I have had this issue raised with me a few times of late, and this evening I have conversed with another member. There has been the suggestion that the site is Bird focused.
Firstly, It is not my role to tell people what to post to the forums, so if bird photographers are more active and it concerns you, then start posting more photos from other genre, and level out the imbalance you perceive to exist. I am not about to tell the birders to stop posting cause a landscaper is concerned about how many bird threads there are.
Secondly, it was pointed out that the competitions are often full of bird entries. So I decided to get some stats. Since 17th January we have had 21 photo of the week competitions. In that time a bird photo has won 4 times. So whilst the competitions might have a lot of bird entries, the results show that they do not necessarily win..all the time. I also went back through several recent competitions to see how many bird entries there were. I got 21 bird entries and 135 non bird entries.
So, if you feel there are too many bird photographers and threads/competition entries on AP, there is one solution as I see it, start posting more stuff that isn't birds and start critiquing those threads. We cannot have more non-bird stuff, unless the people concerned about it, start posting more non-bird stuff on the site.
However from the above, the perception that the site is bird focused appears to be not as true as some are making it seem.