A bird-napper could be on the loose with some very valuable cargo.
Somebody apparently snatched a Humboldt penguin from its cage at a zoo in southwestern Germany, police concluded Monday, warning the bird could easily die if it's not returned soon.
Zookeepers at the Luisenpark in Mannheim noticed the penguin missing during a routine count Saturday of the South American birds -- about 20 in all, Deutsche Welle reported.
After a search of the grounds, zoo personnel found no signs that the flight-less penguin escaped or was attacked by another animal -- so police said it was stolen.
"We hope that the perpetrator's common sense prevails and that he quickly gives back the penguin," a police spokesman told the news agency.
Still, cops said the penguin had some identifying characteristics that could give it away. The bird had a chip implanted in its body and a number 53 on its wing.
The bird measured about 20 inches tall and weighed roughly 11 pounds, according to zookeepers.
Zookeepers were pleading for the return of the bird, saying that without its special diet and controlled environment it may not survive.
The Associated Press contributed to this report.