The Moth Snowstorm: Nature and Joy (16 page)

BOOK: The Moth Snowstorm: Nature and Joy

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And Denis had a candidate for what might be killing off the insects in towns and cities like London: motor vehicle pollution, and specifically, the introduction of lead-free petrol into Britain, in 1988; for not only did that represent the major change in the composition of vehicle exhaust fumes in previous years, but there was also a strong temporal correlation between the introduction of unleaded and the sparrow decline itself (as a couple of canny readers had noticed, in our initial trawl of ideas). At first, unleaded sold in only tiny amounts, but sales picked up rapidly during the nineties, leading to the complete phasing out of leaded petrol at the end of 1999, and the uptake clearly paralleled the London sparrows’ demise. It was the substitute chemicals added to the petrol to replace the lead and reboost the octane rating, Denis believed, which might be causing the problem, and he focused on two additives in particular: benzene and MTBE (methyl tertiary butyl ether), both of which had health and safety question marks against them. He accepted there was no scientific evidence as yet linking MTBE or benzene directly with house sparrows, but he thought that the circumstantial evidence of a connection was strong. Hence he took the view: ‘This is my hypothesis – what’s yours?’

It was intriguing, and a potentially devastating example of the law of unintended consequences. Unfortunately, it was a hypothesis that was very hard to test, as although a highly specialised agricultural research station like Rothamsted might be uniquely equipped to measure insect biomass on farmland, nobody at all, as far as I could find out, was measuring insect
biomass in towns and cities; it was seen as a near impossible job, and anyway, what would be the reasons to fund it? So you simply couldn’t tell if the aphid population of St James’s Park, say, was plummeting. I also felt there was a gaping hole in the theory: New York and Washington had unleaded just as London did, and Paris had
sans plomb
– so why weren’t their sparrows disappearing in the same way?

Yet Denis’s instinct that the proximate cause of the decline might be starvation of the chicks through lack of insects was eventually borne out by a young postgraduate research student at De Montfort University in Leicester, Kate Vincent. For her doctoral thesis, Kate put up more than six hundred sparrow nest boxes in the Leicester suburbs and the adjoining countryside, and monitored them for three years, closely observing the birds’ breeding success. (I visited her and watched her gamely clambering up and down her ladders.) Her finding, in 2005, was remarkable: that in the summer, completely unseen by the outside world, considerable numbers of sparrow chicks were starving to death in the nest, and the closer towards the centre of town the nest was, the higher the mortality. Furthermore, those whose diet had consisted largely of vegetable matter – seeds and scraps of bread – were much more likely to die than those whose diet had contained plenty of invertebrates. (Kate worked out the chicks’ diet by analysing their droppings: in an ornithological labour of Hercules, every time she weighed and measured a chick in the nest, she collected the poo it would tend to deposit in her hand, and then, under the microscope, she could identify in it the tiny remains of insects – an aphid leg here, a beetle mandible there – and estimate their abundance.) The chicks that were dying were largely in the sparrows’ second brood of the year: Kate found an 80 per cent success rate in the first brood, but only a 65 per cent success rate in the second, and with the birds needing between two and three broods annually to maintain their population levels, this could be enough to precipitate a decline.

Eventually, Kate wrote up her findings in a scientific paper with fellow researchers from the RSPB and English Nature (then the government’s wildlife agency), and in November 2008 this was entered for the
Independent
’s £5,000 prize. However, the referees were split. The problem was that Kate’s research revealed the starvation but not why the insects were hard for the birds to find: it was half a solution. One referee said, award the prize. One said, do not award the prize. And the third said, award half the prize. In the circumstances, it did not seem possible to award it. And there, to date, the matter rests.

In early 2014 I went to Guisborough again to see Denis Summers-Smith and talk the whole issue over once more, fourteen years after we had first highlighted it. I spent two enjoyable days admiring his wonderful sparrow archive of more than five thousand items, and his collection of sparrow artefacts ranging from Chinese sparrow fans to Japanese sparrow netsuke, and we talked late into the night of such subjects as, what species was Lesbia’s sparrow? (Denis thinks it was the Italian sparrow,
Passer italiae
, which replaces
Passer domesticus
in the Italian peninsula, although the Spanish sparrow,
Passer hispaniolensis
, also occurs in southern Italy. My friend, the academic ornithologist, Tim Birkhead, basing his view on the sound it made – ‘pipiabat,’ says Catullus, ‘it used to
pipe
’ – thinks it was probably a bull-finch.) And Denis told me of how his involvement with sparrows had begun, which really dated back to 6 August 1944, when he was a twenty-three-year-old captain leading his company of the 9th Cameronians in Normandy, in the race to close the Falaise gap, and a German shell landed by him and almost took off his legs. But not quite: eight operations later he still had them, and lying in hospital in Worcestershire, he became fascinated by the sparrows which came in through the windows of the ward. When he had recovered (although with legs full of shrapnel that set off airport alarms), he began his lifelong study.

He had changed his mind about unleaded petrol and MTBE, although he still believed motor vehicle pollution was to blame for the decline of sparrows in London and other urban centres; now, however, he thought that a major cause of the decline was ‘particulate’ contamination from diesel engine exhausts (essentially nanoparticles of soot that are not filtered out in the nasal passage). This may have led directly to mortality of juvenile birds, he thought.

For my part, I wanted to discuss with him the question that continued to preoccupy me: how could the house sparrow have been ‘singled out’, as it were, for disappearance? How could it vanish from St James’s Park, say, when similar songbirds such as robins and blue tits, blackbirds and wrens, still seemed to lead satisfactory lives there?

The key fact, Denis said, was that sparrows did not disperse.

I asked him what he meant.

He said: ‘They live in a small area, which they get to know very well. They spend their lives within a kilometre. They are completely sedentary, the most sedentary of all passerines. But other small birds, like blue tits or chaffinches, are unable to do this; when they leave the nest, they have to disperse. They have to move considerable distances away, to find food or new partners.’

And how did that relate to the situation in St James’s Park?

Denis said: ‘If the sparrow population in St James’s Park dies out, it will not renew itself, because no new birds will come in. But if the blue tit population dies out, other young birds, which are dispersing, will arrive.’

The implication started to dawn on me.

I said: ‘So is it possible, then, that what went wrong in the ecosystem . . . what made the sparrows die out . . . is actually affecting all species? But the other species, because they are dispersers, are able to renew their populations . . .’

Denis said: ‘Yes.’

‘But we can only observe the effect in sparrows, because the sparrows are the ones that can’t replace themselves . . .’

Denis said: ‘This is my hypothesis.’

‘So what we may actually be looking at is a disguised devastation of all these common species?’

‘Yes.’

I was dumbfounded. ‘This is completely new, Denis. Nobody’s ever said this.’

‘Well I’ve been saying it to a lot of people.’

Was it possible? That
all
the birds of St James’s Park died out, or failed to breed successfully, every year? But all, except the house sparrows, could renew their populations from outside?

That we had actually witnessed something far more wide-ranging than the downfall merely of
Passer domesticus
?

I could not say.

Whatever had done it so effectively to the sparrows, and possibly was doing it without our knowledge to all the songbirds of central London, and possibly even to more organisms than that – including us – remained unknown.

We still had no idea what it was.

•

I come from the north of England, but I have lived in London for forty years and grown to know it well and love it, and when I first realised the sparrows had gone from its heart, I felt the loss as keenly as other people did. And six months after visiting Denis, while writing this book, I was suddenly seized with a desire to go out into central London and look for them, wondering if, two decades after their disappearance, any trace of them might remain.

I approached Helen Baker, who had spotted the birds’ disappearance
almost before anyone else. She had risen in the London Natural History Society and was now its president, but was as fascinated as ever by the sparrows’ fate; she was a receptacle for all the reports which surfaced from time to time, of the odd colony clinging on here and there, in quiet corners. Helen told me she thought there might be three small colonies still in central London, two of them on the South Bank, and on a hot July day we set out in search of them, meeting in the Guildhall Yard, the very hub of the old City. Helen was attending a lunchtime concert in the Guildhall church and while I waited for it to finish I watched the office workers with their sandwiches being half-heartedly hassled for crumbs by the pigeons. When I first came to London, sparrows would have been the hasslers-in-chief.

We began our South Bank search at Borough Market in the shadow of Southwark Cathedral, whose pinnacled tower Shakespeare would have eyed (the churches on the north bank all being consumed, of course, in the Great Fire of 1666). Borough Market epitomises what we might call the Mediterraneanisation of London which has taken place over recent decades – the introduction into the capital of exhilarating new foods and the enthusiasm of crowds for them and habits of eating in the open air (on a sunny day it could almost be Barcelona) – and if ever there was a place where sparrows would thrive, this was it. The local birds knew it too. But they were pigeons and lesser black-backed gulls and, I was delighted to see, a crowd of starlings; of
Passer domesticus
, there was no sign. There was no sign of him either as we skirted the replica of Francis Drake’s
Golden Hind
in St Mary Overie dock and moved up Clink Street past the medieval remains of the Bishop of Winchester’s Palace and out on to the riverbank, and the Anchor Pub. In the garden beyond the old pub, said Helen, sparrows had occasionally been seen over the previous year, and we watched and we listened for several minutes, because with sparrows you may well hear them
cheeping before you see them. The only sound was the laughter of drinkers. There were no sparrows there that day.

Helen’s second potential South Bank sparrow site was another garden, further upstream at Gabriel’s Wharf, and as we walked there I was struck by the number of pigeons, especially outside Tate Modern, the power station turned temple of contemporary art on whose soaring art deco brick tower peregrine falcons – notable pigeon consumers – roosted. ‘It pleases a lot of people that peregrines eat pigeons,’ said Helen, who explained that in the school holidays she was one of the people manning the RSPB telescope trained on the tower so that the public could observe the peregrine pair who had been named Misty and Bert. I wondered how many of the pigeons I was watching would end up as peregrine dinners; they were in the sort of numbers that sparrows would once have exhibited, hundreds and hundreds of them. But there was no sign of the sparrows; not there, not anywhere along the embankment, and not at Gabriel’s Wharf either, where we thoroughly explored the garden in which Helen had in the past counted up to forty; now there were merely sixteen pigeons on the lawn. ‘Oh, this is disappointing,’ said Helen. ‘It used to be such a very good colony. It may be that the food supply has gone. They used to nest in the houses and flats nearby. One would hear them and one would see them, going back and forth from these houses.’ Not any more.

It seemed to me that London was completely sparrow-free; for the South Bank was such a tourist trap, it had so many eating places with people sitting outside dropping crumbs, that in any other European city it would be a sparrow food resource par excellence. But there were none whatsoever. It was uncanny. It was chilling, almost. The disappearance of the birds seemed complete.

Helen had one remaining site to try, which was on the north side of the river, so we walked over Waterloo Bridge and into the West End; we wound our way into a celebrated and historic
area, and Helen said to be on the lookout, for birds had been seen in the street we were in, on the window boxes. ‘Look up, keep your eyes open,’ she said. I could see nothing. We turned into another street, a famous one, and she repeated her exhortation; I could still see nothing. Then, as we were passing a well-known Italian restaurant, I heard it: