Shifting baselines are important too

I've handed the reins of my blog over to Mark Avery for most of June. Mark's sharing the successes and challenges of saving nature around the world in the run up to the Rio+20 Earth Summit.

This time last year, I drove west through the USA, and near the 100^th meridian, soon after I crossed the Missouri river, I started to see a new species of bird beside the road. They were black, occurred in small flocks and had white flashes on their wings. They were lark buntings and I saw them often through several days travel through the grasslands of the prairie.

Only on returning to the UK did I realise that lark buntings had declined dramatically over whatever time period you choose to look at. Historically, the loss of the prairies removed most of their original habitat but over the last 40 years, the lark bunting declined at 6% per annum according to the American Breeding Bird Survey.

If an American birder came to the UK, he or she would see lots of skylarks in most parts of our countryside, and maybe would marvel at their beautiful song and think that all was well with the world. However, if he consulted our Breeding Bird Survey he would find that skylarks have also declined over the last few decades and are one of a list of widespread but formerly much commoner farmland species such as corn buntings, tree sparrows, lapwings and grey partridges which are of conservation concern in the UK, and in many other European countries too.

In the UK, it’s not just many birds which have declined, if we had the same quality of information we would probably be even more shocked at the scale of loss of corn flowers, corn cockles and corn spurreys – plants whose names show that they were once part of the arable farming scene but are now hugely diminished in numbers.

And it’s not just the farmed landscape affected. Woodland butterflies such as wood whites are at much reduced levels and walking through London’s Parks you are far less likely to see a house sparrow than when your parents or grandparents passed that way years ago.

I feel we should be angered by these widespread losses of huge numbers of plants and animals around us. But we will only be upset if we realise that they have occurred. The term ‘shifting baselines’ was coined by the American marine biologist Dan Pauly who pointed out that fisheries managers tend to take a short term view of their stocks and to neglect the much larger declines that have occurred over longer periods of time. It’s only when we have good data that we realise the scale of loss that we have suffered. 

Maybe if I had had an American in the car with me he would have been saying ‘Wow! There aren’t many lark buntings here anymore – I remember when this fence line was covered with them.’ And if he came to the UK I could point out fields where skylarks still sing but where they were once so much commoner.

Reductions in numbers of common species and extinctions of rarer ones are two manifestations of biodiversity loss, and two manifestations of unsustainable living. If we can find more sustainable ways of growing our food, harvesting fish and forests, producing our energy then we can at a stroke reduce our impacts on the natural world around us. That’s an aim for the Rio+20 conference.

Not only are our wildlife surveys fun, they’re also hugely important at helping us monitor how wildlife is faring. Take part in Make Your Nature Count this week - spend just one hour counting the birds and the other wildlife that visit your garden or green space and send us your results.

Dr Mark Avery is a former Conservation Director of the RSPB and now is a writer on environmental matters. We’ve asked Mark to write these 20 essays on the run up to the Rio+20 conference.  His views are not necessarily those of the RSPB.  Mark writes a daily blog about UK nature conservation issues.