Thursday, February 13, 2014

Common Bird Profile: Northern Mockingbird

Northern Mockingbird (Mike Baird)
Northern Mockingbird (Mimus polyglottos)

I didn't really appreciate Northern Mockingbirds till I lived in Arkansas. I grew up with watching mockingbirds in Ohio but there are so many of them here in Arkansas. They live in all the bushes around my apartment complex and fight constantly. Their beautiful song fills the spring air and their complex mimicry fools even the best birders.

What mockingbirds are known most for is their ability to mimic a wide variety of sounds. Many birders who have been sent on wild goose chases after one species or another only to find out it's a mockingbird.

One of the main reasons birds sing is to attract or maintain a connection to a mate. Some species have elaborate dances, flight displays or vibrant colored plumage to attract mates. Mockingbirds look plain, but they make up for it in their singing ability. Female mockingbirds have been found to choose mates with larger repertoires [1]. Mockingbirds don't only imitate other birds songs, they have also been documented imitating a wide variety of other sounds from their environment. A friend of mine had a mockingbird learn to imitate her alarm clock, much to her annoyance since the mockingbird started singing far earlier then she wanted to wake up each morning.

We still don't know exactly how they learn these songs, but researchers in North Carolina have found mockingbirds learn songs that  are the easiest to mimic and the most similar to the songs they already know [2]. Over time this could lead to a wide range of vocalizations as they gradually expand their repertoire. Mockingbirds often mimic sounds in repeats of three, which can make picking them out as opposed to the actual birds song a bit easier. Why they repeat songs is not well understood. It may be connected to how they learn the songs or have something to do with maintaining the songs in their memory [3].

What we do know is mockingbirds are singing machines which may sing for hours and hours, even all night during the breeding season. Mockingbirds ability to pick up any sound in their environment has caused some problems for scientists studying other species. Mockingbirds in northern California mimic Black Rails. This made it challenging for the scientists who were out surveying for the elusive rails because they had a hard time distinguishing between the mockingbirds and the actual rails [4].

This video is a great example of the repertoire of these birds, see if you can pick out the different species this mockingbird is imitating, and the car alarm about 10 seconds into the video.

Northern Mockingbird (Manjith Mainickara)

While mockingbirds are plain in coloration they are a great example of coloration with a purpose. The color white is rare in nature, except in cases where it's used for camouflage (like in Snowy Owls) white is typically used as a form of communication.

The white tail of the white-tailed deer is a sign of alarm to the deer around it and lets an approaching predator know it has been seen. By letting the predator know it's been spotted it can decide if it wants to pursue a prey item without the element of surprise [5].

Northern mockingbirds have been shown to use the white on their wing patches in a similar way. When they are faced with a predator they 'wing flash' to make themselves appear larger, intimidating the predator and to signal to other mockingbirds that there is a predator nearby [6].

Mockingbirds are a fantastic species to find in your neighborhood. Their fearless behaviors and diverse voices make them fun to watch. So spend a little time now and throughout the spring looking for some mockingbirds as you explore your local area and see if you can discover any unique noises your mockingbirds have learned!

- Auriel

[1] Howard, R.D. (1974) The Influence of Sexual Selection and Interspecific Competition on Mockingbird Song (Mimus polyglottos) Evolution 28:3 (428-438)
[2] Gammon, D.E. (2013) How is model selection determined in a vocal mimic?: Tests of Five hypotheses. Behaviour. 150:12 (1375-1397)
[3] Gammon, D.E., Altizer, C.E. (2011) Northern Mockingbirds produce syntactical patterns of vocal mimicry that reflect taxonomy of imitated species. Journal of Field Ornithology. 82:2 (158-164)
[4] Conway, C.J., Gibbs, J.P., 2001. Factors influencing detection probability and the benefits of call broadcast surveys for monitoring marsh birds. Laurel, MD. [5] Bildstein, K.L., (1983) Why White-Tailed Deer Flag Their Tails. American Naturalist 121, 709–715.
[6] Dhondt, A.A., Kemink, K.M. (2008) Wing-flashing in Northern mockingbirds: anti-predator defense? Journal of Ethology. 26:3 (361-365).

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