This November 2014’s website header was created by Alex Fontana taking a background scene and loading it into GIMP. Then cutting out (cropping) over a dozen silhouettes of crows in various positions, removing each of the crows’ immediate backgrounds with an alpha channel, scaling and rotating each crow on to a different individual layer of the castle background and saving the batch of layers as a GIF file to create the admittedly rough animation that you see here.
The big trick with loading the GIF file into a WordPress site is that you can never change the size or crop it without having the animation stop working. So you have to consider the size of the picture you want before you can even start making the GIF.
Like Photoshop, GIMP is a paint / graphics program. Like Blender though GIMP is open source software and totally FREE. Ever get into a Blender situation where you want a UV map or color texture copyright free but can’t find what you’re looking for? Consider using GIMP. You can get the free download here –> GIMP