A Rufous-tailed hummingbird, Amazilia tzacatl, flies while approaching its nest on a tree in San Jose June 1, 2015.

Caribbean flamingos are seen in their enclosure at Antwerp's zoo, Belgium, June 1, 2015.

A butterfly is pictured on a leaf inside the Butterfly Garden at Antwerp's zoo, Belgium, June 1, 2015.

Butterflies are pictured on a leaf inside the Butterfly Garden at Antwerp's zoo, Belgium, June 1, 2015.

A seal swims in an open air aquarium at Antwerp's zoo, Belgium, June 1, 2015.

Visitors watch fishes in the Aquarium area at Antwerp's zoo, Belgium, June 1, 2015.

A Rufous-tailed hummingbird, Amazilia tzacatl, is pictured nesting in a tree in San Jose June 1, 2015.