By Jason Knight
Bird sounds and behaviors can be used to help locate hidden animals on the landscape. Whether it is a bobcat camouflaged into a thicket, an owl sleeping high in a dense tree, or a deer moving off through the brush, nearby songbirds modify their behaviors and vocalizations. A person can learn to detect these changes in bird activity to determine where and what other animals are present in the landscape that would otherwise be hidden from the observer.
The first step in learning to interpret bird sounds is understanding how to recognize the difference between alarm calls and what is often referred to as baseline behaviors. Most song bird sounds can be categorized into one of five major categories of calls. The first four are considered baseline behaviors, while the fifth type of vocalization indicates a break in the baseline, where potential danger is being communicated.
Birds are known to sing to establish territory, as well as to attract a mate. Some birds only sing in the spring during the breeding season, while others sing year round, most frequently at dawn and dusk. Songs are generally longer vocalizations and often include a variety of notes in a sequence. A song indicates normal baseline behavior. As an example, a song sparrow's song is usually made up of three clear notes, followed by a complex series of trills. It can be represented as, "maids, maids, maids, put on your tea kettle-ettle-ettle."
Call notes are short communications, often single notes. They are generally used between mates or members of a flock to signal each other's whereabouts and to point out food. These notes are commonly used when a group of birds is traveling and/or feeding. Companion calls are also considered baseline behavior. As an example, a song sparrow's companion call note sounds like, "jep". In the woods you might hear an individual call out, "jep", and then its mate may make the same call a moment later.
Baby birds in a nest will make a racket as they beg for food. Even after young birds have matured into juveniles, they will often follow the parent birds around while making distressed calls to beg for food. Though these calls sound urgent, they still represent baseline behavior, as there is no imminent danger being communicated. Juvenile begging calls sound like a somewhat more agitated version of a companion call.
Birds often compete for territory, mates, and food sources. It is quite common for two individuals of the same species to trade aggressive call notes back and forth, perform posturing, and even chase one another. While these aggression calls can sound very intense, they are yet another form of baseline behavior. Aggression calls often sound like a very intense version of a companion call. Oftentimes the only way to differentiate an aggression call from an alarm call is to listen to and observe how other nearby birds are reacting to these sounds. If other birds in the area are continuing with business as usual, it is most likely a normal bird to bird aggression call.
This type of call is what indicates that the bird has identified a potential danger/predator on the landscape. This is the type of bird sound that can tell us when and where there is an animal hidden on the landscape. These calls are often short and can be louder and/or higher in pitch than companion calls. It could be described as the difference between saying, "hey", and "hey!!!". Before making an alarm call, the bird usually flies to a safe location. For example, if a house cat were sneaking through a hedgerow and a wren sees the cat coming, the wren would fly to the top of the hedgerow (out of the cat's reach), and then begin alarm calling at the cat below. This is often followed by nearby birds stopping their normal activity and flying up to perches to gather information about where and what kind of danger might be present.
One of the best ways to begin learning how to interpret bird sounds is to pick an outdoor location where you can view birds. Visit that same spot frequently and observing for more than a half hour at a time. As you spend time watching, you will begin to recognize the different behaviors in the birds that frequent your area. When a potential alarm call is noticed, it is an opportunity to investigate the area. You may be pleasantly surprised to discover a resting hawk or hunting weasel.
For more information on birds and their calls check out AllAboutBirding.org