Amphibian population estimates and ecosystem assessment on the Durango Nature Studies property
Keagan Felker
Introduction
The Durango Nature Studies is a nature center that is located on Bondad Hill in southwest Colorado, just south of Durango. The property is made up of a pinion-juniper forest, and includes a pond, and many animals including elk, deer, amphibians, insects, and many species of reptiles. It is a semi-desert ecosystem that rests right on the Florida River. One of the amphibians that can be found on the Durango Nature Studies property is the bullfrog (rana catesbeiana). The status of bullfrogs in Colorado is classified as an “invasive species”. Invasive species are a concern on the property because they are taking over the native amphibian population in the area. Invasive species are a concern because they affect the native population of other amphibious life in negative ways, whether it’s killing them off, pushing them out of their natural habitat, or bullying them around. The presence of bluegill and bullfrogs is especially harmful to leopard frogs (rana pipiens) mainly because the bullfrogs bully the native leopard frogs into the open water and make them bait and ultimately a tasty meal for the bluegill fish that live in the Durango Nature Studies pond. The status of leopard frogs in Colorado is “state special concern”.
Natural History
Leopard frogs (rana pipiens) generally eat insects, worms, and spiders. Leopard frogs prefer wet prairies and sedge meadows, or along any open body of water – premiere riparian habitat is their first choice. Bullfrogs (rana catesbeiana) eat insects, crayfish, smaller frogs, and anything else that’s small enough to fit in their large mouths. They prefer to reside in ponds, quiet stream pools, reservoirs, or deep marshes.
Methods & Materials
During the tests, four pitfall traps were set up (two by the pond and two by the river) and checked daily to collect anything that happened to fall in and not be able to climb back out. A pitfall trap is something that can be placed in a hole in the ground - in this case a five gallon bucket - which once something falls in it, it is unable to get back out. Visual encounter surveys were conducted around the pond for each day for four days to observe the diversity of organisms that would spend time around the pond. One, one-hour marking session was conducted to tag the frogs so they could be tracked and identified. A one hour recapturing session was also conducted to make sure that all the frogs recaptured were marked and accounted for. Water chemistry tests were also conducted to test the nitrate levels, phosphate levels, dissolved oxygen levels, and pH levels in the pond and river water. Four random “veg plot” surveys were conducted to determine the diversity of plants in that area. Macroinvertebrates were collected from the Florida River by using two methods –the ‘kick method’ and the ‘dip net method’. The ‘kick method’ consists of at least one person standing downstream holding the net, and the other person(s) kicking up rocks and other objects from the bottom of the river to release macroinvertebrates and other debris to float downstream into the net. The ‘dip net method’ was used to collect macroinvertebrates from the pond by dipping a net into the water and collecting invertebrates in that manner.
Results
The water chemistry data suggests that the nitrate, phosphate, dissolved oxygen, and pH levels are somewhat higher than they should be in the Florida River and somewhat higher than normal for the pond as well. The 2012 Water Sample that shows the number of invertebrates caught in the pond, and the number of invertebrates caught in the river. It’s comparing the data from last year to the data from this year, which shows that in the past year, the diversity index of macroinvertebrates in the pond has risen by .22 and the diversity in the river has decreased by .15.
Conclusion & Discussion
The data shows that there is low water quality in both the Florida River and the pond on the Durango Nature Studies property. The dissolved chemical levels are relatively high for healthy water quality. It also shows that the number of entire macroinvertebrate species in the river has increased by 94 since 2011, and the number of macroinvertebrates in the pond has decreased by 82 since 2011. What’s been learned about the amphibian population is natively made up of leopard frogs, but once the bullfrogs were introduced to their habitat, they began pushing the native species of leopard frogs around and wound up pushing them into the water where the leopard frogs became easy bait for the bluegill that reside in the pond. What was learned about the water quality is that this year it has higher levels of components such as nitrates and phosphates in the water. This means that the levels are too high and the quality is too poor to support the life of a stonefly, but is adequate enough to support mayflies. No suggestions come to mind for ways that the tests should be altered. The tests conducted were fairly successful in terms of how data was collected and how experiments were held. One suggestion that can be made for the leopard frogs to be more effectively observed is to set up more pitfall traps. Another suggestion would be to construct another way to monitor the quantity of frogs inside the perimeter of a certain area, such as the “veg plot” method that was used, perhaps calling it a “frog plot”.
Bibliography
http://www.durangoutdoors.com/wildlife/bullfrog.htm
http://www.durangonaturestudies.org/
http://www.smm.org/warnernaturecenter/animals/leopardfrog
Keagan Felker
Introduction
The Durango Nature Studies is a nature center that is located on Bondad Hill in southwest Colorado, just south of Durango. The property is made up of a pinion-juniper forest, and includes a pond, and many animals including elk, deer, amphibians, insects, and many species of reptiles. It is a semi-desert ecosystem that rests right on the Florida River. One of the amphibians that can be found on the Durango Nature Studies property is the bullfrog (rana catesbeiana). The status of bullfrogs in Colorado is classified as an “invasive species”. Invasive species are a concern on the property because they are taking over the native amphibian population in the area. Invasive species are a concern because they affect the native population of other amphibious life in negative ways, whether it’s killing them off, pushing them out of their natural habitat, or bullying them around. The presence of bluegill and bullfrogs is especially harmful to leopard frogs (rana pipiens) mainly because the bullfrogs bully the native leopard frogs into the open water and make them bait and ultimately a tasty meal for the bluegill fish that live in the Durango Nature Studies pond. The status of leopard frogs in Colorado is “state special concern”.
Natural History
Leopard frogs (rana pipiens) generally eat insects, worms, and spiders. Leopard frogs prefer wet prairies and sedge meadows, or along any open body of water – premiere riparian habitat is their first choice. Bullfrogs (rana catesbeiana) eat insects, crayfish, smaller frogs, and anything else that’s small enough to fit in their large mouths. They prefer to reside in ponds, quiet stream pools, reservoirs, or deep marshes.
Methods & Materials
During the tests, four pitfall traps were set up (two by the pond and two by the river) and checked daily to collect anything that happened to fall in and not be able to climb back out. A pitfall trap is something that can be placed in a hole in the ground - in this case a five gallon bucket - which once something falls in it, it is unable to get back out. Visual encounter surveys were conducted around the pond for each day for four days to observe the diversity of organisms that would spend time around the pond. One, one-hour marking session was conducted to tag the frogs so they could be tracked and identified. A one hour recapturing session was also conducted to make sure that all the frogs recaptured were marked and accounted for. Water chemistry tests were also conducted to test the nitrate levels, phosphate levels, dissolved oxygen levels, and pH levels in the pond and river water. Four random “veg plot” surveys were conducted to determine the diversity of plants in that area. Macroinvertebrates were collected from the Florida River by using two methods –the ‘kick method’ and the ‘dip net method’. The ‘kick method’ consists of at least one person standing downstream holding the net, and the other person(s) kicking up rocks and other objects from the bottom of the river to release macroinvertebrates and other debris to float downstream into the net. The ‘dip net method’ was used to collect macroinvertebrates from the pond by dipping a net into the water and collecting invertebrates in that manner.
Results
The water chemistry data suggests that the nitrate, phosphate, dissolved oxygen, and pH levels are somewhat higher than they should be in the Florida River and somewhat higher than normal for the pond as well. The 2012 Water Sample that shows the number of invertebrates caught in the pond, and the number of invertebrates caught in the river. It’s comparing the data from last year to the data from this year, which shows that in the past year, the diversity index of macroinvertebrates in the pond has risen by .22 and the diversity in the river has decreased by .15.
Conclusion & Discussion
The data shows that there is low water quality in both the Florida River and the pond on the Durango Nature Studies property. The dissolved chemical levels are relatively high for healthy water quality. It also shows that the number of entire macroinvertebrate species in the river has increased by 94 since 2011, and the number of macroinvertebrates in the pond has decreased by 82 since 2011. What’s been learned about the amphibian population is natively made up of leopard frogs, but once the bullfrogs were introduced to their habitat, they began pushing the native species of leopard frogs around and wound up pushing them into the water where the leopard frogs became easy bait for the bluegill that reside in the pond. What was learned about the water quality is that this year it has higher levels of components such as nitrates and phosphates in the water. This means that the levels are too high and the quality is too poor to support the life of a stonefly, but is adequate enough to support mayflies. No suggestions come to mind for ways that the tests should be altered. The tests conducted were fairly successful in terms of how data was collected and how experiments were held. One suggestion that can be made for the leopard frogs to be more effectively observed is to set up more pitfall traps. Another suggestion would be to construct another way to monitor the quantity of frogs inside the perimeter of a certain area, such as the “veg plot” method that was used, perhaps calling it a “frog plot”.
Bibliography
http://www.durangoutdoors.com/wildlife/bullfrog.htm
http://www.durangonaturestudies.org/
http://www.smm.org/warnernaturecenter/animals/leopardfrog