It was hardly a surprise to hear the mighty roar of a lion at the Indianapolis Zoo. Chances were it was just Nyack, the zoo's "very vocal" 10-year-old male African lion.
But an "unusual amount of roaring" last week prompted the zoo's animal care staff to rush to the outdoor lion yard and investigate, Reuters reported, citing a news release from the zoo.
Upon arriving, they discovered a primal scene.
Nyack was locked in a fierce battle with Zuri, a 12-year-old lioness and the mother of his children - and he was losing.
"She had Nyack by the neck," the zoo's curator David Hagan told Reuters, describing the Oct. 15 attack. Attempts were made to separate the pair, but Zuri held on until Nyack stopped moving, Hagan said. A necropsy revealed the lion had died from suffocation due to injuries to his neck, the Indianapolis Star reported.
The sudden attack, which happened before the zoo was open to the public, has left staff and lion experts completely baffled: Why would a female lion attack a male she was not only familiar with but who also fathered her cubs?
A definite reason may never be known, but lion expert Craig Packer, director of the University of Minnesota's Lion Center, told The Washington Post that Nyack's death may be linked to his "unusual relationship" with Zuri.
"She apparently dominated him for the whole time they were together," Packer said. "That in itself is almost unheard of."
He added, "I've never heard of a female that was that dominating of a male, ever."
For eight years, Nyack and Zuri coexisted without incident and had "done really well together" during that time, Hagan told WIBC. "We don't know what the precursor to the fight was," he said.
In a Facebook post announcing Nyack's death on Friday, the zoo wrote that it will conduct a "thorough review to attempt to understand what may have led to this." Zuri and her three cubs, one of whom was present during the deadly clash, are all OK, the post said.
Zuri will remain at the zoo, WIBC reported. According to Reuters, there are no plans to change how the lions are being managed.
Part of the zoo's efforts to figure out what happened included calling Packer, who has extensively studied lions in the Serengeti. He described the attack as "surprising" and "so unexpected."
"They called me because they were puzzled, and I agree it's puzzling," Packer said. He added of the attack, "It was completely unprovoked and it was certainly not typical."
Zuri killing Nyack is bizarre for two reasons, Packer said: He was the father of her cubs and she engaged him one-on-one.
Though the details of the incident are shocking, female lions attacking males is not unprecedented. In September, video footage showed a pack of lionesses attacking a male lion at the West Midland Safari Park in England, the BBC reported. That lion had been introduced to the pride only last year, according to the BBC.
In the wild, Packer said he has also observed females attacking a nomadic male, but only in an attempt to chase the "strange" lion away and protect their cubs. They might be trying to harm the male, but the intention is not to kill, he said.
Sukari, the lions' 3-year-old daughter, was in the enclosure during the attack and Zuri is described as an "attentive and protective mother," who is usually keeping an eye on her cubs, according to the zoo. But Packer said Sukari did not appear to be "at risk from anything."
Rather the incident, he said, may stem from the "unusual combination" of a "meek male" and an "all-powerful female."
"I don't usually associate this kind of personality with a female lion," he said. "The fact that it developed at all is fascinating."
Nyack was described by the zoo as "laid back." Zuri, however, was "large and very dominating," Packer said. According to the zoo, Zuri only weighed 25 pounds less than Nyack.
Male lions are usually much larger than females and more aggressive, and "being next to a large male is like living next to a keg of dynamite," Packer said.
"The females will be annoyed with the males sometimes and will kind of swat at them, but they're pretty careful not to provoke them too much," he said.
That did not appear to be the dynamic between Nyack and Zuri. Given Nyack's meekness, Packer said it was likely Zuri didn't receive the "usual pushback from the male that would be normal in this species," which in turn allowed her to exercise dominance over him.
"Apparently, the male was always very subordinate to her, which is totally strange," Packer said.
During last week's brutal fight, Packer said Zuri attacked Nyack twice. The first time, Nyack managed to escape, but Zuri followed him, he said.
"It was the second time that she got him that she seems to have crushed his throat," he said.
Nyack's death left the zoo's staff devastated, Hagan told Reuters. On social media, many who visited Nyack shared photos and paid tribute to him.
"My heart is broken," one person wrote on Facebook. "He was the best part of the zoo."
Another user reminisced about going to the zoo early in the mornings just to hear Nyack roar.
One person shared a photo of Nyack "calmly" leaning against the glass of his enclosure just days before his death. Zuri was laying just a couple feet away and "all seemed well," the person wrote.
Packer said it still remains a mystery why Zuri only attacked recently, adding that animals are "very unpredictable."
"The female just seemed to be having a bad day," he said.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)