"Just another day in the neighborhood," wrote original poster Bobby Lee, who discovered the cowbirds dining in a car-park.
But according to local animal rescue and pigeon advocacy group Lofty Hopes (yes, Vegas has a dedicated pigeon charity) the admittedly stylish accessories could have a detrimental affect on their wearers.
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"At first, I was like, oh my God that's cute!" founder Mariah Hillman told KVVU. "Then, I was like, wait a minute – how did they get those hats on there?"
"Did they glue them? And what does that mean for them?" she wondered. "Is it something that's going to impede their flight or attract predators?"
Hillman, who was joined in the interview by her daughter and their pet pigeon Edgar — himself wearing a diaper and a leash — have vowed to track down and trap the behatted birds to try and remove them humanely.
"We drove up and down here yesterday for a good two hours just handing out business cards to any location where I saw pigeons and people," she said. "If you see these birds, just feed them until I get here. I'm only three miles away and I'll come trap them."
Mariah said her team — whose slogan is "a pigeon positive movement" — previously spent two weeks tracking down an injured pigeon before nursing it back to health.
"They are basically seem as the homeless of the bird community," she lamented.