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

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.

Data from: Weather-driven dynamics in a dual-migrant system: moths and bats

Animal migrations generate large spatial and temporal fluctuations in biomass that provide a resource base for many predator-prey interactions. These interactions are often driven by continent-scale weather patterns and are difficult to study. Few studies have included migratory animals on more than a single trophic level or for periods spanning multiple entire seasons. We tracked migrations of three species of agricultural pest noctuid moths over the 2010-2012 autumn seasons as the moths traveled past a large colony of migratory Brazilian free-tailed bats (Tadarida brasiliensis) in Texas. Increases in moth abundance, mass of bats, and duration of bat activity outside of the cave were correlated with passage of cold fronts over the study area and related increases in northerly wind. Moth responses to weather patterns varied among species and seasons, but overall moth abundances were low in late summer and spiked after one or more cold front passages in September and October. Changes in bat mass and behavior appear to be consequences of bat migration, as cave use transitioned from summer maternity roost to autumn migratory stopover sites. Weather-driven migration is at considerable risk from climate change, and bat and moth responses to that change may have marked impacts on agricultural systems and bat ecosystem services

Chapter 8. Insect migrations and the ecology, behavior, and population dynamics of bats

Insectivorous bats consume a huge diversity of prey, with patterns in prey consumption resulting from bat responses to the ecology and availability of insects. Insect migrations involve huge spatial and temporal inputs of energy and nutrients that provide dietary bonanzas for bats. Although insect migrations are often predictable, overlap with major life history features of bats, and significantly influence bat ecology, behavior, and population dynamics, insect migrations have received little notice from bat biologists. Correspondingly, despite the ubiquity, scale, and ecological significance of insect migrations, the migratory behavior of most insects remains poorly understood. Insectivorous bats can provide crucial information on insect movements. Because many migratory insects are agricultural pests, this information is important to crop protection and a better understanding of the ecosystem services of bats. We discuss the needs and opportunities for productive research collaboration between insect migration researchers and bat biologist

Brazilian free-tailed bats (Tadarida brasiliensis) adjust foraging behaviour in response to migratory moths

Insect migrations represent large movements of resources across a landscape, which are attractive to predators capable of detecting and catching them. Brazilian free-tailed bats (Tadarida brasiliensis I. Geoffroy, 1824) consume migratory noctuid moths, which concentrate in favourable winds resulting in aggregations of prey that attract bats hundreds of metres above ground. While T. brasiliensis are known to feed on these aggregations of migratory moths, changes in their foraging behaviours have not been linked to moth migration events. We investigated possible shifts in the batsâ foraging behaviours when moths are migrating with respect to altitude and moth abundance. We recorded 1,104 T. brasiliensisâ echolocation call passes at ground level and at altitudes of ~100m and ~200m above ground level. We found proportionally more bat activity at higher altitudes when migratory moth abundance was high. We also found that bats decreased call frequency and bandwidth and increased call duration at higher altitudes, and behaved similarly with increasing moth abundance even at ground level. Our results support predictions that bats change foraging behaviour in response to seasonal availability of migratory moths, and document alterations in echolocation call parameters that are consistent with optimizing prey detection.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

2010 Data

Contains raw data from the 2010 field season, including bat, moth, and weather data

2012 Data

Contains data from the 2012 field season, including bat, moth, and weather variables

2011 data

Contains data from the 2011 field season, including bat, moth, and weather variables