Data from: Increased mortality rates caused by highly pathogenic avian influenza virus in a migratory raptor

Highly pathogenic avian influenza virus (HPAIV) has caused extensive
mortalities in wild birds, with a disproportionate impact on raptors since
2021. The population-level impact of HPAIV can be informed by telemetry
studies that track large samples of initially healthy, wild birds. We
leveraged movement data from 71 rough-legged hawks (Buteo lagopus) across
all major North American migratory bird flyways concurrent with the
2022–2023 HPAIV outbreak and identified a total of 29 mortalities, of
which 11 were confirmed, and an additional ~9 were estimated to have been
caused by HPAIV. We estimated a 28% HPAIV cause-specific mortality rate
among rough-legged hawks during a single year concurrent with the HPAIV
outbreak in North America. Additionally, the overall annual mortality rate
during the HPAIV outbreak (47%) was significantly higher than baseline
annual mortality rates (3–17%), suggesting that HPAIV-caused deaths were
additive above baseline mortality levels. HPAIV mortalities were
concentrated within the Central and Atlantic flyways during pre-breeding
migration and peaked in April 2022 when large-scale HPAIV mortalities were
reported in other wild birds throughout North America. HPAIV exposure was
most likely caused by scavenging or preying on infected waterfowl, as
rough-legged hawks are known to opportunistically scavenge during the
nonbreeding season. We utilized movement data to identify a
continental-scale HPAIV cause-specific mortality event in rough-legged
hawks that has the potential to exacerbate ongoing population declines.
Our study highlights the usefulness of monitoring movement data to
pinpoint sources of mortality that can help better understand the drivers
of population change, even if studies are focused on other research
questions.