By Raghav Narayanswamy and Keita Sin

Another week, another rare bird at Chek Jawa! The Stripe-throated Bulbul Pycnonotus finlaysoni is another bird previously recorded in Singapore, just in April last year in fact. The details were first published online two months ago and last month the Records Committee came to the conclusion that this bird, recorded at Upper Seletar Reservoir, was more likely an escapee than a wild bird. With the recent sighting at Chek Jawa, some key discussion points have changed, so we reconsidered the previous record again alongside our review of the Chek Jawa bird. 

After extensive deliberation our committee reached split decisions on both records, and with no majority of votes in favor of treating either bird as being wild, the species has been placed in Category D. Category D species are not in the Singapore Bird Checklist; they would otherwise appear in Category A, but there is reasonable doubt that the records are of truly wild birds. (The exact vote counts for the Chek Jawa bird were 4 wild, 4 escapee; and for the Upper Seletar bird, 3 wild, 5 escapee.)

There are a considerable number of points to consider in favor of both sides, and we will summarize them below. Ultimately, there are no clear answers, but we aim to use the evidence available to weigh the likelihoods of each scenario. The fact that several committee members did not vote in the same way is a feature of our robust process, and signifies the difficulty in assessing these records. The end result or categorization of a species is also by no means set in stone; rather it is open to change as and when new information becomes available. 

Feather condition

There are no indications that the feather condition is poor or unnatural. However, bulbuls are small birds, kept extensively in captivity – it is not hard to find a bulbul in a pet shop with normal feathers. 

Status in the pet trade

The Stripe-throated Bulbul is a songbird kept extensively in captivity across Southeast Asia (Chng & Eaton, 2016; Limparungpatthanakij, 2022). It is often kept for cross-breeding with Red-whiskered Bulbuls, and records from Bangkok, which is in the middle of the species’s range, are treated as escapees due to their high prevalence in the pet trade. The increasing scarcity of Red-whiskered Bulbuls in the wild due to trapping is also likely contributing to higher trapping pressure on other bulbuls with pleasant songs, including Stripe-throated – leading to more possible sources of escapee Stripe-throated Bulbuls across the region (Limparungpatthanakij, 2022). YouTube searches for this species’s Thai and Malay names reveal hundreds of hits, several ostensibly advertising their video as a means to trap wild Stripe-throated Bulbuls. Several others feature birds in cages, many of which appear to have normal feather condition. While we did mention previously that you can “find and buy nearly anything in a cage these days”, the volume of trade in this species is likely to be extremely high in comparison to the birds we’ve been getting so far (SBP, 2023). What’s important here is that more than simply being ‘present’ in the regional pet trade – which by itself does not really indicate anything – it is quite a popular species as well. Its high presence in captivity elsewhere in the region may indicate popularity locally as well; the regional pet trade is closely intertwined. Anonymous sources have also informed us that this species is locally traded.

Habitat/Location

Chek Jawa is a prime location for visitors to turn up, and the location is an argument against the escapee hypothesis. But we do have surprisingly many records of introduced bulbuls on Pulau Ubin, including Black-crested and Red-whiskered. Either these birds are adept at dispersing from our main island, or they have been kept on Ubin at some point, or there is some kind of hidden influx of wild Black-crested and Red-whiskered Bulbuls from further north. The last possibility is near impossible to verify and best treated as unlikely given these species are also highly traded in captivity, and the first two would unfortunately throw this bird’s origins into question too. 

Having said that, the location is still a point in favor of the case that the bird is wild.

Status in southern Peninsular Malaysia

eBird range map for Stripe-throated Bulbul. Here is a link to the map if it does not load immediately. This simplified map does not do a good job of illustrating how rare this species in Johor (zoom in to view the the full eBird map with hotspot pins for a clearer impression). 

Many of the species which have recently been added to our checklist, or recorded as visitors (see Table 1 below) are indeed quite scarce in Johor. Examples include the Scarlet-breasted Flowerpecker, Black-and-white Bulbul, and White-crowned Hornbill. However, the Stripe-throated Bulbul is markedly rarer than all of them in Johor, even though it is known to tolerate more degraded habitats than those species. All time eBird records for Panti show well over 100 records of Black-and-white Bulbul and Scarlet-breasted Flowerpecker and at least 10 of White-crowned Hornbill, yet only 5 of Stripe-throated Bulbul. Similar results have been observed from Gunung Bekok and Gunung Belumut in Johor. Surveys there found this species to be the second-least frequently encountered bulbul among the 15 species recorded, second only to Scaly-breasted Bulbul which has no confirmed records in Singapore (Peh et al., 2005).

Meanwhile, the Stripe-throated Bulbul is actually quite common in all sorts of habitat from Malacca northwards, so the very abrupt drop in abundance in the south suggests its dispersal outside its core range is infrequent.  This is also in contrast to the other species listed above, which are scarce to rare throughout their range. It would be more straightforward to construct a case for the species’s dispersal if it was more common, or becoming more common, in Johor, where vast areas of suitable habitat are available. At the same time, the deforestation explanation, which we believe is pushing several of these species out of Johor’s forests, does not apply as well here; the species is simply very tolerant of low-quality forest habitats, to the point that it appears to be benefiting from forest degradation across its range (Nor Hashim, 2013; Wells, 2007).

We did note, however, a recent sighting from Gunung Pulai Recreational Forest in Johor, which may indicate the early signs of a southward influx of this species. The good news is that we will probably have good indications that such an influx is occurring, with more observers at birding sites in Johor such as Panti and Lenggor. Our RC decisions are never cast in stone and constantly move with evolving evidence; please post your records on eBird or let us know if you see this species in Johor!

Species	Status in Singapore (a)	Status in Peninsular Malaysia (b, c, d)	Status in pet trade	Records
Brown Fish Owl	Absent historically	Absent in Johor, restricted to N Malaysia	Unclear; owls are traded	Hindhede (1), Hindhede (2) (both Escapee)
White-crowned Hornbill	Recorded in 1987, presumed escapee	Rare in primary forest, Johor	Unclear; hornbills are traded	Chek Jawa (Accepted)
Great Slaty Woodpecker	Visitor, possible past resident	Scarce in forest	Probably very infrequent	Singapore Botanic Gardens (Accepted)
Black-thighed Falconet	Former resident	Scarce in forest and forest edge	Probably infrequent	Lorong Halus (Accepted)
Black-and-red Broadbill	Former resident	Common in forest edge, degraded habitat, mangrove	Probably very infrequent	Chek Jawa (1), Sungei Buloh, Sensory Trail, Chek Jawa (2) (all Accepted)
Large Woodshrike	Former resident	Common in forest	Probably very infrequent	Chek Jawa (Accepted)
Black-and-white Bulbul	Absent historically	Scarce in forest; highly nomadic	Probably infrequent	Chek Jawa (Accepted)
Stripe-throated Bulbul	Absent historically	Very rare in Johor, common north of Malacca	Regular	Upper Seletar, Chek Jawa (both “Limbo”*)
White-chested Babbler	Former resident	Common in variety of habitats	Probably infrequent	Chek Jawa (under review)
Lesser Green Leafbird	Scarce resident; recent records on Ubin believed to be visitors	Common in forest	Fairly regular	Chek Jawa (1) (Accepted), Chek Jawa (2) (Accepted)
Scarlet-breasted Flowerpecker	Absent historically	Scarce in forest	Probably very infrequent	Chek Jawa (Accepted)

(a) Wang & Hails, 2007; (b) Wells, 1999; (c) Wells, 2007; (d) eBird

* Species with status “Limbo” are provisionally not accepted as wild birds in Category A but are placed in Category D, recognizing the possibility that the bird originated from captivity.

Table 1 Records of Sundaic visitors treated as very rare in our checklist, as well as other possible Sundaic visitors not included in our checklist, Jan 2022–present.

(Cover photo: Stripe-throated Bulbul at Chek Jawa on 9 May 2023. Photo credit: Raymond Siew.)

References

Chng, S. C. L., and J. A. Eaton (2016). Snapshot of an on-going trade: an inventory of birds for sale in Chatuchak weekend market, Bangkok, Thailand. BirdingASIA 25, 24–29. Link

Limparungpatthanakij, W. L. (2022). Stripe-throated Bulbul (Pycnonotus finlaysoni), version 2.0. In Keeney, B. K. & Maleko, P. N. (Eds.), Birds of the World. Cornell Lab of Ornithology, Ithaca, NY, USA. 

Nor Hashim, N. E. (2013). Comparative study of understorey birds inhabiting selected logged and virgin lowland forests. University of Malaya. Link

Peh, K. S.-H., Jong, J. de, Sodhi, N. S., Lim, S. L.-H., & Yap, C. A.-M. (2005). Lowland rainforest avifauna and human disturbance: persistence of primary forest birds in selectively logged forests and mixed-rural habitats of southern Peninsular Malaysia. Biological Conservation, 123(4), 489–505.

Singapore Birds Project. (2023). Singapore’s first wild White-crowned Hornbill. Link

Wang, L. K. & Hails, C. J. (2007). An Annotated Checklist of the Birds of Singapore. The Raffles Bulletin of Zoology, 15(Suppl), 1–179. Link

Wells, D. R. (1999). The Birds of the Thai-Malay Peninsula (Vol. 1). Academic Press, London.

Wells, D. R. (2007). The Birds of the Thai-Malay Peninsula (Vol. 2). Christopher Helm, London.