Avoiding predators is a constant worry by many birds. Many birds use specialized vocalizations, called alarm calls, to alert other birds to the presence of a predator.
Chickadees, part of the Paridae family, are known for their “chick-a-dee-dee-dee” call, from which they get their name. While the “fee-bee” sound is their normal call, the “chick-a-dee-dee-dee” call is used to sound the alarm when a predator is in the area.
A 2005 study by researchers from the University of Montana shed light on how the number of “dees” in a chickadee’s alarm call correlates with the size and threat level of the predator. The study looked at vocalizations among black-capped chickadees (Poecile atricapilla). These small songbirds form flocks of 6-8 birds during the non-breeding season and use a series of calls to interact.
Chickadee alarm calls
Chickadees have two main alarm calls: a high-pitched “seet” for flying predators and a loud “chick-a-dee” for stationary predators. The “chick-a-dee” call serves multiple purposes, including mobbing a predator and conveying information about food and flock identity. Researchers studied chickadee alarm calls by presenting them with various predators, ranging from small, agile raptors to larger, less maneuverable ones, and recorded over 5000 calls to analyze variations.
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Research indicates that chickadees can differentiate between predators of different sizes and adjust their alarm calls accordingly.
More dangerous predators prompt more calls with more “dee” notes
The study found significant differences in the chickadee’s alarm calls based on the predator’s size and threat level. Smaller, more dangerous predators elicited more calls with more “dee” notes, whereas larger predators prompted fewer calls. Playback experiments confirmed that chickadees respond more intensely to calls associated with small predators, indicating that these calls effectively communicate the level of threat to other chickadees.
These findings show how complex chickadee alarm calls are, as they combine elements of both identifying the predator and indicating the level of danger. The “seet” and “chick-a-dee” calls provide general information about the predator’s type, while variations in the “chick-a-dee” call detail the specific threat level. This complex signaling system allows chickadees to convey nuanced information about their environment and enhance their survival.
Communication and survival
The chickadee’s ability to convey detailed information about predators through its alarm calls is a testament to the complexity of avian communication. By varying the number of “dees,” chickadees provide their flock with crucial information about the type and severity of the threat. This communication system enhances their survival by enabling more effective and coordinated responses to predators.
References
Templeton, C. N., Greene, E., & Davis, K. (2005). Allometry of alarm calls: black-capped chickadees encode information about predator size. Science, 308(5730), 1934-1937. DOI: 10.1126/science.1108841
Fonte : National Geographic
