How have introduced cats affected pelecaniform breeding colonies on islands?

The introduction of domestic cats to isolated islands has had a devastating impact on pelecaniform breeding colonies. Because these birds typically nest in areas free of mammalian predators, they often lack the necessary defensive behaviors to protect themselves and their young from such threats, a vulnerability known as ecological naivety.123

When cats are introduced to these environments, the consequences for pelecaniforms—including tropic birds, boobies, and frigate birds—are often severe:

• Extermination: Many populations have been completely eliminated from their traditional, accessible breeding grounds on main islands.1
• Displacement: Surviving birds have been forced to abandon their primary nesting sites, often confining their breeding to small, inaccessible offshore islets where predators cannot reach them.1
• Global Impact: Feral cat populations are recognized as a significant driver of biodiversity loss, having contributed to the extinction of approximately 30 island bird species worldwide.3

Ethically, the protection of these vulnerable species is paramount, as human-introduced predators fundamentally disrupt the natural balance of island ecosystems and threaten the survival of native wildlife.23