What do driving on the right side of the road, tipping a server, the English language, and a cellphone all have in common? They are part of something we call "culture."
Many traits are inherited. Hair color, height, shape of the ears all are determined to some extent by the genes received from our parents. In contrast, culture is passed along through observation and learning, not genes.
Culture is surprisingly rare in animals other than humans. Animals aren't dumb. They learn from experience, but this knowledge is rarely passed on to the next generation. Chimpanzees provide an exception. Family groups of chimpanzees make and use a variety of tools to gather food, and young chimps learn to make these tools from their parents. Simpler examples of culture can be found among dolphins, elephants, crows and geese.
Perhaps the clearest example of culture in animals involves birdsong. Our most accomplished singers learn their songs from others. Wrens, warblers, sparrows and thrushes are songbirds that learn by imitating others of their kind.
However, not all birdsong is learned. Flycatchers are not songbirds, and their songs are innate. Somewhere in their DNA is the "sheet music" for their song. But songbirds — the ones that learn their songs — are different.
If you take a newly hatched white-crowned sparrow and raise it without ever letting it hear another white-crowned sparrow sing, as an adult that bird will sing.
But it won't sing a white-crowned sparrow song. Singing is programmed in the genes, but not the proper song; it must be learned.
The hermit warbler, one of the most common breeding birds in our forests, is one of the best examples of culture singers. The hermit warbler is a songbird. It is unmistakable with its bright yellow head, assuming you can ever see one high in the canopy.
If you bike up Morton Street above Ashland and into the forest, you can hear the hermit warblers sing a quick, clear, ringing song that ends with a decisive down-slurred note. If you drive to Fish Lake or Howard Prairie for a day of fishing, you will hear a very different dialect among the hermit warblers. Their song is buzzy, and each syllable is higher in pitch than the last. It sounds like a different species entirely.
Take your out-of-town visitors to Crater Lake, and the birds you pass at Union Creek will sing a slow, whistled song. All these birds belong to the same species. They look identical, and I'm sure they are genetically indistinguishable. Soon after leaving the nest, each male listens to those around it and learns the song it will sing as an adult. The unique dialect that each population sings is one of the best examples we have of culture among animals.
In all there are 10 different hermit warbler dialects in Jackson and Josephine counties. For those of you who struggle with learning to identify birds by song, I'm sorry. Your job just got harder.
I suppose now is not the time to tell you that each male hermit warbler has more than one song. I'll save that story for another time. For now enjoy the spring and good luck.
Stewart Janes is a biology professor at Southern Oregon University. He can be reached at firstname.lastname@example.org.