Thank you! Unfortunately there are inconsiderate, ignorant people out there that will take a picture they like off the internet and post it to their own page, often even claiming it as their own. I try and avoid uploading the high res version to any website to prevent people downloading this, instead I use a smaller version which is obviously worth less to thieves. You could also always right a message next to your pictures stating that they are not to be used/posted without credit or your permission.
Good luck with your own blog! :)