Mound Ants

A couple of more photographs from my Monday trip to Forest Hill Nature Area.  In the open field at the back of the property I found this large ant mound.

Large ant mound at Forest Hill Nature Area - this mound measures approximately 24 inches across

Initially I thought this was a mound made by Allegheny Mound Ants (Formica exsectoides), but when I looked closer the ants looked wrong.  Allegheny Mound Ants have dark abdomen with a red thorax and head.  These ants had a dark abdomen and head with a red thorax - that meant that they could not be Allegheny Mound Ants.  After some internet research, I think this ant is probably another ant in the Formica genus.  My best guess is that these ants are from the species Formica ulkei.  There is no common name for this species.

Formica ants - probably Formica ulkei

I looked around to see if I could find any other active mounds in the field.  I didn't find any additional active nests, but I did find several old nest mounds including this one.

Abandoned ant mound