The activities are as follows:
- Teacher Guide
- Student activity, Graph Type A, Level 2
- Student activity, Graph Type B, Level 2
- Student activity, Graph Type C, Level 2
- Grading Rubric
9,000 years ago humans invented agriculture as a way to grow enough food for people to eat. Today, agriculture happens all over the globe, and takes up 40% of Earth’s land surface! To make space for our food, humans must clear large areas of land, creating a disturbance, or drastic change, to the habitat. This disturbance removes the native plants already there, including trees, small flowering plants, and grasses. Many types of animals including mammals, birds, and insects need these native plants for food or shelter and will now find it difficult to live in the area. For example, a woodpecker bird can’t live somewhere where there are no trees, because they live and find their food in the trees.
However, some disturbances might help some animals because they can use crops for the food and shelter they need to survive. One example is the cacao tree, which grows in the rainforests of South America. Humans use the seeds of this plant to make chocolate, so it is a very important crop! Cacao trees need very little light. They grow best under the large trees found in rainforests. To get lots of cacao seeds for chocolate, farmers need to have large rainforest trees above their cacao trees for shade. In many ways, cacao farms resemble a native rainforest. Many native plant species grow there and there are still taller tree species. However, these farms are different in important ways from a native rainforest. For example, there are many more cacao trees than found in native rainforests. Also, there are fewer small flowering plants on the ground because humans that work on cacao farms trample them as they walk around the farm.
Part I: Skye is a biologist who wanted to know if birds from rainforests could survive when their habitat was replaced with cacao farms. To begin, she counted birds and determined their abundance in each habitat. Skye chose one rainforest and one cacao farm and set up two transects in each. She spent 4 days counting birds along each transect, for a total of 8 days in each habitat. She had to get up really early and count birds between 6:00 and 9:00 in the morning because that’s when they are most active!
Part II: Skye was shocked to see so many birds in cacao farms! She decided to take a closer look at her data. Skye wanted to know whether the types of birds she saw in the cacao farms were different or the same as the birds she saw in the rainforest. She predicted that cacao farms might have different types of birds living in them than the undisturbed rainforest. She thought the bird types would differ because each habitat has different types of food available for birds to eat and different types of plants for birds to live in.
Skye broke her abundance data down to look more closely at four types of birds:
- Toucans (Eat: large insects and fruit from large trees, Live: holes in large trees)
- Hummingbirds (Eat: nectar from flowers, Live: tree branches and leaves)
- Wrens (Eat: small insects, Live: small shrubs on the forest floor)
- Flycatchers (Eat: Small insects, Live: tree branches and leaves)
Featured scientist: Skye Greenler from Colorado College
Information on study location: Skye’s study took place in a 10 km2 mixed rainforest, pasture, agro-forest, and monoculture landscape near the village of Pueblo Nuevo de Villa Franca de Guácimo, Limón Province, Costa Rica (10˚20˝ N, 83˚20˝ W), in the Caribbean lowlands 85 km northeast of San José.
There is one scientific paper associated with the data in this Data Nugget. The citation and PDF of the paper is below.
Greenler, S.M. and J.J. Ebersole (2015) Bird communities in tropical agroforestry ecosystems: an underappreciated conservation resource. Agroforestry Systems 89: 691–704.