Feeding Habits of Aves of Northern Illinois
The huntress spots her prey at last. Stealthily, she slithers from the path, careful to stay in the dappled light of the forest floor. Mindful of each twig underfoot, she feels her way through the tangle of underbrush. She takes careful aim. Spotted! The Melanerpes erythrocephalus cocks a knowing head in her direction. It’s now or never. She shoots. Today’s prize, however, is only another picture of empty tree branches. Undeterred, she’ll be back.
Where To Start
I felt whatever project I chose needed to be useful. To study and not pass on that knowledge is little better than not studying at all. After talking to scientists at the Illinois Department of Natural Resources and the Fermi National Accelerator Lab, I met Margaret Gazdacka, a naturalist for the Fox Valley Park District’s Red Oak Nature Center. A knowledgeable ornithologist, Margaret was enthusiastic and helpful. Red Oak Nature Center had a perfect area for bird watching, and Margaret said that data about which types of seeds and feeders birds preferred would be useful in helping the center determine which to use, as they are on a limited budget and want to make the best use of the seed She also introduced me to the Audubon Society and their quest for the Melanerpes erythrocephalus, the red-headed woodpecker (Kane County Audubon Society 2008). Margaret was also able to provide observation data on local birds since 1979.
I wanted to be sure my data was accurate, so I got several books on bird identification and looked up their specific characteristics. I researched types of seeds and talked over with Margaret which seeds attract birds to plan for my study.
Come Over And Bring A Friend
Two types of observation were needed: formal and informal. To gather formal data, I went to the Red Oak Nature Center every Saturday from 8 a.m. to 10 a.m. for five weeks. I would sit quietly and record which bird species I saw at which feeders, and at what times. After I had recorded my observations for the day, I would change the seed in the feeders, from the seed I was currently observing to the seed I would be observing the next week. This was to give the birds time to know the new seed was there, and to insure that the birds who were at the feeder for my next observations were there for the seed I was observing, not for the previous seed. The five different seeds I used were: safflower, black oil, mixed seed, suet, and thistle.
I saw that these observations could produce a cross-section of useful data. Originally, I formed three hypotheses. Hypothesis one [H1] was that the mixed seed would draw the greatest variety of bird species. My second hypothesis [H2] was that the mixed seed would attract the most birds to the feeder because of the diversity of seeds to suit different tastes. My third hypothesis [H3] was that the feeder with the most visits will be Feeder 2 because it is in an open area, giving the birds plenty of escape routes, and that the Plexiglas feeder will be able to accommodate more birds because of the way they could perch on it.
I used several styles of feeders; a Plexiglas feeder, two tube feeders, each in different locations, and a squirrel-proof feeder, a metal box with a perch on a fulcrum. The weight of a squirrel lowers the perch and closes the feeder off. The last was a low-platform feeder (map in Appendix A). Since I could not observe 24 hours a
day, I would also rely on informal observations from others at Red Oak and my own bird hikes. It was on one of these that I sighted the red-headed woodpecker that the Audubon Society was looking for, and I also saw my first bald eagle. During one hike I walked down a creek bed and found a pool where many different species of birds were gathered. I asked myself why these birds weren’t at the feeders. Later in my experiment, using different seeds, I saw many of the same birds I had seen that day on my hike. I was not the only person sighting birds, though; Margaret, the Red Oak staff, and other visitors were also sighting them. As a way of keeping me posted on the goings-on of the birds, Margaret would e-mail me about whatever birds were recently spotted. The Red Oak staff did the same on the sightings board posted by the nature center’s entrance.
Getting Down To Business
After the second week, I made an important discovery. Birds, it seems, do not observe daylight savings time. For the next three weeks I needed to adjust my start time to 7 a.m. As that is an hour before the staff arrives, I needed to prepare for sitting still in cold weather. Temperatures ranged from 29°F to 41°F with significant wind, which meant I was out in many layers of clothing.
Even though it was well below freezing, I seemed to be seeing more birds. I asked Margaret about this and she said, “Cold is worse for birders but better for birds.” The reason one sees more birds in cold weather is because fowl are warm-blooded; they must keep moving in order to keep up their body temperature.
Some birds such as the black-capped chickadee were not very discriminating and were frequent visitors. On the fourth week I noticed some chickadees had gotten fatter but others were extremely thin. We had a storm during the week, and the thinner birds had probably come in seeking shelter.
I noticed occasional lulls of about ten minutes with no birds. Sometimes this coincided with a circling hawk or a large gust of wind. However, when one bird was brave enough to return, they all rushed back. It appears that they subscribe to the safety-in-numbers philosophy.
Lemonade from Lemons
After three weeks of observations, I saw that the 2008 essays had been posted. Sarah from Virginia had done a project very similar to mine. It took the wind out of my sails briefly, but then I remembered what my science teacher, Mr. Ozarka, had quoted from Sir Isaac Newton: “If I have seen further it is only by standing on the shoulders of Giants.” Since valid scientific results must be reproducible, I looked at my project as an opportunity to build on previous research. Sarah is from Albemarle County, Virginia, which is at 38.01º latitude and 750 feet of elevation. I live at 41.80º latitude and 676 feet of elevation, so we would expect to see similar results. I noticed that Sarah and I had observed similar species of birds, although not completely the same, even though we used different kinds of seed.
"All men by nature desire knowledge." — Aristotle
I took my data and totaled up the different visits per seed type, feeder type, and species, and formulated my data into charts to better draw my conclusions. I then proved or disproved my three original hypotheses. Hypothesis 1 was incorrect; the seed type that drew the greatest variety of bird species was suet. This may be due to the fact that suet has 38% fat and mixed seed has only 3%. Birds may need this additional energy to sustain them in the coming winter.
My second hypothesis was correct, because the mixed seed had 34.8% of visits while the next closest (safflower) had only 27.2%.
My third hypothesis that Feeder 2, the Plexiglas feeder, would get the most visits was correct. It got over 100 more visits than any other feeder. One benefit may have been that birds can see the seeds inside, drawing more visits.
In the last 25 years, the Fox Valley area has gone from a smattering of towns and farmlands to an endless blanket of Generica that melts into Chicagoland. How has this development affected the bird community? I was exceedingly fortunate that the Red Oak Nature Center shared over 20 years of wildlife observations with me. I then hypothesized that because of increased development over the last two decades, the number of bird species will have declined.
I charted the sightings over the past 20 years then, to remove the anomalies, I recalculated the data using only birds sighted for five years or more . My hypothesis was wrong: 35.1% of the birds I sighted were birds that had been sighted for more than five years out of the last 20. And I even saw a new one, the prized red-headed woodpecker. Birds are apparently using this river area as an oasis from the human sprawl.
The limitations of the survey are that the data isn’t from a specific set of circumstances, time, and location. There are two years with no recorded data, and some years with limited data. It depended on the people doing the observing and writing down. It appears that some naturalists were more enthusiastic recorders. I still consider this an extremely valuable source of data to show how species have changed in the area over time.
I was nearing the end of my experiment, and I noticed that only 5.3% of the birds used Feeder 1, which is a tube feeder only 0.3 meters away from the window.
I wasn’t sure if birds avoided that particular feeder because it was under an overhang in an L-shaped section of the building, and thus they couldn’t fly away in any
direction in case of danger. Or maybe they were avoiding the window because they could see me inside. I believed it was the latter [H5]. To test my hypothesis, I put tint on the window so I could see the birds but they couldn’t see me, and I did another week of observations with mixed seed to compare against my mixed seed results. The birds still avoided the window like the plague; only 0.7% visited, so I concluded that the birds were avoiding the feeder because of the shape of the building and the lack of escape routes.
Passing The Torch
I wanted to find a way to help out the nature center using my data, because making scientific discoveries isn’t useful if that information isn’t shared with others. So I wrote and produced a book, Birds of Northern Illinois. I also wrote a guide to help young birders identify a species on the fly. They write down its size and colors, and then use the book to find the bird, as the bird will likely fly away before it can be identified. Because younger students might have trouble thinking of a bird in terms of inches, I compared the sizes of birds to everyday objects I put these items into a bird identification kit. The kit includes two binoculars, ten copies of the
inexperienced birder’s guide, ten copies of Birds of Northern Illinois, and 12 markers.
One fear I had while making the birding kits was that a lot of paper would end up on the trails. To solve that dilemma, I laminated all the papers and included dry-erase markers to make the kits reusable.
The Last Chapter
You may be wondering what happened to our friend Melanerpes erythrocephalus. Even though I saw many species of woodpecker at the feeders, Mr. Redhead still eluded capture on film. My one sighting was added to the data at the Audubon Society and as a first sighting for the Red Oak Nature Center. Don’t worry, I’ll be back!
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