Breeding biology of Red-backed Shrikes (Lanius collurio): distribution, performance and post-fledging survival in Denmark

Daniel A.F. Bloche*, Kasper Thorup, Kent Olsen, Per Ekberg, Peter Ellegaard Larsen, Knud Erik Strange, Anders P. Tøttrup

*Corresponding author af dette arbejde

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Abstract

Agricultural intensification and habitat degradation across Europe have caused declines since the 20th century in populations of birds adapted to open landscapes, such as the Red-backed Shrike (Lanius collurio). Effective conservation strategies require knowledge on species' breeding biology. To understand the status of the Danish breeding population better, we investigate which factors affect their breeding parameter (i.e. distribution, performance, post-fledging survival and behaviour). Our focus on the post-fledging period addresses present knowledge gaps due to the importance of this, yet under-studied, phase of passerines' breeding cycle. We studied breeding pairs on different habitat types with Denmark-wide Citizen Science data, complemented by data of local projects in Northern Zealand and Northern Jutland (Denmark). Significantly fewer pairs were found in agricultural habitats and more in forests, semi-natural open habitats and synanthropic habitats. Pairs in forests had a significantly higher breeding productivity compared to agricultural or semi-natural open habitats for data from the years 2000 to 2021. Some project sites showed significantly higher number of fledglings compared to others, indicating that these sites are potential core areas for breeding productivity. Over the last two decades, the mean breeding productivity across Denmark was stable with 2.3 fledglings per successful pair. The survival rate of ringed fledglings increased during the post-fledging period, likely due to their increase in more active and independent behaviour. The relatively low breeding productivity found in this study calls for further studies including detailed data from potentially secondary habitats like agricultural areas to understand the effects of habitat on population fluctuations.

OriginalsprogEngelsk
TidsskriftOrnis Fennica
Vol/bind100
Udgave nummer2
Sider (fra-til)69-83
Antal sider15
ISSN0030-5685
DOI
StatusUdgivet - 2023

Bibliografisk note

Funding Information:
Acknowledgements. We are grateful for the financial support from the Scientific Committee at Dansk Ornitologisk Forening (DOF), which made the fieldwork possible. Citizen Science data is an important part of this study and therefore we also need to thank every volunteer, who entered records of breeding Red-backed Shrikes on DOFbasen. Further thanks go to Morten Bentzon Hansen for the opportunity to use netfugl.dk as a platform to call for Citizen Science effort, as well as to Daniel Palm Eskildsen for providing us with the breeding locations of Red-backed Shrikes from the Danish Breeding Bird Atlas.

Publisher Copyright:
© 2023 University of Helsinki. All rights reserved.

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