Opinion: Aidan Semmens wonders how much of our wildlife will reach a ripe old age, thanks to the mess that we humans are making of our world.

As I sat in the garden enjoying the summer evening sun, my attention was caught by a movement in the bushes. Not this time one of the dunnocks which are our year-round companions, and not big or heavy enough to be just another pigeon or blackbird.

No, it was a blackcap foraging for berries, not in a black cap, but a smart russet brown one befitting her gender. Happily I had my camera to hand, so here she is. I'm very fond of her and her trim, dapper mate.

Most summers for the past decade we've had blackcaps for neighbours. They always nest in the same holly bush just beyond our back gate, and I've often wondered whether it's the same pair returning year after year, or perhaps ensuing generations.

And, if one was fledged here, whether it was the male or the female returning to its early home.

All of which raises the question: how long do small birds like blackcaps live? And the answer, it turns out, is not entirely straightforward.

Most sources give a typical blackcap lifespan of two years, which might suggest we've had several generations of visitors.

But then the Animal Ageing and Longevity Database – a great resource to discover – gives a maximum age in the wild of nearly 14.

So it seems at least possible that the pair busy in the garden hedge right now are the same two birds I first spotted 10 years ago. Statistically unlikely, perhaps, but certainly plausible.

Because this is the thing about life expectancy: not many creatures die of old age. Most succumb to accident, disease or being eaten by other creatures long before their bodies wear out. Which means those that survive those perils may live many times longer than the average for their kind.

The same statistical pattern used to apply to human beings – and in some parts of the world it still does. Some individuals can live to a ripe old age through wars and grinding poverty. Most won't, so the average is relatively low.

Which brings me back to the question: what is a ripe old age for a bird?

Of course, it depends on the bird. One wild albatross was ringed on Midway Atoll in the North Pacific in 1956 while incubating an egg. Since the species doesn't breed before the age of five, she must have been at least 62 when she was spotted again in 2013, rearing another chick.

Some pelicans and an occasional eagle make it into their 50s. Buzzards can reach their late 20s and those red kites now taking to our skies may go well into their 30s.

The oldest recorded dunnock, or hedge sparrow, was 20. The garden warbler – a close relative of my blackcaps – can live to 24 in captivity. And that familiar little charmer the chaffinch has been known to reach 29.

All of which I find fascinating in itself – and I hope you do too. But it should also give us pause to think.

As the most wasteful and destructive species on this planet – by far – we have a responsibility to all those other creatures we share it with. And if we make it uninhabitable for them, even the birds we take for granted are not necessarily easy-come, easy-go, short-lived beings that can quickly bounce back.

The fulmar, that brilliant navigator of the wind currents around our sea cliffs, can live in the wild to at least 51.

I shall write more another time about fulmars, which are truly marvellous birds. For now I'll just note that scientists believe every grown fulmar in the world – every single one – and every albatross has some plastic in them. Which is just one reason to wonder how many will make it to old age.