"It is common in these situations where you have urban ponds because it messes up their normal ecosystem," Mr Mills said.
"Bread is like junk food and like junk food it can cause nutritional problems."
An excess of it also created long-term problems for the birds as they eventually lost the ability to forage naturally for themselves - as their cousins in the wild do.
"And they don't pass on those food-finding skills to their young."
The illnesses the birds developed through excessive bread also meant they were often unable to forage even if they wanted to.
As well as digestive and nutritional issues, they often developed "angel wing" where there wings would arch out, appearing to be broken.
And as they spent much of their lives on often unhygenic ground and abrasive surfaces like paths and parking areas, they developed "bumblefoot" after abrasions to their feet became infected.
Mr Mills saw for himself the amount of bread being dished out to the birds during the mission to round up the most seriously affected birds.
"There was bread lying everywhere uneaten - they were all full."
While it was not a time for finger pointing "because we've all been guilty of it at some stage", it was a time for pond visitors to consider what they were feeding the birdlife, and how much of it was being used. He suggested chicken feed as a better, healthier alternative.
They took away several ducks for treatment and rehabilitation, and Mr Mills said if the infections and illnesses were at a low level they could be treated. Some however would face euthanasia if they were clearly suffering severely.
"Sadly the damage is already done for a lot of them," Ms Flynn said, adding that while signs had been put up to advise people to hold back feeding bread it was too late for many.
Mr Mills said the birdlife at the park would continue to be monitored and more rescue and recovery missions were likely.
"We have some good eyes down there that keep us informed and Liv is there regularly and we are there to support what she is doing."
