Hannah Richards knows the
digestive systems of Texas horned lizards inside and out. She studies what goes
in, and what comes out. Her work with the iconic lizard has earned her a grant
from the Horned Lizard Conservation Society (HLCS), and her findings may help zoos
save funds on the lizards’ upkeep.
Richards, who earned her
master’s in biology from Midwestern State University this spring, received the
grant from the HLCS to extend the research performed for her thesis titled “The
digestive efficiency of Texas horned lizards fed different species of prey.” The
work is intended to determine the effects of declining traditional prey and the
physiological effects of diet on wild versus captive animals.
Historically, horned lizards
feasted on harvester ants, but that population may be declining. Richards
wondered what other prey could take their place and if a substitution would
affect the lizard. Charles M. Watson, Associate Professor of Biology and
Richards’ mentor, said that lizards in the area also eat beetles, and that they
may digest beetles more efficiently, getting more energy from beetles than ants.
As part of her studies, Richards
has been monitoring the lizards on a nearby ranch to investigate the diet
composition and available prey. She also is working with the Dallas Zoo to determine
the digestive efficiency of the lizard when fed different prey items. By
studying their intake and output, she will determine how efficient these
lizards are at deriving energy from their primary prey (harvester ants) and
prey they eat in smaller amounts (beetles). She is also investigating whether
lizards supplement their ant diet with beetles or if the beetles are
incidentally eaten while feeding upon ants.
At the zoo, Richards feeds
horned lizards different insects then studies their feces to determine the digestive
efficiency. “The zoo spends a lot of money to feed them ants when other more
available insects may be just as good or better,” Watson said.
The grant will allow her to
continue the research with the zoo throughout the summer. When complete, the
study will make predictions on the evolution of nutrition adaptability with the
decline of the harvester ant and increased nutrition from other prey. The study
will also provide information to help find new places to relocate the lizards. The
Texas horned lizard is listed as threatened in the state of Texas, but not
listed as a federally endangered species.
This spring, Richards was
named Outstanding Graduate Student in the College of Science and Mathematics,
and was recognized as the top graduate student by the Biology Department.
Richards presented her
research at the Society for Integrative and Comparative Biology meeting in San
Francisco, and to other zoos and state agencies to discuss the diet of Texas
Horned Lizards and the implications of other insects being fed to the lizard.
The Horned Lizard Conservation
Society is dedicated to protecting horned lizards by documenting and
publicizing their values and conservation needs, promoting horned lizard
conservation projects, and assisting with horned lizard management initiatives.
The HLCS annually sponsors research that has direct conservation applications.
Contact Watson at Charles.firstname.lastname@example.org for more