Temperature and microclimate refugia use influence migratory timings of a threatened grassland bird

Ramos, Rita F., Franco, Aldina M. A., Gilroy, James J. and Silva, João P. (2023) Temperature and microclimate refugia use influence migratory timings of a threatened grassland bird. Movement Ecology, 11 (1). ISSN 2051-3933

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Abstract

Background: Seasonal changes in resource availability are known to influence the migratory behaviour of animals, including both timing and distance. While the influence of environmental cues on migratory behaviour has been widely studied at the population level, it has rarely been examined at the spatial scale at which individuals experience their environment. Here, we test the hypothesis that individuals exposed to similar large-scale environmental cues may vary in migratory behaviour in response to the different microclimate conditions they experience at fine scales. Methods: We combine high-spatial and temporal resolution microclimate and habitat information with GPS tracking data for a partially migratory threatened grassland bird. Data from 47 little bustards (Tetrax tetrax; 67 breeding events) tracked between 2009 and 2019 was used to (i) evaluate individual consistency in migratory behaviour (timing and distance) and (ii) assess whether the local environmental characteristics experienced by individuals – and in particular their use of microclimate refugia - influence distance and timing of migration, from and to the breeding sites. Results: Migratory distance was consistent for birds tracked over multiple years, while the timing of migration showed high variability among individuals. Departures from breeding areas spanned from May to August, with a few birds remaining in their breeding areas. Vegetation greenness (a proxy for food availability) was positively associated with the time birds spent in the breeding area. The best model also included a positive effect of microclimate refugia availability on breeding season length, although an interaction with temperature suggested that this effect did not occur at the highest relative temperatures. The return date to breeding grounds, although spanning from September to April, was not influenced by the environmental conditions or food availability. Conclusions: Food availability, measured by a vegetation greenness proxy, was associated with later migration at the end of the breeding season. Availability of cooler microclimate refugia may also allow for later departures from the breeding sites in all but the hottest conditions. Management measures that increase microclimate refugia availability and provide foraging resources can thus potentially increase the length of the breeding season for this species.

Item Type:	Article
Additional Information:	Data Availability Statement: The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Funding Information: RFR work was funded by Fundação para a Ciência e a Tecnologia (FCT) through a doctoral grant (SFRH/BD/14889/2019). JPS was funded by the FCT under contract DL57/2019/CP 1440/CT 0021. Work supported by the European Union’s Horizon 2020 Research and Innovation Programme under the Grant Agreement Number 857251.
Faculty \ School:	Faculty of Science > School of Environmental Sciences University of East Anglia Research Groups/Centres > Theme - ClimateUEA
UEA Research Groups:	Faculty of Science > Research Centres > Centre for Ecology, Evolution and Conservation Faculty of Science > Research Groups > Environmental Biology Faculty of Science > Research Groups > Organisms and the Environment
Depositing User:	LivePure Connector
Date Deposited:	17 Feb 2025 14:30
Last Modified:	17 Feb 2025 20:30
URI:	https://ueaeprints.uea.ac.uk/id/eprint/98524
DOI:	10.1186/s40462-023-00437-7

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