The Calgary Zoo's investigation into the Feb. 11 death of an otter named Logan revealed that he drowned after becoming fatally entangled in a pair of pants, which he was given to play with by staff members, according to the Telegraph. The Canadian zoo called the error "unacceptable" since it claims the pants were an "unauthorized enrichment item," according to the Atlanta Journal Constitution.

Animals are usually given toys and objects that allow them to "problem solve, play, experience new tastes [and] keep them mentally enriched," with each animal having its own approved list of items that keepers should not deviate from, according to comments made by the Calgary Zoo on Facebook.

The zoo's general curator, Colleen Baird, refused to reveal how the pants ended up in the exhibit, citing "human error."

"It's irrelevant how exactly the pants got in there, it's more that the pants got in there in the first place... We take animal deaths very seriously," said Baird, according to the Calgary Herald.

Logan's death is the latest piece of bad publicity for the zoo, which has come under fire over the years for the number of animals that have died in unusual circumstances, according to CNN. A penguin died after swallowing a stick in 2013, and almost all of the stingrays put into a new exhibit in 2008 suffocated as a result of poor water quality. Most famously, a polar bear named Misty passed away in 1999 after having been prescribed Prozac, according to CBC News.

In its statement on Facebook, the Calgary Zoo referred to its animal care protocols as "the most stringent in the industry" and said the staff members responsible for Logan's accident have been disciplined but not fired. The zoo also stated that training regarding animal protocols will be given to the entire staff "to prevent an incident like this from ever happening again."