Well, no, they weren't really in danger of starving. But our old cat (18 years old) has been on a special prescription diet for years that seems to keep him pretty healthy and we were almost out of food. The problem is that the store where we used to buy cat food is more than 7 miles away, which is a pretty far bike ride to carry a 20 lb bag of (very expensive) cat food. One option was to get a Zipcar, but that just meant that the price would climb even higher. The problem was we couldn't find our original prescription, and the local vet within walking distance required a checkup (minimum $70) before they'd let us buy the food from them.
The good news was that we'd paid a visit to Angell Memorial Animal Hospital with this cat years ago, but we were still in the system, so we could buy the food from them. And they're only about a mile away. It turns out that my bike basket and back rack (with the help of a few bungee cords) are capable of carrying a 20 lb bag of cat food. (Though I very much want a bike trailer. It looks like we might be able to borrow one from a friend)
And guess what, Angell even charged $1 less than our old place--we should have checked and changed a long time ago. But when you have a car, it's easy to just keep old habits in place, because the costs to your wallet and the environment are not so readily apparent. With the car gone, we have to reevaluate all our old pathways and habits.