My graduate students have all been hard at work on their thesis projects this summer. To highlight their work, I have asked them to participate as guest bloggers and tell us a little bit about their work. Today's guest blogger is Anna Meyer. Anna is working on an M.S. in Natural Resources Management at Texas Tech University. Her project examines ant abundance and density, particularly in the context of horned lizard declines. Below, she shares some of his recent field experiences.
These blissful RIFA-free days were likely
before my time. RIFA (Solenopsis invicta) have been spreading
across the Southeast United States since they were introduced in the early
1900s. Finding themselves in a new
ecosystem without predators, they quickly took advantage of the opportunity and
were off, starting in Alabama and following Manifest Destiny westward. These tiny pioneers are now occupying Central
Texas, and are populating our field sites, to great consternation. Despite the controversy surrounding RIFA, I
found them less interesting than the other ant group I was studying: red
Red harvester ants are a distinctive ant that are a primary component of
the horned lizard diet, and I had great fun collecting these and
mark-recapturing them. Aside from the
lizard tracking, this was probably the best part of my summer. One of my tasks was to capture harvester ants
and mark them with tiny dots of bright nail polish. They showed little distress after being
marked (although they displayed great rage during the marking process), and it
was amusing to see 100 harvesters with silver gasters going about collecting
seeds, determined to carry out their work.
After this eventful summer, I am back at school and I too am going about
carrying out my work. At the moment I’m prepping
samples so that I have even more data about these charismatic ants and their
importance to the ecosystem, before departing for another interesting field
season next summer.
I end here with some
pictures from a lively field season: Our field sites were amazing and I was
very grateful for the opportunity to use them.
Along with ants and lizards, the sites sheltered a variety of wildlife:
painted buntings, vermillion flycatchers, scissor-tailed flycatchers, great
blue herons, vultures, bobwhite quail (and supposedly Montezuma quail), foxes,
mountain lions, axis and white tailed deer, and many many more birds, plants,
animals, and insects. And most
importantly of all (to us), at least one site had several THL!
“I haven’t seen a horny toad in a dog’s years!” –Probably one of the top five phrases I’ve heard this summer (I would say ‘watch out for snakes!” won by a slim margin). I’m not entirely sure how many years this means as it doesn’t seem to be a standardized measure, nor am I sure how dog years translate to lizard years, but the point is fairly clear: “I haven’t seen a horned lizard in a long time”.
Fig.1-An Interpretation of ‘Lizard Years’, an image from the short film “Where did the Horny Toad Go?”, by ‘Jar of Grasshoppers’ (to see more visit http://jarofgrasshoppers.com/category/horny-toad/)
I spent this summer at three properties in Central Texas tracking Texas horned lizards (Phrynosoma cornutum) and surveying ants. My surveys focus on harvester ants and red imported fire ants (RIFA), two types of ants implicated in the continuing decline of the Texas horned lizard (THL). I have been attempting to estimate, roughly, how many colonies of these ants are at each site. Of the many factors that are implicated in the decline of the THL, the RIFA invasion is a very popular one. I’ve had many people tell me: “The horned lizards are decreasing because of the fire ants. We didn’t used to have those around here.”
Fig.2-The general range of the RIFA or ‘around here’. (Image from ars.usda.gov)
Fig.3-The red harvester ant, Pogonomyrmex barbatus. (C) Anna Meyer 2013
Fig.4-Red harvester ants while ‘marks’ are drying. (C) Anna Meyer 2013
Fig.5-Juvenile THL at Blue Mountain Peak Ranch (C) Anna Meyer 2013
|Fig 6-- Juvenile THL during measuring process (C) Anna Meyer 2013|
Fig 7- Juvenile male THL who grazed from the harvester ants I was observing and
stayed in my plot for roughly two hours. (C) Anna Meyer 2013|
|Fig 8-- Unidentified scarab beetle at Camp Bowie (C) Anna Meyer 2013|
|Fig 9-- Dung rollers at BMPR (C) Anna Meyer 2013|
Fig 10-- Female THL with radio transmitter who buried herself in the late morning as temperatures increased. (C) Anna Meyer 2013
|Fig 11-- Tarantula hawk (Pepsi spp.) at a ranch (C) Anna Meyer 2013|
Fig 12-Tarantula (Aphonopelma spp.?) at BMR (C) Anna Meyer 2013