Rebirding – Benedict Macdonald
This post is part of a series of posts about reading the 2020 Wainwright Prize longlist, full details here.
This is a second book that I read before the prize longlist was announced. As a geography teacher I found this really interesting and also provided lots of extra knowledge for someone who is always interested in the birds in his garden, but does not really have the patience for birdwatching.
Please see below my notes from the book:
Hedgerows are thought of as a traditional aspect of the English landscape, however they were introduced from about 1790. “We now mourn the loss of hedgerows and their wildlife, yet these are a recent invention in the great scheme of things. This life-support system briefly expanded the scrubland empire of birds, whose declines have come back to haunt us as, two hundred years later, over half of our hedgerows have been removed once more.
Crop rotation was invented 8,000 years ago in the Middle East, long before soil chemistry was understood. Until 1930s, rotation was trundling along and its premise was simple. Your soil can only provide so much. Growing the same crop in the same place depletes the soil’s nutrients. A side effect of crop rotation was promoting bird diversity. Both benefited from a range of food and nest sites, because whilst one field was doing on one-thing, another was doing something else. This increased the variety of the menu on offer across the year, and promoted the small-scale mosaic of habitats in which many of our scrubland birds evolved in the first place.
On average, Britain has lost 50% of its hedgerows since the way, and many arable counties, especially in eastern England, a great deal more. In the absence of our wooded grasslands, hedgerows kept our remaining trees connected and alive. A hedgerow made of bushes is a habitat. A hedgerow with trees is a highway. From a bird’s perspective, an ancient hedgerow is the continuation of a wood. Ancient hedgerows with oaks don’t just increase feeding and nesting sites. They connect woodlands to one another, allowing birds to move across landscapes. If you rip wooded hedgerows from a landscape, you’re destroying not just homes – but highways. Even in a countryside devoid of large woodlands, small copses, connected by hedgerows, can function as big woods. Many birds, including marsh tis, do not seem to notice that their hazel woodland has become synthetic, long and thin. Nor do Britain’s dormice.
Since 1970, corn buntings have declined by 90%. Since the 1930s, second to house sparrows, we’ve lost more biomass of tree sparrows than any living bird: 97% have vanished since 1970 alone, and for every tree sparrow we see today there were 30 in the early 1970s. These birds’ dual diet, of summer invertebrates and winter seeds, has been cleansed from modern farmland all at once. Since 1973, we’ve lost 93% of our grey partridges. Herbicides, have starved their chicks, which now have just a 30% chance of survival.
It is the habitat assessments written by cuckoos and curlews that matter – not those committed to thousands of sheets of paper each year. The birds are telling us, by their absence, as much as their presence, quite what a waste land we have created in Britain – even if the wider aspect of trees and fields appears the same. Britain’s birds are pointing us to trophic collapse. We need to listen , and learn.
English oaks have more associated insects than any other tree. Southwood’s study found 284 invertebrates associated primarily with oak. Around 380 of Britain’s 900 moths are wood-dependent, with 220 alone supported by deciduous oak. Open grown oak has six times the woodland cover of a forest tree. 200 year oaks are quite a sight, they have nothing on 500 year oaks.
Meta-populations or meta-communities can provide mechanisms for survival. Isolation by contrast, breeds extinction. It is fundamentally unnatural for that single pair of house martins in your village to be defying the community based rules by which their species evolved. Only birds in robust populations stand the test of time. For a shrike population to have a 95% chance of surviving for 50 years, in favourable conditions, you’d need 80-90 pairs in that population. Such a population provides viability, where insurance is provided against predation, bad summers, inbreeding and other mechanisms that drive decline.
As a rule, we always underestimate the scale and connection that birds need, perhaps because these connections have been lacking from our landscapes for so long. We forget that aggregation is important to a whole range of species. Birds exercise better defence against predators in large populations, alerting one another to danger.
With its large sympathetic landscapes now reduced to the size of postage stamps, Britain has become an island of islands. Only the largest of these are proving big enough to sustain populations of birds. If food is why individual pairs of birds are failing to survive, and bad stewardship is preventing the return of our wildlife, isolation is why birds are vanishing from the map – as populations in habitat-islands collapse all at once.
No impulse exists in resident birds to cross hostile habitats and find a better home. A capercaillie, will not go blustering through the towns of Scotland in search of a new forest. Once confined and isolated, the forest where it was born becomes the limit of its knowledge. Such birds can only be restored through reconnecting habitat, or reintroducing birds from scratch. This is why golden eagles will mostly dance over Wales in any of our lifetimes – until conservationists put them back in.
There is more landscape dynamism, rewilding and birdlife in Berlin than in most counties of southern England. Berlin has eagles and ospreys, shrikes and wrynecks. Birds that have vanished from Britain are thriving here. Many animals, such as wild boars, beavers and goshawks, live right within the city. At least 170 breeding species of bird, more than in most British counties or any British nature reserve, thrive around Berlin.
British gardens, as a collective, have the potential to form a network of nature reserves unparalleled in Europe. Our gardens account for 18% of land use in urban areas. Around 22 million people – and 87% of all homes – have access to a garden. Birds in gardens are often fed, whereas those in the countryside often starve. Higher temperatures in our towns and cities increase winter survival. Gardens are to twenty-first-century Britain what the hay meadow was to the eighteenth century – a massive life-support system, tipping the odds greatly in the favour of some birds.
Britain’s squared hedges, the sprayed bases of trees, the lifeless lanws, in aggregate wipe out wildlife on a massive scale. Garden warblers were first noticed in the bushy maze of our village gardens. How many villages are bushy enough to hold them now?