Just to show you how easy it is to "steal" and change photos. (Hope you don't mind for the example).

When you post a pic on the internet, be prepared for them to be used by others, because some will. I personally have no issues if someone wants to copy mine for educational reasons or just to use for comparison - i.e. animal identification, bird id's etc. If you post your pics small as you have, there is not a lot anyone can do with them apart from re use on the interned e.g. advertising.
After resizing, save the pics at a lower resolution than just hitting save - 50% or medium comes up on most editors. Even lower if you prefer.
I use Photocleaner to add my name. Quick and easy.

http://www.photocleaner.com/download.html