Project Reflection

In Biology, our most recent project was to create a species monitoring and control plan for the northern leopard frog and the bullfrog on Durango Nature Studies Nature Center. The class conducted numerous experiments and tests prior to this project, but I was absent from these. I have been attending Animas High School for a little over a month now, and was thrown into this project with next to no background on the subject. The research paper was my first scientific research paper, and most of the knowledge in the paper was gleaned within a two week period. Hopefully it was worth something.

In an article I read just recently, non-native species were being defended, the author saying that, "[Being indigenous doesn't] mean its presence is good for the environment." Species spread naturally. Some are less healthy for the environment, some are more healthy. Sane with indigenous species. Overall, we should judge species on their impact on the ecosystem, not their origins.

So what does this mean about my project? Was it pointless? Did I waste a month on nothing??? This article seems to say that. After all, the bullfrog is an invasive species and there is no definitive proof that it substantially harms native frogs. From my perspective, this article said precisely that we focused on the wrong species. I think focusing this project on zebra mussels or some such species would've been far more productive to others outside our small learning community.

And that is not to say that I do not think this project was productive. Sure I think we had the wrong target species, but the rest of the class and I learned a lot about formal research papers, and I personally learned a lot about managing my time and speed studying. Like I said in my first paragraph, I was thrown into this project late, and had a lot of catching up that I had to do. That involved a lot of research and more than one late night on projects. As time progressed, I got better at time budgeting, and finally turned in a pretty dang good project.

Species Management Plan for Rana pipiens & Rana catesbeiana on the Durango Nature Studies Nature Center Property

Ryan Ehrig and Marisa Mueller.

Durango, CO

2011

Plan development first draft

Leopard frogs are being threatened by bullfrogs on Durango Nature Studies property. This could be due to the habitat on the DNS property. Leopard frogs have fairly specific habitat needs. In infancy, eggs and tadpoles need very similar environments. Eggs are laid in a pond about 30-60 m in diameter, about 10° C and a max depth of 2 m. the ponds dry once every few years, and were unconnected to other water sources. The ponds also lack any fish life. This isn’t a breeding requirement for the frogs, but very few tadpoles live to adulthood in ponds inhabited by fish. The larval stage lasts 58 to 105 days. After the larval stage, sub-adult Rana pipiens may migrate to ponds better feeding sites at larger, more permanent lakes. During the summer, the Northern leopard frog spends much of its time away from its breeding pond. They usually go to grassy clearings where the grass is up to 30 cm tall. R. pipiens can travel “from 0.5 – 3.0 km from water in this species, and Dole (1971) notes that subadults move up to 5.2 km away from natal ponds” (Smith and Keinath, 2004). It is thought that R. pipiens feeds in this environment as adults. This may be so they can find more food to store for a possible hibernation during the winter. Northern Leopard frogs may hibernate underwater in streams or rivers during winter months. Anoxia tends to be an issue during hibernation, so R. pipiens will try to find a body of water with a high dissolved oxygen (DO) level. It is also essential for R. pipiens to overwinter in an area with a low population of predaceous fish. The water is optimally at a pH of above 5.9 for all of the life cycle. Also, water pollution will cause decreased motility and health in R. pipiens. (Smith and Keinath, 2004)

The habitat at DNS could also be fostering the growth of the American bullfrog Rana catesbeiana. American Bullfrogs are very resilient and can easily adapt to environments. They preferably live in densely vegetated ponds that are relatively deep and permanent. They can also take advantage of man-made lakes. Throughout life, R. catesbeiana lives in water above 15° C and tends to feed near the banks of its breeding pond. There are usually two to three male frogs per pond due to cannibalism and fierce breeding competition. R. catesbeiana is a very generalist predator, and will eat anything small enough to swallow. This includes other amphibians, which threatens the native species when R. catesbeiana is introduced to a foreign ecosystem. Bullfrogs are also a vector for a very destructive fungus, Batrachochytrium dendrobatidis. B. dendrobatidisis an amphibian fungal infection that has been linked to the decline and extinction of amphibian species worldwide, and is more prevalent in bullfrogs. Bullfrogs are very destructive to alien environments. (Spitzen, 2010)

Durango Nature Studies property has a problem with R. catesbeiana wiping out the native R. pipiens around their lake and the Florida River on DNS property. DNS property contains a pond about 4000 sqft and a mid-size stream that runs through the property. DNS contains a “wide variety of habitats - riparian, meadows, oak woodlands, pinion-juniper forests, and desert arroyos” DNS property seems to be well suited for both species.

Unfortunately, the water quality at DNS doesn’t seem to be very good. There is a large presence of coliform bacteria in the water, indicating that other harmful bacteria and protozoa thrive in the water. Also, the water tested at a pH level of between 8 & 9. Finally, the water had a macroinvertebrate biodiversity index dangerously close to 1.0. The pond actually had an index of .98. Obviously, the ecosystem in the waters on DNS property aren’t very stable. Overall, the water is suitable for amphibian life. Bullfrogs will fare much better in this environment than Leopard frogs.

Plan Implementation

Animas High school is going to manage bullfrogs with pitfall traps. During the mating seasons of frogs in temperate climates, these frogs come out from their wintering grounds to go to the breeding ponds. Before May, Animas high school students will place many low fences along the DNS ponds which the frogs have to cross. On a short distance the students will place dry pitfall traps along the fences to let the traps collect all of the frogs. The students will check the traps daily. After that the students will separate the leopard frogs from bullfrogs. The leopard frogs will be released again and the bullfrogs can be eliminated in two different ways. The first method would be Carbon Dioxide which is a humanely acceptable method to terminate the bullfrogs. CO2 is a potent central nervous system depressant and thus causes rapid unconsciousness. It therefore reduces the bullfrogs’ sensitivity to pain. Once euthanized, the frogs can be used for 2012 educational purpose, such as dissection.

The people who will organize the eliminating of bullfrogs can be the Animas High School Students, Animas High School staff and the Durango Nature Study. The eliminating is going to start in May where the Frogs start to mate at the DNS pond. The pitfall traps will go around the DNS pond and the distance between the pitfall traps and the DNS pond will be approximately 2 meters. The traps will be set up 1 month when the mating seasons ends and the Durango Nature Studies employees will checked the traps every day. The equipment will be 5 vinyl plank, 1 hand shovel, 1 CO2 tank, 1 cooler, 1 bucket and 10 animal roofs. The cost will be approximately incurred about on $184.

Plan Monitoring

The aforementioned plan will have an effect on the R. catesbeianapopulation, but human alterations to natural habitats will inadvertently affect other animal populations. The biggest impact on the ecosystem on DNS property will be the low fence. Bullfrogs won’t be the only animal that has to get around the fence. The proposed pitfall traps will undoubtedly catch other kinds of frogs and small mammals, having an unknown effect on the total ecosystem, not just the bullfrogs. These traps could also promote other invasive species besides R. catesbeiana by providing the weak invaders with an easy food source. Unless traps are checked daily, there is a high possibility that animals will take advantage of the easy, helpless prey in the traps. In addition, the traps could injure larger animals by catching the animal’s foot and breaking its ankle. Also, larger animals could potentially hurt themselves on the fence we set up when fleeing from prey. This could cause a decrease in the population of ungulates in the nearby area because they get injured on the fence as they flee a predator and get caught easier due to their wounds. The potential drop in wildlife population will have unforeseen effects on the stability of the surrounding ecosystem and could cause the local elimination of more than just the bullfrogs targeted.

To monitor progress with the bullfrog elimination plan, once yearly students from Animas High School will hunt DNS property to capture a sample of the bullfrog population. After the R. catesbeiana population sample is caught, the students will count the specimens and humanely dispose of the bullfrogs using CO2. This process will be repeated annually until such a time when the AHS students are unable to find a R. catesbiana specimen during the sample collection day. At such a time, a committee of volunteer biologists will make an assessment of the DNS property to determine the effectiveness of the bullfrog elimination plan and the overall stability of the ecosystem on DNS property. After a thorough review of the data and capture procedures, the committee will rule if the DNS property is free of bullfrogs. After the ruling on this matter is affirmative, Shannon-Weiner tests, pH tests, and other such tests will be taken of the environment on DNS property to determine the level of stability and health in the ecosystem. If all tests determine that the ecosystem is doing well, then the plan will be decreed successful.