BULWER’S PETREL Bulweria bulwerii

BULWER’S PETREL Bulweria bulwerii 

L 26–28 cm, WS 68–73 cm. 

IDENTIFICATION 

Smallest true petrel of region, but substantially larger, longer-winged and longertailed than Swinhoe’s Storm-petrel, which it superficially recalls. Flight action buoyant and erratic, with wings held slightly forward and bowed; a series of rapid wingbeats followed by a short twisting glide. Generally keeps close to water. When
feeding, circles or zigzags low over surface. Only occasionally fans tail to reveal wedge shape; tail normally looks long and tapering (sometimes held slightly raised). Usually solitary at sea. Does not normally follow ships. Most likely to be confused with vagrant Jouanin’s (q.v.). 

Distinguished fromdark shearwaters and Swinhoe’s Storm-petrel by even longer-winged appearance, long, pointed tail, flight action (see above), bill shape (much shorter than in shearwaters, thicker than in Swinhoe’s
Storm-petrel) and size (much smaller than dark shearwaters, substantially larger than Swinhoe’s Storm-petrel). Bill usually pointed well downwards in flight. Paler brown diagonal band across upperwing coverts is visible only at close range. 

VOICE 

At breeding colonies gives a low barking ‘chuff’, repeated at varying speed and pitch, recalling steam engine.

STATUS/HABITAT 

Uncommon. (Map note: in summer marine range extends north of Azores and east to waters off Portugal. Found all year around Cape Verde Is but mostly disperses into tropical Atlantic for winter.) Breeds in holes and crevices on rocky slopes near shore. Pelagic away from breeding colonies.