Birding Tan Phu Forest, Vietnam (Part 1)

Tan Phu Forest is about 2 hours North of Ho Chi Minh City, and the location of a few bird blinds set up by a Vietnamese who used to be a park ranger at Cat Tien National Park and probably learned about the economic potential of attracting foreign birders. I guess that it is easier to set up blinds here than in the national park – and many of the star birds are quite similar.

To be fair, this post will not focus on them – there will be a separate post on pittas of Southern Vietnam and another on kingfishers. My way of squeezing more blog posts out of my birding trips.

Here are a few photos from the area. Kind of an innocent version of tropical China, but I guess that is a rather naive view …

Most birders coming here presumably do not have babblers as their main targets, even though there are quite a few species here, and some of them are quite attractive as well.

Take the Scaly-crowned Babbler, with its chestnut crown. eBird seems not to have seen this part of the bird, calling it a “small, dull, brownish babbler”.

The species name of cinereum is not very convincing either – it means ash-colored and thus also ignores the main feature of the bird.

As is often the case, I marvel at the weird German names of species – in this case, “Schuppenstirn-Zweigdrossling“.

Hearing birds in a noisy environment can be difficult – and the noise often does not come from humans but from nature itself, cicadas being particularly obnoxious. While this is an annoyance for birders, it may have much more serious consequences for the birds themselves. Imagine being a single bird and sending out a lonely-hearts message to potential companions, only to stay single forever as your singing is drowned out by the noise of insects. How do birds deal with this issue? A paper looked at this issue for several birds including the Scaly-crowned Babbler. One can tell the paper is very recent (March 2024) as it fashionably claims to have utilized machine learning.

Apparently, the birds do not change their singing depending on the singing of other birds – but if the cicadas completely drown them out, they avoid co-chorusing with them.

Strangely, eBird seems much more sympathetic to the Buff-breasted Babbler, calling it a “rather graceful-looking brown babbler” despite admitting that its “almost completely unmarked appearance distinguishes it from most other babblers in range”.

Regarding the artistic merits of the Buff-breasted Babbler, the HBW sides with me rather than with eBird in describing the species as a “featureless smallish babbler”.

A paper describes the breeding of the babbler – nothing interesting really, “Egg clutch size was in the range 3–4”, “nestlings hatched almost simultaneously”, “eggs were incubated by both the males and the females”, “both parents invested in intensive parental care”. This leads the authors to conclude “This information can be used to help with conservation planning in the area and elsewhere.” And why not.

Abbot’s Babbler is named after William Louis Abbott (1860 – 1936), an American medical doctor, explorer, ornithologist, and field naturalist who had the good fortune of receiving a big inheritance when he was about 26 years old and who then promptly and understandably stopped practicing medicine (source).

His CV includes weird and wonderful entries such as this one for the year 1894: “went to Madagascar to enlist in the native ‘Hova’ army against the second French occupation of the island, until local suspicion of foreigners forced his resignation”.

Again, eBird is not quite convinced of the esthetics of this species, calling it a “plain, sandy-brown babbler”.

Despite not being overly attractive and thus presumably not having particularly attractive chicks, a substantial number of pairs of Abbot’s Babbler are double-brooded (source).

And to avoid all this effort being wasted, they select their nesting sites carefully, choosing locations with a higher percentage of foliage cover and a greater cover and abundance of rattan plants compared to random locations in the same forest (source).

The Puff-throated Babbler looks a bit more distinct and also gets a better eBird review, being described as a “personable” babbler.

One study looked at whether the proximity to a road makes it more likely that a nest gets robbed by the usual suspects (not humans, but rather Northern Pig-tailed Macaque, Green Cat Snake, Crested Goshawk, and Common Green Magpie). This study included a number of nests of the Puff-throated Babbler.

Surprisingly, the chance of a nest being robbed is greater in the forest interior than close to the road, as three of the four predator species listed above (all except the magpie) prefer hunting there. Unfortunately for the writer of this post, for the Puff-throated Babbler, the chance of a nest being robbed is similar close to the road and in the forest interior, so citing this paper in connection with this species is a bit pointless.

The Pin-striped Tit-babbler apparently occasionally uses beetles as part of its preening, a behavior described in a longer article on anting in Malaysian birds that is part of a massive online report with some very nice photos.

The Pin-striped Tit-babbler is also mentioned in a report on the occurrence and role of blue facial skin in South-East Asian birds – it is an exception from the other species listed in that it shows pinkish rather than blue neck skin when calling.

If the Indochinese Green Magpie wants to display color, it can presumably do this using any part of its body.

Similar to PVC garden benches gradually changing their color outdoors, the feathers’ green, yellow, and red colors bleach to dull light blue, whitish, and brown if exposed to prolonged bright sunlight (HBW).

Despite these color variations, the species name hypoleuca (whitish) does not seem to make any sense at all.

The Common Emerald Dove seems to use better colorants – as far as I know, its color does not change if it spends a lot of time on a beach or in the sun.

This is good as staying in cities (where there is more shade) is not really an option for it – in cities, its cooing is inaudible above the traffic noise. This is in contrast to other dove species, particularly the Spotted Dove, which manages to adjust its cooing to reduce the masking effects of traffic noise (source).

The Racket-tailed Treepie is a rather magical-looking bird, though I am afraid my photos do not fully do it justice.

While that presumably makes them popular with birders, they are much less favored by small birds. A paper describes them preying on small birds (warning: graphic photos of a young White-headed Munia being eaten) and robbing nests.

There is not really much scientific information about the Laced Woodpecker, and the scientific species name vittatus (“banded, ribboned”) does not give me much to talk about either.

As with many woodpeckers, the sexes are color-coded, with the red forehead indicating the male.

One ringed individual – no red on the forehead, thus a female – was later seen again in a location at least 1.5 km away over open water, indicating that the species either is a good swimmer or does not mind flying over water over such distances. The same observation also proved a possible life span of this species of at least 14 years.

eBird calls the Black-and-Buff Woodpecker an “adorably tiny and stout woodpecker”, a much nicer and friendlier description than the one in the HBW (“small, short-tailed woodpecker”).

Unfortunately, this woodpecker seems to be even less researched than the previous one. The HBW entry is basically a list of things not known about the bird:

“Poorly known. Research required to determine its feeding ecology and breeding biology.”

“Habits not well known.”

“Breeding Mar–Jun. No other information.”

The White-crested Laughingthrush looks a bit too posh to me – I would probably feel a bit uncomfortable having it around me all the time. It would probably insist on drinking wine instead of beer and frown whenever I order a pizza.

The species is a cooperative breeder – birds other than the parents help feed the chicks.

However, sometimes birds arrive at or near the nest with food and then proceed to eat it themselves rather than feed the chicks. One scientist named this behavior ‘deceptive helping’ and thought it was a form of advertisement that individuals used to enhance their status within the group (source) – a rather cute theory, I think. Unfortunately, it is probably not a correct theory as birds also showed this behavior when no other birds were watching.

Just some photos of a female White-throated Rock Thrush – it migrates through Shanghai, so anything I can say about it I have probably said already.

I was aware that sunbirds and spiderhunters are related (I figured it out from them being close to each other on the pages of bird guides) but I was not really too sure about the details. So, I did what everyone would have done short of reading a book (god forbid!) – I asked ChatGPT. Here is the answer:

Sunbirds and spiderhunters are both part of the Nectariniidae family, but they have distinct differences in terms of their morphology, behavior, and habitat preferences. Here are the key differences:

Morphology:

1. Size and Shape:
   • Sunbirds: Typically small to medium-sized birds with a slender, curved bill adapted for feeding on nectar.
   • Spiderhunters: Generally larger than sunbirds with a longer, more robust, and strongly curved bill, which is adapted for extracting spiders and insects from foliage.
2. Plumage:
   • Sunbirds: Often brightly colored with iridescent feathers, especially in males. Females tend to be more subdued in color.
   • Spiderhunters: Usually have more muted plumage compared to sunbirds, with many species being predominantly green, brown, or yellowish, which helps them blend into their forest habitats.

Behavior:

1. Feeding Habits:
   • Sunbirds: Primarily nectar feeders but also consume insects and spiders, especially when feeding young.
   • Spiderhunters: As their name suggests, they specialize in hunting spiders and other small invertebrates, although they also consume nectar.
2. Foraging Style:
   • Sunbirds: Often seen hovering like hummingbirds to feed on flowers, but they can also perch while feeding.
   • Spiderhunters: More likely to glean insects and spiders from foliage, bark, and flowers. They rarely hover while feeding.

Habitat:

1. Range and Distribution:
   • Sunbirds: Found across Africa, the Middle East, and parts of Southeast Asia, inhabiting a variety of environments including forests, savannas, gardens, and shrublands.
   • Spiderhunters: Primarily found in Southeast Asia, from the Indian subcontinent to the Philippines, with a preference for forested areas, including lowland and montane forests.

Vocalizations:

• Sunbirds: Typically have high-pitched, rapid, and often melodious songs and calls.
• Spiderhunters: Their calls are often harsher and less melodious compared to sunbirds.

Nesting:

• Both sunbirds and spiderhunters build pendant nests, but the specifics can vary between species. Sunbird nests are often more elaborately constructed with finer materials, while spiderhunter nests might be simpler.

Not being as educated as ChatGPT, my own modest contribution to this topic is just to show a few examples of sunbirds and spiderhunters as seen at Tan Phu:

Crimson Sunbird …

… (the species name siparaja apparently is Malay for  army general) …

… Purple-naped Spiderhunter …

… (which eBird calls “dark and mostly drab sunbirdlike”, confirming ChatGPT in the first part and confusing everyone in the second part – one contributor on a bird forum even states that it depends on the list you use: “Of international lists, IOC keeps it as a sunbird while Clements has it as a spiderhunter”) …

… and Little Spiderhunter …

… (a bird that sadly is getting rare in Bangladesh, most likely due to the overuse of pesticides, as described here).

Finally, the Orange-necked Partridge. It was only discovered in 1927, and until 1991, it was unclear whether it still existed (source).

Its range as indicated in the HBW is extremely small – just a few spots in Southern Vietnam and a little bit of Cambodia – and it is listed as Near Threatened.

While nowadays hunting and deforestation are the main threats, in the past, the use of herbicides like Agent Orange and Agent White during the Vietnam War may have reduced its number (source).

History Sidebar: The slogan “Only we can prevent forests” was used by the U.S. Army’s Chemical Corps during the Vietnam War, a reference to their use of defoliants like Agent Orange to remove forest cover and crops used by the Viet Cong and North Vietnamese forces.

Climate change is a particular threat to the Orange-necked Partridge due to its restricted range and reliance on lowland areas, cutting off the escape route to slightly more elevated areas with corresponding lower temperatures. Or to put it scientifically (from a paper examining the effect of climate change on 55 different species of pheasants and relatives): species such as the Orange-necked Partridge “with a limited range will lose suitable habitat for dispersal following habitat shifts due to climatic change”.

There are quite a few candidates for the name “David” which is commemorated in the species name (davidi). However, the HBW states that the right one is Louis Henri André David-Beaulieu (1896-1969), a French colonial administrator in Indochina and naturalist. Unfortunately, I could not find any dirt on him, even though I would be surprised if there is none given his position as a colonial administrator.