Google Plus Joined Twitter back in 2011.
May 1, 2015, they sent out their first tweet:
Hello Twitterverse! Can we get some love for our #firstTweet?
— GooglePlus (@GooglePlus) May 1, 2015
Right now, they are responding to people that Tweet to them with animated GIFs, something that Google+ is very popular for.
Will G+ begin to tweet more? Is there an announcement coming? Who knows.