Welcome to my Biology page!
If you want access to my BioBlog, click this link:
Leopard Frog project
Species Management Plan for Rana pipiens & Rana catesbeiana on the Durango Nature Studies Nature Center Property
Elizabeth Duncan
Durango, CO
2011
Field Condition Form
The habitat of the northern leopard frog (Rana pipiens) can be versatile, yet very specific. Northern Leopard Frogs need to be in a wet, marshy environment to grow, breed and lay their eggs. Werner and Glennemier (1999) found that northern leopard frogs require and breeding pond with an open canopy. Leopard frogs start off their life in shallow breeding ponds, 30 - 60 m in diameter, and 1.5 -2.0 m in depth (Merrel, 1968). Rana pipiens have been known to hatch in gravel pits, stock ponds and beaver ponds (Corn and Livo, 1989). Bluegills were stocked in the pond 10 years ago, the current population unknown. Flowing streams serve as an overwintering site for leopard frogs. The water is standing and can dry out or become lower during droughts (Werner and Geinnemeier, 1999) As they grow older, they tend to leave the water and venture on to land. They prefer grassy fields by streams and ponds and the grasses can be up to 30cm high, and tend to be dry (Spitzen, 2010). Leopard frogs, when adults, can move as far away as 5.2 km away from natal ponds. (Dole, 1971). In the fall, Leopard frogs (Rana Pipiens) overwinter. Rana Pipiens migrate to overwintering sites such as under the water in ponds. (Emery at al, 1972 Hammerson, 1999)
Bullfrogs preferably live in large, deep water that is densely vegetated. They require permanent wetlands for breeding. The bullfrog is mainly aquatic, but can spend considerable amounts of time on land. (Clarkson and Devos, 1986).
One of the reasons that bullfrogs are invasive is because of how rapidly they can reproduce. A female bullfrog can lay as many as 20,000 eggs in a layer of 1 egg thickness. This spawn can have a surface of 1,000 - 2,000 cm squared. After some time (approx. 20 minutes) the spawn sinks and starts to develop. Larger, older bullfrogs produce more hatchlings than younger ones because of size-related advantages in competition for mates or production on large clutches. (Howard, 1983) Bullfrogs also have negative impacts on native amphibian species such as Rana Pipiens because of the large tadpoles of this species and outcompete the larvae of native species. (Blaustien and Keisecker, 2002; Kats and Ferrer, 2003) In addition to rapid reproduction, bullfrogs are aggressive generalist predators and have the ability to out-compete native amphibians for resources throughout their life cycle.
The DNS (Durango Nature Studies) property contains the habitat requirements for both leopard frogs and bullfrogs. DNS is located by Bondad, Colorado and contains 142 acres of land. The Florida River runs along the property, some parts stream off into ponds, giving leopard frogs and bullfrogs the habitat to thrive. DNS has many kinds of habitats within the 142 acres: Juniper-Pinion forests, desert arroyos, meadows and oak woodlands. The frogs tend to keep close to the ponds and river in the juniper-pinion forests.
Animas High School has done a field study on leopard frogs and bullfrogs at DNS and have found that leopard frogs are consistent around the pond and bullfrogs seem to be scarce. They found that there were 10 leopard frogs and 2 bullfrogs around the pond. The pond water results for nitrate came to 1ppm, meaning that the pond is considered unpolluted. The results for the level oxygen in the pond came to 6.5 mg/L, meaning that the pond absorbs less oxygen than the river (which was 8.5 mg/L). Making the river a more desirable place for gilled species. The results for pH levels in the pond were between 8&9. Part of Animas High School’s field study was looking at how biologically diverse the pond and river are by looking at how many macroinvertebrates were in each water source. Looking at the amount of macroinvertebrates in the river, they were able to see how biologically diverse the pond is. On the scale of 1 to 5, 1 being low and 5 being high, the DNS pond’s results were 0.98. That tells them that the pond has a low diversity index. The diversity index for the river was 1.02. Making the river more biologically diverse. Last, the results for phosphate in the pond came to 2ppm, meaning that plant growth in the pond is high. High plant growth contributes to bullfrogs because they hide themselves in vegetation for protection. (Spitzen, 2010)
Water Quality Data: Pond
| Pond | Results | Conclusions |
| Nitrates | 2ppm | Normal |
| Phosphates | 2ppm | High |
| Dissolved Oxygen | 6mg/L | Normal |
| pH | 8.5 | Alkaline |
| Coliform | + | Present |
(Figure 3)
Water Quality Data: River
| Florida River | Results | Conclusions |
| Nitrates | 1ppm | Normal |
| Phosphates | 1ppm | High |
| Dissolved Oxygen | 8mg/L | Normal |
| pH | 8.5 | Alkaline |
| Coliform | + | Present |
(Figure 4)
Macroinvertebrate Data: Pond
| Macroinvertebrate | Quantity |
| Damselfly | 53 |
| Mayfly | 41 |
| Midge | 5 |
| Caddisfly | 2 |
| Dragonfly | 1 |
| Blackfly | 0 |
| Coleoptera | 0 |
| Stonefly | 0 |
| Total | 102 |
| Diversity index | 0.98 |
(Figure 5)
Macroinvertebrate Data: Florida River
| Macroinvertebrate | Quantity |
| Damselfly | 0 |
| Mayfly | 125 |
| Midge | 15 |
| Caddisfly | 120 |
| Dragonfly | 0 |
| Blackfly | 5 |
| Coleoptera | 5 |
| Stonefly | 0 |
| Total | 270 |
| Diversity Index | 1.02 |
(Figure 6)
Management and Monitoring Costs
Budget: $2,000
| Vendor | Item | Cost Per | Quantity | Total |
| | Nets | $8 | 10 | $80 |
| | Boxes | $8 | 10 | $80 |
| | Tagging Kit | $252 | 1 | $252 |
Total: $917
(Figure 7)
Reflection
This project was about the management of bullfrogs and the monitoring of leopard frogs. During this project, I studied the fieldwork that we conducted at the Durango Nature Studies property. This work being sorting macroinvertebrates, assessing water quality, keeping count of how many bullfrogs and leopard frogs that we saw present and calculating the biodiversity of the pond and river. In result of this process, I created tables and graphs to show all that we have found.
The summary of the article “Time to stop worrying about invasive species?”: If a native species is hurting plants and animals around them, then it’s ok. They’re native. The examples are the Cane toad in Australia, zebra mussels in the Great Lakes and the pine beetle. They define invasive species as a nomadic species. (not direct quote)
Bullfrogs should be a concern in Colorado because they are outcompeting native species such as the leopard frog. The bullfrog is also a global concern because it’s not only invading in Colorado, it’s invading in many places around the globe such as Russia and Belgium. The work that we have conducted has been worthwhile because we all were able to gain an understanding of what the bullfrog does to our native species and makes us more aware of this issue. Maybe we won’t be able to do anything about it right now, but in the future, when we have our plans worked out, we can establish them and put them into action.
What I learned from this project is that our native species are very important to our ecosystem and that the cycle wouldn’t be complete without them. Along with that, I gained an understanding of how the invasive bullfrog have changed that. I also learned how to write scientific literature, which will be good to know in the future in high school.
