Tuesday, September 13, 2011

Feeding the Birds: An Experiment (or Two...)

We just love the birds in our yard. We live in the city, but we have a large lot because our house used to be a multifamily home. We cram as much of the natural world into our yard as we can, and plant it with things that will attract birds and butterflies.

As part of our study of Exploring Creation Through Zoology I: Flying Creatures of the Fifth Day, we conducted an experiment on seed preferences of our backyard birds (Lesson 2: "What Makes a Bird, a Bird?"). This was also a connection to the September Edition of the Handbook of Nature Study Newsletter: Weeds, Seeds and Other Delights. Here is how to conduct it in your backyard:


  • 2 styrofoam plates or 2 other identical "feeders"
  • 2 kinds of seeds (we used black oil sunflower seed and Niger thistle seed)
Note: We reviewed the terms dependent variable (seed preference) and independent variable (seed type), and introduced a new term, confounding. We reviewed the importance of having only one independent variable (the kind of seed), so it is very important that the feeders are the same. Otherwise, the difference in the feeders will introduce confounding into your experiment.

  • Place the feeders in an open space where they can be viewed.
  • Observe them, keeping track of how many visits each feeder gets. We observed our feeders over the following several days, and made a simple tally chart to record visits. As an extra, we decided to record the species of birds who visited each feeder, as well.
A little word on the experiments in Apologia Science's Young Explorers Series, from the scientist-mom:

When you conduct an experiment, you are testing to see the effect of you independent variable (here, seed type) on the dependent variable (seed preference).  In order to measure this, you are assuming that any differences in seed preference are ONLY due to the independent variable-- so you must make sure there are no other factors that could affect the dependent variable. If we put one feeder in a wide open space, and one under a shrub, then we introduce another factor which would affect birds' preference in the seed (i.e., availability of cover), and we can't say that the results were only due to the type of seed.

You will notice that the experiments in the Young Explorers Series (for elementary students) very simple and use common items. This is deliberate, so that you spend more time reviewing the principles and the scientific method. The directions for each experiment include a discussion of "big kid" scientific terms and concepts, and concentrate on methodology, rather than complicated equipment or steps, letting your child spend more time on the actual inquiry part of science.

When children are older (middle and high school), we will want them to follow complex, multistep procedures with precision. This is a skill, by itself. So, for now, we are keeping the procedures simple, so we can concentrate on the components of the scientific method.


  • Null Hypothesis: Seed type has no effect on the number of visits to each feeder.
  • Alternative Hypothesis: The type of seed affects the number of visits to each feeder.
Maliks' hypothesis: "I think the thistle seed will get more likes."


Here is how we set up our data table, and our results:

Niger Thistle Seed

Black Oil Sunflower Seed

English (House) Sparrow – II

Northern Cardinal – II
Mourning Dove – I



We  accepted our alternative hypothesis, that the type of seed influences bird seed preferences in our yard. Malik also concluded that different birds prefer different types of seed.

Sometimes, a picture says it all.

In a research paper, scientists then include a section called Discussion, where the scientist talks about the particulars of an experiment, what surprised him (or her), what didn't go as planned, and what adjustments would be made next time, to better test the hypothesis. This is also the section where the researcher tells what next experiments should be done, as a result of these findings. This section was not included in the lab report from the Apologia materials, but we included it. Here are the three areas that might have affected our results.

1. Human activities. When we first set up our experiment, my son asked, "But won't the birds fly away every time we open the screen door?" In fact, we did notice this, and it was challenging to actually catch the birds feeding, although it was clear they did.

2. Cat activities. As Malik put it in his conclusion, "The cats were on the ground, and so were the feeders."

3. Feeder location. We saw that the types of birds that came to the feeders were birds that don't mind feeding on the ground. My son expected goldfinches to come to the thistle seed, since we see them on the thistle feeder all the time, but they do not feed on the ground, and we didn't observe them.

We would repeat this experiment by hanging the feeders where we could observe them through a window.


In the photo, above, you can see the net bag that used to contain our Smart Suet. It was very popular with the birds (but a little soft in the heat -- we'll put the rest out once the weather gets cold). They pulled it off the hanger and finished it off.

The Handbook of Nature Study has some helpful hints about how to turn your yard into a haven for nature (pp. 43-44), and for the basics of beginning bird study with young children (p. 28). See also Barbara McCoy's blog by the same name, Handbook of Nature Study, for an article on Making Your Yard a Wildlife Habitat.