The mysterious death of a penguin at Germany's Dortmund Zoo has prompted a probe, police said Tuesday, in the latest case of an unexplainable animal death or disappearance at the zoo.
The zoo had informed police on Monday that three Humboldt penguins had gone missing, before later finding one of them "dead with injuries" in the flamingo enclosure.
The death comes just weeks after a sea lion was mysteriously found dead in its enclosure.
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The other two penguins remain missing, said police, adding that they were investigating if there had been a "theft of the penguins or whether there had been a violation of the animal welfare act".
At the same time, officers have not ruled out the possibility that the birds simply escaped.
The zoo said it would carry out an autopsy on the penguin on Wednesday, but the latest disappearances came just weeks after a sea lion was found dead in its enclosure.
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"This is one in a series of similar incidents this year," the zoo said in a statement.
Three pygmy marmosets -- the world's smallest monkeys -- and two dwarf agoutis -- a type of rodent -- were stolen in August, the zoo said, adding that it had since installed security around the clock.
In early November however, the 21-year-old sea lion was found dead, with a zoo autopsy finding that it had been severely beaten in the head.
The zoo believe that an intruder beat the animal to death, but police have ruled this out.
Penguins! Unlike the dodo, this flightless bird has figured out how to make a go of it, capturing our hearts into the bargain. With winter well underway, and a historic blizzard pummeling the east coast as we speak, what better time to chill with some pictures of penguins? Enjoy these amazing creatures!
Once waterbound, penguins are fantastic swimmers that can zoom through the ocean at some 15 to 20 miles per hour.
There are 18 species of penguin, ranging in size and even color.
Sometimes they're blue.
Some penguins receive checkups from tiny robot penguins. This remote-controlled fake penguin's job is to read radio tags placed by researchers on actual penguins.
A penguin couple holds hands, or flippers. Penguin couples are monogamous during mating time.
It can vary a bit by species, but wild penguins can live from 15 to 20 years or so.
Emperor penguin siblings take in the scenery. The Emperor is the largest species of penguin. When these two grow up they'll weigh around 75 pounds and stand about 3 feet 7 inches tall.
Emperor penguin chicks will begin to fledge once they hit about half their adult size.
This nest has a mouth to feed. Penguins eat krill, fish, squid and other types of marine life they can fetch while underwater.
This African penguin, found on the continent's southwestern coast, is also called a jackass penguin, although it won't answer to that name.
Penguins are quite nearsighted when on dry land. It's underwater where their vision really steps it up. There, they can really hone in on the colors of the ocean such as blue or violet. Such eyesight helps them avoid being eaten by killer whales or leopard seals, their chief predators of the deep.
King penguins, that is. They're the second-largest penguins, after the Emperors.
Penguins do enjoy a crowd. The Southern hemisphere wins the penguin population census. It's tempting to think penguins mostly hang out in Antarctica, but they're actually all over the lower half of the planet, and further north than you might guess. From islands in the South Pacific, to Australia, New Zealand, South America and South Africa, you can find penguins making a living. There are even three species that call places as far north as the Galapagos Islands home.
Should this gang on the ferry ride decide to go for a swim, they could stay underwater for about 15 to 20 minutes and go as deep as nearly 300 feet (91 meters).