UNIVERSITY OF COPENH AGEN FACULTY OR DEPARTMENT Space use strategies of two Palaearctic migrants on the wintering grounds A study of winter territoriality in the Common Chiffchaff and Subalpine Warbler Dina Abdelhafez Ali Mostafa Supervisor: Kasper Thorup Co-Supervisor: Torben Dabelsteen Submitted on: 2 October, 2017 Name of department: Natural History Museum of Denmark Behavioural Ecology - Section of Ecology and Evolution - Department of Biology. University of Copenhagen Author(s): Dina Abdelhafez Ali Mostafa Title and subtitle: Space use strategies of two Palaearctic migrants on the wintering grounds : A study of winter territoriality in the Common Chiffchaff and Subalpine Warbler Topic description: An investigation of the chosen space use strategies and territoriality in two migrant songbirds wintering in the Sahel. Supervisor: Kasper Thorup – Torben Dablesteen Submitted on: 2 October 2017 Grade: Number of study units: 2 3 2 Table of contents PREFACE ............................................................................................................................ 4 SUMMARY .......................................................................................................................... 7 BACKGROUND .................................................................................................................. 9 Why study birds on their winter ground ...................................................................................................................... 10 Sociality as an extension of space use strategies ........................................................................................................... 11 The winter strategies of the two species: what is known so far?................................................................................. 15 The species: .................................................................................................................................................................. 15 Common Chiffchaff (Phylloscopus collybita) : ........................................................................................................... 15 Subalpine warbler (Sylvia cantillans): ......................................................................................................................... 18 SPACE USE STRATEGIES IN TWO PALAEARCTIC SONGBIRD MIGRANTS IN WINTER: PATTERNS OF TERRITORIALITY, ASSOCIATION AND VOCALISATION IN THE COMMON CHIFFCHAFF AND SUBALPINE WARBLERS WINTERING IN NORTHERN SENEGAL. ................................................................................................... 21 Abstract ........................................................................................................................................................................... 21 Introduction .................................................................................................................................................................... 21 Materials and methods ................................................................................................................................................... 22 Study site...................................................................................................................................................................... 22 Radio tracking .............................................................................................................................................................. 22 Playback experiments .................................................................................................................................................. 23 Statistical analyses ....................................................................................................................................................... 24 Response to Playback .................................................................................................................................................. 25 Results .............................................................................................................................................................................. 26 Discussion ........................................................................................................................................................................ 31 Conclusion ....................................................................................................................................................................... 35 REFERENCES .................................................................................................................. 36 APPENDIX ........................................................................................................................ 43 3 Preface The idea behind this project started with my interest in the field of animal behaviour in general and communication in particular. To start with I was looking for a research topic that related to bioacoustics, which will present the opportunity to learn how to collect acoustic data and analyse it. The other behaviour that I wanted to learn about was animal migration, and ideally communication underway. Because I was very keen on carrying out fieldwork, I approached Professor Kasper Thorup at the National History Museum as his team currently studies migration in songbirds, and we started developing the idea for a thesis research. I also asked Professor Torben Dabelsteen to co- supervise, because of his expertise in animal behaviour in general and bioacoustic in particular, and he kindly agreed to. Bird song and calls during the breeding season are well studied for a myriad of species, but little is known about the occurrence and function of the former once breeding is accomplished. The original design of this study was to collect recordings of spontaneous winter song in a chosen songbird species and attempt to correlate it to a function, and to supplement that with playback experiments to investigate the birds’ reaction to conspecifics’ song. As breeding season singing is established to serve the function of attracting a mate and establishing/maintaining a territory, the hypothesis was that winter song should serve the latter purpose due to the absence of breeding during winter for migrants, and that this territory would be only used for foraging, as opposed to the breeding season territory that is also used for nesting and raising the young. In 2011, Kasper has collected some tracking data on four songbird species at the Djoudj National Park in Northern Senegal, where many migrant species that breed in Eurasia spend the northern winter season. We found conflicting reports of winter song in the Common Chiffchaff in the literature, and similarly for the closely related species Willow Warbler, and decided to focus on the former since a recent study investigated the behaviour in Willow Warblers in 2014. I performed some preliminary analyses using the tracking data for 2 of those species to detect the existing patterns of space use – territoriality or otherwise – and to find out if any flocking patterns existed for the Chiffchaffs. The results did not support either territoriality or flocking for the Chiffchaffs, but showed evidence for territoriality in Subalpine Warblers. Therefore the second species we chose as was Subalpine Warbler, as a species exhibiting territoriality in winter, its behaviour offers a clear point of comparison for the species of main interest. Due to scheduling difficulties, the field work ended up taking place during the end of the northern winter season, right during the departure of Chiffchaffs from the study site in Northern 4 Senegal. During the period of fieldwork, the numbers of Subalpine Warblers were sufficient for the purposes of the study. On site, pilot trials showed that Chiffchaffs did not sing spontaneously, nor did they respond vocally to playback of conspecifics’ song. Accordingly, the focus was shifted to documenting the behavioural responses during the playback session. The playback data was then used along with the tracking data from 2011 to construct a multi faceted picture of the two species’ use of their environment, showing home range sizes, flocking/association patterns for Chiffchaffs only – since a territorial species like Subalpine Warblers will not associate- and responses to conspecifics’ song. This report consists of two parts; the first part is an introduction where I try to present the basic concepts and current knowledge in areas relevant to the study. Concepts like migration and types of space use strategies are presented, followed by a look at the ecology of the two migrants of interest on their wintering range. I will therefore present a summary of what is currently known of the two species’ ecology on their breeding and non breeding ranges for contrast The second part of the report is the manuscript that present the investigation carried out in Senegal. First, I present the investigation of association patterns and home range sizes and their overlap for individuals of the two species using tracking data collected during January 2012 at Djoudj National Park in the north of Senegal. The second part investigates the territorial behaviour of the two species using playback experiments to quantify the presence and degree of aggression triggered by conspecifics song; these experiments were carried out at the same site during February/March 2017. The results are then compared to previous studies