A surge of migrating owls has kept researchers at the Mugaha Marsh Banding Station in northern B.C. busy as the birds pass through the region in unusually high numbers. Jeannine Randall, a bird biologist at the Mackenzie Nature Observatory, located about 200 kilometres north of Prince George, described the current season as exceptional. Typically, the station catches around 100 owls, but this year they have already captured 266 with two weeks remaining, marking a record-breaking year.
The significant increase in owl numbers caused a shortage of the specific tracking bands required for monitoring the birds, particularly the larger size bands needed for saw-whet owls. Due to the high demand, these bands were on backorder from the bird banding office. While seeking assistance from other organizations, it became evident that the owl population boom was widespread, leading to similar shortages at other stations.
According to Randall, the spike in owl numbers is likely linked to the abundance of small rodents, which serve as the main prey for these birds, especially the newly hatched ones. However, despite the positive numbers at Mackenzie, Rémi Torrenta from Birds Canada pointed out that overall owl populations in the province have been declining over the past 25 years, with some species experiencing stable or increasing numbers while others, like the northern saw-whet owls, are on the decline.
Torrenta explained that the current owl influx is part of a well-documented four-year cycle, where an abundance of owls leads to a subsequent crash in the rodent population. This phenomenon, known as a mass eruption, forces the owls to migrate south in search of food when resources become scarce. To monitor these trends, Birds Canada coordinates the Nocturnal Owl Survey, a citizen science program that relies on volunteers nationwide to track owl populations each spring.
The banding project at the Mackenzie Nature Observatory plays a crucial role in this broader scientific research by providing essential data on owl populations and migration patterns. Randall emphasized the importance of studying these patterns, citing a recent instance where an owl originally banded in Victoria in 2024 was recaptured at the station, offering insights into the species’ travel behaviors and highlighting the significance of ongoing monitoring efforts.