#wildresearch

Weather affects rates of mass gain in migratory birds during stopover

During migration, birds use stopover sites to replenish their fat reserves, which serve as energy stores. Weather affects food availability and foraging conditions, which in turn affects the rate at which they can refuel.

sing 10 years of data collected from Iona Island Bird Observatory, we found that birds gain mass more quickly with increasing temperatures, but they gain mass more slowly with increasing precipitation. These effects vary between bird species and between seasons: weather effects are stronger in spring than fall and in insectivorous warblers compared to more generalist sparrows.

Our results suggest that with changes in weather due to climate change, insectivores may be more sensitive than birds with more generalist diets like sparrows.

Iona Island is an important stopover site for migratory songbirds

Every Spring and Fall thousands of songbirds pass through Iona Beach Regional Park on their way to or from their northern breeding grounds.

Data from 10 years (2010-2019) of migration monitoring at Iona Island Bird Observatory (IIBO) shows that birds who stay longer at Iona are able to gain more fuel for the next leg of their journey.

Our results show that Iona Island provides important stopover habitat for migratory songbirds. Continued monitoring efforts at IIBO will help us understand how anthropogenic changes to Iona Island affect migratory birds.

The data from IIBO show that long-distance migrants tend to accumulate fat faster at Iona than short-distance migrants.

Birds also gain fat faster in the spring than the fall. Spring migrants are under pressure to arrive at their breeding grounds early and secure better territory