The Lava Heron, also known as the Galapagos Heron, is a species of heron endemic to the Galapagos Islands. The adult is slate-grey, which helps it blend in with the hardened lava. The back feathers typically have a silvery sheen and it has a short crest on its head.

But is this not a Yellow-crowned Night Heron?
The Yellow-Crowned Night Heron is larger than the Lava Heron standing around 2ft (60cm) tall. Could be very similar.