Thanks for submitting this inquiry for your birthday display use case. While you may add profile fields as outlined in the documentation here:
Unfortunately, there is currently no birthday widget that would be able to integrate with the profile fields. If you'd like to see this in the future, I'd recommend submitting an feature request idea in the Ideas for Jive space. If this is an important feature you'd like to look into customization options, just let me know and I'll be happy to put you in touch with our Professional Services team.