Little Grebe – bill colour variation

posted in: Morphology-Develop. | 0
#1 Little Gribe.

“Little Grebes (Tachybaptus ruficollis poggei) have colonised the peninsular since the 1950s and locally retain their ‘breeding’ plumage right through the year. I noticed a feature today that I had missed in the past. I saw a pair where one bird had an orange-pink upper and lower mandible (#1 above). The proximal part of the upper mandible was black.

#2 Little Grebe.

“Little Grebes are classical described as having a black bill; also note that the bill in adults often has a white tip (not mentioned in some sources) and there is a light yellow-white rictus (gape of mouth) in adults (see comparison in #2 above; adult with black beak #3 below; both birds #4 bottom).

#3 Little Grebe.

“I looked at other resources and there are number of Little Grebes in the OBI database with similar beak appearance, all labelled as adults or even adults in ‘breeding’ plumage. I wondered if this was a change from a juvenile to adult beak pattern but OBI even has a bird with such beak colouration feeding young (Santanu Chatterjee, January 2018). It could be that young adult birds (able to breed) but have delayed development of this adult beak colour.

#4. Little Grebes.

“Note that T. r. poggei is differentiated from other subspecies by the pale yellow eyes, among other features.

Dato’ Dr Amar-Singh HSS
Ipoh, Perak, Malaysia
7th February 2019

Location: Malim Nawar Wetlands, Perak, Malaysia
Habitat: Extensive ex-tin mining area with pond/lakes, wetlands, fish farming

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