The Swallow-tailed Kite is a graceful and acrobatic raptor that is found throughout the southeastern United States during the summer breeding season. As temperatures cool in the fall, Swallow-tailed Kites embark on a lengthy migration to their wintering grounds in South America.
Overview of Swallow-tailed Kite Migration
Swallow-tailed Kites breed in the southeastern United States from March to July. After the breeding season ends, they gather in large communal roosts in preparation for fall migration. The migration typically begins in late August or early September as the birds ride thermals and updrafts southward. Some kites migrate over land through Central America and into northwestern South America. Others opt for a lengthy transoceanic flight over the Caribbean Sea and western Atlantic to reach northern South America.
By late September, most Swallow-tailed Kites have reached South America. They spend the boreal winter primarily in the Amazon basin regions of Brazil, Peru, Bolivia, Colombia, Venezuela, and the Guianas. Smaller numbers reach Argentina, Paraguay, and southeastern Brazil. Swallow-tailed Kites favor wetland, riverine, and forested habitats while overwintering in South America.
As spring approaches, the kites begin their return migration north in March and April. Again, some opt for an overland route while others make the harrowing 6000+ mile transoceanic flight directly to the southeastern United States. Most Swallow-tailed Kites have returned to their breeding grounds by early May to start the nesting process again.
Detailed Look at Autumn Migration
The autumn migration of Swallow-tailed Kites from their breeding range to wintering grounds is a spectacle of endurance and navigational ability. Here is a more in-depth look at how it unfolds:
Pre-Migration Staging
Prior to migration, Swallow-tailed Kites start congregating in large communal roosts, with counts sometimes exceeding 1000 birds at a single site. These staging areas allow the birds to feed on abundantly available insects and lay down fat stores to fuel migration. Major roosting sites used include cypress swamps, pine plantations, and marshlands.
Departure and Route
Migration departures begin in late August and peak through mid-September. Kites waiting for perfect weather conditions to embark on their journey. Clear skies, calm winds, and the assistance of thermals allow for efficient long-distance travel. Banding data shows the birds departing breeding sites in Alabama, Georgia, and Florida initially take a southwesterly track towards the Gulf Coast.
From there, migration strategies diverge. Some kites opt to follow an overland route, traversing Central America and northwestern South America through Mexico, Panama, Colombia, and Venezuela before reaching the Amazon Basin. This continental route covers 3000 to 4000 miles.
However, the majority of Swallow-tailed Kites embark on a lengthy transoceanic migration over 2000 miles across the Caribbean Sea and western Atlantic Ocean. This takes them to northern coastal areas of South America like Guyana, Suriname, and French Guiana. While a risky route, flying over water allows the birds to avoid barriers and find helpful tailwinds.
Timing and Speed
Most Swallow-tailed Kites have reached northern South America by late September. Early migrants may arrive by mid-September while stragglers continue to pass through the Caribbean through late October. Based on banding data, kites cover an average of 100 miles or more per day, but speeds of up to 200 miles per day have been recorded.
Notable feats include a four year old kite that migrated from Florida to Guyana, a distance of 2300 miles, over just 11 days. And another kite that flew from Georgia to Suriname, covering 2200 miles in 13 days. This equates to averages of 209 miles and 169 miles per day, respectively.
Navigation
The ability of Swallow-tailed Kites to navigate over thousands of miles of land and ocean to a winter home they’ve likely never seen before is a remarkable feat. Experts believe they orient themselves using the earth’s geomagnetic field, visual landmarks, celestial cues from stars or the sun, and an internal circadian rhythm and natural compass orientation.
Their sense of smell may also help lead them along bush burning wind currents or zones of higher humidity over tropical forests. Once they reach South America, the kites are thought to follow river valleys and other land contours that provide leading migration lines.
Wintering Grounds in South America
After their marathon migrations, Swallow-tailed Kites settle into winter homes in various countries across northern and central South America:
The Amazon Basin
The majority of the kites winter in wetland, flooded forest, and gallery forest habitats in the Amazon Basin regions of Brazil, Peru, Colombia, Bolivia, and Venezuela. Here they find ideal foraging as water levels drop in the dry season, concentrating prey like insects, tadpoles, small fish and reptiles. Numbers peak from November to March.
The Guianas
Guyana, Suriname and French Guiana host significant wintering populations of Swallow-tailed Kites in forest and savanna areas. Many kites reach these countries after their trans-Atlantic flights from the SE United States and find plentiful food sources.
Argentina and Paraguay
The grasslands and wetlands of northern Argentina and Paraguay also attract smaller numbers of wintering kites after their overland migration through Central America. They occupy habitats like the Rio Pilcomayo National Park wetlands.
Southeastern Brazil
Some Swallow-tailed Kites migrate down the Atlantic coast of Brazil to reach wintering areas in the southeast part of the country in states like Sao Paulo. They favor wetlands and marshes in this region.
Spring Migration North
As days lengthen and temperatures warm in early spring, Swallow-tailed Kites once again get the urge to migrate north and start their return trips to North America. Here’s an overview of this second great migration:
Timing
Swallow-tailed Kites begin leaving their South American wintering grounds in March and April. Early departures are noted in Colombia and Venezuela around late February. Peak migration occurs through the Caribbean islands in April as the birds ride favorable tailwinds. Most kites have returned to the southeastern U.S. by early May.
Routes
As in autumn, some kites opt for overland routes through Central America, while most embark on transoceanic flights spanning 2000+ miles over the Caribbean Sea and Western Atlantic Ocean. Their internal compass leads them back to breeding sites with incredible accuracy.
Speed and Duration
Northbound migration may take slightly longer than in autumn, with kites covering around 80-100 miles per day. But favorable winds can boost flights to 200 miles in a day. Duration is typically 1-2 weeks for overland migrants, while transoceanic fliers can take 3 weeks to a month to reach the U.S. after island hopping and rest stops.
Challenges
Banding studies show migratory losses are higher for northbound kites than southbound ones. Exhaustion, starvation, storms and accidents all take a toll. Headwinds and a lack of helpful thermals also slow progress. Despite obstacles, these resilient raptors are driven to reach their breeding areas.
Incredible Navigation
The migration journeys made by Swallow-tailed Kites, covering thousands of miles overland and ocean twice a year, are an incredible display of stamina, endurance and navigational ability. Scientists are still working to fully understand how these birds accomplish such feats of precision guidance. Their resilience against the odds makes Swallow-tailed Kites one of nature’s great avian adventurers.
Conclusion
The Swallow-tailed Kite undertakes an epic annual migration of 3000 to 4000 miles between its breeding range in the southeastern United States and wintering grounds in South America. After nesting ends, kites gather in large roosts before embarking on southbound migration in late August and September. Some follow an overland route through Central America, while most make daring transoceanic flights across the Caribbean and Western Atlantic to reach northern South America.
Key wintering areas are the Amazon Basin, the Guianas region, Argentina, Paraguay and southeastern Brazil. As spring approaches, the journey is reversed, with northbound flights beginning in March and April. Upon reaching the southeastern U.S., the kites mate and nest again. Their navigational prowess and endurance power this odyssey across continents guided by geomagnetism, visual landmarks, winds, and other natural cues.