The human owners of Nature Cat and his friends are well-off enough to have time-shares in several different vacation homes, and routinely take vacations together.
- That's why their pets are able to go on so many nature adventures at the seashore or in the mountains, despite other episodes' showing that the nearest major city to their hometown is Chicago.
Nature Cat, Squeaks, Hal and Daisy are all owned by different members of an extended family.
Tying into the above, it explains why they're able to go to such varied locations that are nowhere near Chicago (the beach, the desert) and why they all go together: Their owners are all different households of an extended family that live in the same neighborhood and bring their pets on family vacations. Houston's owner isn't part of that family, which is why they often communicate with him remotely: Houston's back in the suburbs with his owner.