WASHINGTON (AFP) - A United States animal shelter was "in shock" after receiving more than 800 parakeets during the holiday weekend - delivered in two batches by the son of their owner who had kept them all enclosed in one room.

The Detroit Animal Welfare Group, based in the northern state of Michigan, posted on Facebook about a "Christmas present we were not expecting" - saying the "birds came from a very unhealthy situation".

It said a first group of 497 birds were dropped off on Dec 23 - crammed into seven cages. The owner's son then returned on Sunday (Dec 26) with an additional 339.

"The irresponsibility of the owner is infuriating," the group wrote on Facebook, saying the birds were "smothering each other and needed immediate help".

"We were in shock," it said, "but could not turn them away."

Working with other local organisations, the group was able to find temporary housing for the parakeets.

"It truly takes a village to help these animals," it said.

Ms Kelly LeBonty, the rescue group's director, told local newspaper the Detroit Free Press the birds "were very, very stressed".

"They were barely moving. We had to get them out and into different cages."

The son told Ms Lebonty that he believed his father had only planned to breed a few birds, but it got out of hand, and he was now spending US$1,200 (S$1,630) a month to feed them all.

The parakeets, some visibly injured or malnourished in photos posted by the group, will be available for adoption after they are evaluated by a veterinarian.

The Detroit Animal Welfare Group cautioned that "owning a parakeet is a six- to 15-year commitment."

"They require not only food, water and daily cage cleaning but also daily interaction, enrichment and flight time."

In Michigan, owners can be prosecuted for not providing adequate care to their animals.

Ms Lebonty said the group had not contacted the authorities, noting that she's happy the family took a "step in the right direction", by reaching out for help.