Happy New Year from an ecological interpreter in the dampness of the Rift Valley in East Africa!
The western wall of the Great Rift Valley viewed from 'the patch' at Ol Mesera tented camp. January 2, 2010.
There has been a huge movement of Common Swifts into the Northern Rift Valley, south of Lake Natron which straddles the Kenyan border, in the weeks since Christmas.
We saw several thousand swifts, divided into flocks of a few hundred in each, feeding either just above the ground in 'tight swirling tornados of black darts' or in broad bands at about 100m moving steadily ahead of rain crescents shifting across the valley. Swifts in these ambling bands were frequently heard to 'scream' as were the accompanying Nyanza Swifts which may have been local birds. Both species were widespread over regenerating pasture land and seemed to be especially common near to the west wall of the valley, immediately north of Lake Manyara (see photo) on December 31 and on January 1 & 2.
The first few African White-rumped Swifts that we have seen for a long time (they've been absent since late June) have also appeared hereabouts.
Meanwhile in Arusha the chunky dashing Horus Swifts are back at their colonies in the White-fronted Bee-eater burrows of the remaining korongos (wadis). Unfortunately several colonies have been destroyed by the road widening activities now taking place along the upgraded Nairobi-Dar highway.
Little Swifts are truly abundant now and are benefitting perhaps from the increase in tall buildings, especially factories, being built across Arusha.
About thirty Scarce Swifts, together with fifty moulting House Martins, made an appearance one day last week, just around sunset, feeding over the renaissance jungle of our Mount Meru suburban garden. African Palm Swifts, Alpine and Mottled Swifts remain in Arusha district but in much reduced numbers compared with their abundance in the late dry season; at least that seems to be the case with respect to the last two species at lower levels around Mount Meru.
Barn Swallows in particular are quite disturbingly rare these days; and hirundines in general are relatively scarce around Arusha - my local patch, at Kimemo-Burka, being irrigated, especially the lucerne fields, provides in effect a late dry season (or drought-bound) staging-post for some species. I saw up to forty-five Red-rumps in one flock there on several days in November. The numbers of Brown-throated (Plain) Martin and emini Red-rumped Swallow and Lesser Striped Swallow there seemed to have peaked between October-mid November. The few pairs of Wire-tailed Swallow in West Arusha appear to have foresaken their breeding sites, at Burka/TGT, as the area becomes ever more heavily developed.
Whilst at Ol Mesera a pair of Mosque Swallow arrived and began nest-prospecting around the amazing grey boles, pitted and swollen, of three huge Baobabs, for which the lodge is named. This is a large swallow of more lethargic habits, often see perching in trees. As Mackworth-Praed and Grant describe it:
"A single tin-trumpet-like call harp and a guttural croak, a trilling mew is also reported. Much more a species of large timber and woodland, and only rarely builds in houses."
They make me think:
"There's some small calidris sandpiper, or a hawk!"
as they call when they steal upon you!
Some data and discussion of current environmental conditions being faced by migrant birds throughout north-eastern Africa is in the post below:
Posted via email from Afrotropical's posterous
