The Yellow-billed Cuckoo (Coccyzus americanus) and the Mangrove Cuckoo (Coccyzus minor) are two closely related species of cuckoo found in North America. Though similar in appearance, they differ in their habitat preferences, breeding behaviors, diet, and vocalizations. Understanding the differences between these two species can help birders properly identify them in the field.
Quick Facts
Yellow-billed Cuckoo
- Scientific name: Coccyzus americanus
- Length: 11.8-12.6 in
- Wingspan: 13.4-15.8 in
- Weight: 1.5-2.2 oz
- Main habitat: Deciduous forests, especially near water
- Diet: Insects, caterpillars, fruits
- Distinctive calls: Loud, repetitive “kowlp” sounds
- Breeding: Monogamous, nests in trees
- Eggs: Greenish-blue, 2-5 per clutch
- Conservation status: Least concern
Mangrove Cuckoo
- Scientific name: Coccyzus minor
- Length: 11.8-13.4 in
- Wingspan: 14.2-15.7 in
- Weight: 1.1-1.8 oz
- Main habitat: Mangrove swamps, hammocks
- Diet: Insects, spiders, snails
- Distinctive calls: Rapid “ka-ka-kowlp”
- Breeding: Monogamous, nests in trees
- Eggs: Pale blue-green, 2-4 per clutch
- Conservation status: Near threatened
Geographic Range
The Yellow-billed Cuckoo has a wider geographic range than the Mangrove Cuckoo.
Yellow-billed Cuckoo
The breeding range of the Yellow-billed Cuckoo extends across much of the eastern half of the United States and up into southern Canada. Its wintering grounds are in South America, primarily east of the Andes Mountains. Though still relatively widespread, the cuckoo’s populations have been declining in parts of its range.
Mangrove Cuckoo
The Mangrove Cuckoo is found in coastal areas of the Neotropics, ranging from southeastern Mexico down through Central America and much of South America. In the United States, breeding populations are limited to south Florida and a few parts of southern Texas. Its winter range extends into parts of northwestern South America. Habitat loss has caused the cuckoo’s populations to decline significantly.
Habitat
The two cuckoo species prefer quite different habitat types.
Yellow-billed Cuckoo
During the breeding season, the Yellow-billed Cuckoo inhabits open woodlands with clearings and dense scrub vegetation. It especially favors riparian woodlands along rivers and streams. Its habitat includes deciduous forests, forest edges, abandoned farmlands, and parks or preserves near water sources.
Mangrove Cuckoo
As its name implies, the Mangrove Cuckoo is most closely associated with mangrove swamps and coastal hammocks dominated by mangrove trees. It also utilizes other tropical and subtropical habitats such as scrub forests, plantations, and parks with dense vegetation. Mangroves provide food, shelter, and nesting sites.
Physical Description
The Yellow-billed and Mangrove Cuckoos appear very similar, with grayish-brown upperparts, white underparts, long tails, and a slight crest. Refer to key differences in size, bill color, eye ring, and tail pattern for identification.
Size and Proportions
- The Yellow-billed Cuckoo is slightly larger than the Mangrove Cuckoo.
- The Mangrove Cuckoo has a proportionately longer tail compared to its body.
Bill
- The Yellow-billed Cuckoo has a thick, yellow lower mandible.
- The Mangrove Cuckoo has a black bill.
Eye Ring
- Yellow-billed Cuckoos have a bold yellow eye ring.
- Mangrove Cuckoos have a thin, indistinct eye ring.
Tail
- Yellow-billed Cuckoos have bold white tail spots on the tips of most tail feathers.
- Mangrove Cuckoos have small, indistinct buffy spots only on the outer 2-3 tail feathers.
Vocalizations
The repetitive calls of these cuckoos are quite distinct. Listen for the following differences:
Yellow-billed Cuckoo
Its most common call is a loud, ringing series of notes that sound like “kowlp kowlp kowlp kowlp”. This call is often described as sounding like a dropping ping pong ball.
Mangrove Cuckoo
Its call is a faster, more nasal series of notes, sounding like “ka-ka-kowlp ka-ka-kowlp”. The notes run together more closely than the Yellow-billed Cuckoo’s call.
Breeding and Nesting
The breeding ecology of these species differs in geography, timing, and nest sites used.
Geography and Timing
- Yellow-billed Cuckoos breed in temperate North America between May and September.
- Mangrove Cuckoos breed in tropical areas between March and August.
Nest Sites
- Yellow-billed Cuckoos build flimsy stick nests in the branches of deciduous trees.
- Mangrove Cuckoos nest almost exclusively in mangrove trees, often lower in vegetation.
Diet
Both cuckoos are primarily insectivorous, but they tend to feed on different prey based on their habitat.
Yellow-billed Cuckoo
Its diet includes caterpillars, katydids, cicadas, grasshoppers, beetles, and some fruits. It often feeds on tent caterpillars and gypsy moth caterpillars, which can be pests.
Mangrove Cuckoo
It eats insects like beetles, sticks, treehoppers, flying ants, and spiders. Snails are also an important food source. It sometimes feeds on small lizards and frogs.
Conservation Status
Due to declining populations, the Mangrove Cuckoo is considered more threatened than the Yellow-billed Cuckoo.
Yellow-billed Cuckoo
This species is classified as Least Concern by the IUCN Red List. Habitat loss is reducing populations in parts of its range.
Mangrove Cuckoo
This species is classified as Near Threatened by the IUCN Red List due to its small and declining population. Mangrove deforestation is the major threat.
Conclusion
In summary, the Yellow-billed and Mangrove Cuckoos can be distinguished by habitat, physical traits like bill color, vocalizations, geographic ranges, and nesting differences. Properly identifying between these similar species aids in monitoring their conservation status and protecting their distinct habitats. Birders should listen and watch closely to pick up on their subtle variations in the field.