Why do birds sing?

When you are first learning how to identify birds by the sounds they make, it may not be that important for you to make the distinction between what is a song versus what is a call. However, as you become familiar with the song of the Oak Titmouse, for example, you may notice that the next time you see them, they are singing something else. Then you may notice that they are also making another kind of call. Before this becomes overwhelming, rest assured that the Titmouse is not out to confuse you, but merely showing you its full repertoire of songs and calls. To make some sense out of all of the varied sounds that birds make, Jon Young, in his compelling book What the Robin Knows, organizes them into five basic categories of songs or calls:

  1. Songs
  2. Companion calls
  3. Territorial aggression
  4. Young begging calls
  5. Threat - alarm calls


A song, to quote Donald Kroodsma, in his book The Singing Life of Birds, is "...usually the male, typically high on a perch, uttering what is often a fairly complex vocalization. It's what a male does especially when he is on a territory by himself and when he is unpaired. These songs are thought to help establish and defend a territory as well as to attract and impress a mate."

Notice that Kroodsma says "...are thought to...establish...". We don't really know why birds sing, but we infer it - and so far, it's the best theory going. What we do know is that it is the female that does the choosing, and she makes her decision at least in part on the male's song. However, what exactly she listens for, and how she decides, is not yet well understood.

Companion calls

Companion calls are made by paired individuals or feeding groups of birds. They are usually simple notes, frequently given as the bird is foraging. They can be thought of a simple way of keeping in touch, especially with birds that are feeding or moving about in dense foliage. "I'm over here", the Jay or Towhee or Goldfinch seems to say. The other bird, or birds, calls back, "I hear you, and I'm over here".

A specialized type of companion call is known as duetting. More commonly heard in the tropics, it is made by one of a pair of mated birds, then the other, calling back and forth to one another so rapidly that from a distance, it sounds like one bird. Again, this type of call is usually heard in habitats with dense foliage.

Territorial calls

Territorial calls are mainly given by males at the borders of their territory, especially in response to the presence of another male. This definition may seem to overlap somewhat with Kroodsma's song definition, but the difference is that now the male has a mate. There are various levels of territorial calls, depending upon the type of encounter. For two male Song Sparrows that have adjacent territories, they each share some of the same songs, but have other songs that are not shared. If one of them sings one of the shared songs and is perhaps encroaching on the territory of the other, the second male will sing the exact same song back, signalling his elevated threat level. If one sings one of the shared songs, and is not encroaching, the second male may sing a shared song, but not the exact same song. This signals that the threat level posed by the first male is not threatening. If a stranger arrives in the area and sings, the male will sing another song, not in the shared group of songs with his neighbor.

Begging calls

Begging calls are given by the young, from as soon as they hatch to well after fledging in some species. Begging calls are also made by females of some species during mating rituals. The notes are usually simple, plaintive notes, and frequently high-pitched to make it harder for any predator to locate them.

Alarm calls

Alarm calls are given when a bird sees a predator. Many small birds have very similar alarm calls, all high-pitched notes near 7 kHz (see sonograms page for more about pitch) that make it difficult for the predator to locate them. The alarm calls alert others of their own species, and even other species, to a threat. It has been discovered that some species even have different alarm calls for hawks than for ground predators.

This becomes intriguing for the birdwatcher, for if you can learn the different alarm calls, then you will know where to look for a potential bird predator. One bird in particular, the Bushtit, is very good at spotting hawks as they fly over. When I hear their group trilled alarm calls, I immediately look up, and am frequently rewarded with the view of a Cooper's Hawk or Red-Shouldered Hawk flying over. At the same time, you can observe response behavior in other birds nearby. Upon hearing the Bustits' trills, the Towhees crouch low to the ground, and flatten all of their feathers close to their bodies, looking skyward.

Even more fascinating are the results of research done with Black-capped Chickadees†. The researchers found that the Chickadees added varying numbers of "dee-dee-dee's" to their "chick-a-dee" call, depending on the threat level of the predator. This alarm call is used when mobbing a predator that is perched (a high "seet" is used for flying raptors). The smallest, and most dangerous predators for a Chickadee (such as a Pygmy Owl) received the most "dee-dee-dee's", the largest predators (such as a Great Gray Owl) received the least. No similar studies have been done on Chestnut-backed Chickadees, though I have heard them make repeated alarm calls at times. I will have to pay more attention to them next time, and look to see if they are mobbing a perched owl.


Repertoire refers to the total number of songs and/or calls that a species sings. With many species, there is only one song, so once you learn it, you will know that bird whenever it sings in your area. The White-crowned, Golden-crowned, and White-throated Sparrows are all good examples of this. Other species, such as the Song Sparrow and the Bewick's Wren, have many songs in their repertoire. When they sing, they typically repeat one song several to many times, then switch to the next song in their repertoire. A Bewick's Wren may have 16 or more songs, a Northern Mockingbird, upwards of 200 songs, and the Brown Thrasher has over 2,000 songs! Luckily, many of the songs have a similar "flavor" to them, and once you have learned one, the others get easier.



Okay, so you've gotten used to that Dark-eyed Junco singing its trill from the top of a tree since February. Now it's the end of March, and you hear another trill, but somehow, it seems a little different - the notes waver, then drop right at the end. Is it still the Junco, or could it be yet another confusing bird, right when you thought you had it down! Look and listen carefully and see, it could be a sound-alike to the Junco, the Orange-crowned Warbler, recently returned from the tropics.

Another month passes, and you are happy - now you can separate the Orange-crowns from the Juncos - well, most of the time. But wait, another trill, and slightly different yet again! This one sounds more "dry", not as musical as the Junco, almost like an insect. Could it be? Yes, another sound-alike, the Chipping Sparrow.

The best way to learn to separate these confusingly-similar songs is by repetition: Watch and listen to the Dark-eyed Junco as much as you can early in the season. When the Orange-crownd's arrive, you should be able to tell that it is something very close, but just a little bit different. When in doubt, always check by finding the singing bird (I still get mixed up every once in a while).

Even better is finding the two species singing near each other, something we had in 2013 during our Annadel class. First one, then the other sang, Junco, then Orange-crown, back and forth. Even when hearing them one right after the other, they do sound very similar. And be careful too, because the Orange-crowned's song does not always drop at the end. I have heard it go up, or even stay more level like the Junco's. The Chipping Sparrow seems easier to tell apart, as it's song is much flatter than that of either the Junco or Warbler. They also tend to stay in drier habitats, such as edges of woods with grassy fields.

Here are some other sound-alike groups:


American Robin
- rich, slow, and melodic notes, "cheery, cheerilee..."
audio file: American Robin [49 KB]1

(after listening to each file, you may need to click your browser's Back button to return here)

Black-headed Grosbeak
- like a Robin with voice lessons, notes more complex, smoother.
audio file: Black-headed Grosbeak [78 KB]

Western Tanager
- like a Robin with a sore throat, notes more scratchy, clipped
audio file: Western Tanager [29 KB]2


Warbling Vireo
- a fast series of distinct warbling notes that sound like it's talking very fast.
audio file: Warbling Vireo [29 KB]3

Purple Finch
- notes slurred together, more burry, notes less varied.
audio file: Purple Finch [20 KB]4


Say mimic, and usually the first bird name anyone comes up with (after parrot) is the Mockingbird. MockingbirdIn fact, the family that the Mockingbird belongs to is called Mimidae. Mockingbirds incorporate the songs and calls of many birds that they hear, as well as other sounds - alarms, sirens, etc. They frequently repeat a phrase at least three times, and sometimes eight or more times, before going on to the next imitation. It is thought that the more songs and calls a Mockingbird is able to mimic, the more desireable he may be to the female. Older male Mockingbirds know more songs and have a much larger repertoire. Younger males have fewer learned songs, so it may be clear to a listening female that the young Mocker doesn't have much experience. An interesting thing I have observed with the Mockingbird on our property is that he will start singing the Ash-throated Flycatcher's song a month or more before the Flycatcher's arrival date. He learned it the year before, and has remembered it all through the winter.

Though they are certainly one of the best mimics in the world, they are not the only ones in Northern California. There are several other species that can imitate other birds, and many other sounds as well.

California Thrasher - another Mimid, mimics songs and calls of other local species to its repertoire.

European Starling - convincing, especially with whistled types of calls, like Varied Thrush, Cedar Waxwing, creaking doors, fire alarms...

Steller's Jay - great at hawk imitations, especially Red-shouldered Hawk.

Lesser Goldfinch - incorporates many snippets of other species' calls into their songs.

Western Scrub-Jay - it only imitates others in its rarely heard, very low-volume warbling song.


Some songbirds, though not all, have dialects within the species. Just like people, birds in a different area sound a little different, even though they look just the same.

White-crowned Sparrow - studies of the Nuttall's subspecies in the 1960's and 1970's in the Point Reyes National Seashore showed that there were at least six dialects of song, with birds in each area mostly staying put. Young birds mainly learned their dialect from their fathers, though some fledged and moved to another dialect area nearby, then learned that dialect.

Spotted Towhee - On a walk one day just 15 miles from where I live, the "chweee" call of the Towhee sounded different from what I am used to. I spent several minutes hunting down the "new" bird before I realized it was the Towhee. This highlights a consideration with the recordings you may have on your smartphone or other device. The location that the recording was made is very important - listening to a recording of a Spotted Towhee from Arizona may sound quite different from the one you are listening to in Sonoma County, CA.


†Templeton et al., Science 308(5730):1934-1937

1American Robin: © Eric DeFonso, XC103059. Accessible at
Creative Commons Attribution-NonCommercial-NoDerivs 2.5

2Western Tanager: © Chris Parrish, XC21763. Accessible at

3Warbling Vireo: © Eric DeFonso, XC103099. Accessible at

4Purple Finch: © Eric DeFonso, XC105761. Accessible at

House Wren

House Wren

Hard is the hert that loveth nought,

In May, when al this mirth is wrought,

When he may on these braunches here

The smale briddes syngen clere

Her blesful swete song pitous…

–Geoffrey Chaucer, c. 1365


Website and photographs 2013 by Gordon Beebe