Zoo Tycoon

This is referring to the Animals photo collection. Each animal type has a photo album. To fill up an album for an animal, you need to take a picture of each specific species of that animal (and for some animal types, each rare alternate version). You can tell if a picture is for an animal type that you don't already have a pic for if when you save the picture, it says saving to Animals photo album. If it says saving to Photo Journal, you already have a pic of that animal.

Progress for this carries across all zoos in all modes (other than Tutorial). You can view your progress on this in Start Menu->Albums->Animals.

To get this achievement quickly, choose an animal that has only one or two species, add them to your zoo, and then take a picture. The achievement should pop as soon as you save the last picture for that animal type.

Animals requiring only one picture to fill up an album are:

Binturongs (Tropical Pool mini-exhibit)
Fossas (Savannah Rock mini-exhibit)
Meerkats (Savannah Rock mini-exhibit)
Red Pandas (Tropical Pool mini-exhibit)
Tortoises (Tropical Lawn mini-exhibit)