I’m teaching Foraging Behavior in my Animal Behavior Class this week. I was searching for some information in my files to share with my students to illustrate the concepts discussed in class: optimal foraging, foraging decisions. I then came across this blog post I wrote but never published. I attended the 12 Biennial Conference of the International Society of Behavioral Ecology (2008) at Cornell University. It was my first time live blogging a science conference and my first time interviewing scientists about their work. I was especially interested in presentations and posters that I could share with my blog audience because it focused on familiar animals often found in backyards and bird feeders, like this project.
Dr. Piotr Jablonski and Dr. Sang-Im Lee of the Seoul National University of South Korea shared with me some interesting findings of their research in the Mexican Jay of Arizona. Though this bird is not really an urban or suburban animal, it is closely related to common city jays like the scrub jay (of Florida ). Like most birds, the Mexican Jay forages for seeds to eat. Seeds are a popular bird food because they are highly nutritious food item in a relatively small package. Like most scientific studies, their interests in the birds feeding behavior was piqued by their curiosity when they noticed birds would seem to sample seeds before finally selecting one to eat.
So, they devised an experiment with peanuts in the shell to see if the birds were actually sample seeds based on their weight. Peanut shells are relatively light and come in many sizes with 1-3 nuts in the shell typically. But not all nut shells are equal; some shells have fewer nuts, some shells are missing nuts and so on. So Piotr, Sang-Im, and other colleagues presented the Jays with small and large peanut shells – some of the shells were empty, some filled. And the Jays would actually pick up and sample the shells. They preferentially chose the larger shells filled with nuts and did not choose the empty shells. Smart birds, huh? And when there were large shells with only one nut and a small shell with one nut, they preferentially chose the smaller shell! Why? Though the payoff was exactly the same, the researchers think it has to do with the birds ability to somehow perceive expected payoff. The larger shell should contain more nuts, so if only a single nut is to be rewarded, then choose the naturally smaller nut package.
The great thing about their research is that you can do a very similar study in your own backyard.
Do seed eating birds choose their food items well? When they are harvesting seeds – from a tree or feeder – do they select the filled or empty shells more often?
How to test it:
This requires some work on your part, but the payoff could be tremendous.
Select one or two bird species to observe and watch. Pick a species that is a dedicated seed eater like cardinals; they love sunflower seeds.
Purchase a bag of the seed, not a mix. Go through the seed and separate the empty from the filled shells.
Place an equal amount of filled seeds and empty seeds into two different pans. (You can count the number of seeds or weigh them).
Place the pans outside and 3 feet apart. This is your feeding station. Step back or go inside and watch the birds from inside.
Count the number of birds that visit your feeding station and count how many visit each pan. If you really want to go a step ahead, use a timer to see how long birds stay and visit each pan.
At the end of your observation period, count or weigh your pan and see how many seeds were removed. Did the birds harvest more filled seeds or empty seeds?
Share your results of your hard work with others. Perhaps write up a report for school or for your neighborhood newsletter.
Good luck and let me know how it goes.