"[The tree] only flowers for three to four weeks, maximum. It attracts the tui every year - it's quite a phenomenon," says Mr O'Reilly, who isn't sure why the birds behave as they do.
"They get a bit cheeky and sometimes make a hell of a row. They behave as if they are drunk and are very noisy. I've been told they get drunk, but it might be just their behaviour at this time of year.
"It's wonderful how they know to converge on this tree. The older I become, the more amazed I am with this planet."
Despite having a selection box of trees and shrubs in the garden to choose from, Mr O'Reilly says the only one that attracts the tui in such numbers is the Taiwan cherry.