Endemic tiger beetle seeking shade
(photo courtesy of Phyllis Bovin)
You may have seen islands surrounded by a sea of water before,
but have you seen a sand island surrounded by a sea of vegetation?
If you have visited Great Sand Dunes you have. In this special way,
the dunefield of Great Sand Dunes is a sand island isolated by hundreds
of square miles of vegetation. Although a few smaller dunefields
can be found east of Colorado's Front Range, to find other expanses
of dunes, you will need to travel to Utah, southern New Mexico,
or western Nebraska. Great Sand Dunes is the only major dune system
in this area. Because of their isolation from other sandy habitats,
several species of sand-loving insects are found at Great Sand Dunes
and nowhere else in the world.
Even if these endemic insects tried to go live in other places,
they wouldn't be able to fly far enough to find a suitable sandy
homewith a suitable mate! This is their only home, unless
the climate changes and sandy corridors bridge the gap by linking
Great Sand Dunes with dunefields elsewhere.
How did these insects get here in the first place? Sometime
during the last Ice Age, there may have been more habitat for sand-loving
insects than there is today. Although it was colder, it may also
have been drier for long periods of time. This allowed more dunefields
to exist in North America. But when the climate warmed about 13,000
years ago, rain fell more often and the great expanses of open sand
dunes became smaller and vegetated. Bare fields of sand became more
isolated. In the San Luis Valley, one extremely sand-loving species
of tiger beetle was cut off from its relatives and, over time, became
just a bit more specialized (and different) than its closest relative.
At least that's the theory of why the Great Sand Dunes Tiger Beetle
and a number of other endemic insects are found only at Great Sand
Recently, researchers have studied the life history of one of these
endemic insectsthe Great Sand Dunes tiger beetle, known to
scientists as Cicindela theatina. They spent a number of
summers studying the behavior and habitat preferences of C. theatina.
Some of the details of their research are available in the Field
Notes at right.
Study these Field Notes and use them to help you complete A
Day in the Life of a Sand Tiger for a clue.
Explore Great Sand Dunes’ web page on Insects for more on the unique endemic species of the park.