Black Woodpeckers Dryocopus martius use stepping stones between woodland units

ABSTRACT

Capsule

Black Woodpeckers Dryocopus martius used small patches of trees as stepping stones when crossing areas of open land during daily movements within their home range in the non-breeding season.

Aims

To document that Black Woodpeckers, although an obligate forest species, frequently cross areas of open land within their daily home range, using solitary trees or small patches of trees as stepping stones during these movements.

Methods

We mounted GPS-loggers on 11 Black Woodpeckers and recorded their position every 5 min for approximately 1 week. Three woodpeckers stayed within continuous forest for the duration of the study, or failed to meet assumptions, and were therefore excluded from the analysis. The remaining eight Black Woodpeckers all moved between discrete woodland units at least once during the study period. Using a habitat use-availability framework, 54 GPS-positions located in gaps of open land between separate forest patches were analysed.

Results

Black Woodpeckers showed a significant preference for trees at low tree availabilities in the open land. However, we could not rule out that their preference for trees was proportional to availability when tree cover was high (> 82% tree cover). The median distance traversed to a location in open land between forest patches was 731 m.

Conclusion

Since the preference for trees was especially pronounced at low tree availabilities, we suggest that Black Woodpeckers use solitary trees or small patches of trees as stepping stones when traversing open areas within their daily home range. We hypothesize that this behaviour lessens the costs of living in a fragmented habitat, and that conservation of trees in open land may contribute to conserving Black Woodpecker populations in areas with fragmented forests.

Acknowledgements

Hans Christensen provided invaluable help by locating the Black Woodpeckers based on his extensive experience from intensely monitoring the local population of Black Woodpeckers for four decades. He also participated in all parts of the fieldwork for this project and provided feedback on an unfinished first draft of this manuscript. Sadly, Hans Christensen passed away before the manuscript took its final form and we regret that he did not see the final outcome of his labour on this project. We appreciate the help from Lars Dalby, who provided the overview map of the study area. We thank the Bird Ringing Centre at the Natural History Museum of Denmark, Copenhagen, for their support and for providing permissions to ring and mount GPS-units on the Black Woodpeckers. Finally, we value the cooperation with private landowners and the Danish Nature Agency.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Frands Christian Frantsen’s Scholarship.