University of Oulu

Kajanus, M. H., Forsman, J. T., Vollstädt, M. G. R., Devictor, V., Elo, M., Lehikoinen, A., Mönkkönen, M., Thorson, J. T., & Kivelä, S. M. (2022). Titmice are a better indicator of bird density in Northern European than in Western European forests. Ecology and Evolution, 12, e8479.

Titmice are a better indicator of bird density in Northern European than in Western European forests

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Author: Kajanus, Mira H.1; Forsman, Jukka T.2; Vollstädt, Maximilian G. R.1,3;
Organizations: 1Department of Ecology and Genetics, University of Oulu, Oulu, Finland
2Natural Resources Institute Finland, Oulu, Finland
3Center for Macroecology, Evolution and Climate, GLOBE Institute, University of Copenhagen, Copenhagen, Denmark
4ISEM, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
5Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
6Finnish Museum of Natural History, Helsinki, Finland
7National Marine Fisheries Service, NOAA, Seattle, Washington, USA
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.2 MB)
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Language: English
Published: John Wiley & Sons, 2022
Publish Date: 2022-04-19


Population sizes of many birds are declining alarmingly and methods for estimating fluctuations in species’ abundances at a large spatial scale are needed. The possibility to derive indicators from the tendency of specific species to co-occur with others has been overlooked. Here, we tested whether the abundance of resident titmice can act as a general ecological indicator of forest bird density in European forests. Titmice species are easily identifiable and have a wide distribution, which makes them potentially useful ecological indicators. Migratory birds often use information on the density of resident birds, such as titmice, as a cue for habitat selection. Thus, the density of residents may potentially affect community dynamics. We examined spatio-temporal variation in titmouse abundance and total bird abundance, each measured as biomass, by using long-term citizen science data on breeding forest birds in Finland and France. We analyzed the variation in observed forest bird density (excluding titmice) in relation to titmouse abundance. In Finland, forest bird density linearly increased with titmouse abundance. In France, forest bird density nonlinearly increased with titmouse abundance, the association weakening toward high titmouse abundance. We then analyzed whether the abundance (measured as biomass) of random species sets could predict forest bird density better than titmouse abundance. Random species sets outperformed titmice as an indicator of forest bird density only in 4.4% and 24.2% of the random draws, in Finland and France, respectively. Overall, the results suggest that titmice could act as an indicator of bird density in Northern European forest bird communities, encouraging the use of titmice observations by even less-experienced observers in citizen science monitoring of general forest bird density.

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Series: Ecology and evolution
ISSN: 2045-7758
ISSN-E: 2045-7758
ISSN-L: 2045-7758
Volume: 12
Article number: e8479
DOI: 10.1002/ece3.8479
Type of Publication: A1 Journal article – refereed
Field of Science: 1181 Ecology, evolutionary biology
Funding: Kvantum Institute at University of Oulu funded the work of M.H. Kajanus and J.T. Forsman; Kone Foundation funded the work of M. Elo and J.T. Forsman; the work of A. Lehikoinen was funded by Academy of Finland (grant 275606); and the work of S.M. Kivelä was funded by Academy of Finland (grant 314833).
Academy of Finland Grant Number: 314833
Detailed Information: 314833 (Academy of Finland Funding decision)
Copyright information: © 2022 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.