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First Albinism-Like Pigment Aberration in a Rhesus Macaque Documented in Assam’s Brahmaputra Valley

Albino rhesus macaque near Murree, Pakistan
Research · Anatomy & morphology

A juvenile male rhesus macaque (Macaca mulatta) with an unusual pigment aberration was documented on 23 November 2024 at Koroioni village in Assam’s Nagaon district. The animal had a uniformly pale cream-coloured coat and bluish eyes and stood out clearly from normally pigmented members of its troop.

The phenotype was albinism-like, but not genetically diagnosed

The authors stop short of describing the macaque as a classic complete albino. Its cream-coloured coat and bluish eyes did not match the complete loss of pigmentation and red or pinkish eyes usually associated with complete albinism.

They suggest that the phenotype could be consistent with a form of oculocutaneous albinism and mention SLC45A2, a gene involved in melanin biology and associated in humans with oculocutaneous albinism type 4. No genetic analysis was performed on the macaque, so this remains a hypothesis based on appearance rather than a demonstrated diagnosis.

Adult males chased and attacked the juvenile

The short communication also records unusual social interactions. Adult males were observed chasing and attacking the juvenile, which had visible scratches and bite marks. The paper notes that the aggression may have followed a separation from its mother; the authors also suggest that its conspicuous colour may have contributed to the response. Neither explanation was tested.

Local residents intervened to prevent further injury, and the juvenile was later returned to its natural habitat in stable condition.

The novelty claim applies specifically to the Brahmaputra Valley

The observation is not the first report of an albino or similarly colour-aberrant rhesus macaque in India or even in Assam. The authors’ claim is narrower: they knew of no previous published record from the Brahmaputra Valley.

The value of the report therefore lies in documenting the phenotype, exact locality and associated behaviour. The genetic cause of the pigmentation and any direct link between colour and aggression remain unresolved.

Sources and image credit

  1. Bora, N., Buragohain, S., Borah, D. J., Bora, C., Choudhury, S., & Das, J. (2026). Albinism in a juvenile rhesus macaque Macaca mulatta (Zimmermann 1780) from the Brahmaputra Valley of Assam, India (Primates: Cercopithecidae). Natural History Sciences, 13(1). https://doi.org/10.4081/nhs.2026.879Primary short communication published 13 January 2026. A juvenile male rhesus macaque in Assam’s Brahmaputra Valley had a uniformly light cream coat and bluish eyes rather than the complete depigmentation and red or pinkish eyes typical of classic complete albinism. The authors considered an oculocutaneous form possible but conducted no genetic analysis, so the proposed genetic mechanism remains speculative. Adult males were observed behaving aggressively towards the juvenile. The authors identify this as the first documented record from the Brahmaputra Valley.

Image: Razan Ahmed — albino rhesus macaque (Macaca mulatta) near Murree, Khyber Pakhtunkhwa, Pakistan, photographed 9 June 2017; representative colour-aberrant rhesus macaque, not the juvenile from the Brahmaputra Valley short communication. Source: Wikimedia Commons. · CC BY-SA 4.0 · Source

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