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Northern Mockingbird #2

Northern Mockingbird, Part ll

The Prince of Musicians
(Mimus polygloyyos)
by Jon Friedman

(Shani and I co-authored an introductory article on the Northern Mockingbird in the November-December 1998 newsletter. It can be accessed by going to the Birding Articles archive on our wildbirdsonline.com website. This article provides further information on one of our most popular songbirds.)
Image by Richard @ SearchNet Media

North American range
There are many species of mockingbirds throughout the new world. Mockingbirds are only found throughout North, Central, and South America. In North America we observe two species, the very common Northern Mockingbird and the very rare Bahama Mockingbird. While there are three species found in the Caribbean, only the Bahama Mockingbird is known to actually, on rare occasion, be found on the continent.  And, it has only been recorded in the southernmost portions of Florida, from extreme southeastern Florida across the bottom of the state west to the Florida Keys. Both species are long-tailed, short-billed species usually found in open areas near dense bushes. Suburban habitats are well suited for mockingbirds. The Northern Mockingbird is the more aggressive and conspicuous while the Bahama is more secretive.

While historically thought of as a southern bird in the United States, and its densest populations do occur in the warmer southern states, it has spread its range northward in recent decades. It can now be found along the northern tier from Washington State to Maine and in the southernmost parts of the Canadian provinces. It is considered a resident bird wherever it is found, with the possible exception of the northernmost parts of its range.

Official state bird
Five southern states have officially declared the Northern Mockingbird as their state bird. The five states (Texas, Florida, Arkansas, Tennessee, and Mississippi) had different reasons for their decisions. Some of the reasons include familiarity, musical and mimicking abilities, exhibiting the pioneer spirit, its “matchless charm,” its close association with humans, and other qualities we admire – their spirit of ebullience, boldness, tenacity, responsibility, and independence.

Introduction to new ranges
The spread of their range was encouraged and promoted by Acclimatization Societies that sprang up late in the nineteenth century. These groups were composed of nature and bird lovers, wealthy families and individuals, and others with strong European roots; mockingbirds reminded them of the Old World nightingales. These societies would capture or pay for mockingbirds from southern locations and transplant them into new areas like Hawaii, California, Washington, and the Dakotas. Many did not survive but enough did to gain a foothold in the new environments. Being quite adaptable, some populations were able to expand their numbers and range. Old World nightingales were also introduced but they were unable to adapt. Local protection laws began appearing by the turn of the century and many caged birds were released. In most such cases, caged birds born into captivity rarely survive in the wild.

Interestingly, the Northern Mockingbird has been documented in the British Isles, beginning in 1978. The first few sightings were dismissed as accidentals. But, over the course of the next several years more than thirty sightings have been verified in Great Britain. It is now believed that these birds have gained a foothold across the pond and are probably breeding there. It has been determined that the species is large enough, weighs enough, and has a large enough energy capacity to cross the Atlantic Ocean.

Photo by Doris Evans

Insects and fruits comprise the vast majority of the mockingbird’s diet. Researchers have documented the stomach contents of mockingbirds throughout their range and determined that about 52% of their food intake is insects, while about 48% is fruits and other vegetative matter. On rare occasion they may eat a very small number of seeds or grains. Wild fruits are the favorite of these birds. They’re particularly fond of holly, smilax, woodbine, sumac, and a host of other wild berries. In populated areas they may learn to raid gardens and eat grapes, pomegranates, citrus, and other cultivated fruits.

Photo by Richard at SearchNet Media

Crop pests?
In agricultural areas, these birds have been mistakenly identified as crop pests. Most birds considered crop pests do extensive damage to crops because they are flocking birds. When hundreds, or even thousands, of birds descend upon fields with crops growing, the results can be significant. But a single mockingbird, or even a family of mockingbirds, eating crops in the field: the loss is miniscule. But many farmers see almost any bird in their fields as a pest and many mockingbirds have met their death in those fields. Arthur Cleveland Bent, the chief author of several volumes on the life history of North American birds, reported that a single grape grower near St. Augustine, Florida, killed more than 1100 mockingbirds over a period of time for daring to eat his grapes and, out of retribution it seems, buried their bodies beneath the vines. To this day, many farmers believe the mockingbird is a crop pest. In the past 15 to 20 years, ornithologists have been analyzing mockingbird stomachs and concluded that there’s “nothing to prove that the Mockingbird eats domestic fruit to an injurious extent.”

William L. McAtee, a federal biologist studying the economic importance of birds to agriculture, noted that almost exactly half of the 417 stomachs of Northern Mockingbirds collected in the American South contained mostly animal (insect) matter. Most significantly, the food remains were mostly insects that truly are crop pests. Harmful varieties of weevils, cucumber beetles, chinch bugs, cotton worms, boll weevils, and grasshoppers constituted the majority of their diet while domestic fruits, mostly raspberries and blackberries, accounted for only 3% of their stomach contents.

Mockingbirds are known to be fiercely territorial. Almost everyone who has observed them has a story to relate in this regard. Mockers hold two types of territory. Monogamous pairs hold breeding territory which the male defends during nest building, egg-laying, incubation, and nestling and fledgling stages. A smaller, second territory is their winter territory. While the first territory is nesting territory, the second is centered on their food source(s), usually a fruit-bearing tree or bush. Both the male and female will defend their food source from other birds who share similar tastes in foods. Species such as robins, starlings, woodpeckers, and others who also prefer fruits must be driven away to insure their own survival. The intensity of territorial defense is probably linked, especially in cold weather, with securing an adequate supply of food. Breeding and nesting territories are inhabited first by the male as early as mid-January to mid-February. Once the male has located one or more nesting sites, the female arrives. Winter territory will be occupied from mid-August/ mid-September till the following breeding/nesting season. Mockingbirds are very mindful of other mockers’ territory and rarely invade those other territories. In cases of severe food shortages, mockingbird families or groups will trespass neighboring territories and be more successful than individual mockers. Birds, it seems, understand strength of numbers.

Photo by Doris Evans

Territory and mating
While mockingbirds are generally thought of as monogamous, there are documented instances where bigamy, polygamy, and polyandrous relationships have been recorded. These situations are rare, however. More often, some mockers fail to find a mate. Males, particularly young males or older males who lost their mates, will sing to attract a mate. Their singing can continue for a matter of a few days to weeks or even months, even through the night, until they successfully attract a mate. If not successful in singing to attract a mate, the male may abandon the nest he built and the territory itself. In such a case, the male must find another unoccupied territory and sometimes this means an unsuccessful breeding season.

Photo by Richard at SearchNet Media

Singing abilities
Regardless of what one knows about mockers, most birders acknowledge it is the most popular and probably the best singing songbird in North America. Our earlier article goes into some detail regarding this attribute. We know mockers are born with the inherent ability to mimic as many as 35 other species of bird sounds as well as a wide array of more bird, animal, human, natural, and mechanical sounds. As adults, they have mastered over 200 other sounds, calls, and songs. Some experts believe throughout their lifetime they may learn about 2000 such vocalizations. Donald J. Borror, one such expert, concludes that of all the Mimidae family (includes all the thrashers and catbirds) are excellent vocalizers known for their loudness, pitch, quality, and large variety of phrases. However, says Borror, the mockingbird is more musical, with fewer discordant or jarring notes, and tends to be more repetitive. A male will sound a phrase several times in succession before changing to another, and within that phrase there may be several notes that sound like other species. This copying of other birds’ calls and songs is more characteristic of mockers in the northern portions of their range. One plausible explanation is that as the density of mockingbirds decreases, the opportunity to hear and learn from each other also decreases, so that individuals are forced to copy the notes of other species.

The male’s powerful, sustained song proclaims his gender, establishes a territory, attracts a mate, and synchronizes breeding behavior. There is disagreement about whether song is important in maintaining a territory and in keeping out intruders. Mockers do not defend a territory with song in the sense of singing as they physically chase out intruders and trespassers.

Socially, song identifies the species and calls convey information about enemies or dangerous situations. Mimicry may possibly enable a particular bird to exclude from its territory members of the species whose song it imitates. Mockingbird song probably serves to identify one individual to another and perhaps satisfies or fulfills that individual’s commitment to life. While this is an unscientific observation, the complexity, duration, and enormous amount of energy and attention which many Northern Mockingbirds give to singing seem to argue against our attempts to deprive them of emotions.

Photo by Richard at SearchNet Media

Popularity as pets
From the earliest of times in American history, as pioneers began to look westward, until protective laws, both state and federal, were instituted, mockingbirds were among the most popular of caged birds. With proper care and diet, they have been known to live long lives – probably as long as they would have lived in the wild. Hand-raised baby mockers didn’t have the vocal range of their wild relatives as they were limited to less natural sounds while confined within the human world. They fared better in individual cages rather than aviaries as they were not to be trusted among other birds due to their fierce territoriality and aggressive stances towards birds they assume to be intruders. Caged birds were fed dozens of spiders daily to keep their protein levels up and to keep them from becoming sluggish. Iron from a rusty nail in their water cup addressed diarrhea. Kerosene in the cage regularly removed lice, and a touch under its wings and vent killed any of them on a mocker’s body. By keeping cages clean and captives properly fed, bird fanciers were guaranteed pleasure, satisfaction, and companionship. Keeping caged wild birds reached its zenith at the end of the nineteenth century until new conservation laws came about by the beginning of the 20th century.

Henry Nehrling, a museum ornithologist, complained, “With many people it is a mere fashion to keep a Mockingbird.”. They take nestlings, leave the cage outdoors so that the adults will feed them, and then neglect the fledglings. He noted that “great cargoes” of young mockingbirds entered the New York and Chicago markets in June, usually selling for five dollars apiece. Adults sold for as much as twenty-five dollars and still found ready buyers. There was great demand for caged birds to provide singing entertainment for the humans who owned them, but there were also great losses and most died of mistreatment, neglect, or ignorance.

Caged observations
In later years, researchers working with caged mockingbirds noticed that in captivity, the birds seemed to increase their powers of mimicry. This may have been due to the fact that there was less to attract their attention and mimicry became a pleasant way to while away the hours; or it may be only man’s delusion, since only in captivity can we observe birds for long periods of time and at every hour of the day. One conclusion researchers arrived at was that the talent for mimicry varies among individuals and species just as the production of song itself is not constant even in a single family of birds. Another interesting observation was that mockers seemed to be influenced by bright moonlight, when their feats of jumping and tumbling while singing were most astonishing. This observation has been noted by many scientists and researchers who have studied these birds.

Image by Richard @ SearchNet Media

Conservation efforts
The Audubon Society drew attention to the slaughter of wild birds to provide ornamental feathers for stylish hats and bonnets, along with the keeping wild birds in cages, in an article published in 1886. Audubon sounded the call for bird appreciation and bird study in order to determine how various species contributed to the “balance of Nature.” One aim of this new movement was to press various state legislatures to legally distinguish game birds from nongame birds and to protect the nongame birds year round. The “Model Law,” as it was known and promoted by the Audubon Society and the American Ornithologists’Union, listed beneficial and harmless species, including the mocker, and differentiated them from pests. As state after state adopted the Model Law’s provisions, nongame birds received sufficient help that many species recovered from being hunted and captured for the pet trade. As the 20th century progressed, state and federal legislation made it illegal for the general public to keep wild birds as pets. Some species, like the Passenger Pigeon and the Carolina Wren, were either hunted or collected into extinction. But many other species, as a result of the new laws, were able to stabilize their numbers and, in time, flourish. Happily this is the case for the Northern Mockingbird – our most popular songbird today!

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