Species Management Plan for
Rana pipens &Rana catesbieana on the Durango
Nature Studies Nature Center Property
Joe Wilson & Kaleb Johnson
Durango,CO
2011
The objective for this wildlife management plan is to increase the population of northern leopard frogs and eliminate the population of bullfrogs on the Durango Nature Studies property. The reason the landowner wants to eliminate the population of bullfrogs on their property is because bullfrogs are an extremely invasive species and can negatively impact the native amphibian population.
Animas High School has conducted visual encounter surveys, water quality tests, and wildlife inventory. This fieldwork was done in order to estimate frog populations and assess habitat quality. This allows for informed management decisions.
The property is used for various nature related programs and workshops, such as Children Discovering Nature, Summer Programs, that include Junior Naturalists camp and field days. Also, local organizations, such as Fort Lewis College, would conduct various studies on the property such as water tests and weather surveys. Because of their focus of educating the public about natural systems, it is high priority for Durango Nature Studies to maintain native ecosystems on their Nature Center property.
The budget for management and monitoring is 2,000 dollars. Management can take place on the Nature Center property only and cannot disrupt ongoing research.
Plan Development: Kaleb Johnson
Northern leopard frogs require different foods during its different stages of life. Northern leopard frog tadpoles usually feeds on free floating (Franz 1971) vegetation (Merrell 1977), such as algae and other aquatic plants (Hendricks 1973). The sub adults and adults usually eat insects. They have also been known to eat anything that can fit into their mouths including smaller leopard frogs. Small gardener snakes, humming birds, and yellow warblers have been found in the stomachs of northern leopard frogs (Breckenridge 1944). Over all the sub adult and adult leopard frogs are adaptable feeders.
The American bullfrog (Rana catesdeiana (Shaw 1802)) needs various habitats during its life stages. When the bullfrog is a tadpole it prefers to develop in permanent slow or non-flowing bodies of water (Santos-Barrera et al. 2008) and it takes about a year to develop (Ryan, 1953; Willis et al., 1956; Govindarajulu et al., 2006). The adult bullfrogs prefer to live in water that is large, deep, and densely vegetated. Despite the fact that they are aquatic they spend a lot of time on land (Clarkson and Devos, 1986).
As with the northern leopard frogs the American bullfrog needs different foods during its different stages of life. Bullfrog tadpoles mainly eat aquatic vegetation around the bank of the ponds (Jooris, 2005). The young and sub adult bullfrogs usually eat invertebrates (Corse and Metter, 1980; Albertini and Lanza, 1987; Beringer and Johnson, 1995). Adults can eat anything they can fit into their mouths (Corse and Metter, 1980; Albertini and Lanza, 1987; Beringer and Johnson, 1995).
The Durango Nature Studies property is 140 acres and is located outside of Durango (Figure 1). The DNS pond is located on the northwestern edge of the property. The DNS pond is about 47.5 meters long. The Florida River runs through the DNS property. The habitats on the property consist of sage-rabbitbrush riparian, meadows, oak woodlands, piñon-juniper forests, and desert arroyos.
Animas High School students conducted field research in order to assess habitat quality on the Nature Center property. Nitrate levels were found to be 1ppm in the pond and 2ppm in the river; this is considered medium to high for aquatic systems. PH was found 9 in the pond and 8 in the river; which is alkaline which is good because amphibians prefer slightly alkaline water which the pond and river are. Phosphate levels were found to be 2ppm in the pond and 1ppm in the river; these numbers are considered to be high which could result in an algal bloom. The dissolved oxygen in the pond is 6.5, which is medium and 8.5 for the river which is high which means that both the pond and the river can support a variety of life. Both the pond and the river have a low biodiversity index.
Plan implementation: Joe Wilson
To help decrease the bullfrog (Rana catesbieana) population at Durango Nature Studies direct removal tactics and monitoring will be used. Animas High School students will put a series of five pit fall traps around the pond at Durango Nature Studies. A pit fall trap consists of two buckets submerged in the ground with a guide vane between the two buckets (Mississippi 2003). By capturing frogs at Durango Nature Studies, Animas High School students will separate the leopard frogs from the bullfrogs and release the leopard frogs and euthanize the bull frogs. This will be done over a course of three weeks where a group of Animas students will go out every day and sort and euthanize frogs. The way that Animas high school students will euthanized the bullfrogs by placing them in a cooler of CO2 to suffocate the frogs and then incinerate the carcasses use them for dissect them
To make the pit fall traps themselves Animas High School students will need to take two five gallon buckets and poke twenty to thirty descent size holes in the bottom, so if it rains the water will drain away. Also they will need to cut a piece of OSB sheathing into a 10x36in plank. Then submerge the buckets so that the bucket is level with the ground and place the plank four inches in the ground between the two buckets so that the plank is against both buckets. The two buckets will need to be baited in a way, whether with preservatives or insects. Supplies will be purchased at Home Depot in Durango and will cost approximately thirty five dollars.
After the bullfrog population has been diminished the Animas High school students will collect five male leopard frogs (Rana pipiens) and five female leopard frogs to later be returned to the pond. The reason for this is to repopulate the pond after Animas students kill all other living things in the pond by putting Rotenone in the pond. The reason for killing everything in the pond is to eliminate the main predator of the leopard frog in the Durango Nature Studies pond, the Bluegill fish. Rotenone is the most effective way to eliminate all species in the pond (noble (I don’t have that year)) doing this will make it easier for the leopard frogs to reproduce because the bluegills will not be disturbing the leopard frog eggs.
The leopard frogs needed to repopulate the pond can be collected by the pitfall traps that were used before to capture the bullfrogs. After the Rotenone is put into the pond, Animas students will need to wait up to six months to reintroduce the frogs back to the pond. In the time that it takes for the Rotenone to dissipate from the pond water, the leopard frogs that are collected can be kept as pets by the Animas high school students.
In conclusion, Animas high school students will capture bullfrogs (Rana catrsbieana) and leopard frogs (Rana pipiens). Animas students will euthanize the bullfrogs and capture ten leopard frogs, five of each sex to repopulate the pond. After the leopard frogs are captured the chemical rotenone will be introduced to the DNS pond to eliminate anything alive in the pond. Once the rotenone has been eradicated from the pond the leopard frogs can be reintroduced to the pond
Plan Evaluation: Kaleb Johnson
The proposed plan will have multiple effects on the DNS property. After the last stage of the plan is implemented the pond will be unusable for 6 months until the Rotenone dissipates from the water. Any activities involving the pond will have to be postponed for about 6 months after the Rotenone is released. The plan will majorly affect the plants and animals that live in or around the pond or depend on the pond for survival by killing all the fish in the pond. The environmental impact of Rotenone has yet to be fully evaluated but its affects are greatly reduced in mammals than it is in fish, insects, and amphibians because it is harder to absorb into the blood stream of mammals than it is for fish, insects, and amphibians. The death of all those species could result in starvation of some other animals there is a chance that it won’t because the Florida river is only a few yards away. There is also a chance that some of the Rotenone might get into the Florida river and result in the death of some of the animals there. Even is some gets in the river the affect would be small because the river would wash the Rotenone away. Over the entire plan should have the desired effect of eliminating the local bullfrog population and increasing the local northern leopard frog population.
After the plan is implemented and after the Rotenone has dispersed the DNS property will have to be monitored for the continued presence of bullfrogs and to make sure the northern leopard frog population in increasing as planned. There should be a Mark Recapture Study at least once a year during the early spring just after the frogs come out of hibernation so they will be easier to catch. The method used to catch the northern leopard will be same one used in the plan implantation.
There are various conditions that need to be fulfilled to be sure that the plan is successful. One of those conditions needs to be that no bullfrogs have to be sighted for three years because that is the time span that it takes for bull frog tadpoles take to develop. Also the northern leopard frog population densities need to exceed previous levels.
Figure 1
Figure 2
Figure 3
Figure 4
Macroinvertebrate Data
Figure 5
| DNS Pond | ||
| Results | Conculsion | |
| Nitrates | 1ppm | Low |
| Phosphates | 2ppm | High |
| Dissolved Oxygen | 6.5 mg/L | Adequate |
| pH | 8.5 | Alkaline |
| Coliform | positive |
Figure 2
| DNS River | Results | Conclusion |
| Nitrates | 2ppm | Low |
| Phosphates | 1pmm | High |
| Dissolved Oxygen | 8.5 | Adequate |
| pH | 8.5 | Alkaline |
| Coliform | positive |
Figure 3
Vendor | Item Description | Cost per unit | Quantity | Total cost |
Home depot | 5 gallon buckets | 2.98 | 10 | $25.00 |
Home depot | OSB sheathing | 10.97 | 1 | $10.97 |
Off road hunting.com | Rotenone | 22.50 | 1 | $22.50 |
Wallmart | cooler | 39.88 | 1 | $39.88 |
Amazon.com | 20oz CO2 tank | 17.62 | 1 | $17.62 |
Total | $115.97 |
Figure 4
Macroinvertebrate Data
| Pond | River | ||
| Damselfly | 53 | Caddisfly | 120 |
| Mayfly | 41 | Mayfly | 125 |
| Midge | 5 | Midge | 15 |
| Caddisfly | 2 | Blackfly | 5 |
| Dragonfly | 1 | Coleoptera | 5 |
| Blackfly | 0 | Stonefly | 0 |
| Coleoptera | 0 | Damselfly | 0 |
| stonefly | 0 | dragonfly | 0 |
| Diversity index | 0.98 | Diversity index | 1.02 |
Figure 5
Species management plan Reflection
During this project we did these past few weeks we conduced fieldwork, analyzed data, created charts, created a spices management plan, and a monitoring plan based on the data we collected. For our field work we went on to the DNS property and tried to catch bullfrogs, we also collected macroinvertebrates and sorted them. We conducted Shannon Weiner index, and assesses water quality. We created charts on what we found in the water. We created a species management plan to help reduce bullfrog population and increase northern leopard frog population.
The main point of this article is that maybe invasive species are not as bad as people think they are. The examples that are given are the zebra mussels that are non-native to the great lakes and the cane toads that are non-native to Australia. This article suggests that invasive species should be defined as a species that doesn’t belong in the ecosystem not if it is native to the area or not.
I think that nature can take care of its self; it has been taking care of its self way before humans were here so I think us as humans should let nature take its own course. It’s the same around the world as it is in Colorado, so I think it isn’t a problem, and we should let it change how it will. Honestly I really don’t think it’s that much of a problem so I don’t think it was worth while
During this project I learned how to write technically well. I learned that an ecosystem is a fragile thing and can be disrupted by even the smallest things. During this project I did learn how to read scientific literature. I also learned how to use a guide to identify species. I do have a better understanding of invasive species but I do not think it is an issue. Trough out this project I defiantly gained a lot of presentation skills. During this project I did learn some about analyzing scientific data with math.
P.S I also think that we as humans are the worst invasive species and we need to change the way we use or resources
