|Red-capped Robin-chat, Lake Duluti July 2011|
In the bush behind a white-starred forest robin was hopping about (sorry, no pics), and then (finally) I found the greenbuls I'd been hearing - grey-olive greenbuls, and something of a speciality of Lake Duluti being easier to see there than just about anywhere else I know.
|Grey-olive Greenbul, Lake Duluti 2011 - check the pale eye, pale legs and warm tail|
Now, birding in tropical forests is often a frustrating experience. You hear a few calls, but see little. Until suddenly, as today, loads of birds all at once. Here in Tanzania you get this phenomenon both in the forests proper as today, but also in the dry forests and woodlands of the savannah (and particularly in miombo - if you've ever looked for bits in miombo you'll know quite how empty it can be for ages, before suddenly you find a little group). Why is this? Why do we get mixed species flocks in tropical forests? To most guides based here, there's nothing unusual about this, but it is pretty different to the experience most northern birders will be familiar with - in temperate forests there's usually birds all around, all the time - only in the harsh winter period do you get forests apparently empty of birds (and of course many have migrated for the season), and then a mixed group of several species. But perhaps this gives us some clue - the relative harshness of the environment.
|Robin-chat - probably Ruppell's but see comments below! (both are present at Duluti), July 2011|
|Giant millepedes would be great food for some - but not everyone!|
|Soldier Pansy, Junonia terea (I think) were common and probably good to eat - but only if you can catch them!|
Some birds are really birds of mixed-species flocks , rarely occurring in single species flocks (in the savannah, how often have you seen red-billed buffalo weavers feeding in a single species flock? Much more likely they're with lovebirds, starlings, other buffalo-weavers and/or hornbills), whilst others seem to be more opportunistic in their joining of mixed flocks – again a savannah example would be of hornbills who seem quite happy either in small groups of their own, or together with several other species. In fact, where people have studied the phenomenon in some detail, it seems that it's often one or two species that start the mixed flock in the morning, and their calls attract the other species to them before they start the foraging patterns, yet some breeding birds will join flocks as they enter their territory, travel with the flock until it reaches the other side of their patch, and then head off on their own again. So the individuals in a mixed-species flock can be quite dynamic as the flock moves across the landscape. All very interesting I think...
|Soldier ants - Siafu - are common in the forests but not followed by birds|
Interestingly, the same sorts of thing happen in South American forests and many of them there are particularly associated with driver ants (the South American answer to our safari ants or Siafu). The birds forage along the moving front of the ant group, either eating the ants themselves, or the animals fleeing the upcoming invasion. I'm not quite sure why this doesn't seem to happen with siafu – there were several trails in the forest this morning, but as usual no birds attending. Any idea?