IPhone : NSThread Retain Count

Why is the Retain count of my thread = 2?? It gets incremented after the start method why ?

How does Retain count work for NSThreads

        @implementation ViewController

        - (void)viewDidLoad {
            [super viewDidLoad];

            NSThread *thread;

            @autoreleasepool
            {
                thread = [[NSThread alloc] initWithTarget:self selector:@selector(check) object:nil];
                    NSLog(@"RC == %lu",(unsigned long)[thread retainCount]);
                [thread start];
            }

            NSLog(@"RC == %lu",(unsigned long)[thread retainCount]);

        }// presently stopped here on breakpoint

        -(void)check{
            for (int i = 0 ; i< 100000; i++) {
                NSLog(@"NEW THREAD ==%d",i);
            }
        }
        @end