As a result, more old hens are showing up at animal shelters, where workers increasingly respond to reports of abandoned poultry.
"The numbers are exploding. We had hoped that the fad had peaked and maybe we were going to get a little bit of a break here, but we haven't," said Mary Britton Clouse, who operates Chicken Run Rescue in Minneapolis.
In 2001, she had six calls from people seeking homes for abandoned chickens. That rose to nearly 500 last year, said Clouse, who takes animals from the city's animal control department and works with local humane groups to place unwanted birds.
As winter approaches the number of abandoned chickens rises, Clouse said: "The summer fun is over."
Chickens begin laying eggs where they're 4 to 6 months old and are most productive for about two years, University of Wisconsin poultry specialist Ron Kean said. Egg production drops off significantly after that, but the hens can live another decade or more.
Urban chicken populations have been on the rise since the mid-2000s, championed by people who wanted to know where their eggs came from and whether the animals were free-range and hormone-free. It's unclear how many people have backyard chickens and there's no official count of the number of cities that have approved chicken-friendly ordinances.
Clouse said the problem worsened around 2007, and her organization and others began pleading with cities to either deny requests to allow backyard chickens or to budget for regulation, inspection of coops, and enforcement of animal cruelty laws. It didn't slow the trend.
"What you've got are all these people who don't know what the hell they're doing. They're sticking these birds in boxes the size of battery cages in their backyard," said Clouse, who like many opponents of keeping urban chickens advocates a vegan diet.
Many backyard chicken keepers build or buy elaborate fence-enclosed houses with elevated nesting areas to make the chickens feel safe. Some communities, including Madison, offer tours to show off chic coops.
Aside from the eventual drying up of egg production, there are a number of headaches that backyard chicken farmers may face.
Feed, shelter, litter, and veterinary bills add up, and chickens are vulnerable to predators and must be in a secure shelter. Their feed can attract rodents, and chickens can contract parasites requiring veterinary care.
Plus, there's always the chance that a baby chick turns out to be a rooster.
Most cities don't allow roosters because their crowing is a nuisance, but determining the sex of a baby chick isn't easy. Kean said about one in 20 chicks turns out to be a rooster, a surprise that he thinks is a bigger problem than the unwanted elderly hens.
The U.S. Department of Agriculture said it's seeing an increasing number of requests for data and is considering a nationwide survey of cities to see how many permit them. In April, the agency published a report on urban chicken owners in Denver, Los Angeles, Miami, and New York, finding 1.7 percent of Miami residents had their own flocks, followed by 1.2 percent in L.A. and less than 1 percent in the other two metropolitans.
The survey results mirror what observers anecdotally say occurs in cities that pass local ordinances allowing chickens — small numbers of people actually get birds. Kean said the issue of abandoned chickens, while real, is often overstated by animal rights activists.