IF you care about the natural world and how to protect it, Peel Street in Glasgow is a very important street indeed. It may not look particularly special when you first see it, but the clues are in the details: the hedges, the nooks in the walls, the crannies in the buildings. Together, they form a kind of network, a subtle system, a natural circuit-board. And it’s helping to keep one of Britain’s most recognisable species alive.

But the question is: will we see them? The expert I’ve come along with today, Peter James, says he’s not entirely sure how big the colony of house sparrows is on Peel Street so he can’t guarantee they’ll be around while we’re here. But, just as we’re starting to head up the street, we hear them, singing out their loud, boisterous warnings to each other. Then we see them, scooting over our heads to hide in a bush. Eventually, about seven or eight of them pop out and sit at the top of the branches to check whether the danger is over, heads flicking from side to side. Then: off they go.

Peter says he’s grown to love the birds in this colony in the last year or so. He admits that when he first started working on the Glasgow House Sparrow Project, he didn’t know that much about them. But then he got to recognise their characteristics – they’re fierce and loud and charismatic and they’re supremely good at living in colonies that exploit the scraps humans leave behind. They particularly like cities and towns and live on the streets, like Fagin’s children.

But there’s a problem. Sixty years ago, the house sparrow was the most numerous bird in Britain, particularly in big cities, but since the 1960s the population has declined by a shocking 99 per cent and Glasgow is no exception. The song of the house sparrows used to be the soundtrack of the city’s Victorian buildings, and parks, and shipyards, but slowly, the numbers fell and the volume was turned own. Now you barely hear them.

Peter, a zoology student at Glasgow University who’s been working on secondment to the Glasgow House Sparrow Project, says part of the problem is that cities have changed and so have the people who live in them. “Sparrows started to thrive in cities,” he says, “because there was an abundance of food in litter and loads of different nesting sites, particularly in the nooks and crannies of old-style buildings with the eaves that stretch out a wee bit further than they do in modern housing.

“But street cleanliness has gone up and buildings are better maintained. I think it’s unlikely that the population of house sparrows will recover to what it was in the 1960s because cities are so different.”

Peter says other factors may be at work too. “There has been a rise in the number of sparrow hawks,” he says, “although we’re not really sure if that has driven the population decline. And cats may be factor.

“A lot of residents also blame magpies and gulls and say they are causing not just house sparrows but all kinds of birds to decline. But I think there’s a vendetta against magpies – yes, they're opportunistic so they’ll take eggs if they need to, but the RSPB is doing a lot of research into these kind of birds to establish if there is a causal link between their rise and other species’ demise. Magpies will eat chicks and eggs if they don’t have food, but if there are plenty of insects, they won’t bother. We’re not finding anything definitive.”

The lack of a definitive cause for the decline is one of the problems with house sparrows and other species too: in many ways, we still don’t know that much about their lives, and there are some misunderstandings about them as well. Which is a good point in the story to give you some of what we do know. House sparrows are part of the passerine family of birds made up of small garden birds that lives in hedges and trees. The males have a black bib and eyes, grey cap and an all-grey patch on their cheeks; the females are less obvious and duller (it’s pretty much always the way in the natural world) but look out for female's eyebrow stripe and the streaked brown and black wings. Females also have paler bills than the males.

You will probably hear a house sparrow before you see one – their song is typically short, repetitive note – and the calls are usually to communicate warnings between the group. The males will also be much louder during the breeding season, which lasts from March through to late summer. When we visit the Partick colony in late August, it's about possible that they may still have young - in a good year, a breeding pair could raise three broods in a year.

Where do they live? They like to be close to humans (who feed them nuts and seeds in their gardens and drop litter now and again); they also like the cracks and holes left in old buildings but they also take very well to nesting boxes. If you’re going to put boxes up, group a few together because that’s how house sparrows like to live. They’re a gregarious species and they like to stick with their mates in the colony.

All of this means that house sparrows are tough old birds, and adaptable too. The good news too is that the Glasgow House Sparrow Project seems to have uncovered some ways to arrest their decline. The project was started in 2014 and used a network of volunteers to monitor the 121 colonies in the city, including the one around Peel Street in Partick. The exact numbers in Partick are hard to state definitely because the size of the colony fluctuates from year to year due to changes in the weather or the food supply, but typically it has around 100 individuals with 10 to 20 breeding pairs.

The aim of the Glasgow House Sparrow Project was to take a detailed look at the Partick colony and others in the city and several questions were uppermost in their minds: is the population still falling and what can we do to arrest the decline? The hopeful conclusion is that the number of birds may be stabilising. The project has also identified ways in which all of us can help.

Further along Peel Street, Peter points at one of the solutions: a big hedge outside a block of flats. House sparrows use hedges as cover from predators, and when they’re feeding, and sometimes for nesting, and the type of hedge they like is a high and dense one with plenty of gaps that they can use as entrances and exits. The hedge is a house sparrow’s fortress and kitchen and nursery – they’re absolutely vital – and as we walk along the street, we see the house sparrows flitting in and out of them.

“What we’ve discovered,” says Peter, “is that it’s not just a case of simply planting hedges, it’s about having the perfect kind of hedge. This is one of the biggest lessons we’ve learned. A hedge that’s been heavily maintained is like flying into a brick wall for a bird, so perhaps during the breeding season in the summer, people could care a little less about the aesthetic appeal of the hedge. We call it lazy gardening – people don’t have to maintain their hedges as much because it’s better for the birds.”

Peter recognises that the idea of being less neat might be a tricky message for some homeowners and gardeners to put into practice, but he says there are other things that people can do to help, like putting out feeders all year round. In the summer, about 30 per cent of the house sparrow’s diet will be made up of insects, but even then, says Peter, it is a good idea to help the birds out with some extra food in the garden.

The problem for the house sparrow is that there are fewer insects around in the summer of 2019 than there were in previous years. More than 40 per cent of insect species are declining and a third are endangered, partly because of the use of pesticides, and the knock-on effect is being felt by birds like house sparrows. One of the ways that the Glasgow House Sparrow Project has been responding to this problem is by planting wildflower meadows at ten sites across the city. More flowers equals more insects equals more house sparrows. At least, that’s the hope anyway.

The bad news is that there are some people – and it’s hard to credit this - who may be actively working against house sparrows: some building developers for example. The law as it stands means that developers can’t cut down trees or vegetation if there are birds nesting in them so what some developers have started doing is putting netting round trees and hedges to stop the birds gaining access. It has outraged bird lovers and the RSPB, which has been campaigning to put a stop to the practice.

Peter is equally horrified. “The netting is incredibly upsetting,” he says. “I don’t need to spell out how terrible it is. I saw it for myself in the news and was very disheartened by it, although thankfully, I haven’t seen any of it in Glasgow yet. It’s the wrong way to do it and cruel and it should be banned.”

The practice of netting hedges aside, Peter is cautiously optimistic about the longer-term prospects for the house sparrow. Overall, he says, the project found that 2018 was a reasonable year for the birds – the breeding was not as good as the best recorded in 2014 but it was much better than the catastrophic breeding season in 2015 when Glasgow’s house sparrows produced virtually no young at all.

“We see massive fluctuations in the breeding success of house sparrows in different years,” says Peter, “But what we do say is that in Scotland it is stabilising a little bit. We’re not sure how much it is due to our own project or whether it’s another external factor. There are still a lot of things we’re uncertain about, but the fact that it’s stabilising in Scotland is quite hopeful.”

We can see the signs of hope for ourselves in Peel Street. As we head back down the street, we reach Partick Burgh Hall and there on the railings outside are a few birds from the colony. For a while, they sit and scan the sky, then suddenly, they break out into their version of a car alarm – chirrup, chirrup, chirrup – and they’re off again. It is the klaxon of the bird world, their warning system, and it’s a kind of warning for us too: look out for the birds, protect them before they go, let them sing loud.