Friday, 7 December 2012

Common birds (1)

Speckled Mousebird, Arusha. Cute, and really quite interesting...
OK, I've been away from here for too long (sorry!), but to encourage me to actually get down and do something, I've decided to start a new little mini-series here on common birds. As any of you who knows me is aware, I happen to rather like birds and will happy spend hours sitting wathing birds at a pond, or even trudging through kilometers of rift valley lakes to count waders. And I have a secret theory that actually, everyone loves birds, they just down all know it. The problem is that there are a lot of different birds out there (do watch Ethan as he tries to see as many as possible this year and records his exploits over here!), they often move rather fast, and people can be easily confused at first. So I thought we'd break it down into some very simple stages and try and start with 50 of the most common / obvious birds on safari or about towns in Tanzania. For each one my challenge is to briefly describe the key features to help you identify it, and then to say something interesting about it. If all goes well, I might even expand my remit to include non-birds, but we'll start with 50 common birds and see how that goes. Rather than throw it all at you in one go (and because there's no way I could write that much in one sitting!), I think I might try three species a post. It might also get a little interactive this way, if anyone wants to help me identify the top 50 species, that would be great,a nd if you've got your own preferred 'factoids' about any of the species, please do chip in!

So, let's start today, in no particular order, with the Speckled Mousebird.

Identification is straightforward: it would be a small, non-descript brown bird if it were not for the extremely long tail (total body length about 35cm, half of that being tail). Overall, speckled mousebirds are brown with greyer head and red legs and face. They also have a short crest. The only species that it's likely to be confused with are other mousebirds, blue-naped mousebird being the other most common in Tanzania, though that species tends to occur in drier habitats and is always greyer (not brown) and has a completely different call (speckled almost squeek like mice, whilst blue-naped whistle).

Two mousebirds warming up together! Tarangire
Something interesting Speckled mousebirds are mainly fruit eaters and are often thought mainly a pest of garden fruit crops. However, their habit of swallowing smaller fruit hole (including the seeds) and then flying further means they are important for carrying seeds of fruiting trees and bushes around the landscape. Their name 'mousebird' comes from the unusual feathers on their body which, unlike in most birds, are loose and unconnected, rather like fur. Combined with their habit of crawling through bushes and rather weak flight 'mouse bird' seems a sensible name! They are also unusual for their habit of sometimes sleeping in groups hanging upside down - something they also do to let the warmth of the sun assist in digestion of a large meal. In fact, this behaviour identifies one of the most interesting things about the group, their extraordinary ability to regulate and vary in body temperature.

Humans maintain a very strict body temperature of around 37 degrees Celcuis - 39 degrees and we're seriously sick, 35 and hypothermia sets in. Birds in general are similarly constant, though most species are often a bit warmer, at around 41 degrees (good for keeping hands warm on a cold morning). Speckled mousebirds, however, can drop their temperature by more than 10 degrees overnight (less if they sleep huddled together - an activity that can save them 40-50% of the energetic costs of keeping warm), and so they have to warm up each morning in the sun. It certainly reduces energetic costs, and when food supplies are low they allow their body temperature to fall even more, though they are slow to respond when at low body temperature, so there must be a potential predation risk. They're also cooperative breeders, with helpers from previous breeding seasons helping to raise each season's young as well as the parents - an activity no doubt encouraged by the need to be in groups at night to stay warm. And the final interesting fact I've come up with is the fact that mousebirds are the only avian order that is completely restricted to Africa - ther order used to be much more widespread, but all living mousebirds are today in sub-Saharan Africa, making them something of a living fossil - the last few species of a once widespread and ancient group of birds.

Next up, the African Pied Wagtail.

African Pied Wagtails are often around buildings...
Identification is again easy. They are small, long-tailed black and white birds, always active on the ground or on buildings. Actively wags wail up and down, particularly after landing. The songs and calls are cheerful musical notes often heard around towns.

Something interesting African Pied Wagtails are almost entirely insect eaters. As well as eating insects that live on the ground, they actively seek flying insects hiding in cracks and holes around our houses, providing a valuable service (other wagtail species have been observed eating at a rate of several insects per minute, giving a total daily intake of over 20,000 flies per day!). Given that the particularly like feeding on dung flies, this is a very helpful job. Their association with humans and our buildings is extraordinary and it's hard to find the species far from towns and villages, suggesting that until recently they were probably rather scarce. Although they usually nest in trees, they will happily even nest on our houses.

Finally, (for today) let's look at the Yellow-billed Kite.

This Yellow-billed Kite is hunting tourist lunches
at Ngorongoro (thanks to for picture)
This time Identification is not so straightforward. These kites are large, all bown birds,  adults have a bright yellow beak that is often noticable even at some distance. With long wings and a long, forked tail like a fish, their distinctive floating flight on arched wings makes them easily recognisable, though from Septemner to April they can easily be confused with a visitor from Europe and Asia, the Black Kite, which has very similar plumage and behaviour. These northern visitors tend to be somewhat paler and with deeper forked tails, but certain identification can be very difficult, and it might be better in many cases to simply call them Yellow-billed / Black Kites. From September to April they can easily be confused with a visitor from Europe and Asia, the Black Kite, which has very similar plumage and behaviour. These northern visitors tend to be somewhat paler and with deeper forked tails, but certain identification can be very difficult.

Something interesting Yellow-billed kites are common in cities across Africa, with Black Kites taking over as summer visitors to Europe, and resident across Asia and Australasia. As well as a small resident population, 'our' kites are joined be migrants from south Africa between May and September when the species can be very common in many cities and towns. To my mind, the best thing these birds do is some absolutely fantastic flight. If I could fly, I'd want to be as maneouverable as a kite - watching them swoop and glide as they hassle other birds to steal their food (behaviour called kleptoparasitism) - or cleverly stealing unsuspecting tourists' lunch boxes is always a pleasure (though I do the latter from the safetly of my own car...)! Although they do often steal other food, they're also pretty good hunters themselves, and will eat just about everything, from birds at bats caught in the air, to fish plucked from the water!

1 comment:

  1. I once watched a movie on the Ngororgoro Crater and it was really funny because the torists would eat their lunches outside and then get dive bombed by the kites. But they are great acrobats from what i have seen. I think the acrobat of colorado is the common raven they can soar at great heights and make incrediable dives. Mated pairs also do courtship flights in which the couple mirror each other in flight. I have seen them do this in the spring and it is so cool.