small shearwater off Buenos Aires- Manx?

[John Chardine]

I will shortly be sailing out of Buenos Aires south to the Falklands. In previous trips we have seen flocks of a small black and white shearwater outside and south of the mouth of the Rio de la Plata. Little and Manx are possible for the area and I've been calling them Manx. The underwing pattern seems to fit Manx. What has surprised me is how many we see- not just one or two but flocks of sometimes 100s.

Should I continue to call these Manx?

[Paul Guris]

Without my resources at hand, I'd call these birds Manx over Little (a group whose taxonomy is being re-visited). The wings and bill both look too long for any for form of "Little" to me. The clean underwings, lacks of white wrapping up onto the rump, and especially the white line curving behind the ear coverts all look perfect for Manx. The white mark isn't always visible, but as far as I know it's pretty much unique to Manx.

[John Chardine]

Thanks Paul. I had a feeling you might know what was going on here!

[john jackson]

Those birds are indeed Manx. This species winters off the Atlantic coast of South America, so your sightings are in line with the known distribution.

[John Chardine]

Thanks for the confirmation John.

[Enrique Patino]

John, If you are leaving from Buenos Aires, you may want to say you are going to Las Islas Malvinas - at least if you try to speak Spanish to local folks!