A geostatistical approach to estimate high resolution nocturnal bird migration densities from a weather radar network

Authors: Raphael Nussbaumer, Lionel Benoit, Gregoire Mariethoz, Felix Liechti, Silke Bauer, Baptiste Schmid

Year: 2019

Publication: bioRxiv

Publication Link: http://dx.doi.org/10.1101/690065

Access: Open

Keywords: Aeroecology, Bird migration, Geostatistical modelling, Interactive visualisation, Kriging, Radar network, Spatio-temporal interpolation map, Weather radar

Abstract: 1. Quantifying nocturnal bird migration at high resolution is essential for (1) understanding the phenology of migration and its drivers, (2) identifying critical spatio-temporal protection zones for migratory birds, and (3) assessing the risk of collision with man-made structures.
2. We propose a tailored geostatistical model to interpolate migration intensity monitored by a network of weather radars. The model is applied to data collected in autumn 2016 from 69 European weather radars. To cross-validate the model, we compared our results with independent measurements of two bird radars.
3. Our model estimated bird densities at high resolution (0.2º latitude-longitude, 15min) and assessed the associated uncertainty. Within the area covered by the radar network, we estimated that around 120 million birds were simultaneously in flight [10-90 quantiles: 107-134]. Local estimations can be easily visualized and retrieved from a dedicated interactive website: birdmigrationmap.vogelwarte.ch.

4. This proof-of-concept study demonstrates that a network of weather radar is able to quantify bird migration at high resolution and accuracy. The model presented has the ability to monitor population of migratory birds at scales ranging from regional to continental in space and daily to yearly in time. Near-real-time estimation should soon be possible with an update of the infrastructure and processing software.

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