A blood-spattered man has been arrested after a pigeon was beheaded in Bryant Park.

Police say Daniel Dentre, 34, was arrested for trespass Wednesday after an onlooker outside the New York Public Library called to tell them a pigeon was being assaulted.

Cops arrived at about 1:45 p.m. to find Dentre at the park with blood spattered on his shirt.

After they interviewed him, Dentre admitted to "hurting" the pigeon in the park. Cops said they also found evidence of the decapitated pigeon.

Meanwhile horrified witnesses posted pictures on social media of the aftermath.

The pigeon's head had been removed. It's body lay breast-up on the ground, it's head - cleanly severed - not far from the leg of one of Bryant Park's tables set out for the public.

One Twitter user described tourists and locals alike fascinated by the incident. One was taking high quality photos of the pigeon torso and head with a DSLR camera, they said.

Dentre was arrested for trespassing because he was in the park after hours, cops said. According to the New York State Department of Environmental Conservation, it is not illegal to kill a pigeon if is it "a nuisance", although there was no indication the pigeon in this case was being a nuisance.

It is illegal to kill the bird if it has a leg band or is an Antwerp or homing pigeon.

Dentre was taken to the hospital for psychological evaluation, and it was unknown whether he would be charged.

He has no known residence and may be homeless, police said.