Over the past century the three long-winged, 'spotted and barred', Snake-Eagles have been considered either three separate 'entities', or three forms of the same 'entity'. Presumably they became more or less reproductively isolated from one another during some moister period in the distant past; perhaps nearly three million years ago?
In the modern era in the northern Old World one finds the obligate migrant form with which European and West and Central Asian birders are most familiar i.e. the Short-toed Snake-Eagle Circaetus gallicus; in the sub-sahelian belt across the great bulge of western Africa one finds Beaudouin's Snake-Eagle (C.beaudouinii) and in southern and eastern Africa this form is repaced by the Black-chested Snake-Eagle (C.pectoralis).
According to Roberts VII at ten months of age pectoralis will show broad brown tips to the belly feathers; however the same source quoted in Roberts states that at six months the first black feathers should appear on the upper breast. Now as far a I have noted, or can recall, or see from the few rather poor quality photogarphs neither of the two Osugat birds showed any black chest feathers whatsoever.
Osugat Update - so, in the same place, on the same day, a year later; we have two photos, of two birds, of two different ages - yet presumably of one and the same form/species or hybrids between two forms/species?
It seems to me a rather bizarre coincidence that not until exactly one year later, and after maybe forty further visits to the Osugat in between times, and many score of days birding on safaris elsewhere in Tanzania, should another very similar, boldly marked bird appear before me - i.e. 'a barred and spotted' Short-toed / Black-chested Snake-Eagle. Remarkably it was crossing almost exactly the same part of the Osugat plain and was also heading for the "Kilimanjaro- Meru migrant raptor gap" and the huge expanse of the snake-rich Maasai steppe beyond!
Clearly I might be missing them at other times here; yet must ask - does anyone else see such heavily marked (spotted on breast and barred on flight feathers) Black-breasted Snake-Eagles in East or Southern Africa; and more particularly do they see them during the boreal summer - that is between April and September?
'Spotted and barred' Snake-Eagles in Tanzania
Over the past century the three long-winged, 'spotted and barred', Snake-Eagles have been considered either three separate 'entities', or three forms of the same 'entity'. Presumably they became more or less reproductively isolated from one another during some moister period in the distant past; perhaps nearly three million years ago?
In the modern era in the northern Old World one finds the obligate migrant form with which European and West and Central Asian birders are most familiar i.e. the Short-toed Snake-Eagle Circaetus gallicus; in the sub-sahelian belt across the great bulge of western Africa one finds Beaudouin's Snake-Eagle (C.beaudouinii) and in southern and eastern Africa this form is repaced by the Black-chested Snake-Eagle (C.pectoralis).
According to Roberts VII at ten months of age pectoralis will show broad brown tips to the belly feathers; however the same source quoted in Roberts states that at six months the first black feathers should appear on the upper breast. Now as far a I have noted, or can recall, or see from the few rather poor quality photogarphs neither of the two Osugat birds showed any black chest feathers whatsoever.
Osugat Update - so, in the same place, on the same day, a year later; we have two photos, of two birds, of two different ages - yet presumably of one and the same form/species or hybrids between two forms/species?
It seems to me a rather bizarre coincidence that not until exactly one year later, and after maybe forty further visits to the Osugat in between times, and many score of days birding on safaris elsewhere in Tanzania, should another very similar, boldly marked bird appear before me - i.e. 'a barred and spotted' Short-toed / Black-chested Snake-Eagle. Remarkably it was crossing almost exactly the same part of the Osugat plain and was also heading for the "Kilimanjaro- Meru migrant raptor gap" and the huge expanse of the snake-rich Maasai steppe beyond!
Clearly I might be missing them at other times here; yet must ask - does anyone else see such heavily marked (spotted on breast and barred on flight feathers) Black-breasted Snake-Eagles in East or Southern Africa; and more particularly do they see them during the boreal summer - that is between April and September?