BirdingNZ.net

Thanks for asking the question, Steve. They are notoriously tricky at this stage so I asked David James about the bird currently being seen at Gt Mercury Island via Facebook and he has now replied to say why he thinks it is a Lesser Frigatebird:

"Lesser Frigatebird, first cycle. 1st and 2nd cycle frigatebirds are a little variable and very difficult. Greats in juvenile plumage can have spurs in 1st cycle, but they are only ever short and originate from the middle sides of an oval white belly patch. This bird definitely does not have an oval belly patch, It is vaguely triangular. The spurs originate near the front of the belly patch. Blocking out the spurs in the attached images shows a belly patch not oval at all (not perfectly triangular). The breast band has started moulting out so the front edge of the belly patch is no longer straight. A black neck ring seems to be developing, which is diagnostic of Lesser."

Here's a few pictures I took of the bird. If a different angle would be helpful for ID then I can try to find a shot.

The bird seems to come in to Huruhi Harbour (home bay) each evening following fishing boats and hoping for some fish scraps to be chucked overboard. If you're hoping to get out looking for it this is probably the best time of day. For us the bird hadn't been visible for the whole day but when we started chucking chunks of bait to the gulls it instantly soared in (appearing to possibly come from the hills).

Even if you miss the frigatebird it's a great spot to go birding. We had an abundance of Red-crowned Kakariki, Bellbird, Tui, and Kereru present in the bay and occasional Reef Heron and Kaka.

Cheers,
Caiden

Thanks Caiden, great shots,

The Frigatebird is still present according to a bloke on facebook who says its flying over his Yacht this morning