I do! I put in their approximate birthday and when I acquired them. I weigh mine every month to keep track of their gains and losses and keep that in there. I also put in dates that they go to the vet, get wormed, medications. Finally, I mark the months they hibernate (for those that do hibernate.) I know it seems like I'm crazy (or like I have nothing better to do with my time) - but I have a lot of animals and foster as well, so I have to keep careful track of everyone. Hope that was helpful to you!
I have an EXCEL worksheet, a page for every tortoise in my own collection. Once a year I take a new picture of the tortoise and attach it to the file. Then I weigh and measure and note it on the worksheet. If I have to take the tortoise to the vet, its noted on the sheet. Or if eggs are laid, etc.
I am in the process of putting the info into the computer, but its hard for me because I like to have the hard copy in the file. Its just so easy to look at the file and the picture all at once, rather than to pull up the file and have to go search for the picture in "my pictures."
Yes, I have one for each tort. The one for Chewy (hatchling) is the most extensive. For Chewy I keep weekly weights, how many soak's and daily diet. In the warm months I keep track of how much time is spent outside just in case a major dip in weather or too much inside time is a catalyst of an illness. I used to document temps and humidity but now it is constant so I no longer have to do it.
We actually use a calendar and write down weight and size on certain dates and keep track of when we change the substrate and get new lightbulbs, or just any info that needs to be jotted. I like seeing it this way so you can see how they progressed throughout the year.
I just have a notebook for weights. I have often thought of doing a much more detailed journal, but I've never followed through with it. I do think its a great idea.
I don't keep a journal in any scientific form, but I do have my blog where I write any notable experiences, changes in behavior, new additions to his diet. It's partly for interest reading back in future years, partly to tell his story and partly for me to look over how he's changed.
I finally got my excell worksheet together for all of mine, I am just doing the weight right now but will start to add other info soon. I have a lot of missing data, but luckly I had a little of it on here in some of my threads..
Every morning I record what they're fed, whether they received a soak, supplements, or any changes in behavior etc. I also record their lengths and weights 1/month, and the last time I cleaned or changed substrates.
It keeps me honest about cleaning and helps me avoid monotony in their diet.