Female birdsong: Part 1

Several weeks ago, I wrote the casual comment that at this time of the year, male fledglings are learning their species’ birdsongs from their dads. Sometimes such a remark can lead in unexpected directions, as one regular reader asked me the straightforward question, “Don’t female birds also sing?” 

I’m going to answer this question in two columns, beginning this week with a general discussion about songbirds and ornithological research, and concluding next week with some specific information about North American and Thurston County birds. 

Virtually all birds vocalize, so what is a songbird? Of the approximately 11,000 bird species worldwide, over 4,000 are classified as songbirds. But what is a songbird, exactly? 

The organ that allows birds to vocalize is called the syrinx and virtually all birds have this organ. Similar to other animals (including humans), as they exhale, birds have the ability to pass some of that air through the syrinx, producing sound.  

A male Nashville warbler singing.

Liam Hutcheson | For The JOLT

What distinguishes songbirds from all the others is the series of very fine muscles attached to the syrinx that allow them much greater ability to control the syrinx, and thus to produce the many sounds we associate with birdsong.  

Songbirds have another unique ability: They can learn new vocalizations, and teach them to their offspring (not only offspring — songbirds can learn song from each other). These are the vocalizations that we are hearing from songbirds like warblers and sparrows each spring and sometimes throughout the year.  

A singing chipping sparrow, sex unknown.

Liam Hutcheson | For The JOLT

And now to the question at hand: Do female songbirds sing? The answer is yes, for most of the 4,000 songbird species the females do sing, sometimes a song similar to males, and sometimes an entirely different song.   

But this leads us immediately to a second question: Why isn’t this general knowledge? The reason seems to be that, as the science of ornithology began, the study was oriented toward the nearby birds of the northern hemisphere temperate zones of Europe and North America.  

In the northern hemisphere’s temperate zones and in areas further north, many of the songbirds of these zones migrate south for the winter.  Each spring, they return to establish their breeding territories. And, the songs of males are a key element of this territorial competition. They sing to declare possession of their new home territories.  

Most of these species migrate as large flocks and not as mated pairs. Thus, in addition to claiming territory, these singing males are seeking mates. Sometimes their courting even includes feeding this prospective mate. It’s a significant physical challenge for males and therefore a good test of breeding fitness. 

When first studying birds and identifying species, ornithologists depended almost exclusively on the physical appearance of collected specimens (including eggs and nests). These physical differences are often part of a species common name (bristle-thighed curlew would be an extreme example). Beyond physical characteristics, early ornithologists and ordinary bird watchers alike might include bird songs in their species descriptions.  

For migrating females, the greatest physical challenges — aside from migrating long distances — are mating, constructing a nest, producing and incubating eggs, and then feeding her young, sometimes without the help of her mate. It seemed reasonable to these early ornithologists, therefore, to assume that females were too busy to invest energy in singing or learning to sing.  

Almost all the early scientists studying birds were themselves males. It is of no great surprise, therefore, that they focused primarily on the overt territorial activities of males, including documenting their varied and impressive vocal abilities.  

About 100 years ago biological research, including bird studies, evolved away from collecting and cataloging museum specimens and into field work — studying animals in their natural habitats and documenting their behavior. Eventually these field studies were publicized and resulted in what we now consider common knowledge about animal behavior.  

What does all this have to do with the “males do the singing” perspective? When ornithological field researchers ventured in the tropics, they encountered new songbird species and for most of these species the female was an active singer. What was going on? 

Tropical songbirds are generally non-migratory. They often mate for life and the pair itself, rather than the male alone, defends a breeding territory, often over several years. The females of these pairs generally sing as loud and aggressively as the males. For some species, the pair sings a back-and-forth duet of nearly identical songs. For others, the two sexes have different songs that defend territory and also may serve different purposes.  

In addition to vocal duets, females will sometimes increase singing when there are other females nearby, suggesting that for some species song has a sex-specific territorial defense. Constant singing, however, has an energy cost, however, and females generally reduce singing when nest building and egg laying begins. But there are exceptions.  

A blue-gray gnatcatcher.

Liam Hutcheson | For The JOLT News

For example, in Australia there are small songbirds called fairy wrens that have been extensively studied. They look vaguely like our North American blue-gray gnatcatchers. In addition to paired singing with her mate, the female sings a soft, quiet song when she enters her nest and incubates her eggs. The young learn the song while in the egg and after hatching sing it softly to provoke mom to feed them.  

Many small songbirds like fairy wrens are subject to nest parasitism — another species like a cuckoo laying an egg in the nest for the host to raise. The fairy wrens’ soft song overcomes this difficulty, as the alien young cannot sing the feed-me song and starve. 

Birds, both locally and around the world, are endlessly complicated and fascinating. Thank you, faithful reader, for asking your question and sending me off to seek the answers. 

George Walter is environmental program manager at the Nisqually Indian Tribe’s natural resources department; he also has a 45+ year interest in bird watching. He may be reached at george@theJOLTnews.com 

Photos for this column are provided by Liam Hutcheson, a 19-year-old Olympia area birder and avid photographer.