What does the weather forecast tell us about little ringed plovers?
This bird migrates from northern Europe, where it breeds, to southern India. Their migration route is along the Indo-European flyway and is more than 7,000 kilometres long. The distance of their journey is the main reason why similar research has not yet been conducted. Collecting data on migratory birds is extremely difficult, but recent advances in bio-logging (data collection using sensors placed directly on the animal) have made it possible to observe migratory birds throughout the annual cycle.
Little ringed plovers use staging sites such as lakes, rivers, rice fields, residual flood waters, or pastures. If the temperature is high and/or conditions are dry (both factors were monitored in this study), there is a reduction in the quantity of invertebrates available, and these are important food for birds. The consequence of insufficient nutrition is that little ringed plovers are unable to compensate their energetically exhausting migration, which decreases their survival rate. Temperature and precipitation, via the amount of food, therefore affect the demographic composition of this bird population.
There are several staging regions on the Indo-European flyway: post-breeding staging, non-breeding, pre-breeding, and breeding. Research has shown that the amount of precipitation during the post-breeding staging period is more important for survival than during other times of the year. Dry conditions during this period are probably more critical, because post-breeding period occurs after an energetically-demanding breeding staging, as well as the moulting of flight feathers. Birds are depleted after this period and worsened conditions during migration might even be fatal for them. Post-breeding staging coincides with the summer monsoon, which brings humid air and precipitation from the ocean to land. Wet conditions therefore ensure there is enough water and food in the habitats where little ringed plovers exist.
The amount of precipitation on the migratory route of little ringed plovers varies both in time and place. Precipitation variability during post-breeding staging explains almost half of all alterations in the survival rate of these birds. The effect of average surface mean air temperature on survival rate is, unlike precipitation, extremely weak. This demonstrates that, when studying large-scale population dynamics, weather should definitely not be neglected.
Brlík, V., Pakanen, V. M., Jaakkonen, T., Arppe, H., Jokinen, J., Lakka, J., Blomqvist, D., Hahn, S., Valkama, J., & Koivula, K. (2022). Survival fluctuation is linked to precipitation variation during staging in a migratory shorebird. Scientific Reports, 12(1), 19830. https://doi.org/10.1038/s41598-022-24141-5
Eliška Leštinová
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