One presumes that dangers would be considered first and then if the log was secure, build the shelter. Realize that a 20' beach log, common in Alaska anyway, need only be dug out for the length of your body, hence the ends are still secured in the sand. As far as critters, there are regiona concerns for snakes and other critters, but unless you are rummaging around their den in the first place I don't think they would try to enter your domain. You will probably be squirmin' enough to scare most other critters away! Bottom line, it pays to be cautious, learn what you can about your surroundings...and be careful.
Touring Kayak Paddles
Gedi Convertible Helmet