The Blue Petrel is often confused with the different species of prion. And within that group, it get’s even more complicated if you want to come to the proper ID. There are around seven species of prion that can be seen in the Southern Ocean, three of which that can be seen in or around the Drake Passage. I write ‘around seven’, as the taxonomy of this genus is also complicated… In the Drake and around South Georgia and the Falklands, the Slender-billed and Antarctic Prions are common and we regularly see thee Fairy Prion.
Like the Blue Petrel, the prions are greyish-blue with a black line over the wings and back. They are fairly easily separated from the Blue Petrel by their black tip on the tail and different head pattern. The differences between the different species of prion is another story altogether. Many hours are spent in the bar of the ship going over the different prion pictures to identify them. This is often the best way to get a positive ID, but even then experts (which I’m definitely not) don’t always agree. The main differences between the species are found in small differences in head and bill pattern and a different size and shape of the black tip on the tail.
But apart from hard to ID, it’s always really nice to see these birds fly around the ship. Sometimes they can be seen in groups around the ship or even swimming on the water (if the seas are not too rough). Sometimes they blend in with the grey seas, sometimes they stick out more and sometimes they almost fly over the bow of the ship and are they too close to the camera to focus.