"I think that around Arusha the majority of the population departs in May-July (they show clear signs of migratory restlessness in that period) returning from September onwards and I imagine, with no hard evidence to support this, that they largely go west or north west presumably into the greater Congo basin."

Back in the 1980's I led a few July tours to Kenya so have dug out my notes for then.  I have the following records:

1987:  Seen on 6 days out of 15 with 25 on the 8th (Naro Moru to Nakuru) and 30 on the 10th (Nakuru to Naivasha).

1988:  Seen on 3 days out of 15 with 10 on the 6th (Naro Moru to Nakuru) and 30 on the 12th (Mara to Naivasha).

So back in the late '80s they were certainly present in good number in early-mid July.

My feeling is that their absence this June was unusual.  There is no doubt that the majority of birds had moved out.  I was actively looking for them every day that we spent in the Nakuru - Naivasha area and especially on the morning of 4 July at Naivasha when I realised they were missing.

Conditions were perhaps drier than usual, though there seemed to be most of the other 'regular' species present in normal numbers.

Does anyone else have any data to offer from other years?

Best wishes,

David