I use LR as my first and principal image manipulation and sorting software. I am not a heavy generator of photographs so prefer to keep everything in a single catalog. If I was a wedding photographer, taking thousands of shots in a single session, I would be inclined to have a separate catalog for each wedding. You might find it better to have two catalogs, one for your birds and one for everything else. My organisational workflow is as follows.
1. Import - I created an import template which attaches relevant metadata such as my name and copyright info onto each imported picture. Photos are imported into a dated folder.
2. Selection. I check all imported photos for focus at 100%. those which fail this test are flagged for rejection and, after having checked all, are filtered and removed and deleted from the disk.
3. I then flag (P) my favourites from the remaining oictures and rate the best of those flagged with stars. This is important, particularly for weeding out also-rans from near duplicates. Where there are lots of similar pictures, as there would be when make multiples of birds, I delete all unflagged pictures. I generally retain unflagged pictures which are not close duplicates for purpose of record but these are unlikely to be considered for printing. Those which I am likely to print are colour coded blue. Those which have been printed are colour coded red. If I am preparing a selection for some purpose I place them in a collection.
4. Once the selection process is complete I tag photos. I try now to tag all photos. I create tag "folders" such as Nature, Cars, Places, Holidays,which will have keyword tags within them such as Birds. Ferrari, London or Corfu. I oftenhave keyword tags within these sub-sections such as Westminster under Places>London>Westminster. You would presumably want to do something like this for a Nature>Birds keyword chain. I also have plenty of individual keywords such as the names of my wife and children, etc.
I really feel that the use of Keywords is vital in any organisational database.
5. I generally do a first-pass through the Develop module, cropping and rough developing as part of the selection process. However, full tweaking in the Develop module takes place later, generally only on photos which are to be used for competitions, printing, etc, but that is another story.
PS you'd be better posting this under Digital Workflow and PP
Hope this helps