In 1890, the European starling (Sturnus vulgaris) was introduced to the United States. About 130 years later, the starling is one of the most abundant birds in North America. The starling’s success has come, in part, at the expense of cavity-nesting native birds that compete with the more aggressive starlings for nesting sites. This article is intended to aid in identifying European starling nests and eggs.
European starling breeding facts
|Breeding Period||Across North America, beginning in mid-April through mid-July. Breeding periods are more constrained in the northern part of the starling’s range.|
|Nest type||A haphazard-looking nest with a central depression or cup of approx 2.7 – 3.1 inches across and 1.9 – 3.1 inches deep.|
|Substrate & Location||Preferably inside a cavity or structure that resembles an enclosure, 2 to 60 feet above the ground.|
|Nesting Activities||Both males and females build the nest in as little as two to three days. On average, nest construction can take a week. Both sexes incubate the eggs.|
|Egg Description||Eggs are unmarked, pale bluish to pale greenish.|
|Egg Length and width||1.1 in x 0.8 in.|
|Egg-laying||It begins a day or two after nest completion. Female lays one egg every day.|
|Clutch size||Typically 4-5 eggs, rarely 6 to 7 eggs.|
|Number of broods||Double brood in the south, single brood in the north.|
|Incubation Period||Typically 12 days, but ranges from 11 to 13 days.|
After its introduction in New York City, the European starling was confined to New York and surrounding areas. A similar climate in its native range and abundant food derived from human activities led starlings to expand their range.
Now, starlings are established as breeding populations in every state in the U.S. and every province in Canada. Starlings also occur in Mexico and parts of the Caribbean island as winter visitors.
Breeding range based on European Starling species account. allaboutbirds.org.
The European starling is highly adaptable and can live in almost any kind of habitat associated with humans. Starlings forage in open and semi-open habitats, search for food on agricultural land, and do well in urban areas.
Starlings avoid woodland interiors and appear to avoid dry habitats such as western scrub.
Migration and social behavior
The European starling’s migration patterns vary with region, population, and even individuals.
Starlings in the northern states and Canadian provinces, especially those living away from urban areas, tend to migrate south towards less cold regions. Birds that live in urban areas or near reliable food sources, such as farms, tend to be sedentary.
In populations that migrate regularly, some individuals migrate while others are sedentary. Furthermore, birds that migrate do not necessarily migrate every year, but they may be sedentary for some years and migrate in others.
Some young starlings stay in their natal region, while others migrate hundreds of miles to settle in other areas.
When not breeding, European starlings form flocks of all sizes. Large flocks are typically found in areas with reliable sources of food as well as at roosting sites.
The beginning of the breeding period varies between populations in the south and those breeding in the northern part of the starling’s range. The north part is roughly north of 48 degrees latitude.
Birds in the south begin laying eggs as early as mid-March. Those in the north begin in mid-April (New York) and mid-June (further north). Weather conditions can influence the initiation of breeding activities.
Starlings breeding in the south usually have a second brood, whereas those in the north only have one brood per year.
Across the European starling’s range in North America, the breeding period encompasses the period between mid-April through mid-July, with shorter breeding periods in the northernmost reaches of its range.
European starling nest appearance
Compared to other birds, starling’s nests are unsophisticated. The material used and the way it is arranged give the nest a haphazard appearance. Unlike other birds, starlings do not build a nest cup lined with hair, animal fur, and delicate fibers. Instead, their nests have a central round depression that may look like a cup in some nests.
The nest shape and size vary according to the space available in the nesting cavity. Breeding pairs tend to fill up the open space making nests of varying sizes and shapes. On average, the central depression or cup where the eggs are laid measures 2.7 – 3.1 inches across and 1.9 – 3.1 inches deep.
The male starling chooses the nest site and begins to add nest material to claim it. Females inspect these cavities and the males associated with them and choose one. Breeding activities start as soon as the pair is formed.
Starlings tend to return to the same nesting cavity each year, according to studies. Approximately 30% of banded females returned to the same cavity in consecutive years, and 90% of them nested in the same area in successive years.
Returning pairs may add nesting material to an existing nest. When the nest becomes too soiled after its last use, breeding pairs remove all of the material to replace it with fresh material.
In part, European starlings’ success at colonizing new areas can be attributed to their ability to find nesting sites and take over nesting cavities from other cavity-nesting birds.
Starlings use cavities or anything that resembles an enclosure with an entrance hole. They cannot, however, squeeze through a hole smaller than 1 ½ inch.
Besides woodpecker cavities, cavities created by broken limbs, and nesting boxes, starlings nest in crevices of houses, inside traffic light fixtures, open pipes, to name a few.
They cannot excavate their cavities in wood, but they have been known to do so in soft river banks and limestone walls.
Both the female and male begin nest building once the female selects a nesting cavity. They use the available nesting material, including dry grasses, twigs, dead leaves, pieces of plastic and paper, bark, and strings. A nest can be built in as little as 2 to 3 days, but nest construction can take a week on average.
Starling eggs vary in shape from short ovals to long ovals, with an approximate length of 1.1 inches and breadth of 0.8 inches. Egg colors range from pale bluish to pale greenish and are unmarked,
Egg-laying begins as soon as the nest is complete. The female lays an egg every morning until the clutch is complete.
Once the female begins laying eggs, the male stays close to her constantly. During this period, they continue to copulate. The male keeps the female close to ensure the paternity of the eggs.
Studies of breeding starlings found that egg dumping occurs with a certain frequency. Females that do not find a suitable nesting site, those that lose their nests, and floaters are likely to deposit fertilized eggs in other females’ nests during the egg-laying season.
The typical clutch size is 4 to 5 eggs. Clutches of 6 to 7 eggs are less common.
Incubation of the eggs
As soon as the first egg is laid, the female starling begins sporadic incubation. She spends more time incubating eggs until she reaches the penultimate egg and begins full incubation.
Both males and females incubate the eggs, although the female spends more time incubating during the day and does it every night.
Both sexes develop brood patches, but the female’s is more prominent.
European starlings typically incubate their eggs for 12 days before hatching. Incubation can last from 11 to 13 days.
- Caccamise, D. F. (1991). European starling fidelity to diurnal activity centers: role of foraging substrate quality. Wilson Bulletin 103:13-24.
- Feare, C.J., Spencer, P.L. and Constantine, D.A.T. (1982). Time of egg-laying of Starlings Sturnus vulgaris. Ibis 124: 174-178.
- Peterson, B., and G. Gauthier (1985). Nest site use by cavity-nesting birds of the Cariboo Parkland, British Columbia. Wilson Bulletin 97:319-331.