Pine Grosbeak (Pinicola enucleator) Exhibit Collective Vocal Behavior During Foraging Bouts

Pine Grosbeaks (Pinicola enucleator) are boreal finches whose winter ecology and social behavior remain only sporadically documented due to their remote distributions and irruptive dispersions. From 18 December 2023 to 6 March 2024, we conducted repeated daily observations of a flock of up to twelve P. enucleator occupying a temporary wintering range in an urban neighborhood in Oregon. During these observations, we documented a previously undescribed collective vocalization associated with feeding. Comparison with 2674 archived Pine Grosbeak recordings from major bioacoustic repositories revealed that no clear matches between our recording and archives could be established. The low amplitude and coordinated nature of these calls may suggest a collective vocal behavior. These observations highlight the value of sustained, close-range field observation in revealing context-dependent behaviors that may otherwise remain undocumented.