London's wildlife is more prolific than you think; City Hall & Tower Brudge, seen from the Monument.London, to many, is the never ending rumble and roar of planes, trains and road traffic. To me, these are the bass notes that underscore the chattering high notes of sparrows, the caw-caw of rooks and magpies; the rat-a-tats of woodepeckers and the chirping of robins. At home the symphony has the added coughing of squirrels punctuated at night by the rare bark of a fox.

All sorts of critters share London's dynamic spaces with us humans, and now we have an idea of just how much wildlife visits our gardens; thanks to the hundreds who took part in this spring's Make your Nature Count survey.  It was designed to give us some information on what's commonly outside our back doors. The full and detailed results are out this week.

At first glance, there's nothing surprising. I can reveal that pigeons are our most common London bird and we have lots of cats, foxes, squirrels, frogs and toads. Interestingly, Croydon is London's favourite hang-out for badgers, while hedgehogs fancy Harrow. The survey is also the RSPB's first to cover a period when we have summer migrants, so it's given us a snapshot of swifts in the UK. They were recently "amber listed" as a species of conservation concern.

Statistics are always tricky things and can be interpreted in different ways. It's tempting to be drawn in to assumptions based on the data, but this is just the first year and we're hoping it will eventually reveal long-term trends that reflect how birds and other wildlife are getting on. Every species has good years or bad, but if you look at data over a decade... or five, it will flag-up patterns that could show species moving to find better conditions elsewhere or an increase or decrease in numbers that may be cause for concern.

As a conservation charity we're constantly being asked, "what difference will it make to me if such and such a spider or bird goes extinct?" The answer is not always easy and occassionally the honest response is.. "we don't know." Having said that, history has shown that when one strand of nature's web snaps, the rest goes out of balance, often with disastrous consequences. China is a case in point. It's leaders decided sparows were eating too much of their seed crops. They sent people out to scare the birds in to the air and to keep them flying until they dropped dead from exhaustion. It worked and the sparrows were decimated. The following year, the locust population exploded as it hadn't been kept in check by the hungry locust eating sparrows and crops were stripped bare, resulting in serious food shortages and mass starvation.

Survey data shows us that London's sparrows, starlings and swifts are all declining in number. As are bees, many butterflies and a dozen or so plants. We need public support to continue to monitor it all. We need public support to do things that help wildlife, and we need financial support to achieve all of that. We are a needy charity.  Wildlife, particularly birds, are the first to feel the impact of environmental change. People are usually the last to feel its impact. Investing time, effort and cash in the environment is an investment in a better future.