Anything, really. Red-legged frogs. Another frog or toad species. California tiger salamanders. Another salamander, whether newts or ensatinas or aroboreal or Pacific giant salamanders. Native fish like trout or sturgeon. Rattlesnakes. One of the local racers or garter snakes or another species entirely. Desert tortoise. Native lizards. A nocturnal habitat featuring bats or rodents; California has multiple threatened examples of the latter. Some small carnivores. Native birds, whether waterfowl or yellow-billed magpies or burrowing owls or songbirds or shore birds. Even something like peninsular pronghorn, which could certainly take advantage of the open terrain and acreage of the hillside, would make it seem a little more diverse. Heck, I'd even take an exhibit featuring introduced species.
Many of California's local small mammals or amphibians or reptiles could probably use some ex situ conservation, too. I'm not aware of any programs for blunt-nosed leopard lizard, a San Joaquin Valley endemic whose habitat has been decimated by agriculture. Ditto for many others. Panamint alligator lizard. Coachella fringe-toed lizard. Multiple species of kangaroo rat. Like I said, if there are breeding programs, I'm not currently aware of them.
I don't expect them to realistically have all of these species or groups, but those are simply examples of creatures that can use some conservation attention that could add to the exhibit complex.
Are the curassows aggressive with the other species? I know instances of other curassow species being removed from walk-through aviaries for being aggressive with visitors when they are breeding.
Unless of course it is an aviary with cuckoos. Many American zoos have guira cuckoos. Either way, that's a reasonable-sized habitat for either.
Merry Christmas!
