Mark Avery: It demeans us when we let a species die

On 1 September 1914 a bird known as Martha died in a cage in Cincinnati Zoo and the passenger pigeon was extinct. Newspapers across the world marked the event but nearly 100 years later should we give Martha a moment's thought? Indeed, why should we care about extinctions?

Fifty years before Martha died, her species was the commonest bird on the planet, numbering maybe 9 billion birds. They formed colonies of millions of nests and the long, winding flocks darkened the skies from dawn to dusk. A harvesting industry grew up in states such as Ohio, Michigan and Illinois, sending carcasses back to New York and Philadelphia restaurants by the trainload. It seemed as though the well of pigeons was bottomless, but a combination of overexploitation and destruction of their forests drove this superabundant species to extinction.

I visited Cincinnati Zoo recently, paid my $10 entrance fee and headed towards the bronze statue of a passenger pigeon. I sat in the sun and noticed that no other visitors gave the memorial a glance, except a child who stroked the smooth bronze of its head and hurried on towards the caged gorillas.

Its market value did not protect the passenger pigeon (nor the cod, nor the great whales) from overexploitation. Perhaps we should take the lesson that markets don't necessarily work well for protecting species, even those species with well-developed markets and significant value. Theodore Roosevelt saved the wood duck from extinction by introducing hunting regulations and they are a common sight across the US.

Current thinking pays greater attention to the ecosystem benefits provided by species. For example, peat-forming mosses have a value in storing carbon that is lost when we dig them up and spread peat on our gardens. If we valued those services we get for free, then maybe we wouldn't be so careless with them and the natural world around us would provide more food, remove more pollutants, store more carbon and give us a better life, and there would be fewer extinctions.

But what ecosystem services might the world's most abundant bird once have provided? If around in abundance now, they would be a fantastic tourist attraction and communities could live off the visitor dollars. Ecologists suggest that their demise may be a factor in the increased incidence of Lyme disease whose economic costs have been estimated as $1bn per annum.

But it's all a bit thin really. We lost both the economic enterprises that depended on passenger pigeons and any more indirect service they once provided, but I won't try persuading anyone that the US is economically much the poorer for the loss of these birds. But then we don't condemn human genocide on economic grounds, we condemn it on moral grounds. And we don't regulate traffic because each child killed on the road is an economic blow to the nation's economic health, we do it because the loss of life and beauty and hope through careless and selfish action is something to minimise as a matter of principle. So, too, should we look at extinctions. Species extinctions impose economic costs on us, and we pay an economic price for trashing the planet. But it's also just plain wrong – uncivilised, irresponsible and demeaning to us if we continue to do it. Surely those reasons taken together mean that we should do better for species in future?

Conservationists are gearing up for the centenary of the demise of the passenger pigeon. Perhaps President Obama (or Bachmann, Romney or Perry) should visit Cincinnati Zoo that day, or at least invite world leaders to spend time with them contemplating our impact on the world around us.

The writer is former conservation director of the RSPB.