Leach's Storm-petrel Oceanodroma leucorhoa

Leach's Storm-petrel by Glen Tepke and used with his permission. All photographs on this page remain the property of the photographer.

Northern Hemisphere Breeder
Leach's Storm-petrel like all Ocenodroma is a Northern hemisphere breeder and therefore is busy during our summer. Migrates south during our winter.

In the north Atlantic breeds on offshore islands from Maine, Nova Scotia, and Newfoundland. A few pairs breed on Penikese Island south of Cape Cod. Regularly seen in Cape Cod Bay during the summer.  Take the Plymouth or Barnstable whale watch.  Also in Greenland and  at St. Kilda Scotland.

In the north Pacific breeds on offshore islands from Japan to the Aleutians and Alaska and south to the Baja Peninsula.

Winters
Atlantic birds winter off the coast of Brazil. Occurs in all three oceans: Atlantic, Pacific, and Indian.

Nesting
Leach's lays a single egg in shallow burrows 1 -3 feet in length. Both parents take turns incubating and both feed the chick, coming and going from the burrow only at night. Burrows can be collapsed by humans walking about over them and nests are disturbed by dogs and ferral cats.

Young are fed by both parents by regurgitation.

When To See
Immature non-breeding birds can be seen offshore on the edge of the Continental Shelf and at Cashes Ledge in summer. Late fall, especially October, any Storm-petrel on Stellwagen Bank should be closely examined as it is probably Leach's rather than Wilson's Storm-petrel. Also seen from seawatches on Cape Cod during late fall and early winter. This bird is perhaps easier to see on west coast pelagics.

Hard to observe on the breeding grounds as it enters and leaves burrows at night and human presence disturbs nest by collapsing burrows.
 

Identification Similar plumage to Wilson's Storm-petrel. Leach's is larger and has a slightly forked tail. See the photograph by Steve Mirick to the right. A small vertical dark band dividing the white rump is not visible in any of the photos. Legs do not trail behind the tail when flying. Bill, legs and feet are black. White rump patch does not extend down around the rump.  See pictures below. These characteristics are hard to observe at sea. Appears longer winged, has a slower wing beat, and you do not see the legs trailing behind tail. Notice that the trailing edge of the wing has a definite angle. Wilson's shows a straight trailing edge.

With hundreds of Wilson's Storm-petrels around a boat, Leach's can be picked out because of the slightly larger size, different wing shape, and different flight characteristics. However, one pass near the boat is all you get and it is hard to point out to the novice birder

Behavior
Does not follow in the ship's wake. Occasionally follows trawlers (2) which means it could be attracted by chum. Not as likely to patter feet on the surface of the water as Wilson's Storm-petrel. Feeds by sitting on the water and moving forward using legs.