|Cryptozoology, BioForteana, Zoological Oddities, Unusual Natural History||StrangeArk blog|
Historical investigation involves both bibliographic and "active" investigation. What are you looking for? You are seeking clues to the presence of cryptids in the past. If a "lake monster" turns up in your area, historical legends and tales could corroborate your report. If you can't find any evidence for it in the past, it may be a hoax or misidentification.
Native American folklore is an excellent place to start. Your local library may have literature on the Native Americans in your region where you can look for legends of water monsters, thunderbirds, wild men, and other mythological creatures. Check your local museums and historical societies for Native American artifacts. A large number of carvings, petroglyphs, and pictographs show some very unusual wildlife forms.
Next, check out the books and articles on legends from early settlers in your region. Were there any early naturalists that went through your area? They may have jotted down their observations in journals, which may be kept at your local historical society.
Although it is very time-consuming, you may wish to go through newspapers from earlier periods. What may have been considered merely odd back then may now be considered a piece of a cryptozoological puzzle. Many early newspapers are kept on microfilm in libraries or historical societies. (Unfortunately, just as many are gone forever, victims of time, apathy, and poor archival conditions.) Many are hard to read, especially for long periods of time, so don't go into a library expecting to go through several years non-stop. Take a break occasionally. You can always talk to the library staff. They may have ideas about who to contact and where to look for more information. You may also be able to find older citizens who can tell you stories from their youth.
When going through old folklore, keep in mind that most of it will remain folklore. Not every legend is based on a real animal. Linda Milligan's "The 'Truth' About the Bigfoot Legend" (Western Folklore Jan. 1990: 83-98.) shows one way in which a folklorist looks at mystery animals. Take a look through books on legends to get an idea of the patterns that repeat from location to location.
Once you have several reports, look for patterns. Are behavioral traits similar? Do the descriptions from different witnesses match? Do similar habitats show up? Are their seasonal patterns? Does the legend have similarities to myths from other parts of the world?