19th century painting of “Pernis tweeddalii” by J. G. Keulemans
This post was triggered by an avid birder who asked the above question.
In the late 19th century, an Oriental Honey Buzzard Pernis ptilorhyncus with an (until then) never seen before blackish-and-white plumage was collected in the southeast of Sumatra, Indonesia. This specimen was described by British ornithologist Arthur Hay in 1877, under Pernis ptilorhyncus, apparently hesitating to separate it from the very variable Oriental Honey Buzzard.
Subsequently, another two specimens of similar plumage were collected, and the distinct plumage of these birds led ornithologists to treat them as a new species of Honey Buzzard. In 1880, this new species was christened Pernis tweeddalii, in honour of Arthur Hay, who was also known as Lord Tweeddale.
Along the way, it was lumped back into Oriental Honey Buzzard Pernis ptilorhyncus as it breeds with the normal brownish-plumaged OHBs resident in the tropics. Therein lies the origin of the name “Tweeddale morph” of the torquatus subspecies of the OHB.
Dave Bakewell and Peter Kennerley first alerted us to a distinct looking Charadrius plover in their 2008 paper titled “Malaysia’s Mystery Plover” after studying them at Tuas, Singapore in winter of 1993-1994 and in Penang in 2006-2007. This led to a comprehensive study of the plover in question, in collaboration with Philip Round in 2008. They then coined the name “White-faced Plover” for its predominately white looking face.
Following the publication of the article, birders in China started searching for them along the coast. In 2011, a China-based birder Brian Ivon Jones stumbled a breeding population on China’s southern coast. 270 birds were counted at two sandy beaches at Dahu, Haifeng in Guangdong Province.
Further research found that renown British ornithologist Robert Swinhoe had described the form in 1870 based on a specimen collected from Taiwan and had it named Aegialites dealbatus. This was treated as a subspecies of the Kentish PloverCharadrius alexandrinus.
So it was more of a rediscovery and the bonus was that it was accepted by the IOC as a new species following the name given by Bakewell and Kennerley, White-faced Plover, Charadrius dealbatus after the split. Numerous studies have been conducted by researchers thereafter to better understand is taxonomic relationship with other similar plovers.
On the 31 January 2021, all three Charadrius plovers were present at the seawall along Marina East Drive. There were a few pairs of Malaysian Plovers, several Kentish and at least one male White-faced Plover moulting into breeding plumage.
Both the Kentish and White-faced Plovers were seen mixing together and came close to each other for these photos. With these we are able to compare them better side by side.
At first glance, both plovers look similiar. But the first thing you will notice are the lores or rather the absence of the black loral patch for the White-faced. The patch behind the eyes are also visibly darker for the Kentish. Another useful feature for birders to take note of is the black breast typical of the Malaysian and Kentish Plovers, this feature is less pronounced in the White-faced. The black band across the crown is further back on the White-faced Plover, giving it the appearance of a much whiter forehead and an overall paler face. Lastly the Kentish Plover has a darker brown upperparts compared to the lighter, ‘milky tea’ color for the White-faced.
This side profile photo shows that the two plover species are of about the same size with a slightly rounder body for the Kentish. The flanks of the Kentish has more white than the White-faced. The legs of the Kentish do look darker but the length is hard to judge. The most contrasting feature is the shape of the head. The White-faced has a steeper forehead compared to the sloping forehead of the Kentish Plover, giving it a more “dome-shaped” look.
This White-faced Plover has been accepted into the International Ornithological Congress’s checklist after the split, and has now been added into the 2021 Nature Society (Singapore)’s Birds of Singapore Checklist.
Sadanandan, K. R., Küpper, C., Low, G. W., Yao, C. T., Li, Y., Xu, T., … & Wu, S. (2019). Population divergence and gene flow in two East Asian shorebirds on the verge of speciation. Scientific reports, 9(1), 1-9.
Lim, K. S. (2009). The Avifauna of Singapore. Nature Society (Singapore). Singapore.
In the earlier days, popular bird publications such as field guidebooks treat the Buteo buzzards occurring in Singapore simply as Common Buzzard Buteo buteo.
Three publications do not list any subspecies:
Birds of Singapore (Lim & Gardner, 1997)
Birds of West Malaysia & Singapore (Jeyarajasingam, 1999)
Annotated Checklist of the Birds of Singapore (Wang & Hails, 2007)
Birds of Thai-Malay Peninsula vol 1 (Wells, 1999) and Birds of Southeast Asia (Robson, 2000) also treated these buzzards as Common Buzzard Buteo buteo, listing vulpinus and japonicus as the subspecies. The Avifauna of Singapore (Lim, 2009) treated these buzzards as Common Buzzard Buteo buteo, listing japonicus as the subspecies for Singapore.
Now, for the splits.
Birds of Southeast Asia, 2nd edition (Robson, 2008) split the buzzards into two species:
The Common Buzzard Buteo buteo, with vulpinus as the subspecies occurring in Southeast Asia.
The east Asian population as Himalayan Buzzard Buteo burmanicus, as the other species occurring in Southeast Asia.
Birds of Singapore (Yong, et al, 2013) also split the buzzards into two species, but in a different manner:
The Common Buzzard Buteo buteo, with vulpinus as the subspecies occurring in Singapore.
The east Asian population is given a different treatment, as Eastern Buzzard Buteo japonicus, as the other species occurring in Singapore.
No worries, Birds of the Indonesian Archipelago (Eaton, et al, 2016) lumped the buzzards back into Buteo buteo, using the name Eurasian Buzzard. They listed vulpinus, refectus & burmanicus as the subspecies occurring in Southeast Asia, commenting that “Species taxonomy confused, but substantial overlap in morphological characters and extremely limited mtDNA divergence advocate subspecific status of these allopatric breeding forms.”
A Common Buzzard perched on a lamp post at Changi.