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Featured scientist: Richard Holmes from the Hubbard Brook Experimental Forest

Background

The Hubbard Brook Experimental Forest is an area where scientists have collected ecological data for many years. It is located in the White Mountains of New Hampshire. Data collected in this forest helps uncover environmental trends over long periods of time, such as changes in air temperature, precipitation, forest growth, and animal populations. It is important to collect data on ecosystems over time because these patterns could be missed with shorter observation periods or short-term experiments. 

Each spring, Hubbard Brook comes alive with the arrival of migratory birds. Many come from the tropics to take advantage of abundant insects and the long summer days of northern areas. In the spring, avian ecologists, or scientists who study the ecology of birds, also become active in the forest at Hubbard Brook. They have been keeping records on the birds that live in the experimental forest for over 50 years. These data are important because they represent one of the longest bird studies ever conducted! 

Richard is an avian ecologist who began this study early in his career as a scientist. He was interested in how bird populations respond to long-term environmental changes at Hubbard Brook. Every summer since 1969, Richard takes his team of trained scientists, students, and technicians into the field to identify which species are present. Richard’s team monitors populations of over 30 different bird species. They count the number of birds that are in the forest each year and study their activities during the breeding season. The researchers wake up every morning before the sun rises and travel to the far reaches of the forest. They listen for, look for, identify, and count all the birds they find. The team has been trained to be able to identify the birds by sight, but also by their calls. Team members are even able to identify how far away a bird is by hearing its call! 

The study area is located away from any roads or other disturbed areas. To measure the abundance, or number of birds found in the 10 hectare study area, the researchers used what is called the spot-mapping method. They use plastic flags on trees 50 meters apart throughout the study area to create a 50x50 meter grid. The grid allows them to map where birds are found in this area, and when possible, where they locate their nests. Using the grid the researchers systematically walk through the plot several days each week from early May until July, recording the presence and activities of every bird they find. They also note the locations of nearby birds singing at the same time. These records are combined on a map to figure out a bird’s territory, or activity center. At the end of the breeding season they count up the number of territories to get an estimate of the number of birds on the study area. This information, when paired with observations on the presence and activities of mates, locations of nests, and other evidence of breeding activity provide an accurate estimate for bird abundance. Finally, some species under close study, like American Redstart and Black-throated Blue Warbler, were captured and given unique combinations of colored bands, which makes it easier to track individuals.

By looking at bird abundance data across many years, Richard and his colleagues can identify trends that reveal how avian populations change over time.

Scientific Question:

1. How has the total number of birds at the Hubbard Brook Experimental Forest changed over time?

Scientific Data:

2. What data will you graph to answer the question?

Independent variable(s): 

Dependent variable(s):   

3. Create your graph and paste below:

4. Identify any changes, trends, or differences you see in your graph. Include your graph and specifically refer to it when describing those changes, trends, or differences.

Interpret the Data:

5. Make a claim that answers the scientific question.

6. What evidence was used to write your claim? Reference specific parts of the tables or graph.

7. Explain your reasoning and how the data support your claim. Connect the data back to what you learned about the importance of long-term datasets.

Additional Resources for this activity:
For more information on this research, check out the Hubbard Brook Experimental Forest’s page on their songbird research: https://lternet.edu/findings/shifting-songbirds/

For more lessons created from data collected on birds at Hubbard Brook, check out the page “Migratory Birds Math and Science Lessons” from Hubbard Brook: https://hubbardbrook.org/lessons_birds

You can also extend the lesson by checking out this online book that synthesizes the research done at Hubbard Brook Experimental Forest: https://hubbardbrook.org/online-book

There are multiple publications related to the data included in this activity:

• Holmes, R. T. 2011. Birds in northern hardwoods ecosystems: Long-term research on population and community processes in the Hubbard Brook Experimental Forest. Forest Ecology and Management doi:10.1016/j.foreco.2010.06.021.

• Holmes, R.T., 2007. Understanding population change in migratory songbirds: long-term and experimental studies of Neotropical migrants in breeding and wintering areas. Ibis 149 (Suppl. 2), 2-13.

• Townsend, A. K., et al. (2016). The interacting effects of food, spring temperature, and global climate cycles on population dynamics of a migratory songbird. Global Change Biology 22.2: 544-555.

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This dataset and content is provided our by our friends at Data Nuggets.

Visit DataNuggets.org to see the original activity and additional materials