Did they know I was watching?

What a fantastic way to spend a peaceful hour on a sunny Sunday morning.  However, I wonder if the birds knew I was watching.  Almost as soon as my hour was up, about 20 starlings landed in the garden!  However, my two lovely robins appeared.  We have a fat one and a thin one and I have only ever seen then seperately.  However, this morning they both appeeared at the same time.  Magical.