Search page birthday reminders are only shared with friends indicated in a person's preferences in Google+ controls at plus.google.com/up/birthday, according to Chung.
Birthday reminders have long been features in online communities such as leading social network Facebook.Google is weaving the notices into search page results as part of a strategy to mesh its social network with its other online services and products.
"At first you'll only see birthday reminders if you're searching in English on Google.com," Chung said. "We'll be rolling this feature out gradually over the next few days."
Google on Wednesday also began adding social networking features to the suite of "apps" designed for businesses to use online as services hosted in the Internet "cloud."
Google Apps offerings include programs for Gmail, calendars, documents, and data storage.
"We're launching an initial set of Google+ features designed specifically for businesses," product management director Clay Bavor said in a blog post.
"Like Google Apps, we think Google+ can help colleagues collaborate more easily and get things gone - and get to know each other along the way."
The new features will be available to businesses free of charge during a preview period lasting through the end of the year, according to Bavor.