To be clear, each Animal Habitat can be expanded, but they must all be expanded separately. To begin, just head inside your Animal Habitat and click on the "Expand" button at the very top, next to the "Animals" tab. Each expansion requires you to collect the same items that the building was constructed with to begin with. So, for example, in the Cow Pasture you'll need to collect additional Hay Bundles, Stones and Tin Sheets.
The first expansion of each habitat looks to require 15 of each item, and will take your habitat from 20 animals max to 30 animals. If that's still not enough, you can collect 20 more of each individual ingredient and take your capacity to the now current max of 40 animals per Animal Habitat. As usual, you can ask your friends to send you these ingredients, or you can purchase them outright for Farm Cash.
Is 40 animals per habitat enough? That will ultimately be up to you to decide, but if the maximum capacity of Animal Habitats increases even further, we'll make sure to let you know. Now, if only we could have the amount of Animal Feed per Mystery Baby decreased...
Will you expand all of your Animal Habitats, or are there just one or two different buildings that should be larger on your farm? Sound off in the comments.