The poison works by lowering the birds' body temperature and causing them to lose consciousness so, in ideal situations, they can be moved and killed humanely later. But in uncontrolled circumstances they usually die where they fall.
"You can tell because they flap on their back, convulsing a lot and thrashing around - you can only imagine what it's like for the elderly people seeing that because they can't bend down and pick them up."
Kensington resident Barbara Faithfull said she found one bird dead in her driveway and her neighbour had found seven or eight.
She said it was horrible watching the birds convulse.
"Well, it was not pleasant. We were in a dilemma, we were thinking about getting water and putting it out of its misery," she said.
Mr Webb acknowledged Alphachloralose had a purpose but said there needed to be tighter controls around its sale.
"The thing that annoys me is that anyone can buy it. There is a time and a place for it, I know that, but you should have to list your contact details upon purchase."
Mr Webb said if another animal ate one of the poisoned birds it was possible it might be poisoned too. He said it was not the first time several birds had been killed by the poison.
"About three years ago there was a chap who was laying new grass and he put this poison down to stop the birds eating the seeds and hundreds of birds were dying."