Island Updates

Wildlife Habitat & Population Measurement UVM

Post by Science Educator Chloe Tremper

Looking at habitat suitability in the field

Twenty students and two professors from the University of Vermont’s Wildlife Habitat & Population Measurement course spent this past week on Hurricane Island. Professors Allan Strong and Jed Murdoch used Hurricane as a platform to teach field methods for estimating wildlife populations and measuring habitat variables to their students. This course focused on three methods commonly used in the fields of wildlife biology and ecology: mark-recapture, point counts, and habitat suitability index measurements. 

Mark & recapture studies are used to estimate the number of individuals within a species’ population. On Hurricane, the UVM students used this method to estimate the population size of small mammals on the island, as well as determine which species were present.  During their first day on Hurricane, the students broke into four groups and set up grids with 100 traps each on different parts of the island.  The traps were opened early each morning with a sprinkling of oats and some scraps of paper towel placed in each as food and nesting materials.  The traps used were Sherman traps, which are a box-style animal trap designed for live capture of small mammals. When the students checked the traps a few hours later, students recorded whether a trap was open and empty, closed and empty, or closed with a capture inside.  For each individual small mammal that was caught, the students marked a bit of its fur with a marker so that if it was caught again later it could be identified.  As traps were checked, the students were careful to close each so that no animals would be trapped for an extended period of time.

The students also learned how to conduct bird point counts, which are useful for monitoring avian population trends.   Four locations were designated along different trails that students would go to once a day to conduct a count in their smaller groups.  At their first point they did a 30-minute point count.  To do this, the first 10 minutes at the point all birds heard or seen were recorded, the second 10 minutes only new birds that were not noted during the first, and for the third 10 minutes only new birds again were recorded. Over their days there each group did a 30-minute point count at each of the four sites and a few 10-minute point counts at the remaining sites.

On their second to last day on the island, the students went out in the spruce-fir forest of Hurricane to measure multiple habitat variables to determine if the habitat available on Hurricane is suitable for snowshoe hares and downy woodpeckers, neither of which are known to reside on Hurricane.  However, both species habitat preferences were relevant for the purpose of learning how to implement the sampling technique.  Habitat suitability indexes are available for variety species through the USGS National Wetlands Research Center

We were sad to see this lively bunch of students leave at the end of the week but enjoyed getting to know them & appreciated the data they provided us!

Students enjoy Sunset Rock

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