Making sense of Tiger Shrike – first winter vs adult winter

posted in: birds, Morphology-Develop. | 0

Some time ago (October 2017) when I posted a Tiger Shrike (Lanius tigrinus) that I assumed as a first winter bird, Dr David Wells (Wells, D.R. The birds of the Thai-Malay Peninsula: Vol. 2 (Passarines). Christopher Helm, London. 2007) commented that the bird was a winter-plumage adult. David says that the “discovery that adults alternate plumage-types (often completely but not always) came from recapture of ringed birds”. I am revisiting that comment and surmising David Well’s differentiating features for first winter vs adult winter birds. This applies to birds in autumn and not late winter or spring.

 

Feature First Winter

(Autumn Juvenile)

Winter-Plumage Adult
Bill Pink bill with black tip Blue bill
Crown Black barring on the crown (feather tips that wear off progressively), Crown is more or less plain from the start
Ear-covert feathers

(face-mask behind eye)

Pale-tipped Pale-tipped but more basal black than usual in juveniles (dark enough to create a shadow mask)
Primary coverts Always pale tipped Plain, only occasionally pale tipped

 

The top image shows a comparison between a first winter (autumn juvenile) on the left with a bird identified by Wells on the right as a winter-plumage adult. Note that there is glare on the bill of the juvenile on the left but other images of the same bird clearly show the pink bill with black tip. I have previously read blog posts by colleagues wondering why we see mainly juvenile Tiger Shrikes in Peninsular Malaysia & Singapore. The reason may be that we are mistakenly identifying some winter-plumage adults as juveniles

The above image is just for completeness, a bird I saw in my garden on 20th April 2011 which is moulting into summer adult plumage. Note the blue bill, dark face mask and grey developing on the nape.

 

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

Location: Kledang-Sayong Forest Reserve, Ipoh, Perak, Malaysia

Habitat: Fringe of primary jungle

Date: 16th December 2019

Equipment: Nikon D500 SLR with Nikon AF-S Nikkor 500mm f/5.6E PF ED VR, handheld

 

 

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