Dancing on the Ocean

     Wilson's storm petrels are interesting little birds that live on the open oceans, including in the northern hemisphere during summer, when they are not nesting.  We here in the United States sometimes see petrels off the coasts of the Atlantic Seaboard. 
     Wilson's storm petrels are abundant and circumpolar around Antarctica in the southern hemisphere during that hemisphere's summertime.  An estimated 100,000,000 individuals breed on Antarctic coastlines during summer in the southern hemisphere, when it is winter in the northern hemisphere.
     This species of petrels is seven inches long and has a sixteen inch wing span.  They are dark brown with white rumps and flanks.  And they have tube noses, which means they have one large nostril on top of the beak.      
     Wilson's storm petrels are the smallest warm-blooded animal that breeds in Antarctica.  Each pair nests in a crevice in a rock cliff in great nesting colonies of these birds, near the ocean, on the Antarctica continent.  Each female petrel lays one egg per year.  Petrels must live several years to raise enough young per pair to make up for losses and to exist in the millions.  And they have few predators on those rocky cliffs above the ocean.  Unfortunately, however, drifts of snow could cover the petrel's nurseries, killing the young inside.   
     During their breeding season, petrels shuttle between the ocean to catch small fish, shrimp and other tiny creatures from the water's surface and their burrows to feed those critters to their young under the cover of night to avoid the predation of gulls and skuas.  Each bird finds its burrow and youngster by a good sense of smell.  Probably day-traveling petrels were caught and eaten by those large, daytime, predatory birds, which meant their chicks also died, without descendants.  But those petrels that had been active at night, raised chicks to maturity, which reproduced.  Now all petrels are active only at night during the breeding season, because they are descendants of night-flying ancestors.  
     After the breeding season, and during the summer in the northern hemisphere, millions of Wilson's storm petrels drift north into the North Atlantic Ocean to feed on plankton, tiny fish and detritus on the surface, up to New England on the American side and Europe on the other side of the ocean.  Many of them can be spotted from shore at times.
     When feeding from the surface of the oceans, these petrels are in great flocks "dancing on the water".  Each individual flutters and hovers low over the water, with its long legs dangling to it.  Its wings are held aloft or are flapping into the wind or breeze to maintain lift and position just above the water while its pattering feet on the surface tension maintains the bird's stability over the water.  All these little birds, together, feeding just over the ocean water, look like dainty dancers.
     We see Wilson's storm petrels here in the Northern hemisphere only during summer, and then mostly over the oceans.  But their unique way of getting food is interesting to watch from a boat or shore while they are here between breeding seasons.