March 6, 2012

Peer Review: Cohane-Mann ’12 Studies New Zealand Frogs

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In the country of New Zealand, there used to be seven distinct frog species roaming the marshy underbrush.  But due to destruction of habitat, only four endangered species remain today.Rosalyn Cohane-Mann ’12, agricultural sciences, studied one of these species last spring through EcoQuest, an applied field studies program based in New Zealand. Cohane-Mann researched the Hochstetter’s frog, an amphibian about the size of a penny found around the various valley streams of New Zealand.

Her work was a part of a larger, ongoing 10-year study.  Cohane-Mann’s particular focus within the project was twofold: a habitat assessment and a population study of the Hochstetter’s frog. In the habitat assessment portion of her research, Cohane-Mann and a team of American students hiked to different stream sites.  At the different sites, the team used a rating system to determine how viable a certain path would be for measuring frog occurrences.

“We had a meter stick and basically laid it out against the stream edge. In this meter length, we assessed the cover objects for the frogs, like sizable rocks, wood, vegetation coverage,” Cohane-Mann said.  The cover objects allowed the frogs to camouflage themselves.  The frogs would hide away from predators using the various objects in certain paths as safe hiding spots.

Cohane-Mann and the rest of the frog finding team used this meter stick method to assess habitats in two distinct areas in New Zealand. One area had a mammalian predator control system in place to prevent the mammals in the area from preying on the local bird species. The other area she studied had no mammalian predator control. In observing these locations, the team wanted to see if predation management in this area has had cascading effects down the area’s food chain to the frogs, according to Cohane-Mann.Cohane-Mann found that within the managed area, the general habitat was in better condition with more objects that can provide coverage for the frogs. In total, Cohane-Mann, along with her team, found about 60 frogs during their week-long search and most of them were in the managed area where the superior habitats were.

“This suggests that there could be cascading effects from the mammalian predators on these frogs. The mammals that predate on the protected birds may also be disrupting stream habitat or might even be predating on the frogs,” she said.  Also, upon conducting the population study portion of her research, Cohane-Mann found that, compared to previous years, the population of the Hochstetter’s frog increased slightly.

Each member of the frog finding team wrote an individual research paper focusing on the two primary factors, habitat assessment and population survey. Nevertheless, in addition to these two features of frog life, each paper was also permitted an additional unique focus. Cohane-Mann chose to concentrate on frog movements in response to weather patterns.

In her weeklong field study, there were two days of very heavy rainfall in which the stream levels significantly increased. According to Cohane-Mann, this caused the frogs to move away from the stream edge because their habitats were too saturated with water.  “On drier, sunnier days, the frogs tended to be closer to the stream habitat, and when it started to rain, the frogs tended to move outward,” she said.

For Cohane-Mann, one of the best parts of the experience was uncovering an actual frog.  “We would all get super excited whenever we found a frog. We had walkie-talkies and would yell, ‘Found a frog! 32 centimeters!’ The general enthusiasm around the project was really awesome,” she said.

According to Cohane-Mann, she learned many things during her time in New Zealand; however, one of the most important lessons for her was learning the value of working in a team.

“I really enjoyed working in a research team. I think doing individual research is also important and interesting, but I really valued working with people and being able to share the experience with others,” she said.

Original Author: Jessica Harvey

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