| |
Six-lined
Racerunner
(Cnemidophorus
sexlineatus)by
Bonnie Wroblewski |
| Our most recent admit:
a female six-lined racerunner. She was discovered slow to move and freshly de-tailed
in a local barn. With a little bit of TLC and lots of heat, she seems to be on
the road to recovery, energetically chomping down her daily fare of crickets.
The black blotch that extends across her right side is a scar remaining from a
fully healed over wound of the past, which leaves us with great hope that this
tough female will fully recuperate and be back chasing down lunch in the wild
in no time. |
| Photo
courtesy Dove Key Ranch Wildlife Rehabilitation |
Six-lined Racerunners
in Texas: Identifiable
by their fast and jerky dashes and the six light-colored lines that streak from
head to tail base, six-lined racerunners enliven well-drained, sun-filled environs
across all but extreme west Texas.
These 6 – 10 1/2 inch long lizards advertise their age and sex through subtle
coloration schemes: females wear inconspicuous white throat scales, while males
don flashy green to bluish hues along their gular regions. Juvenile racerunners
boast their youth in the form of blue tails, while more mature individuals can
be identified by discreet tan to brownish tails.
Once the proper social
displays have been traded, pairs mate in the beginning of April through late June.
Egg-laden females deposit one to six fertilized eggs in a specially dug brooder
burrow that can be up to a foot below ground. Under favorable conditions, the
act may be repeated once more over the summer, at least three weeks following
the initial deposit. Approximately two months later, blue-tailed youngsters hatch
and dig upwards to the dry grasslands, woodlands, or coastal dunes that will become
their hunting grounds.
Darting out from vegetated cover to snatch the
hapless invertebrates that comprise its diet, a six-lined racerunner can reach
speeds of up to 18 mph! Strong hind legs and elongated toes help to propel these
reptiles swiftly towards dinner or away from numerous aerial and terrestrial predators
(hawks, snakes, and the neighbor’s cat to name a few). In addition to sheer rapidity,
this lizard species’ namesake striping contributes to successful getaways: the
horizontal lines blur in motion, making the desired prey difficult to detect and
impeding the judgment of just how fast that racerunner is racing. At the end of
a chase is usually a safe burrow, which these reptiles excavate to hide not only
from predators, but also from overnight lows and winter cold snaps. In some cases,
the erratically-fleeing racerunner is captured by its attacker and is forced to
use its last chance resort: it drops part or all of its tail. Hopefully, as in
the case of our patient, the pursuer will be distracted and/or satiated by the
still writhing appendage, permitting the main course to escape and sprint another
day. Although caudal autotomy may appear like a win-win situation, the energy
needed to regenerate a new tail may cost a female racerunner the next reproductive
season and tailless lizards risk losing dominance, choice mates, and their original
level of speed and maneuverability. Plus, it’s a one-shot deal: once your tail’s
gone, there’s no using this trick to evade future predators until a new tail has
grown back.
So, as you wilt in the shade sipping an ice cold beverage of
your choice on the next blistering mid-summer’s day, enjoy these hyper, striped
sun-worshippers, zipping around after insect meals and divulging the stories of
near catastrophes by foreshortened tails.
©
Bonnie Wroblewski
http://www.dovekeywildlife.org
May 13, 2010
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