The grand challenges of migration ecology that radar aeroecology can help answer

Abstract

Many migratory species have experienced substantial declines that resulted from rapid and massive expansions of human structures and activities, habitat alterations and climate change. Migrants are also recognized as an integral component of biodiversity and provide a multitude of services and disservices that are relevant to human agriculture, economy and health. The plethora of recently published studies reflects the need for better fundamental knowledge on migrations and for better management of their ecological and human‐relevant effects. Yet, where are we in providing answers to fundamental questions and societal challenges? Engaging a broad network of researchers worldwide, we used a horizon‐scan approach to identify the most important challenges which need to be overcome in order to gain a fuller understanding of migration ecology, and which could be addressed using radar aeroecological and macroecological approaches. The top challenges include both long‐standing and novel topics, ranging from fundamental information on migration routes and phenology, orientation and navigation strategies, and the multitude of effects migrants may have on resident communities, to societal challenges, such as protecting or preventing migrant services and disservices, and the conservation of migrants in the face of environmental changes. We outline these challenges, identify the urgency of addressing them and the primary stakeholders – researchers, policy makers and practitioners, or funders of research.

Size matters in quantitative radar monitoring of animal migration: estimating monitored volume from wingbeat frequency

“…The lowest two kilometres of the atmosphere host huge quantities of animal movements, often invisible to the human eye (Liechti andMcGuire 2017, Reynolds et al 2017), and there is an increasing interest to investigate the function and importance of the aerial habitat (Chilson et al 2017, Bauer et al 2019. There are several methods to monitor the movements of animals in the airspace (Drake and Bruderer 2017), with radar being the predominant technology when it comes to quantifying biomass flows (Chilson et al 2017).…”

Radar aeroecology – a missing piece of the puzzle for studying the migration ecology of animals

“…This limitation is overcome by large-scale and long-term weather surveillance radar networks (Kelly and Horton 2016, Van Doren and Horton 2018, Nilsson et al 2019 (Fig. Importantly, Bauer et al (2019) also correctly point out the major technical problems (e.g. This recent progress stimulated Bauer et al (2019) to identify some of the most urgent challenges of migration ecology that radar aeroecology can help solve.…”

“…the monarch butterfly Danaus plexippus (Inamine et al 2016)). This recent progress stimulated Bauer et al (2019) to identify some of the most urgent challenges of migration ecology that radar aeroecology can help solve. 1).…”

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In a recent Ecography article, Bauer et al (2019) identified the most pressing questions for advancing our understanding of how anthropogenic changes in the environment affect aerial migrants at the macroscale and how these changes consequently influence humans. To surmount the associated challenges, large-scale networks of weather surveillance radar are the suggested solution because addition to measuring precipitation and wind, they also continuously monitor the aggregated biomass movements of insects, birds and bats over large spatial and temporal scales.

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Taking radar aeroecology into the 21st century

“…Over the years, radar has been used to answer a range of ecological questions (Bauer et al 2019) review the most recent contributions of radar based research to address these questions and identify some of the outstanding challenges and priority research areas in migration ecology research. The most urgent challenges across all taxa are methodological in nature as well as understanding the impact of man-made structures and humans activities on migration.…”