From Fish Owl to Gulls

 I visited Cheung Chau the other night and successfully found the Brown Fish Owl at its 'usual' spot along the promenade. As always, it was such a thrill to see this species in the wild, I can never get bored of them. Brown Fish Owl is a widespread species in Hong Kong, you can find them near many streams, as well as water catchments and reservoirs, or in this case the waterfront.

Brown Fish Owl

Many birds in Tai Po Kau are now showing signs of breeding, such as Grey-chinned Minivets which are now getting paired up instead of moving in large flocks. The usually quiet Plain Flowerpeckers are now very vocal and many can be heard throughout the trails.

Grey-chinned Minivet - male

Plain Flowerpecker

I heard the melodious songs of a White-rumped Shama, a species I seldom see at Tai Po Kau. It was behaving in the most classic 'Shama-like' manner, singing loudly in a gully inside the dense forest, it later showed itself briefly. Previously recognised as released or escapes, the number of Shamas reported in Hong Kong the last few years suggests they have now established a small breeding population.

White-rumped Shama

Speckled Piculets can be heard drumming, this one was pecking away near the top of a bare tree, which made it very visible. Another very vocal species at the moment is the Chinese Barbets, where this was a very rare species just a few years back, at least two were calling constantly at Tai Po Kau with several other reported at various sites such as Kadorie Farm, Shing Mun and Tai Lam, the pair at Tai Po Kau seems to be making a nest on a dead tree stump, a good sign that this species is slowly spreading.

Speckled Piculet

Chinese Barbet

A Ring-billed Gull was reported on Saturday at Mai Po, which will be the first ever record for Hong Kong as well as China, unfortunately I had work in the afternoon that day and missed the bird. I tried my luck the next day and ventured out to Deep Bay. The mudflat wasn't particularly interesting, the only notable wader being a Far Eastern Curlew. Many Black-faced Spoonbills now in their breeding plumage, making them even more attractive to look at. Caspian Terns are now in decent numbers.

Far Eastern Curlew

Black-faced Spoonbill

Caspian Tern

Despite not being able to relocate the Ring-billed Gull, there were plenty of other gulls to look at. Large Larus species have always been troublesome group of birds for birders worldwide, the inconsistencies of information of these gulls in Asia have made learning how to differentiate them even more challenging, as taxonomy is being updated every few years. The constant hybridisation of the three (or two) species that occurs in Hong Kong and the physical differences at various age makes identification even more difficult. None the less, gulls are fascinating and well worth spending some time to look into. I can't dare say I am a good 'gull-er', but it is important for birders to keep in mind that gull identification is a constant learning process.

Currently, IOC list that two members of the 'Herring-type' Larus that occurs in Hong Kong are the Vega Gull and Lesser Black-backed Gull. Of which, two subspecies of Vega Gulls are known to occur in Hong Kong, namely vegae vegae and vegae mongolicus. Of these two mongolicus is by far the more common one. Here is a brief update on the large gulls that occurs in Hong Kong.

Vega Gull (mongolicus)

Here is a good example of an adult Vega Gull mongolicus early in the year and in spring, with completely white head, pinkish legs and lighter grey backs. It is important to note that mongolicus moult earlier than the rest due to their breeding grounds being further south. 

Vega Gull (mongolicus) - adult

This below is likely a sub-adult bird showing most of the same features as adult, except for some feathers still retaining on lesser coverts, as well as fine spots on the back of the neck.

Vega Gull (mongolicus) - sub-adult

Likely a 3rd year bird, with very worned out tertiaries, greater and lesser coverts, with 'saddle' developing. Overall structure is that expected of mongolicus, shorter winged than heuglini.

Vega Gull (mongolicus) - 3rd year

Here are a 2nd year bird that shows traits of Vega vegae such as well marked head and neck, although not quite as extensively as one might expect, it is also not quite as blotchy as expected on the flanks or underside. Structurally this feels shorter winged than that of heuglini, so I am leaning towards this being either a vegae or mongolicus, but can't confidently identify these to species level.

2nd  year vegae / mongolicus?

Vega Gull (vegae)

This is the least common of the three 'common' species of large gulls in Hong Kong, adults seen in Hong Kong are usually easily picked up by heavily marked head and breast, as well as pink legs. This is an old photo from Feb 2016.

Vega Gull (vegae) - adult

The individual on the left here I would consider a good candidate as a 3rd year vegae, compared with the heuglini on the right, it looks much chunkier, where as heuglini looks slimmer and more slender. The heavily mottled neck, breast as well as underside is also a good indication for this being a likely vegae.

3rd year vegae (left) and 2nd year heuglini (right)

A very dark looking individual probably a 2nd year vegae, first of all it is very heavily blotched and well marked from head to underside, this is very unlikely to be heuglini or mongolicus. Also note the almost unicolour greater coverts and very thinly patterned scapulars and coverts, giving it an impression of 'light back'. 

Probably two mongolicus (left) and 2nd year vegae (right)

2nd year vegae

Lesser Black-backed Gull (heuglini)

By far our most numerous large gull, local birders usually just refer these as Heuglin's Gulls. adults are easily separable with Vega due to its very dark back, structurally they look more slender and longer winged, leg colour is also a good method to separate them as adult heuglini always have yellow legs. while 2nd and 3rd year birds show similar structure with adults, with darker scapulars and coverts than Vega in general, with a more distinct 'white collar' around the head.

Adult heuglini (left) and 2nd year heuglini (right)

These are the general rule of thumb for 'herring-type' large gulls in Hong Kong at the moment, there are of course a lot of variations and hybridisation are known to exist more often than we would like, therefore it is important to keep in mind that identifying these gulls are sometimes like looking at a spectrum, where you may get traits of both species in one bird, sometimes on more than the other.