Welcome to the forum I too have a Nikon D3100. Now...I don't know if you know how to upload pictures, but if you do know, you could get some advice on how to improve them from other forum members.
The first photo's nice...the only problem being that you've cropped off some of the birds leg and it's tail. It would work if you saw the whole bird, or maybe go for a tighter crop and only see his head and shoulders. The same thing's happened in the second one and the focus seems to be slightly off.