The series of ponds at Reserva Las Brisas near La Alegría de Siquirres in Limón Province is a great spot for close observation of the resident Least Grebe (Tachybaptus dominicus), the smallest grebe species in the Americas. In Costa Rica it is the smallest swimming water-bird. It is found from southern Texas to Argentina but Cornell University notes that it is little studied because of its secretive habits.
We found as many as 5 individuals, one of which was this immature bird with its striped cheek, a feature not shown in Garrigues and Dean‘s standard Costa Rican field guide, The Birds of Costa Rica:
A final beautiful image of an adult bird: