Nighthawk: acoustic monitoring of nocturnal bird migration in the Americas

Authors: Benjamin M. Van Doren, Andrew Farnsworth, Kate Stone, Dylan M. Osterhaus, Jacob Druckerd, Grant Van Horn

Year: 2023

Publication: bioRxiv

Publication Link:

Keywords: bird migration, bioacoustics, acoustic monitoring, machine learning, machine listening, movement ecology, artificial intelligence

Abstract: 1. Animal migration is one of nature’s most spectacular phenomena, but migratory animals and their
journeys are imperiled across the globe. Migratory birds are among the most well-studied animals
on Earth, yet relatively little is known about in-flight behavior during nocturnal migration. Because
many migrating bird species vocalize during flight, passive acoustic monitoring shows great promise
for facilitating widespread monitoring of bird migration.
2. Here, we present Nighthawk, a deep learning model designed to detect and identify the vocalizations
of nocturnally migrating birds. We trained Nighthawk on the in-flight vocalizations of migratory birds
using a diverse dataset of recordings from across the Americas.
3. Our results demonstrate that Nighthawk performs well as a nocturnal flight call detector and classifier
for dozens of avian taxa, both at the species level and for broader taxonomic groups (e.g., orders and
families). The model accurately quantified nightly nocturnal migration intensity and species phenology
and performed well on data from across North America. Incorporating modest amounts of additional
annotated audio (50-120 h) into model training yielded high performance on target datasets from both
North and South America.
4. By monitoring the vocalizations of actively migrating birds, Nighthawk provides a detailed window
onto nocturnal bird migration that is not presently attainable by other means (e.g., radar or citizen
science). Scientists, managers, and practitioners could use acoustic monitoring with Nighthawk
for a number of applications, including: monitoring migration passage at wind farms; studying
airspace usage during migratory flights; monitoring the changing migrations of species susceptible
to climate change; and revealing previously unknown migration routes and behaviors. Overall, this
work will empower diverse stakeholders to efficiently monitor migrating birds across the Western
Hemisphere and collect data in aid of science and conservation. Nighthawk is freely available at

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