Report 44665: Homeowner reports repeated wood knocks near Stanton

It started the spring of 2013 late March-April. For about a month every night I would hear knocks about a couple minutes apart. This went on for a month. I live in the Hatchie River Bottoms. Around September of 2013 it started again. It has started again March of 2014. I have looked but can't see any thing. It is a very wooded area with a lot of wildlife. It seems to be passing thru. I am disabled and can't run into the woods. It usually stars about 8:30 or 9:00 at night. None of my neighbors report any noises. This month it only lasts to about 10:30. Any help finding out what it is would be appreciated.