EPOW - Ecology Picture of the Week

Explanation:  Looking like butterflies dancing over some meadow are these Elliot's (or White-Vented) Storm-Petrels in the Galapagos Islands of Ecuador.  

Poorly studied, this is a subspecies found only in the near-shore waters of the Galapagos Islands.  The parent species is associated with the cold Humboldt Current off the west coast of South America.  
  

These storm-petrels feed on plankton and small fish
from the ocean surface, while fluttering and dancing
among the waves and ripples.
  

Elliot's Storm-Petrels indeed have a white rump,
light wing bars, and, most characteristically,
legs that extend beyond the tail while in flight.
  

While most storm-petrels feed far out at sea in the true pelagic zone,
this endemic subspecies of the Galapagos Islands
tends to feed closer to the island shorlines.
  

 They feed in groups, perhaps mutually attracted to available food source.
   

This endemic subspecies of the Galapagos Islands
seems to be year-round resident, although
no nests have ever been found.
  

This group followed our boat for a ways,
hoping to score some offal or food scraps.

In general, the ecology and biology of this commonly-encountered
species are poorly known and need study.
  
IUCN rates the species as "data deficient," which means that
its population status and threats cannot be determined.