Migration patterns of breeding Hen Harriers Circus cyaneus in Spain

ABSTRACT

Capsule:

Tracked Hen Harriers Circus cyaneus breeding in Spain winter either in the southern parts of the Iberian Peninsula or in Morocco, although migration timing and distances did not differ between birds using different wintering regions.

Aims:

To study, for the first time, the migratory patterns of Hen Harriers breeding in Spain.

Methods:

Eight breeding adult Hen Harriers were tagged in Spain with GPS/GSM transmitters between 2019 and 2022 to study autumn and spring migration between breeding areas in central or northern Spain, and wintering quarters in southern Spain and Morocco.

Results:

Males and females did not differ significantly in their patterns of migration (dates for start and end of migration, duration, daily distance, and total distance) in either migratory period. Individuals started the autumn migration between July and January, with the peak migration in mid-October. Spring migration took place from February to April and peaked in mid-March. Mean (± sd) distances travelled were: daily distance 168.99 ± 80.10 km/day and total distance 995.07 ± 402.90 km in autumn, and 141.74 ± 41.41 km/day and 1035.26 ± 593.51 km in spring. Two types of migration patterns were found: intra-peninsular migration and migration to Morocco. Migration dates and distances did not differ significantly between individuals with intra-peninsular migration strategies and those migrating to Morocco.

Conclusion:

These results are the first to describe the migratory behaviour of Spanish breeding Hen Harriers using satellite telemetry. Knowledge of migratory routes and behaviour are important for planning the conservation of species.

Acknowledgements

The results were obtained thanks to the work of SEO/BirdLife in the Migra program and its funding by Fundación Iberdrola España and Natural England. We thank the numerous individuals, ornithological groups, ringing groups, research centres, forestry agents and technicians from the autonomous communities for their collaboration. Many people from SEO/BirdLife also took part in the work, especially Javier de la Puente, Ana Bermejo and Carmen Fernández. We thank the administration staff who helped in the less pleasant tasks of the project related to invoices and justifications. This paper is part of Jorge García-Macía’s PhD thesis.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Authors’ contributions

S.M., J.G.M., and V.U. conceived the ideas and designed the methodology, A.O. and S.L. collected the data. S.M. and J.G.M. analysed the data. S.M., J.G.M. and V.U. wrote the manuscript. S.M., J.G.M., S.L. and V.U and contributed critically to the drafts. S.L. and V.U. gave final approval for publication.

Data availability statement

All data used in this study are publicly available upon request to data managers in the online data repository Movebank (www.movebank.org). The projects are Hen Harrier in Spain – Migra Program in Spain (project ID: 1169461367) and Hen Harriers in Spain (project ID: 1135251191).

Additional information

Funding

This work was supported by Fundación Iberdrola España (MIGRA program of SEO/BirdLife) and Natural England.