Teachers’ Lounge

Bird Vocalization of the Month: Chicks of the Season

by ocarmi on May. 1st, 2009 No Comments

Species: Bushtit (Psaltriparus minimus); Chestnut-backed Chickadee (Poecile rufescens); Dark-eyed Junco (Junco hyemalis)
Sounds: Bushtit adult and fledgling calls, Chestnut-backed chickadee nestling begging calls and (adult?) defensive noises, Dark-eyed Junco song and fledgling calls (1, 2).

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Bushtit
Bushtit Psaltriparus minimus
Photo credit: sgrace
One challenging part of identifying birds by sound is identifying the calls of young birds—nestlings and fledglings. Nestlings are birds that have hatched and grown a little, but are not yet capable of leaving the nest, and fledglings are birds that have developed enough to be able to leave the nest, but are still guarded and fed by their parents. Parents tend to keep their young well-hidden, to protect them from predators. In addition, the calls of young birds can be very subtle—also as a protection against predators.

However, the young of some species of birds are relatively conspicuous, and some have distinctive vocalizations. I’ve decided to feature three such species of birds that happen to be breeding in the Bay Area right now, so that you’d be able to go out and look for them with some possibility of success!

Bushtits (Psaltriparus minimus) are tiny, grey birds that seem to constantly jump about and make soft, pattering calls. In the winter, they may gather in large flocks of up to 75 individuals! However, during the breeding season, much smaller groups can be seen—a male and a female, sometimes assisted by young males born the previous year. Breeding birds construct incredible, sock-shaped, hanging nests of soft plant materials and cobwebs. These nests can take several weeks to construct! I photographed the nest pictured to the right on a recent local birdwatching trip. They are some of the easiest nests to locate around here—they are often placed in Live Oaks.
Bushtit nest
Bushtit nest in dead branches
of oak tree

While all Bushtit calls are rather soft and subtle, there is a distinct difference between the calls of the adults and the calls of the young. Listen to the calls of these adult Bushtits, which I recorded in Golden Gate Park (amidst the noise of cars and other birds!), and compare them with the calls of these fledgling Bushtits, which I managed to record near the campus of San Francisco State University. Notice that the calls of the young are much faster, and seem to consist of a repeated cascading pattern.

I spent a great deal of time trying to find young Bushtits this early in the season, so as to be able to post their calls on this blog entry. In my (brief) experience as a birdwatcher, the sounds of nestling and fledgling Bushtits in the Bay Area become suddenly apparent en masse right around May 1—so prick up your ears! This is the moment to listen for them!

Another local bird whose young produce distinctive vocalizations, and which fledges around this time of year (in fact, often slightly earlier than Bushtits), is the Chestnut-backed Chickadee (Poecile rufescens).

Chickadees nest in tree cavities, and I suspected I had come across a Chestnut-backed Chickadee nest-cavity one day on campus last week, when I heard these Chickadee begging calls. However, as there were no adults around, I couldn’t confirm my suspicion. I returned later, but by this time it was already dark. Resting my microphone against the cavity elicited this response, which I conjecture was a defensive sound produced by one or both parents brooding the young (keeping them warm). I have never heard this sound before, but have since been told that chickadees will hiss at nest intruders.

The following day I managed to confirm that the nest cavity was that of a pair of chickadees. I took the following pictures of one of the parents with food in its mouth about to enter the cavity (which lies out of view to its right), and of several begging nestlings within the cavity, necks stretched upwards, and gapes wide open. Note the yellow color at the base of the nestlings’ bills. Colorful gapes are thought to facilitate feeding of the young by adults.

[By the way, I featured some calls of adult chickadees in my March entry, “Mid-March Medley.”]

Chickadee with food
Chestnut-backed Chickadee
parent with food
Chestnut-backed Chickadee nestlings
Chestnut-backed Chickadee nestlings
in tree cavity

The final species I will mention today is the Dark-eyed Junco (Junco hyemalis), which nests on the ground in thick ground cover or leaf litter. Juncos are often found in human-altered habitats. As an example of where you might find Junco fledglings, I took this (poor!) photo below of a fledgling on the San Francisco State University campus: the habitat in this case consists of a ground cover of non-native English Ivy with scattered non-native shrubs.

Dark-eyed Juncos produce a variety of vocalizations. The frequently heard song of the male Dark-eyed Junco consists of a long trill. The begging calls of the fledglings are somewhat variable, but these dry rattles are typical. These ticking calls, which resemble the calls of adults, are also typical begging sounds.
Junco nesting habitat
Junco fledgling in English Ivy
ground cover
Adult Dark-eyed Junco
Adult Dark-eyed Junco (Junco hyemalis)
Photo credit: Marcus Smith, Los Angeles
If you happen to watch birds this time of year, please note that the fledglings of Chestnut-backed Chickadees and Bushtits greatly resemble adults in appearance. Young juncos, however, look quite different from adults. Adults, in our area, have dark hoods, brown backs, and light bellies, whereas fledglings are covered in streaks.

Go out there and find some young birds!

Your homework assignment: I posted some rather subtle recordings in this entry! If you feel motivated, listen to them, and familiarize yourself with the sounds of nestlings and fledglings likely to be encountered at this time of year; then pay attention while you’re out and about in case you hear one of these sounds.

However, I have an additional suggestion this time around: Pay attention to the world around you with all your senses! While preparing this blog entry, I heard a sound I had never heard before (the hissing of chickadees at their nest)! It pays to listen! But also keep your eyes open—there is little that is more heartwarming than a parent bird feeding young. Especially at this time of year, when you hear birds, look, and when you see birds, follow them with your eyes. Incessantly calling birds may turn out to be begging fledglings (fluttering their wings and pursuing adults), and if you watch them long enough, you’ll see them get fed.

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