EPOW - Ecology Picture of the Week

A Southern Oceans Wanderer

Buller's Mollymawk (Thalassarche [prev. Diomedea] bulleri), Family Diomedeidae
Chatham Island, New Zealand

Explanation:  This strikingly patterned seabird is a Buller's mollymawk, seen here grabbing a quick fish snack before taking flight from the waters around Chatham Island, some 800 km (500 mi) east of South Island, New Zealand.  

A Buller's what?  Mollymawk?  This is an albatross!   

Yes, the term mollymawk refers to some southern ocean albatrosses that are smaller in size.  Mollymawks still are not small birds; the Buller's reaches a length of 63 cm (25 inches) from bill tip to tail tip.  Albatrosses also have white backs, whereas mollymawks have dark or black "mantles" (backs and wing tops) and are more strikingly contrasted, as seen with this species.  Buller's mollymawks around Chatham Island constitute a unique population with consistently darker pigmentation than found elsewhere.   

Mollymawks and albatrosses are true sea birds and belong to open-ocean ecosystems, coming to coastlines only to breed, and thus are said to be pelagic.  In comparison, gulls are necessarily coastal or inland dwellers, even though they are often misnamed "sea gulls;" they are not pelagic.  

The Buller's mollymawk may range widely throughout the southern oceans from New Zealand to South America.  However, they breed only in the New Zealand seas along the subtropical convergence zone, which demarcates the start of sub-Antarctic climates to the south.  

Mollymawks were previously included in the same genus Diomedea with the larger albatrosses, but recent mitochondrial DNA studies suggest enough of genetic difference to warrant putting them into their own genus of Thalassarche.