I am having problems regarding displaying dates.

I have the ff. code for my query:

global static List<Patient__c> queryPatients() {
         return [SELECT Id, Last_Name__c, First_Name__c, Middle_Name__c,Birthday__c, Civil_Status__c, Gender__c FROM Patient__c ORDER BY Last_Name__c ASC LIMIT 20 ];
    }

When I want to use the data, for example, this.Birthday__c, the value changed.

eg.

1976-03-09 became 195177600000

What must I do to display the right value?

Thank you!