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Side-by-Side Comparison

Attribute	Ainley's Storm-petrel	Wedge-rumped Storm-petrel
Scientific Name	Hydrobates cheimomnestes	Hydrobates tethys
Order	Procellariiformes	Procellariiformes
Family	Hydrobatidae	Hydrobatidae
Conservation Status	Vulnerable	Least Concern
Length	—	—
Wingspan	30.1 cm (11.9 in)	26.0 cm (10.2 in)
Weight	41.15 g (1.45 oz)	27.0 g (0.95 oz)
Diet	--	--
Clutch Size	1	1
Population Trend	—	—

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Conservation Status

Vulnerable

Ainley's Storm-petrel

Least Concern

Wedge-rumped Storm-petrel

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About These Birds

Ainley's Storm-petrel

Ainley's Storm-petrel, 19–21 cm, is a recently described species breeding on the Channel Islands off California, present in winter — unusual among storm-petrels which typically breed in summer. Dark overall, white rump with central grey stripe. Vulnerable; small population and restricted range.

Wedge-rumped Storm-petrel

Wedge-rumped Storm-petrel, 19–21 cm, breeds in enormous colonies in the Galápagos and on islands off Peru. The largest white rump patch of any storm-petrel — nearly triangular, extending to the uppertail coverts. Unlike most storm-petrels, daytime activity at colonies. Planktivore in eastern Pacific upwelling.

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