The Guam Kingfisher, known as 'sihek', is extinct in the wild due to invasive brown tree snakes. These birds played vital roles in the island's ecosystem, controlling insect populations. Their disappearance has led to increased spider numbers and thinner forests on Guam.
Conservation centers now house the remaining 140 birds, aiming for eventual reintroduction. Efforts focus on breeding pairs to save this species from complete extinction.
Summary from source