There was another interesting article in the Autumn issue of BBC Wildlife magazine on the importance of brownfield sites for wildlife.

We all think in terms of brownfield sites being derelict, dangerous and useless. But in fact it provides a whole range iof valuable, and often novel, habitat for wildlife. Indeed often brownfield sites are richer in wildlife than green belt land which tends to be managed and manicured by comparison.

Again the article isn’t online (although there is a short news report) so once more a few pertinent extracts.

Much has been made of the importance of brownfield for wildlife … there’s also an assumption … that it must be the priority for development in order to protect the countryside and the green belt
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a conflict between the need for economic development and the conservation of wildlife habitats near where people live.
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Often, though, the ideal solution is neither protection nor redevelopment but natural regeneration. Some of the pollutants in the soil and ground water of former industrial land can be broken down, neutralised and stored by microorganisms, fungi and plants … the environmental value of these natural decontaminants should not be taken lightly.
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Brownfield land is full of contradictions. On the one hand, many wildlife-rich green spaces in our towns and cities are, ironically, brownfield. They provide the green networks on which these conurbations depend. And on the other, brownfield is far from an exclusively urban phenomenon.
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There are countless brownfield sites … that may never become protected nature reserves, yet nonetheless are important refuges … landfill sites, scrapyards, car parks, skip depots, industrial estates and gravel pits.
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in Britain, some species now depend on the ‘surrogate’ habitats provided by brownfield sites … shrill and brown-banded carder bees … both species of bee now depend on brownfield in the Thames Gateway
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the last outpost of the silver-studded blue butterfly in the Midlands is a disused airfield at Prees Heath Common … the concrete runway, too expensive to remove, protects colonies of black ants that in turn protect the silver-studded blue caterpillars.
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brownfield sustains as many Red Data and nationally scarce invertebrates as ancient woodland.

Dereliction is not the sole qualification for brown field land. Many other places don’t fit the official definition, because they are functioning as intended: railway-line cuttings and embankments, motorway verges, canal towpaths, retail parks and the open spaces backing onto housing estates and enterprise zones … because they are urban or industrial, they are still lumped together as brownfield, and all are of unintended wildlife importance.
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Asphalt and piles of bricks are equivalent to heat-retaining heathland for basking slow-worms and common lizards. Warehouses and towers are like cliffs to nesting peregrines and kestrels. Railway ballast supports plants adapted to growing on limestone.
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disturbance opens dormant seeds in the soil and gives the ‘seed rain’ falling from the air a chance to germinate. Moreover, in brownfield land not used for food production or recreation, there is little or no exposure to herbicides, pesticides, fungicides and chemical fertilisers.

The importance of small, inter-connected wildlife havens is very noticeable, and brownfield clearly contributes much to this.

Here in west London we are lucky. There is a string of open green land running from Richmond north-west through Ealing, Harrow and Watford right out to the farmland beyond the M25. No one piece is more than about half a mile from the next, even if that next piece is only a range of large gardens or a brownfield area. And it is especially noticeable the extent to which birds use these green corridors — a definite SE-NW axis to bird flights is noticeable from my study window.

We do not need more office bocks or airports. We need all the open space we can get, even if that is scrubland, bushes and hedges. Although trees and meadows are just as valuable. Planners please note.

That cheeky chappie of British cities, the House Sparrow is under threat. This much we knew. Numbers have been declining for some years, although the population around us having fallen some years back is now quite healthy again. But scientists are still trying to work out the cause of the decline.

Following up on this, and some recent research, there was an article in the Autumn 2012 issue of BBC Wildlife magazine. The article doesn’t appear to be online, so I bring you a few salient extracts.

The cockney ‘sparrer’ is falling quiet in our cities — and one problem may be too much noise.
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a small, but significant, difference in the chances of their chicks fledging — 21 percent tor those in a noisy area, but 25 per cent for those elsewhere.
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[Research suggests] noise interferes with communication between the patent birds and their offspring, which as a result are fed less often.
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a shortage of invertebrate food in the sparrows’ diet limits nestlings’ chances of survival.
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chicks raised in areas with high nitrogen dioxide levels — ie. close to busy roads — fledge at lower weights.
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Despite its position on Britain’s Red List of threatened species, the house sparrow is not rare — though it has declined, there are about 6 million pairs in the UK.
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Sparrows connect city-dwellers with nature
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the downturn has been rapid. Over 15 years between 1983 and 1998 … sparrow numbers dropped by 90 per cent in one Edinburgh park.
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the drive to renovate buildings and tidy up parks is more significant, depriving urban sparrows of places to nest, feed and take cover. Sparrows and other birds like bits of green space, evergreen cover, bushes … But we have lost a lot of scrub from parks in recent decades.
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house sparrows are more likely to thrive in areas of high social deprivation, either because buildings are in poor repair or because gardens are less manicured, improving invertebrate and seed productivity
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lead-free petrol has even been cited, with the additive MTBE being blamed for killing insects. Cats ate significant predators of house sparrows. Rising numbers of feral pigeons could be transmitting increasing levels of disease.

I don’t agree that domestic cats are the problem everyone makes out. Yes they do kill birds — so do sparrowhawks, kestrels, magpies and crows — but in my experience not that many. And in any event they are generally taking the weaker (who may have perished anyway), thus allowing the stronger a better chance of survival.

But the real lesson for me from this is that basically we don’t know. Or perhaps more accurately, there is no one factor for the decline, but many interrelated factors.

Our sparrows have bounced back despite a decrease in the number of easily accessed roofs in which to nest. But it is noticeable that they inhabit a small cluster of gardens, including ours, with a higher than normal number of bushes, hedges and trees. So the point about cover is well made. They like bird feeders too as they provide easy food, when the Greenfinches and Parakeets can be elbowed aside.

I like sparrows. There are days when you open our front door and all you can hear is three dozen sparrows all going cheep, cheep, cheep! Our front garden hedge is their local village pub. And that’s good.