Ahead of World Migratory Bird Day this Saturday, conservationists are warning that shifting migratory patterns are offering a clear signal of wider environmental stress across the globe. BirdLife International says declining bird populations and changing migration routes are not just a biodiversity concern, but also an early indicator of pressure on ecosystems that support water, food systems and climate resilience. Africa is central to this story, sitting along the African-Eurasian Flyway, one of the world's major migratory corridors.  Peter Ndoro spoke to Dr Paul Kariuki Ndang'ang'a, BirdLife Africa Regional Director