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Activity patterns of Hawaiian forest birds in a fragmented and continuous landscape

February 2, 2022

Activity patterns are a key component of avian life history and behavior, and decisions about how activity periods are structured can have important fitness implications. Despite the importance of activity patterns, individual variability in activity is poorly studied in small birds. We used automated radio telemetry to track Hawaiian forest birds from three dietary guilds in a continuous forest, and in a similar forest that was naturally fragmented in the 1800s by lava flows but supports stable populations of native birds. We generated kernel density profiles of activity (KDEs) over the full tracking period of each bird and used the KDEs to derive seven activity metrics that characterized daily activity patterns. We identified three distinct activity strategies using a cluster analysis of the activity metrics and assessed day-to-day variability in activity strategy to understand intraindividual consistency in activity behavior. We also evaluated the influence of landscape structure, dietary guild and sex on the suite of activity metrics using constrained ordination. Most birds (61%) exhibited high levels of sustained activity throughout the day, while 23% showed irregular activity most of the day followed by a peak in the late afternoon, and 16% were mainly active in the morning. Though activity patterns varied by sex and dietary guild, landscape structure had the strongest influence on activity patterns. Birds sustained high levels of activity throughout the day in the fragmented landscape regardless of dietary guild, suggesting they needed to be more active to obtain necessary resources. However, activity patterns of birds in the fragmented landscape varied more day-to-day, indicating they retained a method for adjusting behavior to match internal and external conditions. This study reveals how a diverse suite of tropical birds has adapted to long-term fragmentation in Hawaiʻi and demonstrates the utility of automated radio telemetry for studying the activity strategies of birds.

Citation Information

Publication Year 2022
Title Activity patterns of Hawaiian forest birds in a fragmented and continuous landscape
DOI 10.1111/jav.02905
Authors Jennifer R Smetzer, Kristina L. Paxton, Patrick J. Hart, Eben H. Paxton
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Avian Biology
Index ID 70234356
Record Source USGS Publications Warehouse
USGS Organization Pacific Island Ecosystems Research Center