Fea's petrel

Fea's petrel (Pterodroma feae) is a small seabird in the gadfly petrel genus, Pterodroma. It was previously considered to be a subspecies of the soft-plumaged petrel (P. mollis), but they are actually not closely related at all. However, P. feae is very closely related to Zino's petrel and Desertas petrel, two other species recently split from P. mollis. The gadfly petrels are named for their speedy weaving flight, as if evading horseflies. The flight action is also reflected in the genus name Pterodroma, from Ancient Greek pteron, "wing" and dromos, " runner". This species is named after the Italian zoologist Leonardo Fea (1852-1903).

This long-winged petrel is 33–36 cm in length with an 86–94 cm wingspan. It has a grey back and wings, with a dark "W" marking across the wings. The undersides of the wings are dark and the belly is white. It has a fast impetuous flight. It picks planktonic food items from the ocean surface. This species is very similar to the Zino's petrel, but is larger and has a thicker black bill.

As all three species in the Pterodroma feae/madeira/desertae complex were once believed to be subspecies of a single species: Pterodroma mollis, the extreme difficulty in telling them apart is easily understood. A summary of data from a morphological study sheds light on the issue:

In overall size feae is closer to deserta and both are bigger than madeira (wing length - f:262, d: 264, m: 248; tarsus - f:34.7, d: 35.2, m: 32.7).

Bill length once again similar in feae and deserta and both larger than madeira (f:29.0, d: 28.6, m: 26.3).

Bill depth by far biggest in deserta, lowest in madeira, and intermediate in feae (f:11.9, d: 12.9, m: 10.5).

In terms of ratios:

(Bill length/wing length) (f:11.1%, d: 10.8%, m: 10.6%) is rather similar in the three taxa.

(Bill length/bill depth) (f: 2.44, d: 2.22, m: 2.53) is lowest in deserta, and highest in madeira. In feae it is intermediate, but more than twice closer to madeira than to deserta.