Identifying Intermediate Egret Ardea intermedia

In Hong Kong, the two common large-sized yellow-billed egrets are Great and Intermediate Egret, while intermediate is the uncommoner one.

In HBW, the Intermediate Egret is a monotypic species Ardea intermedia, split with Plumed Egret Ardea plumifera in Indonesia, Papua and Australia and Yellow-billed Egret Ardea brachyrhyncha which is an African species.

It is very unlikely to find the other two split in Hong Kong so Great Egret will be the one usually be confused with.

For a typical Intermediate Egret usually shows stouter yellow bill with a dark rip, shorter and thicker neck, and the gape-line does not extend behind eye (while Great Egret does). These are enough to make a definite ID in acceptable range.

Intermediate Egret

Identifying Eurasian Golden Plover Pluvialis apricaria

I don't think I have much time to do proper birding until Dec, meanwhile, whatsapp and HDD birding is my major entertainment.

There are four Pluvialis species in the world and we have at least three in HK (with no documented record of American Golden Plover). For the Eurasian Golden Plover Pluvialis apricaria, which is the largest among the three 'golden plover' so the bulky size is quite distinctive, especially side by side with the other two. Also, the rounder head and shorter legs are also clues for the identification when it is seen in East Asia, together with the Pacific Golden Plover.

Comparing American Golden Plover, American shows much greyish tone in plumage with a longer primary projection (Pacific shows the shortest), and both shows coarsely notched tertials comparing the finely notched tertials of Eurasian Golden Plover.

The key feature should be the color of axillaries, for American and Pacific, the axillaries is grey while Eurasian shows pure white axillaries.

We were lucky to see the first and second record of Eurasian Golden Plover in HK before visiting Europe.

Eurasian Golden Plover - Oct 2018 Hong Kong

Identifying Wood Warbler Phylloscopus sibilatrix

Quite a little bit stressed recently and I don’t even have time to do a full day proper birding. Anyway, I can still do some online birding and hopefully I can start some more writing soon.

Phylloscopus are always my favourite but identification is not always straight forward, so I will study and review whenever I can see a new phyllo.

The first phyllo of my Identifying series is the Wood Warbler, quite a straight forward one and a vagrant in HK. Putting it here mainly because the photo is acceptable to show as many ID features as it can, and it is quite fresh - just taken this spring.

The first impression of Wood Warbler is a longish warbler (like the Arctic Warbler complex) but showing lemon yellow throat, supercilium, and upper breast (in good lighting), the underparts is then silvery white which is also distinctive in certain angle. When look at its back, the fringes on tertials recall Yellow-browed Warbler but the primary projection is much much longer than any other usual Phylloscopus in HK.

Anyway, Wood Warbler is quite unmistakable in acceptable view but of course the best identification feature of Phylloscopus is call/song (or DNA well...). And we are glad we didn’t dip this first official record in HK.

Wood Warbler in Hong Kong, Apr 2019

Identifying Ferruginous Duck Aythya nyroca

Wildfowl watching in HK is usually not as enjoyable as in Japan, but sometimes, rare ducks in HK can still give you good view.

One summer, a male Ferruginous Duck was found and a twitch was made successfully. Identifying a male Ferruginous Duck in HK is not problematic: smart white iris, reddish tone on head, flank, and upper breast and white vent and undertail coverts. It lacks the pale whitish flanks which usually occur on Baer's Pochard, a species which can be confused with when both are in female or immature plumage.

In general, the Ferruginous Duck is extremely similar to Hardhead and Madagascar Pochard, luckily they do not overlap in theory.

Ferruginous Duck in Aug 2014, Hong Kong

Identifying Grey Plover Pluvialis squatarola

July is usually the most boring season in Hong Kong. Though some waders migrants are already on their way back, I'm still busy and too hot for a walk outside.

Grey Plover Pluvialis squatarola, also called Black-bellied Plover (usually talking the new world population), is a widely spread species and the largest among the genus Pluvialis.

In the subfamily Pluvialinae, there are four species while three can be found in HK (Grey and Pacific Golden are the two commons, European Golden is a vagrant, we are waiting for the first American Golden!). Being the largest member, Grey Plover can be easily spotted out in a wader flock but for distant birds in winter plumage, they can be confused especially with Pacific Golden Plover.

For Grey Plover, the bill is much stronger than the other three Golden Plover, and the upperparts are greyish, not showing any golden tone. Hallux is unique in this plover species but always difficult to be seen. In flight or stretching, white wing bars, mainly formed by the white spots on the inner primaries, white rump and the distinctive black axillaries should be enough for the identification.

Grey Plover in April 2013 - together with Marsh Sandpiper and Common Greenshank

Identifying Common Swift Apus apus

There are not many swift or swiftlet species in HK so the identification is simply straight forward. The three commonest species are Pacific Swift, House Swift and Himalayan Swiftlet.

Common Swift should be one of the rarest swift species in HK (even it is called common). Due to its larger size, the only confusing species should be Pacific Swift.

For Common Swift, the identification is easy, just note for a large swift species with overall brownish plumage without white rump. The forehead and throat are pale, and the tail is deeply forked.

The call is also different comparing House and Pacific Swift, like this individual we saw in Jan 2015 in Hong Kong, which I heard its call first.

Common Swift - Jan 2015

Identifying Sanderling Calidris alba

Sanderling Calidris alba, one of our favorite waders, as the name alba suggested, it is a very whitish species - very true for winter plumage when comparing to other Calidris species. It is a very chunky and medium-sized Calidris and the most confusing species should be Red-necked Stint Calidris ruficollis in both winter and summer plumage. However, Sanderling is clearly larger with a thicker bill, blacker carpal (difficult to see in field) and more importantly, lacks a hallux (three toes only) which is unique in Scolopacidae (again, difficult to see in field).

As seen below, one of the two friendly Sanderling which were molting to summer plumage seen in HK in April 2016.

Sanderling

In flight, the wing pattern is more contrasting than other Calidris, which shows a very striking white wingbar (form by white base of remiges and black tips of flight feathers and coverts), as the picture below retrieved from HBW.

upperwing pattern of Sanderling in HBW:

Van Gils, J., Wiersma, P. & Boesman, P. (2019). Sanderling (Calidris alba). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/53923 on 14 February 2019).

The feeding behavior of Sanderling can be distinctive too - wave running:

https://www.youtube.com/watch?v=5aV6piJC4Rc

Identifying Asian Brown Flycatcher Muscicapa dauurica

Our flycatchers here are usually passage migrants, like the newly arrived adult Amur Paradise Flycatcher today in HKWP, a species Wing Tung and I saw in Tai Po Kau in late summer when we visited there together for first time. However, we still have some wintering flycatchers, the Asian Brown Flycatcher Muscicapa dauurica is no doubt the commonest one.

Identifying an Asian Brown Flycatcher from the other two common Muscicapa flycatchers - Dark-sided (or called Siberian if split) Flycatcher Muscicapa sibirica and Grey-streaked Flycatcher Muscicapa griseisticta is usually easy but can be challenging in bad angle or light.

First for Grey-streaked, the underpart is usually very well-defined streaked and it shows the longest wing and so primary projection among the three. For Siberian, the underpart is more diffusely streaked or sometiems spotted, created a dirty look. The primary projection of Siberian Flycatcher is shorter than Grey-streaked but longer than Asian Brown, also showing a small, short bill. More, in fall in HK, we can still see the Siberian shows retained juvenile plumage (very spotted look) while very rare for the other two. For the last one, Asian Brown Flycatcher, always shows dirty underpart only (rarely clear streaking / spotted unless in juvenile plumage) and white lore, giving a rather ‘big eye look’, the base of lower mandible is also very broad and wing is much shorter when compare to the other two.

The following is a first winter Asian Brown Flycatcher, note the clear whitish tips to greater coverts and tertials help telling the age.

a first winter Asian Brown Flycatcher, taken in HK International Airport with Tung

There are other Muscicapa flycatchers in HK, the Brown-breasted Flycatcher Muscicapa muttui, can be easily separated from other by its pinkish legs; and Ferruginous Flycatcher Muscicapa ferruginea, shows a completely different plumage.

Spotted Flycatcher Muscicapa striata is also a possibility, especially a first year vagrant in autumn (like the case as Red-backed Shrike). Spotted Flycatcher looks like a Grey-streaked Flycatcher in appearance but shows much more streaked forehead, less rounded head, shorter wing, weaker eyering and diffusely streaked breast..

Identifying Sakhalin Leaf Warbler Phylloscopus borealoides

We just received the latest Forktail and there is an article talking about the separation of Pale-legged Leaf Warbler Phylloscopus tenellipes and Sakhalin Leaf Warbler Phylloscopus borealoides by call.

These two species are extremely difficult to be identified without song as previously thought, so we didn't tick any Sakhalin Leaf Warbler even Wing Tung and I saw plenty good birds in field (like one during butterflying with very long primary projection or some birds in hand). The long primary projection maybe a clue to tell but still some overlapping, especially genetic analysis often prove long PP birds are in fact Pale-legged Leaf.

Now, the call can be a good (formal, scientific) way to separate these two, which Sakhalin calls at a lower pitch (at or below 5k Hz) while Pale-legged much higher. The difference can be told by human ears but still better to record and generate a sonogram to see the exact pitch, like
 the following two sonogram we recorded in Hong Kong (which two birds were seen well but not a chance to ID if no call!).

Sakhalin Leaf Warbler calls at a lower pitch (at or below 5k Hz)

one note of call of Pale-legged Leaf Warbler, higher than 5k Hz (at around 6k Hz)

To tell from other Phylloscopus, that will be easier. This species complex show much paler leg and dark bill with pale tip and pinkish base of lower mandible. And these two species often forage at lower level of trees and bushes.

Sakhalin Leaf Warbler, identified by call in Hong Kong autumn

The two calls can be listened here:
Sakhalin:
https://macaulaylibrary.org/asset/77337291#_ga=2.17219641.128496227.1533826953-143354930.1529308329

Pale-legged:
https://macaulaylibrary.org/asset/75404771#_ga=2.80635799.128496227.1533826953-143354930.1529308329


Reference:
Chananya, H., Jenjit , K., Sontaya, M., Andrew, J. P. & Philip, D. R. (2017) Distinguishing between Sakhalin Leaf Warbler Phylloscopus borealoides and Pale-Legged Leaf Warbler P. Tenellipes on call. Forktail 33: 77-80.

Identifying Fujian Niltava Niltava davidi

Birds of Muscicapidae are often small, active and male is usually colorful. Identification of adult male flycatcher can be straight forward but not always, like the three blue-and-orange niltava species recorded in HK: Rufous-bellied Niltava Niltava sundara, Large Vivid Niltava Niltava oatesi and Fujian Niltava Niltava davidi.

For these three adult niltava, they have whole blackish bill and bluish flight feather, while first winter birds show pale base of bill and brownish flight feather, sometimes pale tip on wing coverts.

Identifying Large Vivid Niltava from the other two is easy in acceptable view, which the Vivid Niltava lacks glossy blue shoulder and neck patch, and has a more extensive yellowish orange throat forming a "V" shape.

To identify Rufous-bellied and Fujian Niltava, a combination of features is needed. In usual cases, Rufous-bellied Niltava shows much more extensive glossy blue crown and shoulder patch, and have a more extensive orange belly (which its name tells) and vent, and a shorter primary projection. Their songs are also different in theory.

All three species can be recorded in HK. Fujian Niltava mainly breeds in mainland China and is an uncommon passage migrant and winter visitor in HK while the other two are vagrants. Wing Tung and I have seen Fujian Niltava in HK several times and were lucky to take a good identifying shot in 2016 late winter, in an urban park.

Fujian Niltava Niltava davidi

Identifying Japanese Night Heron Gorsachius goisagi

Malayan Night Heron Gorsachius melanolophus is an uncommon passage migrant and rare summer breeder in Hong Kong, while Japanese Night Heron Gorsachius goisagi is a very rare and little known species in HK and over the world. So the Japanese Night Heron is always one of our dream list, no matter in HK or Japan. Wing Tung and I decided to twitch this heron once there is news of tame bird in urban parks in Tokyo, Osaka or Kyoto, but we were very lucky to tick this species in Hong Kong before that, an adult in winter plumage (said by the RC, though I still think it is an immature) came to HK in Dec 2014.

Both adult Malayan and Japanese Night Heron look very similar, but still identifiable by looking at the head. For Japanese, it shows rather dull crown and lacks the long crest which Malayan has. Also, Japanese plumage is duller while Malayan is richer chestnut-brown. Bill for Japanese is a bit shorter but this is difficult to tell. In summer (breeding) plumage is easier, Malayan Night Heron shows beautiful bluish facial skin and eyering.

Japanese Night Heron - one of our most memorable twitch in HK

Identifying Pintail Snipe Gallinago stenura

To us, a fantastic photo means showing as many key ID features as it can. By using one photo to tell the identity of the bird species is our ultimate goal. In this first ID post in our blog is a member of Charadriiformes, and also the most challenging genus - the Pintail Snipe Gallinago stenura.

Pintail Snipe in Hong Kong is a common passage migrant and uncommon winter visitor, is always found mixed with other snipes like Common Snipe and Swinhoe's Snipe. In fall, Pintail (and Swinhoe's) usually arrive earlier than Common Snipe, like in August. Then Common Snipe will become the dominate snipe species after November.

Telling from similar Common Snipe can be straight forward if view is good: Common Snipe shows longer bill, thicker black lore and pale edge of scapulars. Also by the call and when flushed, Common Snipe shows a prominent white trailing edge, cleaner underwing and usually flies to a longer distance before landing.

Telling from Swinhoe's Snipe is a real difficult task. In this case, Pintail Snipe is usually smaller, showing rounder body jizz, shorter tail projection beyond wings and no or very small primary projection. Call may also be a clue to tell the difference.

We still don't have any Latham's Snipe in HK and we haven't seen one yet but this species is very possible to be overlooked, so we will create another post if we see one in future.

Anyway, the safest way to tell a snipe is by looking at its outertail pattern.

From left to right: Latham’s, Pintail, Swinhoe’s Snipe. This picture is taken from the Handbook of Australian, New Zealand and Antarctic Birds.

In Aug 2015, Wing Tung and I were lucky enough to take a flight shot of Pintail Snipe in Long Valley, a photo showing the details of the outertail pattern to confirm its identity. We also saw several Pintail Snipes in fall later, wondering if the time for primary molt is an ID feature or not, which, the Pintail Snipes molt their primaries earlier / during their migration as we saw several Pintail Snipes were undergoing molting in this time of the year but not the case in observed Swinhoe's Snipe.

Pintail Snipe, in Aug 2015