Date: 7/9/18 2:07 pm From: DAN SCHEIMAN <birddan...> Subject: Re: A question of mockingbirds
The short answer is that yes, Northern Mockingbirds definitely mimic other birds' sounds, as well as other animal sounds and mechanical sounds. The size of a male's repertoire is a signal to a female of his quality. Females sing too.
Mockingbirds are persistent mimics. Mockingbirds appear to cluster imitations from the same species more often than expected by chance, but this has not been studied in detail.
Mockingbirds have extraordinarily diverse song repertoires consisting of acoustically distinct song types (= song patterns = syllable patterns). These songs are acquired through imitating the calls, songs, and parts of songs of other avian species, vocalizations of non avian species, mechanical sounds, and sounds of other mockingbirds. The proportion of songs imitated is not known and would be extremely difficult to estimate because the entire auditory experience of an individual would need to be known to determine whether a vocalization was acquired through imitation. Geographic variation, although not studied, is likely, given that mockingbirds are relatively sedentary, acquire songs from neighbors, and imitate other species characteristic of the local avifauna.
Males begin to sing sometime during February (as early as late January in southern populations) and continue into August throughout their range. Females rarely sing during the summer, and only when their mates are off the territory (KCD). Males sing during the establishment of fall territories during mid-September through November. Females also sing during this period, but the amplitude is generally lower. Because female song is difficult to sample, no one has estimated the proportion of females that sing during the fall. Females do not sing as much as males during this period. The propensity with which females sing may be greater in northern populations because more birds establish separate winter territories and pairs do not remain together as often as they do farther south. Song by females seems less complex but this has not been studied.
Mockingbirds typically repeat one song type several times before switching to another. Songs are presented in “bouts,” with each bout consisting of repetitions of only one song type. Song types of short duration are repeated more often within a bout than are longer song types (Derrickson 1988 https://birdsna.org/Species-Account/bna/species/normoc/references#REF16157 ). Mockingbirds also vary how often they return to repeat a bout of a particular song type (called “recurrence interval”). Several measures have been developed to describe the presentation of the extensive repertoire: versatility measures (see below), bout length (number of repetitions within a bout), and recurrence interval (number of intervening bouts before a song type is repeated). All measures vary among reproductive stages, behavioral situations, and individuals.
> On July 7, 2018 at 11:59 AM Glenn <000001214b3fcb01-dmarc-request...> wrote:
> We have a lot of mockingbirds around our house, as I’m sure just about anybody who lives in Arkansas does. I enjoy listening to their singing. Most of the time their songs do not sound like any other bird I am familiar with, so I assume these are unique mockingbird songs. However, since I haven’t heard every bird in the world, I can’t vouch for that. Occasionally, the mockingbird that has been living in our holly tree for a few years will sound like a Great-crested Flycatcher. And at other times it will sound like birds I’ve heard before, even though I can’t quite place which bird. So my question, do mockingbirds really mock other birds? The way the human mind works is it tries to make sense out of randomness. For instance, we will see a human shape in the shadows, even though it is only bushes. So, is our mind telling us the mockingbird is singing like an Eastern Bluebird because his song is similar for a few short notes? Or is it really singing a bluebird song? Have there been any studies where a mockingbird has been locked up with a Kookaburra, for example, to see if it will start singing like a Kookaburra? Why does a mockingbird sing? I assume it is to attract a mate. Does a female mockingbird get turned on when a male mockingbird sings like a towhee? Or is it just the number of different sounds that get her attention? What is especially interesting to me is our local mockingbird makes sounds that sound like birds that I know have not been in our neighborhood. And I know our mockingbird is not a world traveler, it stays pretty close to our neighborhood as far as I can tell. So it makes more sense to me to think the mockingbird is singing a bunch of random noise songs, some of which sound like other birds, then it does to think they are singing songs of birds they have never heard before. That was probably more than one question.
> Glenn Wyatt