A Geostatistical Approach to Estimate High Resolution Nocturnal Bird Migration Densities from a Weather Radar Network

Raphaël Nussbaumer,Baptiste Schmid,Grégoire Mariethoz,Felix Liechti,Lionel Benoit,Silke Bauer

doi:10.3390/rs11192233

Raphaël Nussbaumer, Baptiste Schmid + Show 4 more

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https://doi.org/10.3390/rs11192233

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Abstract

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 artificial structures. 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 validate the model, we performed a cross-validation and also compared our interpolation results with independent measurements of two bird radars. Our model estimated bird densities at high resolution (0.2° latitude–longitude, 15 min) 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. 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.

Highlights

Every year, several billions of birds undergo migratory journeys between their breeding and non-breeding grounds [1,2]
( 20 km–15 min), we propose a tailored geostatistical framework able to model the spatio-temporal patterns of bird migration
The model developed here can estimate bird migration intensity and its uncertainty range on a high-resolution space-time grid (0.2◦ lat. lon. and 15 min.)

Summary

Introduction

Several billions of birds undergo migratory journeys between their breeding and non-breeding grounds [1,2]. These migratory movements link ecosystems and biodiversity on a global scale [3], and their understanding and protection require international efforts [4]. Declines in many migratory bird populations [5,6] resulted from the rapid changes in their habitats, including the aerosphere [7]. Changes in aerial habitats are diverse, and their consequences still poorly known. Climate change may alter global wind patterns and the wind assistance provided to migrants [8]. To be more severe, the impact of direct anthropogenic changes, including light pollution that reroutes migrants [9], buildings [10], wind energy production [11], and aviation [12], causes billions of fatalities every year [13]

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