Alabama prisoners who have been on strike for 10 days over unpaid labor and prison conditions are accusing officials of retaliating against their protest by starving them. The coordinated strike started on May 1, International Workers’ Day, when prisoners at the Holman and Elmore facilities refused to report to their prison jobs and has since expanded to Staton, St. Clair, and Donaldson’s facilities, according to organizers with the Free Alabama Movement, a network of prison activists.

Prison officials responded by putting the facilities on lockdown, partially to allow guards to perform jobs normally carried out by prisoners. But prisoners told The Intercept that officials also punished them by serving meals that are significantly smaller than usual, a practice they have referred to as “bird feeding.”

The Alabama Department of Corrections did not respond to multiple requests for comment, though earlier this month they told local reporters that inmates had “not given any demands, or a reason for refusing to work.”

Prisoners told The Intercept they are protesting severe overcrowding, poor living conditions, and the Thirteenth Amendment of the U.S. Constitution, which bans slavery and servitude “except as a punishment for crime,” thus sanctioning the legality of forced, unpaid prison labor. Prisoners said they have voiced their requests in meetings with prison officials but were told their demands were “too great.” Last month, after riots broke out at Holman prison twice in four days, prisoners also circulated a list of demands, including federal assistance, the release of inmates who are eligible for parole, and compensation for “mental pain and physical abuse.” They are planning to circulate an updated list today.

A prisoner serving a life sentence at Holman prison shared photos of his meals in text messages over the last several days. One picture shows a meal made of two slices of white bread, cereal, a slice of yellow cheese, artificial sugar and a brown sauce the inmate said was prune stew. Another meal was made up of two slices of white bread, an apple, and an unrecognizable white mixture wrapped in plastic.

The inmates said they were not complaining about the food itself, but about the very small quantities. “It’s only an issue when the deprivation of any necessity becomes a weapon used against us to make us discouraged,” the man sharing the photos said, adding that officials are using the tactic to break prisoners’ resolve. Still, prisoners have refused to return to work.

“The food is a blatant violation and these violations are the reason that we even formed a strike from the start,” that prisoner said. “We r not supposed to be fed the way they r feeding us, it is not 2300 or 2200 calories that we r suppose to be getting that they have been serving us for ten days straight.”

“We r weak feeling nauseated and having headaches from the lack of balanced meals,” he wrote.