Predators and Prey Living in Harmony

Whether stepping into the National Aquarium's Upland Tropical Rain Forest aviary or walking by the floor-to-ceiling windows of Blacktip Reef's underwater viewing area, guests often marvel at the habitats' complexity, and the diverse species in them. Multi-species habitats at any scale are impressive, especially when visitors spot predators and prey living together. It's hardly surprising one of the most-asked questions we hear is, "How do you keep this species from hunting or eating the others?"

A Trick of the Eye

Sometimes, predators and prey living together is a matter of optical illusion. While our Animal Care and Welfare staff can keep many predatory and prey animals cohabitating without issue, others are always separated. Take the death adder in Australia: Wild Extremes, for example. It looks like it could slide over a few rocks and encounter spiny-tailed monitors or shingleback skinks in the sandy basin next door. These animals might cross paths in the Australian outback; here, though, a carefully placed window stops them from meeting.

An exhibit's design can also have other barriers keeping species apart, like water or rock features that help contain ground-dwelling or non-flighted birds, or strategically placed walls that a reptile couldn't climb.

Being Choosy About Neighbors

More often, though, there aren't barriers in our avian or aquatic habitats. In these cases, staff rely on their expertise and knowledge of the species and individual animals.

Curators are very selective when it comes to housing species together. First, they rarely, if ever, place animals that are specialized hunters together with species they could go after. (For example, the turtles in the Amazon River Forest are generalists, eating a variety of vegetables, pellets, insects and the occasional earthworm. Predators specialized to go after live fish, like mata mata turtles, would not be an ideal choice here.)

If curators do opt to put species together, they're careful. Some predators, like the Johnston's crocodile, could eat a few of the species they live with, but only if the prey are young or small. The simplest solution is to make sure potential prey, like yellow-faced turtles, are all adults when placed into the habitat. That way, they're too big to become snacks.

Even if species aren't part of another's diet, curators use an animal's temperament and behavior to gauge if it's given free rein in an exhibit. By working closely with individual animals, staff have found that species known to be territorial or aggressive can be successfully introduced to shared habitats.

Constant Awareness

Animal Care and Welfare staff are always on the lookout for signs of conflict in habitats. Proactively working to keep the peace means paying attention to every detail. They note any shifts in behavior by both predators and prey, spot and remove injured or aggressive animals, and train individuals to ensure they're fed a set diet and aren't so hungry as to eat a neighbor.

Blacktip Reef is a prime example where guests can see these efforts pay off. More than 70 species live on this artificial reef, including four species of shark and dozens of grouper and snapper—all capable of going after smaller fish.

Aquarists pay close attention while feeding, both from the surface and when on feeding dives, to make sure the smaller fish are in good condition and acting normally. Larger predators, like the blacktip reef sharks and Queensland grouper, are target trained to receive their food at certain spots in the habitat. This allows aquarists to tally every ounce animals eat during sessions and make sure the predators are sated.

While all these efforts greatly reduce the chances fish will be preyed on, it doesn't bring the chance to zero. Sharks especially look for prey that show signs of age, injury or illness and occasionally find one among the hundreds on the reef. But these occurrences are rare.

Challenging. Doable. Worth It.

Making naturalistic, biodiverse habitats is good for many reasons. Though complex to build and maintain, these exhibits increase animals' wellbeing. The re-created habitats let them act as they would in their natural environment, from finding suitable shelter among the complex landscape to building nests and even sometimes reproducing. These habitats are also more engaging for guests who find themselves immersed in these faraway worlds, spotting something new wherever they look.