On the 30th of May 2020, Ninian Lowis took the following photograph in Enonkishu Conservancy.
After consultation with numerous experts, we are excited to confirm that this image depicts a melanistic African Goshawk. Ninian’s photo is one of the best taken of this extremely rare colour morph. For reasons unknown, melanistic African Goshawks appear to be restricted to the highlands of east Africa, with most records coming from Kenya.
A normal African Goshawk photographed along the Oloololo Escarpment in the Mara Triangle
Melanism occurs in raptors when a rare genetic mutation causes increased expression of eumelanin (dark-coloured) pigments in plumage. Several other raptor species in the Maasai Mara exhibit rare cases of melanism including the African Marsh-Harrier and the Ovambo Sparrowhawk.
A rare melanistic African Marsh Harrier in the Mara Triangle, Kenya. Photo courtesy of Tyler Davis.
A normal African Marsh-Harrier in Tsavo National Park, Kenya. Photo courtesy of Mustafa Adamjee.
A rare melanistic Ovambo Sparrrowhawk photographed in the Maasai Mara, Kenya. Photo courtesy of Dave Richards.
A normal Ovambo Sparrrowhawk photographed in the Maasai Mara, Kenya. Photo courtesy of Dave Richards.
It is important not to confuse melanism with other dark-plumages that are frequently observed in polymorphic raptors. Multiple genetically-based colour morphs can coexist in natural breeding populations of polymorphic raptors, irrespective of age or sex. Adult plumage colour and pattern are often similar among these polymorphic raptor species in the family Accipitridae. The standard common light morph has pale breast and underwing coverts, but the rarer dark adult morph tends to be black on the breast and underwing coverts. Augur Buzzards and Black (Great) Sparrowhawks are examples of polymorphic species, with a rarer dark-morph.
The Black Sparrowhawk in particular has been well studied and morph type and plumage pattern have been found to be invariant over time for both males and females. Plumage inheritance follows a typical Mendelian pattern, where the allele coding for the common light morph is dominant and the allele coding for the rarer dark-morph is recessive. Thus, dark-morph plumage in Black Sparrowhawks is not caused by a rare mutation that triggers excess eumelanin production and therefore their darker plumage should not be considered melanism.
A dark-morph Augur Buzzard takes flight in the Mara Triangle. Photo courtesy of Shiv Kapila.
If anyone has records of melanistic African Goshawks from anywhere in their range, please contact us. We are building a database of all records to better understand the distribution and prevalence of these rare and gorgeous colour morphs.