Ground-penetrating radar (GPR) has a wide range of applications, from
geologic mapping to concrete inspection. A recently emerging GPR application
is deployment in biological investigations as a non-invasive technique.
Geophysical mapping of features such as tree roots and turtle burrows has
proved valuable for the understanding of these subsurface systems for
ecological, environmental, or engineering purposes. Four case histories of
GPR investigations pertaining to animal burrows are described: cutter ants
in Brazil, groundhogs in Michigan, and groundhogs, and burrowing bees in
Pennsylvania. Cutter ants ( Atta spp.) in Amazonian Brazil are known to
construct burrows of nearly the same dimensions as groundhogs as they
excavate galleries up to 7 m deep for leaf storage. Cutter ant burrows are
hazardous to heavy equipment and may also cause loss of mud circulation
during rotary drilling. Groundhogs ( Marmota monax), found throughout the
United States, cause unseen hazards, particularly for equestrian facilities
where a sudden collapse can cause severe injuries to both horse and rider.
Burrowing bees ( Colletes inaequalis) are common in the northeastern United
States. The size of the bee burrows is significantly smaller than that of
the cutter ants and the groundhogs. The data for these surveys were
collected over a twenty-year span, crossing several generations of survey
equipment and processing techniques. Together, these four case histories
highlight the historic and current capabilities of GPR systems applied to
mapping subsurface burrow systems. These examples demonstrate the important
impact near surface heterogeneities have in altering ecological,
environmental, or engineering systems and the utility of GPR for mapping
such heterogeneities.