The resurgence of Evening Grosbeak Coccothraustes vespertinus: A 2024-2025 winter revival in Boileau, Québec: A Research Study

The Evening Grosbeak is widely distributed across Canada’s forests but has exhibited significant long-term declines (77-90%) over most of its range since 1970. Project FeederWatch data gathered between 1988 and 2006 indicated a significant survey wide decline in the mean flock size, 27% in 18 years. The number of sites reporting any sighting plunged 50%. Breeding bird survey (BBS) data indicate that the Québec population fell by close to 75% between 1990 and 2014. Data from the Christmas Bird Count, throughout North America, confirm the impressions of long-time birdwatchers that numbers are plummeting dramatically. A 2024-2025 winter research study at the Boileau Biodiversity Reserve-La Ferme de l’Aube site was undertaken to document the population of Evening Grosbeaks. They were observed 100% of survey days with a mean population size of 74.106. From the first winter period observed (2018-2019), the population increased by a dramatic 894%. This resurgence embedded this site as the most important winter residency for Evening Grosbeak, throughout North America in ‘24-’25, and perhaps the most significant anywhere in the last 10 years.