RSPCA chiefs were dumbfounded after the discovery of about 1,000 chicks left in a Lincolnshire field on Friday (18 February).
The chicks, which were all roughly a day old, were abandoned near Crowland. Some were dead when they were being found, but others had to be put down.
The RSPCA said the animals may have originated from a commercial producer nearby, although they did not rule out the possibility of another party carrying out the dumping.
A video is shot using a handheld device and shows the cameraman panning around him to display the vast number of chicks scattered around the field.
A majority of the chicks are found clumped together as they seek out warmth in the winter temperatures, while others are seen hopping around individually.
It has now launched an official investigation into who was responsible, and inspector Justin Stubbs recalls witnessing "a sea of yellow" upon arrival at the field, which he called "unbelievable".
"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."
According to the Press Association a chicken breeder is fully co-operating with the RSPCA's inquiries, after it collected the chicks and returned them to its units.
"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."
Anyone who has any information on the incident has been urged to come forward and contact the RSPCA's inspector appeal line on 0300 123 8018.