A rare antelope died after choking on a plastic cap from a squeezable pouch at Bright Zoo in Tennessee over the weekend.

Leif, a Sitatunga antelope, was in his enclosure on Saturday when a zookeeper was conducting a routine check and noticed the animal was "acting odd," zoo director David Bright told CBS News. Fluid was leaking from the antelope's mouth and the keeper immediately called in the veterinarian team to dislodge the plastic cap. 

But, "The team couldn't do it in time," Bright said.

Bright said the privately owned zoo, which specializes in exotic animals, conducts bag checks for visitors as the zoo does not allow squeezable pouches, among other items.

"The reason is simple - the packaging is dangerous to our animals," the zoo said on its social media page. "If you look at these lids from an animal perspective it looks like food. This is what forced us to do bag searches but yet some people find ways to sneak these in. Guests are able to go to their car or the picnic areas in our parking lot as many times as they wish and re-enter the zoo."  

Bright said since the news of Leif's death became public, people have mostly been supportive but no one has come forward with information about how the cap landed in the enclosure. 

"I would respect the person more if they came forward and took responsibility," Bright said, adding that not knowing exactly what happened or who did it makes it worse.

Bright said the cap "had to be thrown," as there was no other way it could have landed inside the enclosure that was housing Leif, his female mate, and several other animals.

The young antelope was known for his calm demeanor and the zookeepers used to joke that he "liked to be in your pocket," Bright said. He would follow the keepers around during feeding time and often let them touch him. This was markedly different from the other wildlife, Bright said, which tended to be skittish and timid.

Since Leif's death, his mate has been wandering around looking for him, bewildered at his absence, Bright said. The antelope was 7 years old, and would have turned 8 on July 30, Bright said. The antelope could've lived to be 20 or 21 years old, and Bright said he had "plenty of life in him yet." 

In addition to the Sitatunga antelope, a swamp-dwelling animal distinguished by its long splayed hooves, the zoo is home to an addax, bongo and scimitar oryx.

In:
• Tennessee

Cara Tabachnick

Cara Tabachnick is a news editor at CBSNews.com. Cara began her career on the crime beat at Newsday. She has written for Marie Claire, The Washington Post and The Wall Street Journal. She reports on justice and human rights issues. Contact her at [email protected]