Tuesday, December 1, 2009

Autumn Ant Hill

Lower temperatures and shorter daylight intervals signal a decrease in ant activities. The ants are vacating the exposed mound and are moving deeper into the earth where temperature changes are moderated. Damage to the hill, quickly repaired during the summer, now remains untended.

Winter annuals are quick to take advantage of this temporary inactivity. This appears to be Cardamine hirsuta, Hairy Bittercress, a European species that is now naturalized in Ohio. I consider this to be a neutral exotic. It’s not native, but it isn’t causing any noticeable adverse impacts on the native flora, so it’s not currently on my hit list. The plants will flower early next spring and produce seed before the ants either bury or remove the plant from the mound. When the mature seed pods of this plant are disturbed, the two halves part with a little twist that helps propel the seeds around the immediate area. That helps to insure a plentiful supply of seeds at the top of the mound.

Other plants also try to claim space on the mound. This Queen Anne’s lace seedling will not be tolerated by the ants and will be removed before it has a chance to get very big.

The mounds can’t move so they have to take whatever disturbance comes their way. A deer highway has developed beside this mound. The base is being trampled and it looks like a hoof or two has penetrated the top of the mound. Too much damage to the mound could change conditions below ground enough to cause severe hardship to the wintering colony.

The deer didn’t just develop a trail next to the mound; they actually formed a trail with the mound in the center. To follow the trail, a deer has to turn and follow the mound base to get to the other side. It’s like one of those circular intersections you find in some downtown areas. No wonder the mound has hoof marks on top. It’ll be interesting to see what this mound looks like next spring.


  1. Funny - A deer round-about!
    I didn’t know ant hills would get that large in this region. Very neat. (When I was in grade school we regularly fed Doritos to the small ant colonies. Probably stunted their growth.)

  2. ...very cool. I haven't seen an anthill that big..hmmmm..ever!

  3. I'll have to post pictures of some of the really big mounds. The one shown is only about 3 feet across at the base. There are others here that measure more than 6 feet across.