All the birds I've used have been found already dead. No animals were harmed. The unneeded parts were returned to the Earth with respect.
At the time of this instructable, I have no dead birds to work on, so I will post drawings along with photos of the finished results.
Birds can be carriers of salmonella and various parasites, so please wear gloves for your safety, and wash your hands and all tools thoroughly afterwards.
Step 1: FAQ
Since I published this I have been receiving a lot of questions regarding your own preservations. I'm noticing that many recent questions are ones that can be answered by reading some of my replies to others, so to avoid typing out the same answers over and over I am putting a FAQ here. If you are sure these do not answer your question please proceed to ask me. If I do not answer it within a couple days you can presume the answer to your question is in fact in the FAQ.
Q: I found a bird that has some insects/maggots. Will it still preserve properly?
A: No. Even if you manage to get all the insects off, they more than likely have laid eggs that can still hatch and continue to destroy the parts, even after they're dried. Additionally, their digestive enzymes will contribute to a bad odour and the continued breakdown of the flesh.
Q My bird parts have no bugs but they do have a bad or rotting smell. Will it ever go away?
A: No, not even after preservation. The acids and gases of decomposition, once allowed to form, will never leave. The smell may lessen slightly over time, but the parts will always smell unpleasant. Before, during and after preservation it is normal for your parts to smell like warm (but fresh) raw poultry, but they should not smell like they are rotting. Ideally, found carcasses should be no more than a day old.
Q: My parts have been in the box for a few days but now there is a bad odor coming from the box.
A: At no time should any smell be coming from the box. If this is happening, something has gone wrong and the part is not preserving properly. In this case I recommend discarding the part.
Q: How do I know when the parts are fully preserved?
A: They should feel dry and completely stiff. The severing points should be completely dry and hard, and not sticky or moist. If they do not meet these criteria, bury them again for another month. As a rule, legs and wings take at least a month. Heads can take longer, two or more.
Q: I just want feathers, not the parts they're attached to. How do I get them off and clean them?
A: You can simply pluck them. Use your hands as any tools may damage the quills. It will take a lot of time, so be patient. To clean feathers, place them in a bath of 5 parts warm water, 1 part vinegar and 1 part witch hazel. Let them soak for 24 hours. The astringents will help sanitize the feathers and kill any possible feather mites. Remove and spread out flat on a towel to dry. You can use a blow dryer to help speed this up.
Q: I've found an owl, hawk, eagle, or other bird of prey.
A: Before you claim it, first be sure that it is legal in your country or territory of residence to do so. In the US and Canada, it is illegal to possess parts or feathers from birds of prey or migratory birds without a special permit, even if you've just found a single feather in the woods. Being caught with feathers or parts carries a heavy fine or even jail time.
Q: What's the best climate to preserve my parts at?
A: Parts should be stored indoors, at room temperature, in a dry location. Do not preserve outdoors as changing humidity levels and extreme temperatures can add too much moisture, or freeze the parts.
Q: Does the species of bird I have affect how it will preserve?
A: No, the method to preserve it is exactly the same for all birds.
Q: I want to preserve a wing or foot to pose in a certain position. Can I do this?
A: Yes, but in order to do this you will need to nail the part down on a thin piece of plywood or particle board, which then must be placed in the box along with the cornmeal. Otherwise, simply placing it in the shape you want before covering it up will not work, since the muscles and tissues will contract naturally as the part dries.
Q: Can I use something other than cornmeal?
A: Borax and rock salt will also work to preserve, but Borax tends to form a crust on the severed ends and it is near impossible to completely brush out of feathers due to its dustiness. Salt has the potential to cause some mineral staining on the feathers.
Q: I have an already dry part that I want to pluck the feathers off of. Can I do this?
A: Removing feathers from dry pieces is nearly impossible without damaging them. As the skin shrinks and dries, it essentially cements the feather quills into it. You can re-soak the part to restore moisture to the skin; however, this will permanently damage it and should not be re-dried.
Q: Will this method work on rodents or other small animals?
A: Yes, however, fur doesn't have the same coverage as feathers do, so the finished product may look a bit emaciated and patchy whereas feathers do not.
Now back to the instructable!