At the start of Sunday's pelagic out of Portland, in the slowly lifting
mist, I saw an adult Gannet (I don't recall seeing any juveniles all day)
fly past at about 50-100 m with a thick black v shape on its outer tail,
with clear central white notch. Definitely black on the outside of the tail
and white in the centre, opposite to the typical Australasian Gannet.
Unfortunately I was the only one on the boat to see this bird, which
inconveniently disappeared into the mist before anyone else was able to get
on to it. And my camera was still in my bag, trying not to get fogged up!
Checking every Gannet I could, particularly on the way back past Lawrence
Rocks, I could not recreate the appearance of the above bird. When they take
off, I noticed Gannets spread their tail and some have a much wider black
centre than is seen in normal flight. But I did not see a pattern that
looked anything like what I had seen earlier, that is black on the outside
and white in the centre.
I understand that Cape Gannets have been seen on Lawrence Rocks and may have
hybridised in the past. I also understand that the amount of black on an
Australasian Gannet's tail can be variable. Could this be a hybrid bird? Or
is the amount of black on an Australasian Gannet's tail sufficiently
variable to cover this case? Or is a Cape Gannet the logical explanation?
Mark Stanley
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