Professor Darryl Jones is an urban ecology expert and a bird feeder. That combination is incredibly unusual in Australia.

"The predominant advice is generally to avoid feeding birds," Professor Jones said.

"But, since I started investigating this, I've turned my views completely around."

It all started with magpies.

When trying to quantify the types of things that urban magpies were feeding to their chicks, Professor Jones found that he could not identify everything that was being brought to the nest.

The Brisbane-based ecologist tracked the magpies around his neighbourhood and found that they were being fed mince, salami, cheese, diced heart and even steak by local residents.

"We had no idea it was happening to such an extent," Professor Jones told the ABC's Off Track podcast.

"And at the time, like everybody else, I thought, 'Everybody knows you don't feed birds, it just can't be a true thing'."

This sparked a social science survey on bird feeding habits, and the results surprised Professor Jones.

The study found 35 per cent of Australian households spent money on buying food with the specific intention of feeding birds in their backyards.

"Feeding birds is absolutely normal and extremely popular around the world. The only place in the world where it's opposed anywhere is in Australia, yet the proportion of people feeding the birds is about the same," he said.

The bird feeding industry in Australia is nowhere near as developed as it is the USA where, Professor Jones writes in his book, The Birds at My Table, the total annual value of feeders and seed is something like $4 billion.

But it wasn't even the overwhelming amount of bird feeders worldwide that convinced Professor Jones to start putting out seed.

Darryl's golden rules for bird feeding: 1. Cleanliness. Sweep up any left overs and spray with a mix of water and vinegar. Dry and then place new feed. Do this daily. 2. Provide a Snack. Not a meal. Just a little bit of food goes a long, long, way. 3. Never feed birds away from your home. Professor Jones' enthusiasm for bird feeding stops at the front gate. Feeding bread to the ducks and swans at the park is a definite no-no. 4. Enjoy – because really, you're feeding the birds for yourself, not for their benefit

"We moved into a new house that had a feeder already established," he said.

"Within the first couple of weeks I soon realised that all the rainbow lorikeets and magpies and things that were hanging around and looking through the window — they were trying to tell me something.

"So, I became a feeder."

Unexpectedly, Professor Jones found joy in feeding the birds, even though many colleagues admonished him for taking up the hobby.

More than that, Professor Jones has now become an activist for the cause of feeding.

"As long as you are keeping your feeder clean, you're not feeding too much and you're feeding healthy foods, there is nothing to do but enjoy yourself," he said.

'Changing the shape of the wildlife community'

"[Bird feeding] is a really important topic. It's important because of the potential impact we're having. It's important because we're genuinely changing the shape of the wildlife community that lives in the city with us.

"These things we must not shy away from — if you are hosting people coming to your place to feed, you don't allow them to go away sick. You are really, really, careful about how nutrient wise the food is and how clean the plate is. The same goes for birds."

There are documented cases in the USA and in England of bird diseases spreading via bird feeders.

Professor Jones says a bird's feeder intake is "just a top up on what they might eat in a day". ( ABC Open contributor Chris J )

"Thirty per cent of the greenfinch population declined over about a five-year period because of a disease that went through them, all because of feeders [in the UK]," he said.

"Really, one of the most important things is keeping the feeder clean," he said, adding that the idea of the birds developing a dependency on the seed you put into a feeder is a fallacy.

It's actually one of the main arguments against feeding birds from your backyard, whether it be seed eaters like lorikeets or meat eaters like magpies.

Opponents of feeding say that if you feed birds they will forget how to forage for themselves. Then, if you go away on holiday, they will starve.

Sorry, this audio has expired To feed or not to feed

Professor Jones said there was no scientific evidence of dependence except in very extreme cases.

"The standard amount is around about 7 per cent of the food that a bird will acquire in the day, will be acquired at a feeder," he said.

"It's just like a cup of tea and a Tim Tam with a visitor — just a top up on what they might eat in a day, a treat."

Using bird feeding to atone for sins

Almost all feeders say they are motivated by their love of birds and that they get enjoyment from the practice.

Some people, said the Professor, are even drawn to the practice of bird feeding to atone for the perceived sins of humanity.

That is, to make one small gesture of love to their environment in contrast to the broad-scale destruction of habitat in the world.

"This is a seriously profound experience. This is the best way for them to interact with nature," he said.

"This is absolutely important for those people that feed."

Given the very small amount of food that birds take from the feeders and the very great impact they have on the human lives, Professor Jones has come to a surprising conclusion about the trays, tubes and carefully scattered seeds of the world.

"We think our feeders are for the birds. Our feeders are actually for us, but the birds don't seem to mind," he said.

"They continue to willingly bring their lives into our own, and so offer us wonder, hope, knowledge and pleasure."

Watch Darryl's bird feeder streamed live here from February 5 until February 7.