I visited Madeira in early August as part of a family holiday and managed to sneak in two pelagics with the excellent Madeira Windbirds. I must admit its been several years since i've done any pelagics but these two trips brought back all of my old feelings for seabirds and it has definitely been way too long since i've done anything like this.
So our first pelagic focussed on finding Zino's Petrel and we had 2 different individuals and were able to watch them for several minutes on each occasion. It was fascinating to watch them and then go through the photos to see how light, angle, distance, background etc all played their part in changing the overall colour of the bird and also the bill shape. A thinner bill on Zino's than Desertas is one of the diagnostic features. Not being an expert on this, it was a steep learning curve for me. The accompanying photos aren't the best but show how the bill shape varies depending on the view.
In reality, through binoculars it's pretty impossible to gauge accurately. The Zino's Petrel was far more elegant, with longer wings, whilst the Desertas Petrel had a more chunky body, darker 'eye' patch and shorter wings. It really is a bit easier really to focus on the wings, body and jizz....
I really enjoyed the close views of Cory's Shearwater, and a Long-tailed Skua was very interested in our frozen chum block..