A zoo in Poland has released video showing a small Chinese muntjac deer boldly confronting a much larger rhinoceros inside a shared enclosure.

The footage published by Wroclaw Zoo captures the deer, named Mundzak, squaring off against Marusia, a female rhinoceros weighing about 1.7 tons, as the two animals come face to face in the same outdoor paddock.

Zoo staff said Mundzak’s aggressive behavior was driven by elevated testosterone levels, as his female partner is currently in heat. Despite the vast size difference, the deer attempted to defend what he viewed as his territory.

“He needs to release his energy and show who’s boss — even if his sparring partner weighs 1.7 tons. Who would have thought that such a warrior could be hidden in that tiny body?” the zoo wrote.

Wroclaw Zoo explained that Marusia is a greater one-horned Indian rhino born in 2014 in Plzeň, Czechia. She arrived at the Polish zoo from Touroparc Zoo in France in 2019.

The zoo added that a pair of Chinese muntjacs have lived in the Terai pavilion since 2012, when the Asian fauna exhibit opened. Marusia shares her enclosure with gibbons and the muntjacs, using separate indoor areas while sharing an outdoor space.

According to the zoo, Marusia treated the encounter as play, while Mundzak appeared serious in his effort to defend territory. Keepers described the rhinoceros as gentle and aware of her size.