The Great Kiskadee (Pitangus sulphuratus) is a strikingly colored flycatcher found widely across South America. With its bright yellow belly, black cap and wingtips, and loud, rollicking call, the Great Kiskadee is a familiar sight in many Neotropical habitats. But do these boisterous birds migrate seasonally like many of their avian counterparts? Let’s take a closer look at the movement patterns of this widespread and gregarious species.
The Great Kiskadee’s Range
The Great Kiskadee has an extensive range across South America, Central America, Mexico, and the Caribbean. Its breeding range extends from central Mexico south through Central America and much of South America east of the Andes, including Trinidad and Tobago. The Great Kiskadee is found in nearly all habitats within this broad range, from wet rainforests to dry woodlands, savannas, and human-altered environments such as pastures, crop fields, and parks. Abundant and adaptable, the Great Kiskadee reaches its highest densities in open, disturbed areas with scattered trees and tall shrubs for nesting.
Resident Populations
Throughout much of its expansive range, the Great Kiskadee is considered a year-round resident. Breeding populations in Mexico and Central America, northern and eastern South America, Trinidad and Tobago, and many Caribbean islands remain in the same general area throughout the year without making significant migrations. In these regions, Great Kiskadees maintain permanent, all-purpose territories that provide food, nesting sites, and shelter through wet and dry seasons. Pairs may shift and expand their territories somewhat between breeding and nonbreeding seasons, wandering further afield in search of food in the nonbreeding period. But these movements are local and irregular rather than true migrations.
Partial Migration
Some Great Kiskadee populations, however, do exhibit seasonal movement patterns that could be classified as partial migration. In these cases, some individuals migrate while others remain resident year-round. This pattern has been documented in parts of Bolivia, Brazil, Colombia, and Venezuela. Breeding populations in southern Brazil, for example, are greatly reduced during the austral winter months of June to August. It appears that some individuals migrate north at this time, while others remain on their territories. Ranging patterns vary between sexes as well; females tend to move further from their breeding territories than males in the nonbreeding season in parts of the species’ range.
Drivers of Movement
What factors drive this partial migration in some Great Kiskadee populations? As with many other migratory bird species, changes in food availability and habitat suitability likely spur seasonal movements in the Great Kiskadee. In the dry season, decreased insect prey availability may force some birds to wander further afield. And the species’ ability to shift into a wider array of habitats in the nonbreeding period allows it to take advantage of seasonal fluctuations in local conditions. Migratory tendencies in Great Kiskadees may also be stronger in younger birds and influenced by population densities, competition, and breeding status.
Long-Distance Migrations
A small number of Great Kiskadee populations do embark on more distant migrations on a seasonal basis. In western Panama and Costa Rica, for example, breeding populations appear to migrate several hundred miles northwest in the boreal winter, some reaching northwestern Nicaragua. Band returns and sightings suggest a similarly long-distance migration of breeding birds from the Lesser Antilles archipelago eastward to Puerto Rico and the Virgin Islands in winter months. These migratory movements likely reflect seasonal changes in habitat suitability, food availability, and competition levels in the different portions of the species’ range.
Uncertain Origins
Interestingly, the origins of wintering Great Kiskadees across the northern coasts of South America remain unclear. It was long thought that these wintering populations breed in the Lesser Antilles and migrate to the mainland. But recent genetic evidence suggests this may not be the case. Instead, mainland South American breeding populations may account for a significant portion of northern coastal wintering birds. More research is needed to pin down migratory connectivity and delineate populations in the species’ complex range.
Migratory Behavior
In parts of its range where seasonal movements do occur, the Great Kiskadee shows some classic migratory behaviors adapted for travel over longer distances. Populations building up for migration show hyperphagia – increased appetite and foraging rate. This helps birds accumulate the fat reserves needed to fuel migration. Some evidence also indicates that migrating Great Kiskadees make physiological adaptations such as changes in hormone levels and metabolic rates. And like many migratory songbirds, Great Kiskadees travel in mixed species flocks during migration periods for safety and efficiency.
Molt Migration
An interesting additional wrinkle to the Great Kiskadee’s migratory story is the phenomenon of molt migration in the species. This occurs when birds migrate specifically to take advantage of favorable conditions during the energetically demanding molting period when old feathers are replaced. In parts of its range like coastal Venezuela and Panama, Great Kiskadees make special molt migrations in the peak dry season to wetland and mangrove habitats rich in food. Similar molt migrations are made by other tropical bird species as well.
Conservation Considerations
With its broad range across the Neotropics, the highly adaptable Great Kiskadee is not considered globally threatened. But localized declines have been noted in parts of its range. Habitat loss is a concern, particularly the clearing and degradation of suitable nesting habitat such as isolated trees, palm groves, and fencerows. Insecticide use also likely impacts Great Kiskadee survival and reproduction. And the species’ reliance on seasonal movements in at least part of its range means conservation measures like habitat protection need to extend across migratory pathways and destinations.
Conclusion
The Great Kiskadee exhibits a range of movement patterns across its expansive distribution in the Americas. While many populations are year-round residents, others show seasonal migration, partial migration based on sex and age, molt migration, and relatively long-distance movements between breeding and wintering grounds. This diversity highlights the species’ adaptability in using movement to take advantage of seasonal habitat fluctuations and food resources. Conservation efforts for this and other migratory Neotropical birds need to take into account connectivity across the annual cycle. More research is still needed to better understand the Great Kiskadee’s complex migratory systems and identify populations most at risk from habitat loss and other threats.
Population | Movement Pattern |
---|---|
Central America, Mexico, Caribbean islands | Year-round residency |
Northern South America | Partial migration (some individuals migrate seasonally, others are resident) |
Southern Brazil | Winter migration northwards |
Lesser Antilles | Long-distance migration to Puerto Rico and Virgin Islands |
Western Panama, Costa Rica | Long-distance migration to Nicaragua |
Coastal Venezuela, Panama | Molt migration to wetland habitats |
With an estimated global population in the tens of millions and a range spanning over 44,000,000 km2, the adaptable Great Kiskadee remains widespread and locally common. But habitat loss and insecticide use pose threats in parts of its range. Conservation efforts should focus on protecting key breeding habitat such as isolated trees and palm groves, and maintaining habitat connectivity across migratory pathways where seasonal movement occurs.
By combining residency with partial migration, molt migration, and long-distance movements between breeding and nonbreeding grounds, the Great Kiskadee makes the most of seasonal conditions across its expansive Neotropical range. This diversity of movement patterns enables the species to thrive across an array of habitats and fluctuating resources. There is still more to learn about the drivers, timing, and connectivity of the Great Kiskadee’s migrations. But it is clear that movement and adaptability are keys to the success of this boisterous, yellow-bellied traveler.