In most nations, the government “owns” wildlife and can dictate care, licensing and control measures.
Most psittacines fall under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), an international agreement regarding trade in wildlife. Not all countries are signatories. Almost all psittacine species are listed as CITES Appendix categories I (threatened with extinction) and II (in which trade must be controlled in order to avoid utilization incompatible with their survival); in addition, there may be municipal, state/province/district, national and international permits required from health, agriculture and wildlife agencies.
Intervention during a disaster may or may not be protected by international, national or local laws. Collecting injured and ill psittacines, even in life-threatening events, may not be considered legal activity. Where possible, official affiliation with known animal disaster organizations is the best protection against legal issues.
Depending on locale, various agencies and laws may influence "who" and "what" are allowed to work with wild psittacines. Permits and other paperwork required for routine biology research but may not cover rescues during a disaster. Veterinarians must have the correct credentials or licensure for the locale, and in addition, there may be municipal, state/province/district, national and international permits required from health, agriculture and wildlife agencies. Euthanasia is a potentially important legal problem. In some countries and local regions, humane euthanasia is tightly controlled or illegal. For example, Indonesia and several other nations and legal entities do not allow euthanasia under any circumstances. Special permits may be required for pharmaceutical use, antibiotics, and other veterinary products.
Since there is little uniformity on a global or national scale, it will be up to the biologist, veterinarian, and the wildlife rehabilitator to determine in advance exactly what paperwork needs to be filed and maintained.
Links and other resources for legal issues can be found in Contacts and Resources.