Starlings – those birds we love to hate – are with us much of the year and, come February, provide us with signs of spring.

These birds are non-native and have spread throughout the U.S. and much of Canada in little more than a century. They now number some 200 million in North America, which holds about a third of their world population. We know them as European starlings (Sturnus vulgaris), but some scientists who study birds recommend standardizing the English name throughout the world by calling the birds “common starlings.”

Starlings have a dubious reputation as an invasive species, which often prompts us to dismiss them without taking a good look. Yet starlings are surprisingly beautiful, especially in the non-breeding season. They molt, or grow a new coat of feathers, in August. Throughout the fall and most of the winter, these brown-black birds are covered with light speckles in front and on their heads, and the feathers on their wings and backs are edged in gold or cinnamon. These markings help them blend into the winter landscape with its bare twigs and brown grasses.

By late winter, as the breeding season approaches, starlings take on a different look. Both males and females become sleek and all black, with a blue or green iridescent sheen. Males may actually look good to females in ways that we can’t see, since there’s evidence that females prefer males whose feathers strongly reflect ultraviolet (UV) light.

The starlings’ springtime look isn’t due to new feathers. Instead, it comes from wear and tear on the old speckled plumage. Throughout the winter, the light tips and cinnamon edges of starlings’ feathers get worn away, leaving the birds with a sleek new appearance just in time for breeding.

Another sign of spring among the starlings is a more subtle change in appearance: their beaks change color. For most of the year their beaks are dark, but in February they start to turn bright yellow for the breeding season. The base of the lower beak becomes bluish in males and pinkish in females. This change isn’t from wear and tear, but rather, from the sex hormones that prepare the birds for breeding. Levels of these hormones increase as the days get longer.

A third sign of spring is one that we hear rather than see. In February starlings begin to whistle as they search out nest sites. Males direct these spring songs mainly at other males, who are potential rivals. Naturally, rising hormone levels are involved.

Male starlings also sing warbling songs, primarily to attract females, who prefer males with longer and more varied songs. Female starlings also sing.

Starlings make a great variety of sounds, as you’ll notice if you listen to them. They’re also great mimics and are closely related to mockingbirds and catbirds, which are even more famous as mimics. Starlings learn new songs and sounds year-round.

So how did starlings get here? As usual with non-native plants and animals, they didn’t come on their own. They didn’t even come by accident, as happened with many non-native plants whose seeds came mixed with crop seeds or ships’ ballast. A well-intentioned businessman deliberately imported them because he wanted North America to have all the plants and animals mentioned in Shakespeare’s works.

In 1890, 60 starlings were released in New York City’s Central Park, and another 40 in 1891. From there they spread quickly throughout the northeast and beyond. They were common in Massachusetts by the 1920s.

What accounts for their success? Not all non-native creatures do so well in a new environment that they displace other species and come to be regarded as pests and invaders. Unfortunately, human handiwork is largely responsible for the starlings’ success.

As we ourselves have prospered in North America, we have disturbed, developed, and altered the landscape in ways that benefit starlings. We’ve created open areas, lawns, agricultural fields, and networks of “edges” where these birds can forage conveniently for insects and find leftovers from harvests. We’ve put up buildings, bridges, and other structures where starlings can roost in large numbers and find holes for nesting.

Of course, it doesn’t hurt that starlings are very adaptable and intelligent. They’ve spread into urban and suburban areas as well as the countryside. Large forests don’t suit them, but we humans are making unbroken forests less common.

What about starlings helps them to adapt, survive, and multiply? They have many things going for them. For one, they’re very social and spend much of the year in large flocks, which help them survive by providing many eyes to watch for predators and find food. Only in the spring do the flocks break up as males and females pair for breeding.

You may notice starlings walking across the grass in groups and probing the ground for insects with their long, sturdy beaks. They stick their beaks into the soil and then open them with strong muscles, capturing insects and worms that might otherwise get away. They’re not fussy – they also eat fruits, seeds, suet, and grain.

Starlings raise their young in the safety of holes in trees and buildings. This habit makes them especially unpopular, for they compete successfully for nest holes with bluebirds, wood ducks, screech owls, kestrels, woodpeckers, swallows, wrens, and others. Starlings either get to the holes first or evict the other birds.

To prevent starlings from using a birdhouse or bird box, make sure the entrance is no bigger than 1-1/2 inches

Both starling parents warm the eggs and feed and care for the young. Females sometimes lay an extra egg in another starling’s nest, and males sometimes start a second family with a different female while caring for young from the first family. With so much going for them, it’s no surprise that starlings increase in number.

Much as we love to hate starlings, we humans are sometimes compared to them. Are we, too, so successful that we’re spreading wildly and displacing other species? Perhaps we should watch what we say about starlings.