photograph of a Great Blue Heron by Rohan Kamath
first two attempts to introduce the European Starling into
North America failed. The third did not, and what has
followed since those 60 starlings were released in 1890 in
New York City's Central Park has kept ornithologists
alternately astounded, puzzled, and infuriated. Much as
European human settlers did in the preceding years, the
invading birds pushed their way across the continent, taking
advantage of its riches and, where necessary, usurping the
habitat of residents. What enabled the starling to advance
all the way to the Pacific within a mere 60
Starlings were not always pests, although, according to historical records, they have
associated with people since the advent of agriculture. They
were described in detail by Aristotle and Pliny, and the
Romans taught them to mimic human speech. The meager mention
of starlings by European chroniclers before 1830 is thought
to indicate rather limited numbers. After 1830, however,
milder European winters eliminated starlings' need to
migrate or shortened the migration route, and the conversion
of forest into farms created more favorable open habitats
and provided cereal grains for food. These concurrent
changes are thought to have favored double-brooding,
breeding at an earlier age, and formation of ever larger
starling colonies (which probably have higher breeding
success than small ones) and led to a rapid increase in
those populations. Before the turn of the century, the
species was brought to our shores.
Few people like starlings. But disdain of the species may be tempered by knowledge of its biology. Take, for example, its bill. Unlike most of the 130-member starling family, Sturnidae, the European Starling has jaw muscles that work "backward." Instead of using most of their power to clamp the bill shut, these muscles use it to spring the bill open. Thus the bill functions not just to grip prey but also to pry apart obscuring plants. The closed bill is inserted between blades of grass in thick turf or other cover, and then sprung open to expose hidden prey. As the bill opens, the eyes move forward toward each other, permitting binocular vision. This readily observed foraging technique enables the starling to detect not only active prey but also dormant or stationary prey, as well. William Beecher, who made this discovery during a seven-year study of songbird head musculature and skull adaptations, suggests that this unique hunting maneuver was also key to the high rate of survival of starlings during winter.
Consider, as well, starlings' housekeeping. Even more than most cavity nesters, starlings use a wide array of sites and an endless variety of human-built structures. Typically cavity nesters lay their eggs on nothing more than a bed of chips or feathers, but starlings build nests inside their chambers. In addition to gathering dead grasses for those nests, starlings carefully select fresh green vegetation rich in chemicals that act as fumigants against parasites and pathogens. Green sprigs are added to the nest until the eggs hatch. To maintain its insulating properties the nest is kept dry by removing the fecal sacs of the nestlings. Once the chicks are feathered, nest insulation becomes superfluous, the fecal sacs are no longer removed, and fresh anti-parasite greenery is no longer added. Thus, even before fledging, starling nests resemble a pest-ridden compost. But starlings are hardier than many other cavity nesters. They can, for example, withstand the infestation of tens of thousands of mites per nest hole without an increase in mortality. Therefore nest construction includes early (but not late) incorporation of leaves containing fumigants, and minimal, but precisely timed, efforts in nest sanitation, the starling has reduced the energy costs of housekeeping while decreasing the value of its hole for reuse by its competitors.
Starlings are colonial breeders. There are reports of bachelor males feeding the young and, along with the male parent, guarding the nest tree after the fledglings and female parent depart to forage. There may thus be a tendency toward cooperative breeding (which has been found in some tropical members of the starling family) in European Starlings. Observers should be alert for signs of such behavior.
Breeding males may attempt to father a second and even third brood. Their fidelity to mates depends, in part, on the success of the previous brood, but apparently it is not uncommon for males to select a new female for a second brood, perhaps on the basis of her previous success. A family unit usually forages within 200-500 yards of its nest. During nest building and egg laying, unit members make, on average, 30 visits a day to the nest; during incubation this decreases to 18, but when young are being fed, visits jump to 260. Also, visits to the nest may not be restricted to members of a unit. Evidence points to intraspecific nest parasitism -- visiting female starlings are known to dump their eggs in the active nests of other females.
In the winter, starlings become somewhat nomadic but are able to find dormant insects under snow wherever it is not too deep. They show a marked preference for foraging for insects in short grass but are extremely opportunistic and will even rely on fungus to get by in the absence of preferred foods.
Exotic "weeds" often escape the natural controls that limit their numbers at home and may, quite quickly, become pests. Is it possible to control our weed-like starlings? Some think starlings could serve humanity well by ridding pastures of insect infestations, although benefits have been demonstrated under only very special conditions. Nonetheless, a reputation for controlling pests has apparently paved the way for starlings in New Zealand, where nest boxes for them can be found atop many pastureland fence posts. The use of starlings to suppress North American insect outbreaks, however, is unlikely. Instead, programs to control starlings probably will become more common.
Starlings form aggregations with other species which may reach 10 million birds and can be astonishingly difficult to control. Congregations on trees have been discouraged by thinning the canopy. Loudspeakers have been wired throughout vineyards and orchards to broadcast distress calls, which may be effective under some conditions in keeping the birds from roosting. During the past 15 years, where massive winter roosts have occurred, a million or more individuals have been killed at one time by spraying with detergent (which destroys the insulating properties of the plumage). But even these local losses have not put a significant dent in starling populations.
Human modification of North American habitats permitted rapid colonization of the entire continent. Starlings are now ubiquitous, out-competing other such cavity nesters as Eastern Bluebirds, Red-headed Woodpeckers, Northern Flickers, and Great Crested Flycatchers. Within one century, 60 starlings introduced to North America have increased to over 200,000,000 (one-third of the world's European Starling population). How fast and for how long their numbers will continue to grow is uncertain, but it is likely that managing the consequences of their introduction will continue to be difficult, expensive, and (considering the nature of the foe) often unsuccessful.
Copyright ® 1988 by Paul R. Ehrlich, David S. Dobkin, and Darryl Wheye.