A major zoo in touristy parts of Northern Africa (Morocco, Tunisia, Egypt) or Turkey? Perhaps, but those regions have lost some appeal recently due to politics and terror risk. If only things calm down.
Gaziantep has a very good zoo according to the locals, though that's
definitely not the touristy party of Turkey I haven't been, however all the locals swear it's the best zoo in Turkey and a lot of Turks from other parts of the country tell me the same thing. I call Gaziantep "Turkey's Phoenix" (ugly, sprawling, way too hot, and incredibly xenophobic), however seeing as it's known for its food and its zoo it might also be Turkey's San Diego. Any rate, when I was in Gaziantep I never got around to visiting. Seeing the old city and the Zeugma Museum and stuffing my face were higher priorities, and Antep isn't the sort of place you want to spend more time than you have to (at least not in the summer).
There's a lot in that part of Turkey I still want to see (I'd planned to make a circuit of eastern Turkey then realized I couldn't find a car rental place in Antep that offers automatics, so I need to either learn to drive stick before trying it again or rent a car further west), so if I make it to Antep again I'll check out the Zoo and say how it compares to American standards.
I'd completely forgotten until it was brought up that I've been to the Zoo in Izmir Kültürpark. It's free admission (or free admission after a certain hour; I forget) and completely unimpressive. From what I recall there's deer, waterfowl, and a fair number of reptiles. If you're in Izmir, there's so much do do in and especially around the city that a zoo wouldn't necessarily be a priority. However the Kültürpark is right in downtown Izmir, and the zoo could probably be expanded and improved at least somewhat. And Izmir is the only Turkish city with a half-decent light rail system, so I could see a proper zoo on the outskirts. There's a bird sanctuary on the northern periphery which is supposed to be quite nice, however it's something I only learned about as I was leaving Izmir.
Walsrode receives remarkably few visitors (c. 300,000) for a world top aviary and has struggled to keep alive for this exact reason. It is located a bit off the beaten track and being only birds means that some people unfortunately disregard it.
That's fewer than Parrot Jungle received in its last year in its old location over a decade ago. Since moving to the new, more accessible location and de-emphasizing parrots for species the owners assumed visitors would be more interested in seeing, the visitor numbers first stagnated and then went into decline. Since the new location is uglier, more expensive, and deemphasized parrots even before it became "Jungle Island," it's not clear to what degree each of those factors played in that.
Sheridan never includes bird parks or aquariums in his list.
That it's the reason for vogelpark -or any aquarium- continues out of the ranking.
So how many land mammals does an attraction need for Sheridan to consider it worthy of his attentions?