Birds can make some of the most beautiful music in the world. The sweet call of the northern cardinal Cardinalis cardinalis tells us spring is coming. The majestic cry of the red-tailed hawk Buteo jamaicensis evokes a sense of being connected to nature—the sound most movies incorrectly play when they have a bald eagle Haliaeetus leucocephalus on the screen. Loons sound so lonely and remorseful, it can make the heart ache. While those sounds evoke a variety of emotions in humans, birds sing and call for different reasons. Sometimes they may sing to announce their territory, to communicate with their mate, or to attract a mate in the first place.
The San Diego Zoo’s beautiful pair of red-billed leiothrix (pronounced LY oh THRIX) Leiothrix lutea in the enclosure just up the hill from the tigers take singing to the next level. The male has a wonderful repertoire of warbling whistles. He has so many notes, and it varies so much, it sounds like a new song every time he sings. To start the duet, the male spends about ten seconds delivering a gorgeous song before he takes a break. Then it’s the female’s turn. In the pause after the song, the female utters a low-pitched chirp, chirp, chirp, chirp. That’s it! Following the female’s contribution, the male picks right back up with another round of lovely notes. Once he finishes…chirp, chirp, chirp, chirp. Another song…chirp, chirp, chirp, chirp.
1) The female never interrupts the male mid-song; she always waits until he is done to deliver her chirps.
2) The female chirps three to five times—with four being the most common.
3) The male starts his song again after her chirps, but waits for her chirps before he starts up again. This became obvious when I heard him finish his song, but the female didn’t call back right away. She was delayed because she was eating and had just swallowed a large piece of fruit! The minute she could, she chirped to complete her end of the duet.
Why does she chirp? Why does the male seem to find her call so important? I don’t know. I haven’t found any literature to suggest that they are actually “duetting” in the formal sense of the term. But when both of the birds seem to take their cue from each other, I think the term is appropriate. Either way, it is extremely interesting and quite cute!
Check out this vocal pair of birds uphill from the tiger exhibit (just next to the turtle exhibit on Tiger Trail).
On the audio, we first hear the male producing a short song followed by the female’s lower pitched, encouraging chirps. They continue back and forth for some time with the longest and most impressive song at the end of the recording. The female chirped anywhere from seven to ten times between the male’s song. This is a higher number of chirps than I had heard earlier in the month. I wonder if the female chirps more as the pair gets closer to the breeding season? Something to look forward to listening for as winter passes and spring starts to round the corner.
Mike Grue is a senior keeper at the San Diego Zoo. Read his previous post, Pick on Someone Your Own Size!