Mike Connor visited the same park for 40 years. His notebooks are invaluable

In 1985 Uluru was handed back to the Anangu traditional owners; Neighbours premiered; treasurer Paul Keating warned Australia risked becoming a "banana republic"; Kate Bush released the masterpiece Hounds of Love; and in the Melbourne suburb of Bulleen, chemical engineer Mike Connor began visiting a new park. He was 41 and he had recently moved to the area.

"The park wasn't a particularly attractive environment, it was just old farmland," Connor says. Nevertheless, he liked being outdoors. He also, for reasons he can't explain, liked to make lists: "I've always just kept a list of what I've seen and what I've done."

Returning from his walks, Connor would list the birds he saw in Birrarrung Park. He'd loved birdwatching since his childhood in England, where he spent bouts of chronic bronchitis indoors, watching birds outside his window.

As the years, and the bird lists, began to add up, Connor didn't realise he was incidentally chronicling a changing environment and contributing to science.

'Extraordinary' observations

Such long-term observations are "immensely valuable", says Emeritus Professor of Ecology Andrew Bennett, but they are scarce. They can reveal population changes of animals in response to climate change and habitat loss, and disturbances like fire, logging and introduced predators.

Connor saw vegetation return slowly after drought, how wetlands morphed during floods, and he stuck around long enough to see a patchy forest emerge from revegetated farmland along the bends of the Yarra River. (When Connor tells people he meets in the park that the forest around them used to be farmland they're often incredulous.) And he recorded 153 species of birds across more than 800 visits to the park over 40 years.

When Connor wrote to Bennett a few years ago about a study on noisy miners, a native species known to harass smaller birds, Bennett was astounded to discover his decades of observations.

"What is extraordinary in this situation is having observations by the same person, not a series of different observers, in the same park, for such an extended period," the La Trobe University professor says. "In my experience, I've not previously come across such a sustained duration of regular observations."

Together they collated and analysed Connor's records and recently published a paper with their findings. "Some [bird] species declined and disappeared, new species became established, others came and went as conditions changed, and a steady stream of rare birds passed through," they wrote in The Conversation.

They contend that large urban parks, such as the one Connor visits, have high conservation value and such long-term observations provide important insights that might otherwise be overlooked.

Something new

Connor is never bored retracing the same path. As a scientist "you're always looking for change and the reasons for change," he says.

When he talks about the microbial communities he used to study for work, he becomes animated, as if he's back in the lab, seeing a normally imperceptible world appear under a microscope: "It's just fascinating to see how the world works and how everything interacts with everything else."

Visiting the same park for four decades is no different. You'll always see something new, he says, while observing a man in the park filling a crate with twigs and small logs to take home — something he swears he's never seen here before.

Now, Connor walks through the park with the careful, deliberate gait of an octogenarian. As he talks to the ABC, he's constantly interrupted by birds. There are sulphur-crested cockatoos, magpies, noisy miners ("not my favourite bird", he says, scathingly), rainbow lorikeets, and a white-faced heron.

The 81-year-old still writes down the birds he sees, but hearing loss is limiting his birdwatching ability.

One day soon, he says, he'll no longer live close to the park. "We'll have to downsize," he says, "but we're trying to postpone that".

He hopes other citizen scientists will carry on. Not just here, but everywhere. He's especially concerned that more attention be paid to invertebrates. He says we need to know what's here, before it's potentially lost forever.