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Analysis of the Co-Existence the of Bullfrog and Green Frog in Lake

Romeyn According to Microhabitats.

By Ben Ames, Chloe Fross, and Ross Julian

Bullfrog (Rana catesbeiana)

(ADW, 2011)

Bullfrog (Rana catesbeiana) Habitat

Selection

Found on the edges of large bodies of water with grasses (DeGraaf 2001).

Have been found in areas with significant human disturbance (increase in water temperature or aquatic vegetation) (Bruening, S. 2002).

Bullfrog Food Habits

Small prey include fish, other frogs, salamanders, newts, young turtles, snakes, small birds, mice, crayfish, insects, snails, and spiders (DeGraaf 2001).

Hunt for prey in water weeds (DeGraaf, 2001).

Tadpoles are mainly vegetarian, but they can eat dead animals, usually fish (DeGraaf, 2001).

Bullfrog Breeding

Breeds successfully in deep water (DeGraaf 2001).

Known to breed in shrub-sheltered areas (DeGraaf 2001).

Breeds from late May to July (DeGraaf 2001).

12,000 to 20,000 eggs are laid in a mass (DeGraaf 2001).

Green Frog ( Rana clamitans melanota)

(ADW, 2011)

Green Frog (Rana clamitans melanota) Habitat Selection

Known to inhabit the edges of a variety of aquatic habitats (DeGraaf 2001).

Including the edges of lakes, ponds, creeks, woodland streams, lime-stone quarry pools, springs, vernal pools, moist woodlands near water, fens, bogs, tidal creeks, and mill ponds (DeGraaf 2001).

Green Frog Food Habits

The Green Frog hunts for prey in vegetation near the shore (DeGraaf 2001).

Prey include insects and their larvae, worms, small fish, crayfish and other crustaceans, newts, spiders, small frogs, and mollusks (DeGraaf, 2001).

60 percent of their food is comprised of beetles, flies, grasshoppers, and caterpillars (DeGraaf 2001).

Green Frog Breeding

Eggs are deposited in floating masses of jelly attached to underwater twigs and stems in permanent water (DeGraaf 2001).

Breed from April to August; hibernation ends in early spring and breeding begins in May (DeGraaf 2001).

Competition between the Bullfrog and the Green

Frog

There is evidence of strong competition between the two species, with bullfrog tadpoles tending to be the superior competitor because of their higher level of feeding activity (Kentwood D. Wells, 2007).

The competition between the species is influenced by predation (Kentwood D. Wells, 2007).

Competition between the Bullfrog and the Green

Frog

Bullfrogs are observed to be the greater competitor of the two species, but for in ponds without fish, because the bullfrog is less likely to a source of prey to the fish and the presence of fish decreases bullfrog predators (Kentwood D. Wells, 2007).

The competition between the Green Frog and the Bullfrog reduces the growth rates of tadpoles (Kentwood D. Wells, 2007).

Research Question

How do the Green Frog and Bullfrog coexist in the Lake Romeyn habitat?

Hypothesis

The Green Frog and Bullfrog are able to coexist as competing species in Lake Romeyn because of the different use of various microhabitats.

Materials

Minnow traps

Buckets for Counting

Flags for trap identification

Boots

Methods

We set 18 minnow traps in groups of 4-6 in the Lake Romeyn Habitat.

We went out each day for 45 minutes to check the trap data.

We recorded the number of Green Frog and Bullfrog Tadpoles in each trap.

We looked for patterns or distinctions between the microhabitats where the Green Frogs and Bullfrogs were found.

Our site qualifications were based on depth, amount of vegetation and a scale of sediment on the pond’s floor.

Methods 2 (Variables)

Site 1 (plots 1-4): large amount of organic sediment, grasses, medium depth

Site 2 (plots 5-8): small amount of organic sediment, little to no vegetation in the water, very deep-some traps fully submerged

Site 3 (plots 9-12): moderate amount of organic sediment, grasses, medium depth

Site 4 (plots 13-18): moderate amount of organic sediment, little to no vegetation, medium depth

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Pictures From the Field

Site 1

Site 2

Site 3

Site 4

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Results and Analysis

Results

Table 1: The Bullfrog and Green Frog data recorded with empty traps omitted

Date Time Site Bullfrog Green Frog

5/13/11 2:10 PM 1 1 0

5/13/11 2:10 PM 2 1 1

5/14/11 11:30 AM 1 0 1

5/16/11 1:00 PM 4 0 1

5/19/11 6:00 PM 3 0 2

5/22/11 8:00 PM 3 1 0

5/22/11 8:00 PM 4 1 1

5/23/11 1:05 PM 4 2 0

5/24/11 9:00 AM 4 3 0

Results and Analysis 1

Figure 1 shows that both species of tadpole were found in all four sites with varying abundance, but only on seven days of the two week period when data was collected.

According to our data we could find no strong correlations between favorable microhabitats for each species.

Date Time Site Bullfrog Green Frog

5/13/11 2:10 PM 1 1 0

5/13/11 2:10 PM 2 1 1

5/14/11 11:30 AM 1 0 1

5/16/11 1:00 PM 4 0 1

5/19/11 6:00 PM 3 0 2

5/22/11 8:00 PM 3 1 0

5/22/11 8:00 PM 4 1 1

5/23/11 1:05 PM 4 2 0

5/24/11 9:00 AM 4 3 0

Table 1: The Bullfrog and Green Frog data recorded with empty traps omitted

Analysis of Figure 1

Figure 1 shows the number of tadpoles of each species found on each site.

Site 1 had an equal number of bullfrog and green frog tadpoles.

Site 2 and 3 each had 2 green frog tadpoles and 1 bullfrog tadpole, which is not a large enough amount of data to show a conclusive trend. Site 4 was the only site with a significantly larger number of one species versus the other. There were 6 bullfrog and 1

green frog tadpoles Characteristics: moderate

amount of organic sediment, no vegetation, medium depth

Site 1 Site 2 Site 3 Site 40

1

2

3

4

5

6

7

BullfrogGreen Frog

Figure 1: The Bullfrog and Green Frog Tadpoles Found on Each Site to Help Present a Preference of Microhabitats

Figure 1

Figure 1: The Bullfrog and Green Frog Tadpoles Found on Each Site to Help Present a Preference of Microhabitats

Site 1 Site 2 Site 3 Site 40

1

2

3

4

5

6

7

BullfrogGreen Frog

Discussion and Conclusions

Our data was too scarce to draw conclusions of our hypothesis that the microhabitats would allow for the co-existence of the bullfrog and the green frog in Lake Romeyn.

The weather may have been a factor in the presence of bullfrog and green frog’s breeding and developmental activity which would decrease the number of each species in Lake Romeyn.

The temperatures during the two week data collection period were mostly around 50 degrees Fahrenheit, with two days reaching 60 degrees Fahrenheit, and of those days most were rainy causing a decrease in water temperature. Although on two days the temperature reached 60, the water is a

buffer and does not allow the temperature to be altered by one or two days of warm weather (which were not consecutive).

Error and Bias

The weather’s impact on the data collected suggests that in the a future study must be altered by choosing different variables to measure to explain the co-existence between bullfrogs and green frogs other then microhabitats (for example food resources or an introduction of predation, which would require an indoor lab).

Or…one would have to start the lab later in the year

Literature Cited

Degraaf, Richard M and Yamasaki, Mariko. 2001. New England Wildlife: Habitat, Natural History and Distribution. University Press of New England.

Bruening, S. 2002. The Bullfrog "Rana catesbeiana”, Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Rana_catesbeiana.html.Accessed May 01, 2011

Wells, Kentwood D. 2007. The Ecology and Behavior of Amphibians. Chicago. The University of Chicago Press.http://books.google.com/books?id=eDKEKy5JJbIC&pg=PA779&lpg=PA779&dq=competition+between+the+green+frog+and+the+bull+frog&source=bl&ots=EtE1LARTyw&sig=vcp7d2lAyZ0fSI9xrfwtTS2D2QQ&hl=en&ei=hSW-TcfKGs2gtwfK-PXdBQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBgQ6AEwAA#v=onepage&q=competition%20between%20the%20green%20frog%20and%20the%20bull%20frog&f=falseAccessed May 1, 2011.

Myers, P., R. Espinosa, C. S. Parr, T. Jones, G. S. Hammond, and T. A. Dewey. 2006. The Animal Diversity Web. http://animaldiversity.org.Accessed May 26, 2011