Jerimiah Ain’t no Friend of Mine: Bullfrogs & the Wetland
Written By: Sadie Smith, Former Lead Wetland Restoration Technician
As anyone in TMPF can tell you by now, at the wetland I am the passionate leader of the bullfrog management project at the newly opened Rosewood Nature Study Area. But some of you may ask why they need to be managed in the first place, and why do they have to be euthanized? Well, it’s a pretty simple answer; they are not supposed to be here! Even though bullfrogs are not an exotic species imported from a different nation, they are considered invasive west of the Rockies. Which, if you think about it, makes a lot of sense. Without the aid of people actively transporting them as a food source, how else are bullfrogs supposed to summit those mountains? I suppose they could ask a migrating African swallow to grip them by the husk…
So now you might ask yourself, “Well just because they aren’t supposed to be here, how bad can they really be? It’s not like they are as bad as murder hornets…” Well, actually, the American bullfrog has been listed by the IUCN as one of the top 100 most invasive species globally. Due to their large size and non-picky eating habits, bullfrogs can decimate food webs in novel ecosystems. Essentially, a bullfrog’s diet consists of anything that moves that it can potentially fit into its mouth. This includes other frogs, rodents, birds, snakes, fish… in lab settings bullfrogs will even lunge at golf balls rolled past their line of sight. Furthermore, their tadpoles are adaptive, meaning their diet is dictated by which kind of food source is available to them. Tadpoles with high amounts of available plant matter will be vegetarian, but will opt to eat tadpoles of other or their own species and become carnivorous if there is not enough or they run out of available plant matter.
Now, what does all of this mean for Rosewood? Well, the main concern is that the abundance of bullfrogs in the wetland is preventing native amphibian species from establishing in the wetland. One native species of particular concern is the Northern leopard frog; once fairly ubiquitous in Western North America it has experienced a rapid population decline since the 1980’s due to a myriad of problems. This wetland represents some of the last viable habitat for these frogs in Nevada, but establishing a population here would be next to impossible because of the bullfrogs. Leopard frogs are highly susceptible to predation from bullfrogs simply because they do not recognize them as a predator.
So in order to one day introduce leopard frogs, something must be done about the bullfrogs. Taking them out and moving them somewhere else isn’t a viable option, as it would only create a new bullfrog problem somewhere else. Therefore, we have implemented a capture and kill protocol in the wetland. We are not just killing willy-nilly however. Some individuals are collected and stored for later stomach content analysis, so we can see what they are eating and therefore most impacting in the wetland. All of the dead frogs are used as bait for trail cameras and to encourage potential bullfrog predation by some of the predators already present in the wetland such as herons and coyotes. So far, stomach analysis has revealed that their main food source here in the wetland has been crayfish, although only three dissections have been performed at this point.
With these established protocols in place, it is now feasible to manage and control the over abundant bullfrog population at Rosewood, although it will be a slow process. However, eliminating as much of the breeding adult population as possible over time will open up new niches in the wetland, and allow native species to move in. Furthermore, if we can demonstrate an active decrease in the bullfrog population, members of the Paiute Tribe community will work with us to actively introduce leopard frogs from their breeding program, which would not only be a huge ecological benefit but also continue to strengthen our partnership with the tribe.
It has not only been getting the chance to work hands-on removing invasive species and restoring an ecosystem that has made this bullfrog project so enjoyable, but also knowing that this work is fostering an invaluable partnership with the Paiute Tribe and the Reno-Sparks communities. Being able to use the skills and knowledge I paid an unfathomable amount for in college, in collaboration with my rural frog catching upbringing to achieve such goals has been a wildly rewarding experience that I shall keep with me when I leave TMPF forever. I hope that in the future, this work will pay off and instead of hearing the loud booming calls of bullfrogs emanating from the cattails, it will be the soft peeping songs of leopard and chorus frogs.
About the Author:
Former Lead Wetland Technician, Sadie Smith, hails from Vermont but has had the pleasure of calling many places home; from the Eastern Townships of Quebec where she went to boarding school to the sunny coast of St. Petersburg, Florida where she graduated from Eckerd College with a B.S. in Biology. Her favorite pastimes include playing rugby, creating artwork, or spending any kind of quality time outside enjoying nature.