The public is being warned of the dangers of feeding wild deer in the Phoenix Park in Dublin.
The Wild Deer Association of Ireland says it is a growing trend, although it is prohibited, and people are feeding the animals anything from Pringles to carrots.
WDAI Director Damien Hannigan said: "They think they are actually doing the animals a favour."
The practice has become more common with pictures of people close to the deer, including children, emerging on social media sites, the WDAI says.
Aside from the potential ill-effects posed to the wild animals from inappropriate food, members of the public are also putting themselves in danger, particularly now during rutting season, Mr Hannigan said.
He is concerned the wild fallow deer are now associating humans with food.
"If you stand there and look at them and have something in your hand, they will approach you," he said, explaining that this is "only a recent trend".
In October "as the day is shortened it triggers a release of hormones within the buck and the females," he explained.
During this time the animals are "less tolerant of anything", Mr Hannigan explained.
While staff at the park have put up signs and are trying to stop the practice, but Mr Hannigan said it is impossible to fully police the biggest walled park in Europe.
He said members of the public who hand-feed deer are putting themselves and others at risk of being trampled or potentially even gored by antlers.
Mr Hannigan urged people not to leave children unattended in the park and not to feed the deer.
"The OPW recommends people keep 50 metres away, we would say further again," he advised.
The presence of dogs near deer is also a concern, he said.
"Deer will run from dogs regardless of the size of the dog, in a walled park setting with a lot of traffic in it, that is dangerous," he said.
The Phoenix Park has issued advice on its website. It reminds people that they are prohibited from touching or feeding the deer and it advises them to keep a distance of at least 50 metres.
"It is dangerous to approach the deer at any time particularly during May, June and July when the females are protecting their young and during September and October mating season," it warns.
The notice also highlights the threat posed to deer by dogs and recommends owners walk their dogs outside the park during mating and rutting seasons.
On feeding the deer, it states: "Litter and inappropriate food can seriously harm the deer and may even cause death."
Members of the public are also reminded that deer are unpredictable wild animals and can move with great strength and speed.