Getting to Corcovado requires genuine effort, and that friction is precisely what keeps it extraordinary. The park sits on the Osa Peninsula in south-west Costa Rica, and almost all serious birding happens around Sirena station, reachable only by a long coastal hike from La Leona, a boat transfer from Drake Bay, or a charter flight.
There are no day-tripper crowds here — just dense, humid primary rainforest pressing right to the edge of the trails.
Birding starts the moment there is enough light to see by. The forest around Sirena is thick and layered, so you spend a lot of time listening rather than scanning. Scarlet Macaws fly noisily overhead in pairs most mornings and are genuinely reliable — one of the few places I have felt confident predicting them.
Fiery-billed Aracaris work the fruiting trees along the airstrip clearing, which is also your best open-canopy vantage. Baird's Trogon takes patience; follow antswarm activity and work the understorey slowly. Black-cheeked Ant-Tanager is an Osa endemic and genuinely special, though you will work for it in the darker interior trails.
A licensed guide is mandatory, and this is one destination where that rule earns its keep. Local guides from Drake Bay or Puerto Jiménez know the bird calls and the trails in a way no field guide substitutes for. Accommodation at Sirena station is dorm-style and basic — book months ahead through SINAC, the national park authority. Budget lodges in Drake Bay work well as a base for day entries.
Bring rubber boots without question — the trails flood — and go December through April to avoid the heaviest rains and maximise trail access.