The 20-year study on hybridization between the European herring gull (which follows a short-distance migratory pattern) and the Caspian gull (which has a long-distance pattern) shows that interbreeding not only changes “morphological and behavioral traits” but also affects migration patterns. 

Team leader Grzegorz Neubauer from the Ornithological Station of the Polish Academy of Sciences said: “The findings of our study demonstrate that hybrid large gulls exhibit intermediate migration patterns akin to that observed in other migrating and hybridizing species.” 

The scientists also found that the hybrid gulls have favorable conditions for surviving and thriving despite their new migratory pattern, due to their adaptation to human-related food and an abundance of wintering sites.