers affected both the distance and direction of bird community composition shifts, with coasts and elevation having the strongest influence. Combining ecological barriers and community shift projections can identify ecological corridors that facilitate shifts of species and communities under global change.

When differently sized species feed on the same resources, interference competition may occur, which may negatively affect their food intake rate. It is expected that competition between species also alters behaviour and feeding patch selection. To assess these changes in behaviour and patch selection, we applied an experimental approach using captive birds of three differently sized Anatidae species: wigeon (Anas penelope) (~600 g), swan goose (Anser cygnoides) (~2700 g) and bean goose (Anser fabalis) (~3200 g). We quantified the functional response for each species and then recorded their behaviour and patch selection with and without potential competitors, using different species combinations. Our results showed that all three species acquired the highest nitrogen intake at relatively tall swards (6, 9 cm) when foraging in single species flocks in the functional response experiment. Goose species were offered foraging patches differing in sward height with and without competitors, and we tested for the effect of competition on foraging behaviour. The mean percentage of time spent feeding and being vigilant did not change under competition for all species. However, all species utilized strategies that increased their peck rate on patches across different sward heights, resulting in the same instantaneous and nitrogen intake rate. Our results suggest that variation in peck rate over different swards height permits Anatidae herbivores to compensate for the loss of intake under competition, illustrating the importance of behavioural plasticity in heterogeneous environments when competing with other species for resources.

Large scale declines in farmland bird populations are of major conservation concern in many European countries (Donald et al. 2001, Sanderson et al. 2013). Studies explaining the causes of these population changes often focus on changes in agricultural practices, such as increased levels of mechanization, changes in sowing and harvesting times and frequencies, pesticide use and drainage (