About 1,000 tiny chicks were spotted running around a field in Lincolnshire on Friday after being abandoned at just a day old.
The RSPCA has launched an investigation after officers were called to a sea of one-day-old chicks who were dumped in Crowland, near Peterborough.
Members of the public alerted the animal welfare charity to the shocking sight.
RSPCA inspector Justin Stubbs said: “I have never seen anything like it, it was just a sea of yellow. And the noise was unbelievable.
“The chicks are only about a day old and are really tiny and quite delicate. Some of the birds were dead or dying when we arrived so some, sadly, had to be humanely put to sleep.
“Thankfully, most of the chicks did not appear to be suffering.”
It is believed the chicks came from a commercial chick producer nearby and may have been abandoned by a third-party.
The producer is cooperating and assisting the RSPCA with their investigations, the animal welfare organisation said.
“The breeder came to the scene to collect the surviving birds and take them back to their unit,” Stubbs added.
“These tiny birds wouldn’t have survived long out on their own at such a young age and in such unpredictable weather conditions.
“For someone to dump these vulnerable chicks is unbelievable.
“But I’d like to thank all the members of the public who teamed together to help us round up all the birds and confine them in boxes where they could huddle together for warmth.”
Anyone with any information about who is responsible for dumping the birds is asked to contact the RSPCA’s inspector appeal line on 0300 123 8018.