Black-capped and Carolina Chickadees
by Alex Forsythe
There are seven species of chickadees that breed in North America, but only two breed in Indiana: Black-capped and Carolina. Black-capped and Carolina Chickadees are very similar, and their ranges overlap slightly in Indiana, just south of my home so that I can see both birds in just a short drive. It can be difficult to tell the two species apart. The Black-capped has a shorter song than the Carolina, and it has more white wing-feather edging. Where the two species overlap, however, you may find hybrids that not only confuse you in appearance, but also in song.
Chickadees have a very sophisticated signaling system, using their call to warn others about the speed a predator is moving, and the level of threat posed by a predator. They also use different calls for different species of predator. This is done with the "dee" notes. The distinctive "chickadee-dee-dee" call sometimes contains one "dee" at the end, or may contain multiple "dee" notes at the end. Chris Templeton of the University of Washington studied over 5,000 recordings of chickadees using spectrographic analysis and found that there is a reason for the number of "dee" notes in the call ("Chickadees' alarm-calls carry information about size, threat of predator", Chris Templeton, UW Today, 2005). If there are flying raptors nearby, the chickadees use a soft, high-pitched "seet". If they see a stationary predator, they use a loud, wide-spectrum call. The call varies with the size of the predator, as well. The calls can be made in frequencies that humans cannot hear, with up to 23 "dees" at the end of their call to identify each species of predator.
An ongoing project by Ryan Smith and supported by Stockbridge Audubon Society in Fort Wayne involves studying Chickadees in 25 locations around northeast Indiana to determine how patch size influences occupancy, and how the surrounding matrix (urban, suburban, and rural) influences community structure. Ryan suspects that sites surrounded by increasing levels of urban development will result in fewer species of birds in those areas. With building density increasing (In Indiana the number of housing units increased by 10.4% between 2000 and 2010 and the housing density has increased by more than 7 houses per square mile), Ryan is concerned about the impact on the Chickadees.
Chickadees are thrifty and they plan ahead, and these skills help them survive in winter. They require the equivalent of 250 sunflower seeds a day. To make sure they are prepared when food becomes scarce, they store their food. One study found that one bird may store between 50,000 - 80,000 seeds in one autumn (Haftorn, 1959). They choose a variety of hiding places for their food, so if one of their stashes is discovered, the other food supplies will remain intact. Researchers have found that chickadees can remember thousands of hiding places, learning hundreds of new locations every few days ("Cognitive Processes and Spatial Orientation in Animal and Man, Ellen and Thinus-Blanc, 1987).
So the lessons to be learned from a chickadee are these: 1.) Understand and appreciate the dangers in life but keep a sunny disposition, 2.) Practicing and perfecting your power of recall is always a good thing, and 3.) Never put your seeds in one basket!