Sometimes a bird lands and if you are out there with a camera, its best to just take some shots. I found that being ready to take an image as it presents itself to be valuable skill as a photographer. I remember being out for a short hike and really not having any specific thing I was looking for, so it really is the things I encounter along the way that I depend upon for inspiration. If a robin like this lands, then I take it as a good chance to see if I can get some interesting pictures before it takes off again. Maybe I won't see anything too interesting along the way, but that being said, I will still take some test shots along the way to make sure my settings are in a good range for the type of light I am seeing, so I won't have to make to many adjustments once an opportunity presents itself.
