Some critters come directly from Animal Control or the police - either they're confiscated or found wandering loose. The local zoos give out our phone number to people who call in thinking that zoos want the public's discarded exotics. Some are left on our doorstep. Some are abandoned at animal clinics. But, it's important to note that many rescues come from loving homes.
Some people get in over their heads.
Others find that their living arrangements are about to drastically change or they can no longer care for their exotic for one reason or another. Sometimes it's really the people we're rescuing. Regardless, animal give-ups ARE NOT donations. Give-ups cost money. Cages must be designed and purchased.