i guess this post is OT considering this is about attractig wildlife...
There are some things you might do to control wildlife in the garden...like perhaps planting barriers to limit entrance.. this post considers this and feeds the plant a well.... i always thought some o the cactus and perhaps agave with their limited moisture enviornments might be given puncturing defences might be trying to get animals to leave a bit of blood to sustain themselves..
this link is about one even more agressive plant.. for wildlife control..
http://www.nypost.com/p/news/i...

Gordon, thanks for posting that...fascinating plant! I've always thought of the plants with sharp thorns and other spiky type plants as just trying to keep animals from eating them, but who knows...maybe there's some of that other benefit also! I know that on occasion I've left a little blood behind because of thorns and such. Texas has a LOT of plants that have thorns and other spiky parts, not to mention the stinging plants!