Collections are groups of items related to either an animal, habitat, assistant, or special event. When at least one of every type of item in a collection is gathered, they may be redeemed for a reward. They can also be used as supplements for breeding in the Breeding Lab. Collection items are stored in the Collector's Album, which is a tab of the Chores item on the Main Toolbar.
Collections are groups of five items sharing a common theme. They are featured for some animals, habitats, assistants, and special events, while other do not have them. Each item of a collection is represented by an image and a related bit of trivia. Traditionally, four of the five items feature factual trivia, while one includes false, often humorous information.
Collection items can be earned in various ways. Animal and habitat items can be earned by caring for a particular animal, or any animal in a particular habitat. Whether a collection item appears or "drops" from the habitat is random chance, and each action (feeding, cuddling, etc.) is another chance for an item to drop. It is possible, when both the animal type and the habitat they are housed in have collections, to earn an item for each via the same action.
To obtain collection items for assistants, a player must first hire the corresponding assistant. When the assistant is invoked, each action they perform is a chance for an item to drop. If all habitats are sufficiently cared for, and an invoked assistant performs no actions, there is no chance of a collection item dropping. This means that a player cannot simply click to invoke the assistant ad infinitum in an attempt to gain collection items.
Special event collection items are only available during the event period. During an event, caring for any animal type in any habitat may produce event collection items.
Collections are stored in the Collection Album and organized into the groups Animals, Habitats, Assistants, and Specials. Each collection features two prize options. One of each of the five items making up a collection must be turned in to receive a prize. Players are notified via a message box when all five items have been gathered. Prizes include experience points, pet pennies, and paw prints. Habitats or animals with associated collections which are purchased for Zoo Dollars, such as the Lynx or the Swamp Habitat, feature an exclusive decoration as one of their prize choices.
Typically, four of the five items in a collection appear equally as frequently, with the other item being much more uncommon. Since all five items are necessary for prize redemption, over time, this creates an accumulation of certain collection items.
Players can also opt to use individual collection items when breeding in the Breeding Lab. Players have the option of supplementing the breeding process with up to 3 items, which can include the collection items for the animal being bred. Collection items for animal types which can be bred in the Breeding Lab have heart ratings.