Think of a death as a movement out of your stock, a disposition
Open the bird form and navigate to the bird that has died.
Open the Move Single Bird form from the toolbar on the left
This will open the movement form.
Add a new record.
Select Disposition – Death as the movement type and select the cause of death from the list in the cause of death field.
If the cause is not listed you can use the Add button on the bottom of the form and add the new cause of death on the fly without having to come out of the movement form.
Save the record to return to the bird form.
The bird form will now show at the bottom that the bird has died and if you have show full wording ticked in the preferences it will also display the cause of death.