Sunday, March 15, 2009

Portrait - Great Gray Owl

Manitoba is a cold cold place in winter but the opportunity to observe wondrous creatures such as the magnificent Great Gray Owl can dissolve the -40° temperatures, as least in my mind. In winter Great Grays love open habitats like the tamarack bog in this habitat photo.

They also come out to farmland and open country at the edge of the boreal forest, where they are often easier to see.

I usually see Great Grays in winter while driving, but this one I surprised as I walked around the corner of a trail in Birds Hill Provincial Park. This bird was not happy to see me so I took this photo quickly and then backed off. You can tell this owl is upset by the stiffened rictal bristles, which leave the nostrils visible.

The second photo is a crop so you can see this better. In this photo you can also see some of the other features that make Great Grays such excellent hunters. The whole face is shaped like a satellite disk (designed to pick up sound waves rather than radio waves) which channels sound into the asymmetrical ears. The stiffened feathers of the facial disk also aid in this. The “ridge” in the center of the face allows the two ears to perceive sound reasonably independently to increase the accuracy of pinpointing the source of a sound.

Great Grays can often hunt from a perch but their preferred prey is the meadow vole and these are often under the snow in open fields. So Great Grays will fly up,

then hover over a promising sound to get a better fix (this is when their adaptations for silent flight are particularly useful, i.e. the comb-like “teeth” on the leading edge of the outer primaries and the soft plumage),

then they plunge into the snow to grab the unsuspecting vole moving in their tunnels beneath the snow.

They squeeze the vole in their talons and wait until the vole is dead before transferring their prey to the bill (otherwise they risk getting bitten in the face)

And carry their meal away…

Occasionally voles will venture above the surface in winter and then the owls have easy pickings, swooping in

Throwing their feet in front of them (it helps that they have such long legs) and grab their prey

You can see how long the legs are as this bird flies away with their prize (the long legs also help when catching voles in deep snow)

These photos show the owl flying away with the vole (luckily in my direction)

I love to watch Great Grays push off – they fly so gracefully - so here are a few more images.

Great Grays are much tougher to spot in the summer but if you spend enough time sloshing through tamarack bogs you sometimes find them

These youngsters are still covered in down but they are getting ready to fledge

When just fledged, they look somewhat peculiar

With the wing feathers developing first, the underparts appear more downy than the upperparts

You can also see the development of the facial disk

This youngster has just been fed, you see a little drop of blood on the bill. Pretty soon this youngster will start to look like an adult – they grow up very quickly!

Sunday, March 8, 2009

China - babblers and allies

This post is about 4 different groups of related passerines, all of which form a significant part of China’s avifauna and all of which are predominantly Asian in their distribution, viz. the babblers, laughingthrushes, parrotbills, and Old World warblers. If you are a subscriber to Sibley and Monroe taxonomy, all of these groups fall within the one large family “Sylviidae”. In other taxonomies they are variously treated as separate families or only some of them are combined, e.g. Howard and Moore treat the first three of these groups as one family Timaliidae, but the Old World Warbler as a separate family Sylviidae. The latest International Ornithological Congress list (version 2.0) is similar to Howard and Moore except that the Old World Warblers are divided into several families including Leaf Warblers Phylloscopidae, Reed Warbler Acrocephalidae and grassbirds Megaluridae. Clements treats them all as separate families except that laughingthrushes are included within the babblers. By the way, if you’re wondering, laughingthrushes are not thrushes at all but rather large (roughly thrush-sized) babblers often with garrulous laughing calls. There is remarkable diversity within these families in Asia, from “little brown jobs” skulking in the undergrowth to little green jobs flitting in the canopy to some of the most vibrantly coloured birds in the forest (that’s why this post is so long). In some cases, the number of very similar congenitors at one site can be so staggering as to challenge anyone’s identification skills, whereas others are immediately recognizable. If you find a mixed species feeding flock, chances are that some of these birds will be present and, if you are going to spend any time in China, these birds will be a major part of your birding experience.

We begin with the LBJs (little brown jobs), the Bush Warblers. The bush warblers are generally brown in colour, usually with very little pattern other than a supercilium. Most are very skulking and hard to see well and identify – it helps a lot when they sing! Presumably they are called bush warblers because they usually skulk in low shrubbery. The rather unimaginatively named Brownish-flanked Bush Warbler is seen here hopping about in bamboo after a rainstorm.

This Yellowish-bellied Bush Warbler was very obliging, raising their wings to show off their belly colour. It seems a lot of these bush warblers have “ish” names such as brownish or yellowish, an indication of their subtle colours.

The Spotted Bush Warbler (or Southern Spotted Bush Warbler if you are a splitter) has a rather distinctive giss, despite having a very similar overall colour pattern to most other bush warblers. This one is carrying a mouthful of food to feed to their young.

Next we move from the ground to the trees. The leaf warblers are so named because their soft green or greenish-grey colours blend with the foliage. Many of these live in the subcanopy, unlike their cousins the bush warblers down below. In my opinion, this group includes some of the most difficult species to identify by sight in the world (again much easier when they sing). The genus Phylloscopus is particularly challenging. The Tickell's Leaf Warbler is one of the most distinctive Phylloscopus warblers with their strong yellow and olive tones.

Most Phylloscopus warblers have greenish upperparts, whitish underparts and a combination of whitish or yellowish supercilia and wing bars. Here’s a small sample of 4 similar species: Greenish Warbler, Large-billed Leaf Warbler, Blyth’s Leaf Warbler and Eastern Crowned Warbler (clockwise from top left). If you can identify these without hearing them sing you’re doing very well.

It used to be easy to identify the Golden-spectacled Warbler, that is until the species was split into 6 different species. This one is a Bianchi’s Warbler but again, separating these species by voice is much easier than by sight. In some places in China such as Emeishan, several species from the Golden-spectacled Warbler complex coexist on one mountain, although they are separated altitudinally. Altitudinal separation presumably was the trigger for speciation in this complex and reproductive isolation is presumably maintained by song differences.

Some other genera of arboreal Old World warbler are more distinctly patterned, e.g. the three species of Abroscopus warblers. This is the beautiful Black-faced Warbler photographed at Gaoligongshan in Yunnan Province. This photo appears in the Handbook of Birds of the World (HBW).

Next we move to the laughingthrushes, the largest and noisiest of this group. The largest genus in this group is called Garrulax for a reason – they travel in flocks and communicate noisily. They vary from rather plainly-coloured species like this Black-faced Laughingthrush.

to “plain-with-a-splash-of-colour” species like the Elliot’s Laughingthrush (very common in China), seen here singing in the rain and opening the wing wide enough to see the lovely pattern.

to more complicated cryptic plumages like this beautiful Spotted Laughingthrush

to knock-out bold patterns like this Red-tailed Laughingthrush

and their closely related sister species, the Red-winged Laughingthrush. Despite their colours, it is hard to see these skulkers well (I tried hard to get this shot as these birds interacted in dense secondary growth)

We move away from the laughingthrushes into the wondrous variety of other babbler genera. . The handsome Spot-breasted Scimitar Babbler is one of the fascinating scimitar babbler group characterized by long decurved bills that give them their name. They are fairly large babblers clad in cryptic brown, rufous, black and white.

Babax is a genus of 4 East Asian species. This is the Chinese Babax. The babax are another of the babbler groups that are smartly patterned in cryptic colours – very classy in my opinion!

Arguably one of the most colourful babbler genera is Leiothrix, which contains only two species of smallish red and yellow babblers. This is the Red-billed Leiothrix. This species is persecuted for their beautiful song and kept in tiny bamboo cages and teased into singing for their captors. In the cage-bird industry they are known as Peking Robins or Peking Nightingales, although they are not related to robins or nightingales (they’re babblers, although their song is much more beautiful than babbling!). Demand for this species as cage birds has caused notable declines in their population in China.

The other Leiothrix is the Silver-eared Mesia. Though I saw this species in Yunnan, I’m cheating a bit here and including a photo I took in Malaysia, just because I love the way the dark background highlights the overall yellow plumage.

Another colourful genus of babbler is Minla, which contains three species. The Chestnut-tailed Minla is very similar in plumage pattern to the Red-billed Leiothrix, an example of convergence.

Another uniquely Asian genus of babbler is Alcippe, known by the common name of fulvettas. There are 23 species and most are dark brown or grey in colour. The stunning Golden-breasted Fulvetta is probably the brightest of the lot. This one has a pattern that is strikingly similar to Silver-eared Mesia… convergence again? You may have noticed already that quite a few laughingthrushes and babblers have a splash of colour in their wing.

Yuhina is another interesting Asian babbler genus, with 11 species characterized by perky crests. The handsome White-collared Yuhina is one of my favourites.

The last group I will deal with in this post are the peculiar parrotbills – the “paradox birds” (Paradoxornis). Parrotbills are small, mostly brown and grey birds, that are primarily bamboo specialists, although some have adapted to other habitats. The shape of their parrot-like bills is an adaptation to feeding on bamboo. There are 21 species of parrotbills, and they are a uniquely Asian group, unless that is you consider the Bearded Reedling (Bearded Tit) a parrotbill as some taxonomists have done. The Maui Parrotbill (Pseudonestor xanthophrys) is not in fact a parrotbill but rather a Hawaiian Honeycreeper. The distribution of the parrotbills is centered around the Himalayas and the central Chinese mountains, where numerous species of bamboo are found. We begin with two images of the endemic and globally vulnerable Grey-hooded Parrotbill (found on just a few mountains in Sichuan Province). The first shows the structure well and the second shows them in their preferred bamboo habit (another shot published in HBW).

The Brown-winged Parrotbill is one of the smallest parrotbills and they are listed as “near-threatened” by Birdlife International.

The Ashy-throated Parrotbill is yet another small bamboo specialist.

This Fulvous Parrotbill shows how these birds move through the bamboo clinging to the vertical stems with ease.

The beautiful Black-throated Parrotbill has one of the most striking facial patterns of any of the parrotbills.

The Great Parrotbill is a peculiar bird, much larger than most other parrotbills and with a somewhat different bill structure. This species is placed in the monotypic genus Conostoma, in most taxonomies the only parrotbill not in the genus Paradoxornis.

However, to me the ultimate “paradox bird” is a species I saw in Sichuan but never managed a photo of – the Three-toed Parrotbill, with the wonderful name of Paradoxornis paradoxus. This name is particularly applicable since this species is the only passerine in the world with just three toes, the outer toe being tiny and clawless (vestigial) and fused to the middle toe. I’d love to understand this seemingly bizarre adaptation to clinging to bamboo stems, so get in touch if you have any bright ideas!

More photos from China at:
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