On Maui, Haleakala National Park is has many of the island's top trails for wildlife watching. To spot a rainbow variety of bird life, start with the short loop around Hosmer Grove or sign up for a longer guided hike into Haleakala's wet, wild Waikamoi Cloud Forest, managed by the Nature Conservancy. Day hikes and overnight treks around the park's volcanic summit will bring you almost nose-to-beak with nēnē, the endangered Hawaiian goose.
Back along the central Maui coast, Kealia Pond National Wildlife Refuge has built a boardwalk that lets you spy on not just rare native and migratory Pacific birds, but also sea turtles basking down below on golden sands. In West Maui, the Kapalua Resort's hiking trails are open to the public. Explore the shady Maunalei Arboretum of native and exotic trees, then trace the windblown, rocky coastline of Kapalua Bay, where humpback whales swim and give birth in the warm offshore waters in winter.
You can find out more about all of these hikes in my book Top Trails Maui: Must-Do Hikes for Everyone, available in paperback from Wilderness Press and also as an Amazon Kindle ebook.
Slow Down, Save an Endangered Nene on Maui
Hidden Hiking Trails in West Maui
Risks and Rewards in the Big Island's Volcanoes and Valleys
Photo credits: Kihei & West Maui Mountains (Sara J. Benson & Michael Connolly Jr.)