The debate about whether to keep records on paper or in a database goes much deeper, of course, than just bird records. As a database analyst with 30 years birding experience, I can see it from both sides of the fence.
It reminds me of a company I used to work for 10 years ago. They had literally 100,000's of paper drawings stored in a large store room, some dating back 50 years or more. Many of them had faded and become almost unreadable, and a lot of the paper was so old it almost crumbled in your hand if you touched it. The store room took up nearly half the upper floor of the building, you could never be sure of finding the drawing you wanted and the drawings were constantly under threat of damage from leaks etc. The guy who ran the store smoked a pipe, and didn't seem worried at all that he was working in a tinder dry environement where one spark would wiped out half a century of company drawings.
Contrast that to the new CAD system we implemented. We could back up every drawing on the system overnight, every night. Copies were kept in the local bank. The drawings never deteriate, and they could be stored in a fire proof safe little bigger than the average wardrobe. Finally of course, they could be located and copied in seconds.
Of course there were some obvious computer dangers, such as disk crashes and corruption, but the system was Unix based, so there was very little chance of being hit by a virus, and we did take many precautions to avoid unauthorised access.
Your records are much more secure on a database than they are in a book. A database enables you to query the data and sort it in any way you like, in ways which would be impossible with paper records. It also enables you to distribute the data to others easily, such as county recorders etc. I can have my records ready for the County recorder in between drinks on New Years Day if I like. I don't have to spend days and weeks sorting through notebooks. It allows me in seconds to tell you the exact number of, say, Garganey I have seen ever and where and when they were.
I also keep records of all wildlife, not just birds, and I collect it from other wildlife folk around St. Helens. They all have a copy of my database which they email or bring to me periodically, and I append their data to mine in minutes. All of this is passed on to various recorders. In total I send about 20,000 records a year to various moth, butterfly, bird and dragonfly recorders, all in different formats which they can easily read into their databases. Takes me about one hour to do all that, and takes them minutes to read it into their databases.
My records never fade or crumble away, they're not at risk of flood or mould or fire. I have backup copies locked away in fire safes. Yes the software I use will become outdated, but it's no big task to upgrade.
I wrote my own database using MS Access, because I like the flexibility of being able to change it in any way I like.
Unless your note books are works of art, then I would not hesitate to put your records into a database.