Skeletons are spawning way to much!!!

So I was busy playing in my survival world and as I was walking through a desert I saw 5 skeletons within a 2 or 3 block radius from each other and then about 8-10 blocks away from them there was another one (picture attached). This isn't the first time I have seen large amounts of mobs within a small radius from each other in this world. There were also other mobs nearby (mainly behind me which is why they aren't in the photo) so I don't think that they were being forced to spawn in that area.