Monday, 6 February 2012

Free flying Night Herons at Edinburgh Zoo

A visit to Edinburgh Zoo with work allowed me to catch up with both free-flying Night Herons today. These birds are thought to be around 18 and 25 years of age (see here) and are presumably regular visitors to the Zoo's sealion enclosure. Well, that's where they were today, both sitting sunning themselves in the Scot's pine overhanging the pool. I did not have time to check them thoroughly for rings, but from their beak deformities they should be individually identifiable with ease.

The first pic shows a bird with a crossed bill tip with a slightly protruding lower mandible. I assume it has two colour rings on its left leg.

This second bird has an overbite and may well be ringed on both legs, but I was unable to spend the time required to check. Here are some pictures I found on a photography forum of what appear to be the same two birds taken in March of last year.

These Night Herons are of the North American subspecies hoactli, so here is a shot of a real wild hoactli taken in Monterey Harbour, California in April 2010. Its beak is certainly a little more appropriately shaped... The differences between this race and the European subspecies are subtle, but the shape of the cap and thickness of the white line above the eye differ, as does the colour of the bare parts in the breeding season apparently.

Finally, a shot of one of the new residents...


welchs said...

From what I can see the top bird is the ancient bird red-green left (the green is actually blue, but appears green; formerly also red right) whilst the second is the younger yellow-blue vertically split band bird*. The mention of a transmitter in James' message last week** is a new twist, the zoo had previously commented about an ambition to catch them to check for the original transponders (not all were fitted with them, though the old bird above should definitely have had one) so perhaps they have, though I have heard no news on this. More of a shock to their system may be coming though as the zoo are to lose their sealions I believe...


Morg said...

I would agree with your ID of the two individuals. I could not see any transmitters, but both birds did sport some nice long filoplumes that look like tranmitter aerials. That said, I only managed a very quick look.