In years when winter conditions are especially harsh, birds that depend on conifer seeds for food are sometimes forced to leave their homes in northern forests and wander far from their normal ranges to find enough to eat. A new study published in The Auk: Ornithological Advances uses citizen science data to show for the first time that these winter movements—called “irruptions”—lead to a decline in birds’ population density in their breeding range the following summer, suggesting that irrupting birds succumb to the difficulties of avoiding predators and finding food in unfamiliar landscapes.