From Bulbapedia, the community-driven Pokémon encyclopedia.
Rosebay (Japanese: ユカリ Yukari) is a Pokémornithologist, and a character of the day who appeared in A Staravia is Born!.
She encountered Ash and his friends, who were passing through a forested area en route to Oreburgh City. She invited the group to assist her in keeping track of all of the bird Pokémon. However, after spotting a strangely empty Swablu nest and learning the local Hoothoot were missing, Rosebay recalled a lot of Flying Pokémon had been going missing recently.
Using her binoculars, it was soon discovered that Team Rocket had set up a giant net in a gorge to trap the Flying Pokémon. Ash's Starly helped rescue the Pokémon, evolving into Staravia and defeating Team Rocket in the process. Rosebay thanked Staravia for his help and told Ash and his friends that the Pokémon were safe once more.
In the dub, Rosebay speaks in an English accent.