Toga, a 3-month-old jackass penguin, is believed to have been snatched Saturday from a pen at the Amazon World zoo, on the Isle of Wight, in southern England.
Veterinarians estimated the foot-high, brown-and-white penguin would survive only five days away from his parents because it refuses to be fed by human hand.
"I am very pessimistic. I think we have lost it, it has been too long," zoo owner Derek Curtis said.
An $8,750 reward has been put offered by local businesses and well-wishers for the return of the flightless bird, prompting several reports of sightings—none of which have been confirmed.
Zoo manager Kath Bright previously said she feared Toga had been stolen as a quirky Christmas gift, due to increased public interest in the creatures following the recent hit film "March of the Penguins." She has said he was far too small to have escaped from his enclosure on his own.
Toga is too young to have yet had a gender confirmed but traditionally is referred to as a male, she said.