The Willow Tit Parus montanus is distributed across the Palaearctic and into the Oriental zoogeographical region with 15 subspecies. P. m. borealis is the only subspecies in Fennoscandia. Based on 86 skinned museum specimens from Norway (south of 64 oN), we found relatively large variations in the colours of the mantle, the underpart and the cheeks. Birds along the coast are significantly darker and have less white on their cheeks than inland birds. Furthermore, the birds become paler on their mantle, underparts and cheeks towards north and east, and in particular the annual precipitation explains a significant part of the colour variation. This is in accordance with Gloger's climatic rule that points out that feathers tend to be darkly coloured in habitats where relative humidity is high and pale where it is low.
Articles published prior to September 2020 are subject to the following terms: https://boap.uib.no/index.php/ornis/copyright
Articles submitted from September 2020 are subject to the following terms:
Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under the Creative Commons Attribution License CC-BY 4.0 that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work.