Over the last few days there have been bouts of intense activity outside my window as a swarm of birds descends on the feeder. They are mostly blue tits with a minority of great tits and individuals of chaffinch, long-tailed tit, coal tit and mallow tit. It is impossible to count them because each individual stays just long enough to grab a seed before flying into the trees to eat it, but I once counted a dozen blue tits. From the way that the birds suddenly appear, they must be travelling as a flock. This is the time of year that tits, with some hangers-on like chaffinch, nuthatch and treecreeper, form flocks that make a daily circuit through a range of 10-20 acres (it is very variable) in search of food. The flocks develop out of the gangs of juvenile tits that roamed the same area after the family parties dispersed in the summer, with the addition of their parents. The advantages of this communal life depend, in essence, on many pairs of eyes being more efficient than one. The flock members co-operate in finding scattered sources of food and detecting danger. When several birds are feeding together they keep a communal watch for an approaching hawk, so each individual can spend less time looking around and more time feeding than if it were alone. What, you may have asked, is a mallow tit? Marsh tits and willow tits are so similar in appearance that they are often lumped together, unless their distinctive calls can be heard. This mallow tit was the 60th species for my garden. I got good views of it on the feeder at a range of 30 feet, and convinced myself that it was actually a willow tit but it is a pity I didn't hear its voice.
|
