Comal County Cave Swallows in 2003

comal county cave swallow nest distributions

Each triangle is a Cave Swallow nest site in Comal County.
This map shows in red the number of Cave Swallow nests found at each site.
Gray lines are the roads in the county.  As can be seen, all nest sites found were under
man-made strucures along the roads.  These structures were bridges, overpasses, underpasses
and culverts.  Corrugated steel culverts were not used, only concrete culverts, regardless of size.
Railroad bridges were plentiful but not used by swallows for nest sites.
Railroad overpasses however often were used for nest sites.  Many nest variations were
found. 

For those familiar with the county, note the lack of nesting along highway 1863 as opposed
to highway 46.  Hundreds of potential nest sites were checked and highway 1863 had its share.
However recent construction along its entire length has discouraged nesting for the time being.