The arrival of spring varies significantly across the United States due to differing regional climates. Migratory birds are often heralded as the bringers of spring but they too arrive at different times. Some arrive when it is still cold and seemingly inhospitable, leaving many of us to ponder why. Which species arrive early really depends on two main factors.
Firstly is temperature. Even slightly warmer (or less cold) temperatures trigger the emergence of food sources, like insects and plants, which returning birds rely on both along their migration route and back in their breeding grounds. The other reason is the lengthening days. Increasing daylight hours stimulate hormonal changes in birds, prompting them to leave their wintering grounds.
The birds that are the earliest arrivals are often species that can tolerate colder temperatures, have adaptable diets and begin breeding early. Here are some of the birds you are likely to see as winter fades into spring.
Red-winged Blackbird
Red-winged Blackbird migratory patterns are quite complex and vary depending on their geographic location. Generally, those birds that breed in northern regions (like Canada and the northern United States), migrate south for the winter and typically move to the southern United States and Mexico. However, populations in the warmer climates of central and southern regions may be resident, meaning they don’t migrate. The extent of migration is influenced by factors like temperature and food availability.
The spring migration typically occurs from mid-February to May, whereas the fall departure begins as early as August and continues through October. There is also a noticeable difference in migration timing between males and females. In spring, males arrive on breeding grounds first, arriving to establish territories. In fall, females tend to migrate south earlier than males.
The early return of male Red-winged Blackbirds is largely driven by reproductive strategy. Males arrive early to find and then defend prime breeding territories. These areas are crucial for attracting females. The best territories, often those with abundant resources and suitable nesting sites, are highly sought after. Arriving early gives males a competitive advantage in securing these locations. This translates to a higher likelihood of successfully passing on their genes to the next generation.
Killdeer
Killdeer exhibit partial migration, meaning that some populations migrate while others remain in their breeding areas year-round. This is largely dependent on the severity of winter weather. Northern populations migrate south, often flying over areas where resident Killdeer remain. This is referred to as leap-frog migration. Those breeding in the southern United States and along the Pacific Coast tend to be year-round residents.
Spring migration occurs relatively early, with Killdeer returning to northern breeding grounds as early as February or March. This early arrival is one of the signs of approaching spring. Fall migration begins in late summer and continues through autumn.
Killdeer migration, particularly their early spring return, is influenced by a few key factors, and the timing varies significantly depending on latitude. The primary driver is the approaching breeding season and the birds return to establish breeding territories and begin nesting.
The return of the northern migratory birds is also tied to the thawing of the ground, as Killdeer feed on insects and other invertebrates. As the ground thaws and temperatures rise, insects become more abundant. They also need open areas with suitable nesting sites so the timing coincides with the availability of these habitats as snow and ice melt.
American Robins
Again, we have a bird that is found across North America but its migratory patterns are quite flexible, with not all of them migrating. The decision to migrate is heavily influenced by factors like food availability and temperature. Generally, robins breeding in northern regions (like Canada and Alaska) are more likely to migrate south for the winter, typically moving to the southern United States, Mexico, and even Central America.
Robins in southern areas may remain resident, while those in northern areas undertake longer migrations. A primary driver of robin migration is food availability. During warmer months, they primarily feed on earthworms and insects but as the ground freezes and these food sources become scarce, they switch to fruits and berries. If fruit supplies are insufficient, they migrate to areas with more abundant food. They tend to follow warming trends, returning as the ground begins to thaw and preferred food sources become available. For example, they will follow warm fronts, as warm rains bring earthworms to the surface.
During migration and in winter, robins often form large flocks. This contrasts with their more solitary or territorial behavior during the breeding season. This means it is a great time to see them for bird watchers.
Spring migration typically occurs from February to April and fall migration begins in September and continues through November. Males tend to arrive on breeding grounds before females allowing them to establish and defend prime territories, which are crucial for attracting mates.
Tree Swallow
Tree Swallows exhibit distinct migratory patterns within the United States, characterized by both geographic variations and specific behaviors. They are long-distance migrants, traveling considerable distances between their breeding and wintering grounds.
These attractive swallows breed across much of North America, including the northern United States and Canada, and they migrate south for the winter. Their wintering areas include the southern United States, particularly Florida, as well as Central America and the Caribbean.
Both the spring and fall migrations begin relatively early, often starting in July and peaking in the fall. They migrate during the day, often in flocks. Eastern populations tend to migrate along the Atlantic coast, while midwestern populations may follow the Mississippi River and western populations likely travel along the eastern slopes of the Rocky Mountains and along the Pacific coast.
While they primarily feed on insects, they also consume berries and seeds, which allows them to linger longer on breeding grounds and return earlier in spring. They are cavity nesters, and so their breeding ground selection is tied to available nesting locations. Competition for these limited nesting sites is intense and returning early gives them an advantage in securing the best nesting locations.
American Woodcock
The American Woodcock’s migratory patterns are interesting due to their variability and the way they’re influenced by factors like weather. They generally migrate from the breeding grounds located across much of eastern North America, including southern Canada and the northern United States. Wintering grounds are primarily in the southern United States, particularly along the Gulf Coast.
They migrate primarily at night, which makes them difficult to observe during their journeys. Unlike some birds that migrate in large flocks, Woodcocks tend to migrate individually or in small, loose groups. Their migrations generally follow two main flyways, the first being the Eastern Flyway covering the area east of the Appalachian Mountains. The second is the Central Flyway along the area west of the Appalachians to the Great Plains.
American Woodcocks are among the earlier migrants to return in the spring. In some areas, males may begin moving north as early as January, especially in warmer years, but the bulk of their spring migration typically occurs from February through April. Their early return is primarily driven by the need to establish breeding territories and begin courtship displays. Male Woodcocks are known for their elaborate courtship flights and peenting calls, which they perform to attract females.
Woodcocks primarily feed on earthworms, so their return is timed to coincide with the thawing of the ground and the emergence of these food sources. They tend to follow warming trends northward. While they return early, they are also vulnerable to late-season cold snaps and if conditions become unfavorable, they may move southward again temporarily. However, the need to begin the reproductive cycle is a strong driver. Because of the necessity to reproduce, they will often take the risk of returning early.
Eastern Phoebe
The Eastern Phoebe’s migratory patterns are characterized by short to medium-distance migrations, and they are known for being among the earlier spring migrants. They move between their breeding grounds in eastern North America and their wintering grounds in the southern United States and parts of Mexico.
They often return to their breeding grounds in March. This early return is a notable characteristic of this species but they do not leave on migration equally early like other species. They tend to migrate southward in September to November. The extent of migration can vary depending on the specific population and local weather conditions.
Like many of the other early migrants above, Eastern Phoebes return early to establish their breeding territories. Securing a good territory is crucial for attracting mates and ensuring successful breeding. They are known for nesting under eaves, bridges, and other human-made structures, as well as on natural structures and returning early allows them to claim prime nesting sites before other competing species arrive.
Eastern Phoebes are primarily insectivorous and this drives them to return as soon as insect populations begin to emerge in the spring. Also, they are relatively tolerant of cooler temperatures compared to some other insectivorous birds and this allows them to take advantage of early spring conditions. By arriving early and leaving later than other migratory birds, they have the possibility of raising more than one brood in a season.
Wood Duck
Wood Ducks exhibit a mix of migratory and resident behaviors, depending on their location. The extent of migration is primarily influenced by winter temperatures and food availability. Generally, Wood Ducks breeding in northern regions (like Canada and the northern United States) migrate south for the winter. They typically move to the southern United States, particularly along the Atlantic and Gulf Coasts.
Northward migration occurs from February to April and southward migration usually begins in September and continues through November. They utilize the Atlantic, Mississippi, and Central flyways. Common wintering areas include the southeastern United States, such as Florida, Louisiana, and South Carolina, as well as the lower Mississippi River Valley. Wood Ducks often form pair bonds on their wintering grounds, so the male and female often return to the breeding grounds together.
Their return to the north is closely tied to the thawing of waterways and the availability of suitable nesting sites. Milder winters and early spring thaws can prompt Wood Ducks to return to their breeding grounds sooner. Wood Ducks are also cavity nesters, and the availability of suitable nesting sites is crucial. Returning early gives them a better chance of securing these sites.
Northern Pintail
Northern Pintails exhibit complex and widespread migratory patterns, spanning several continents. They have a Holarctic distribution, meaning they breed across northern regions of North America and Eurasia. This results in diverse migratory routes.
These attractive ducks are primarily long-distance migrants, traveling significant distances between breeding and wintering grounds. In North America, they breed in northern regions and migrate south to winter in the southern United States, Mexico, and Central America using major routes like the Pacific, Central, and Mississippi flyways.
Northern Pintails are known for early spring and fall migrations with birds moving northward as soon as temperatures start to warm. Indeed, they are actually very good at following the thawing lines, and will move north as soon as bodies of water begin to open up. They are among the earliest waterfowl to begin breeding and this necessitates an early return to their breeding grounds to establish territories and initiate nesting. They are adapted to utilizing a variety of wetland habitats, including those that thaw relatively early in the spring. Their early return allows them to take advantage of these early-season habitats.
Final Thoughts
Birds return to the U.S. from migration early in spring for a combination of intertwined reasons, primarily focused on maximizing their reproductive success. Early arrival allows birds to secure the best breeding territories and nesting sites, which are crucial for attracting mates and raising young. Competition is often fierce, so being first offers a significant advantage.
Many birds time their return to coincide with the emergence of their primary food sources, such as insects, earthworms, and new plant growth. Early returners can capitalize on these resources before they are depleted.
Birds also respond to environmental cues like increasing day length and rising temperatures, which trigger hormonal changes that initiate migration. They follow warming trends and are very good at following the thawing of the ground, and bodies of water.
Whatever the reasons for their return, they herald the end of the cold weather and we rejoice in their presence.
