Foraging behavior of the Eurasian Three-toed Woodpecker (Picoides tridactylus) and its implications for ecological restoration and sustainable boreal forest management

Martijn Versluijs,Joakim Hjältén,Grzegorz Mikusiński,Jean-Michel Roberge,Sönke Eggers

doi:10.5751/ace-01477-150106

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 duringtwo 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

Highlights

As a consequence of human-induced habitat loss, fragmentation, and structural homogenization, many woodpecker species are threatened or have declining populations (Mikusiński 2006, Lammertink 2014, Vergara-Tabares et al 2018)
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
203 utilized trees in burned forest and 94 utilized trees in unburned forest formed the basis for assessing foraging substrate selection and foraging time spent by woodpeckers (Table 2)

Summary

Introduction

As a consequence of human-induced habitat loss, fragmentation, and structural homogenization, many woodpecker species are threatened or have declining populations (Mikusiński 2006, Lammertink 2014, Vergara-Tabares et al 2018). This especially concerns habitat specialists with strong affinity for old-growth forest or forest subjected to natural disturbances, e.g. windthrow, fire, and insect outbreaks. At the local habitat level, woodpeckers need certain structures for foraging and breeding, such as large old trees and deadwood (Walters et al 2002, Bütler et al 2004a, Roberge et al 2008). Prescribed burning, as a form of ecological restoration, is assumed to be an efficient way to emulate wildfire and to create habitats for a range of different species including woodpeckers (Hjältén et al 2017, Versluijs et al 2017)

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