Hybrid or Variant Spectacled Bulbul?

posted in: birds, Hybridisation, Intraspecific | 0

The Spectacled Bulbul (Rubigula erythropthalmos erythropthalmos) is a common forest bulbul that I have seen very often. The striking feature is the yellow-orange eyelid-rims. The rest of the bird’s plumage is olive-brown with paler underparts (see bird in the image below.

Occasionally I have seen some birds with faint yellow streaks in the breast (see bird in image below) but this is uncommon. Birds of the World (2020) describes the bird as “… breast grey, browner at side and on flanks, infused with pale creamy yellow; belly and undertail-coverts creamy white …”. However, Wells (2007) describes them as “… centre breast grey, browner at the sides and on flanks; and belly and lower tail-coverts plain creamy white …

In September 2021, at the Ulu Kinta Forest Reserve, Ipoh, Perak, Malaysia, I saw a bird (see bird in image below) with a yellow lower belly and yellow under tail-coverts. I wonder if this is a hybrid bird of some variant? If this is a hybrid, it is possibly a hybrid with a Yellow-vented Bulbul (Pycnonotus goiavier analis), in view of limited other plumage changes.

The eBird/Clements checklist of Birds of the World (2021) does not list any known hybrids for either the Spectacled Bulbul or the Yellow-vented Bulbul. But reports of hybrids with the Yellow-vented Bulbul do exist (see below)

Bulbul hybrids are known for some species, for example:

  • Light-vented Bulbul (Pycnonotus sinensis) hybrids with Styan’s Bulbul (Pycnonotus taivanus) are well known.
  • Hybrids of Red-whiskered Bulbuls (Pycnonotus jocosus) in captivity are well known. Techachoochert and Round (2013) describe a number of these hybridisation activities (Red-vented Bulbul P. cafer, White-eared Bulbul P. leucotis, White-spectacled Bulbul P. xanthopygos, Black-crested Bulbul P. melanicterus, Himalayan Bulbul P. leucogenys, Stripe-throated Bulbuls P. finlaysoni, Yellow-vented Bulbuls P. goiavier).
  • Bird Ecology Study Group (2009) reported breeding between a Sooty-headed Bulbul (Pycnonotus aurigaster) and a Yellow-vented Bulbul (Pycnonotus goiavier).
  • More examples of hybrid bulbuls in the eBird/Clements checklist of Birds of the World (2021).

I value hearing the experience of other bird watchers on plumage variation in Spectacled Bulbuls and possibly hybrid sightings.

References:

  1. Fishpool, L. and J. Tobias (2020). Spectacled Bulbul (Rubigula erythropthalmos), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.spebul1.01
  2. Wells, D.R. (2007). The birds of the Thai-Malay Peninsula: Vol. 2 (Passerines). Christopher Helm, London.
  3. Clements, J. F., T. S. Schulenberg, M. J. Iliff, S. M. Billerman, T. A. Fredericks, J. A. Gerbracht, D. Lepage, B. L. Sullivan, and C. L. Wood. 2021. The eBird/Clements checklist of Birds of the World: v2021. Downloaded from

https://www.birds.cornell.edu/clementschecklist/download/

  1. eBird. Light-vented Bulbul (Pycnonotus sinensis)

https://ebird.org/species/livbul1

  1. Techachoochert and Round (2013). Red-whiskered Bulbul: are trapping and unregulated avicultural practices pushing this species towards extinction in Thailand? BirdingASIA 20 (2013): 49–52

https://static1.squarespace.com/static/5c1a9e03f407b482a158da87/t/5c40f90ef950b7549a451e0b/1547761935808/Red-whiskered-Bulbul.pdf

https://www.thainationalparks.com/species/red-whiskered-bulbul

  1. Bird Ecology Study Group Insight into the mixed-species bulbul breeding (2009)

https://besgroup.org/2009/08/23/insight-into-the-mixed-species-bulbul-breeding/

https://besgroup.org/2009/08/13/pairing-of-yellow-vented-and-sooty-headed-bulbul/

https://besgroup.org/2009/08/16/mixed-species-bulbul-feeding-juvenile/

 

Amar-Singh HSS (Dato’ Dr) – Ipoh, Perak, Malaysia

 

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