Nature Diary - October 2008

BRIAN'S COUNTRY DIARY OCTOBER 2008

It’s confession time! I have to come clean! Yesterday I killed a bird. Deliberately. It happened like this. Dave and I were sitting in the conservatory enjoying a quiet drink and a chat, while Jane was working in the office on the computer. A bird landed somewhat awkwardly on the lawn. Thinking it was a fledgling which had not quite grasped the basic rules of flying, we noted it as a collared dove, but continued our conversation.

A short while later both of us noticed there was something odd about it. It had not moved from the spot where it had settled, but seemed to be bobbing the head up and down rapidly, as if feeding on non-existent grain. Then we noticed that its head and the neck were curved strongly forwards, the beak pointing down. It was obviously in some kind of distress, so I approached it to pick it up. As I bent down it panicked and flew up hitting me full in the face. It veered off across the garden with little sense of direction, and hit the conservatory window with some force.

This time I managed to pick it up and saw immediately that it was quite grossly deformed. To add to the curved neck, its head was distorted to one side, and it was blind in one eye. The eyelid was sealed firmly shut and has never been opened, although the bulge of the eyeball could be seen beneath it. The curious movements seemed to be some kind of fit.

This was obviously a seriously disabled bird, so I did what seemed best. I took it behind the garden shed and ended its misery. Although I have been called to do this on previous occasions, it is always very traumatic for me, and I suffered a sleepless guilt-ridden night as a result of this episode.

As on means of fitting a given species to be better able to stand up to the rigours of its environment, a tiny proportion of mutations is produced. Maybe one in a million of these represent an improvement. This refined model stands a slightly better chance of breeding, and of passing on the improvement to its offspring in turn, and so on until it is incorporated into the population as a whole.

The downside of this is that for every beneficial modification there are countless others that fail. For some indeed an early death is inevitable. If I had not intervened in this case, next door’s cat had already picked up on the unfortunate fledgling’s behaviour, and was beginning to show an interest. Starvation could also have been the deciding factor.

Nature may be seen to be cruel in this sense, but the survival of the species is paramount, and those that fail to measure up in any way pay the price.

The last house martins left their nests under the eaves of the houses nearby on September 30th.  By the time we see them again, around the middle of April next year, they will have journeyed 12,500 miles to their winter homes in Africa and back. A majority will be young of the year, some indeed only three or four weeks old. If we say that a successful pair has reared a succession of broods in their mud nests, and produced eighteen young. This gives us twenty including the adults. If the population is to remain steady eighteen of them must die by the time they return.

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