Again, one more article with useful objective. This article will enable you to keep track of those friend who was following you, but because of some reason they have un-followed you from their list. So, If you are interested in that, then you will not be able to do it manually. For that, there is one application or add-on which will help you to maintain this track record.
How Does It Work ?
The name of that application is Google Minus, which will access you data daily, when you will log into your Google Plus + account and it will compare the data with the previous record of your Google + account. The notification of your new follower will be provided to you by Google + itself but, the friends who un-followed you from their account those will be notified to you by this add-on.