Activity lifecycle - onCreate called on every re-orientation

I have a simple activity that loads a bitmap in onCreate. I find that if I rotate the device I can see from the logs that onCreate called again. In fact, because all instance variables are set to default values again I know that the entire Activity has been re-instantiated.

After rotating 2 times I get an FC because not enough memory can be allocated for the bitmap. (Are all instances of the activty still alive somewhere? Or does the GC not clean up fast enough?)

@Override
public void onCreate(Bundle savedInstanceState) {
    File externalStorageDir = Environment.getExternalStorageDirectory();
    File picturesDir = new File(externalStorageDir, "DCIM/Camera");
    File[] files = picturesDir.listFiles(new FilenameFilter(){
        public boolean accept(File dir, String name) {
            return name.toLowerCase().endsWith(".jpg");
        }});
    if (files.length > 0) {
        Bitmap bm = BitmapFactory.decodeStream(new FileInputStream(files[0]));
        ImageView view = (ImageView) findViewById(R.id.photo);
        view.setImageBitmap(bm);
    }
}

From all that I read, onCreate should be called once during the lifetime of an application. Am I wrong about this? How can re-orienting the device cause the activity to be recreated?