Contrasting responses of two passerine bird specie

Authors: Karen Marie Mathisen Simen Pedersen Erlend Birkeland Nilsen Christina Skarpe

Publish Date: 2011/12/27

Volume: 58, Issue: 3, Pages: 535-547

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Abstract

Large herbivores may modify the ecosystem in a way that affects habitat quality and resource availability for other fauna The increase in wild ungulate abundance in many areas may therefore lead to ecosystem changes affecting distribution and reproduction of other species Moose Alces alces in Scandinavia is a good example of a herbivore that has recently increased in abundance and has the potential to affect the ecosystem In this study we investigated how different levels of moose winter activity around supplementary feeding stations for moose affect reproduction in two insectivorous passerines great tits Parus major and pied flycatchers Ficedula hypoleuca The two bird species showed contrasting responses to high moose activity at feeding stations Great tits avoided habitats with high moose activity where fledging success and feeding frequency was lower than at low moose activity habitats Flycatchers nested more often at high moose activity habitats where fledging weight and feeding frequency were higher than at low moose activity habitats Filming of nest boxes with great tits showed an increase in adult Lepidoptera in the diet at supplementary feeding stations for moose and a smaller size of caterpillar prey at intermediate moose activity The results support the hypothesis that herbivores may affect insectivorous passerines through changed arthropod food availabilityThis study was funded by Hedmark University College and the Norwegian Research Council We are grateful to the landowners and the landowner association in StorElvdal municipality and especially Knut Nicolaysen for support providing information about moose feeding and giving us permission to put up nest boxes Thanks go to the numerous students that have been a great help in the field Thanks to Harry Andreassen for help with planning this study to Tom Hætta for going through the video films to Kjell Danell for helpful comments on the manuscript to Tore Slagsvold for advice on filming of nest boxes and bird ecology and to Jos Milner for language corrections Thanks also to Anders Lamberg for building the nest box loggers and to Stephen Parfitt for maintaining them

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