Each year, billions of songbirds cross large ecological barriers during their migration. Understanding how they perform this incredible task is crucial to predict how global change may threaten the safety of such journeys. Earlier studies based on radar suggested that most songbirds cross deserts in intermittent flights at high altitude, stopping in the desert during the day, while recent tracking with light loggers suggested diurnal prolongation of nocturnal flights and common non-stop flights for some species. We analyzed light intensity and temperature data obtained from geolocation loggers deployed on 130 individuals of ten migratory songbird species, and show that a large variety of strategies for crossing deserts exists between, but also sometimes within species. Diurnal stopover in the desert is a common strategy in autumn, while most species prolonged some nocturnal flights into the day. Non-stop flights over the desert occurred more frequently in spring than in autumn, and more frequently in foliage gleaners. Temperature recordings suggest that songbirds crossed deserts with flight bouts performed at various altitudes according to species and season, along a gradient ranging from low above ground in autumn to probably >2000 m above ground level, and possibly at higher altitude in spring. High-altitude flights are therefore not the general rule for crossing deserts in migrant songbirds. We conclude that a diversity of migration strategies exists for desert crossing among songbirds, with variations between but also within species.

Biodiversity and Catchment Anglian Water Services Limited Lancaster House Lancaster Way Ermine Business Park Huntingdon Cambridgeshire PE29 6XU United Kingdom

British Trust for Ornithology The Nunnery Thetford Norfolk IP24 2PU United Kingdom

Center for Macroecology Evolution and Climate Natural History Museum of Denmark University of Copenhagen Universitetsparken 15 2100 Copenhagen Denmark

Centre for Environmental and Climate Research Ekologihuset Sölvegatan 37 Lund Sweden

CESCO UMR7204 MNHN CNRS Sorbonne Université CP135 43 Rue Buffon 75005 Paris France

Department of Agricultural Research in Northern Sweden Swedish University of Agricultural Sciences and Department of Molecular Biology University of Umeå 901 85 Umeå Sweden

Department of Behavioural Ecology Adam Mickiewicz University Poznan Poland Dziczenie pl Gruszki Poland

Estonian Ornithological Society Veski 4 51005 Tartu Estonia and Department of Zoology Institute of Ecology and Earth Sciences University of Tartu 46 Vanemuise St 51014 Tartu Estonia

Faculty of Environmental Sciences and Natural Resource Management Norwegian University of Life Sciences P O Box 5003 NO 1432 Ås Norway

Finnish Museum of Natural History LUOMUS P O Box 17 FI 00014 University of Helsinki Helsinki Finland

Grupo Ibérico de Anillamiento C Daoiz y Velarde 49 Bajo 24006 León Spain

Handbook of the Birds of the World Alive Lynx Edicions Montseny 8 08193 Bellaterra Spain

Institut Systématique Evolution Biodiversité MNHN CNRS SU EPHE 57 Rue Cuvier CP50 75005 Paris France

Institute of Zoology National Academy of Sciences Academichnaya 27 220072 Minsk Belarus

Kvismare Bird Observatory Rulleuddsvägen 10 S 178 51 Ekerö Sweden

Migres Foundation International Bird Migration Center N 340 Km 85 P O Box 152 11380 Tarifa Cádiz Spain

MTA Centre for Ecological Research Institute of ecology and Botany Lendület Landscape and Conservation Ecology Alkotmány u 2 4 2163 Vácrátót Hungary

Natural History Museum of Belgrade Njegoševa 51 Serbia

Natural History Museum of Denmark University of Copenhagen Universitetsparken 15 2100 Copenhagen Denmark

Natural Resources Institute Finland Natural Resources Latokartanonkaari 9 00790 Helsinki Finland

New buildings Howle Hill Ross on Wye Herefordshire HR9 5RD United Kingdom

Nostra Senyora de Montserrat 19 08756 La Palma de Cervelló Spain

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OMPO 59 rue Ampère 75017 Paris France

Pajautos st 11 40 LT 06203 Vilnius Lithuania

Piedalbuccio 20232 Oletta France

RSPB Centre for Conservation Science The Lodge Sandy SG19 2DL United Kingdom

The Czech Academy of Sciences Institute of Vertebrate Biology Květná 8 CZ 603 65 Brno Czech Republic

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