The northern waterthrush (Parkesia noveboracensis) and Louisiana waterthrush (Parkesia motacilla) are two similar looking birds in the Parulidae family. They can be hard to distinguish in the field due to their nearly identical plumage. However, they differ in their habitat preferences, foraging behaviors, songs, and geographic ranges. Understanding the key differences between these two warblers is important for proper identification.
Taxonomy
The northern waterthrush and Louisiana waterthrush were formerly placed in the genus Seiurus, but were moved to the genus Parkesia based on genetic evidence. This change occurred in 2017. Here is a brief taxonomy outline for both birds:
Northern Waterthrush:
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Parulidae
Genus: Parkesia
Species: Parkesia noveboracensis
Louisiana Waterthrush:
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Parulidae
Genus: Parkesia
Species: Parkesia motacilla
Identification
Appearance
In terms of physical appearance, the northern waterthrush and Louisiana waterthrush are nearly identical. They share the same overall size and shape, with a length of 5.5-6.3 inches and wingspan of 8.7-10.2 inches.
Key field marks include:
– Brownish upperparts with black streaking
– Off white underparts with black streaking
– White supercilium (eye ring)
– Pink legs
– Small bill with a slight downward curve
There are a few minor physical differences:
– Louisiana waterthrush has a longer tail and wings
– Louisiana waterthrush has a more buffy brown color on its underparts
– Northern waterthrush has a greyer breast in fresh fall plumage
But these subtle distinctions are very difficult to discern in the field. As a result, visual appearance alone is not a reliable way to tell these birds apart.
Voice
The songs and call notes of the northern waterthrush and Louisiana waterthrush are distinct and diagnostic. This is the best way to differentiate these birds in the field.
The northern waterthrush’s song is a very fast, high-pitched series of teakettle-like notes. It’s often described as sounding like “chip chip chip chip.”
The Louisiana waterthrush has a louder, more rolling warble that drops in pitch at the end. It sounds like “cheree cheree cheree ee-ur.”
The call note of the northern waterthrush is a low, flat “chimp.” Louisiana waterthrush call notes are sharper and higher-pitched, often sounding like “check.”
Listening for these vocal differences is the most reliable way to identify northern vs. Louisiana waterthrushes when you can’t see diagnostic habitat clues.
Geographic Range
The breeding and wintering ranges of these species differ considerably:
Northern Waterthrush
– Breeding range: Boreal forest across Canada, Alaska, and the Northeastern US. Also breeds at higher elevations in the Appalachians.
– Migration: Winters primarily in Central America and northern South America. Migration route goes over the Gulf of Mexico.
– Winter range: Coastal areas from southern Mexico to northwestern South America. Also the Caribbean.
Louisiana Waterthrush
– Breeding range: Eastern US from southern Midwest through Appalachians and into the Northeast. At higher elevations further south.
– Migration: Winters primarily in Central America and northwestern South America. Migration route goes over land.
– Winter range: Southern Mexico, Guatemala, Honduras, Costa Rica, Panama, and northwestern South America.
There is essentially no overlap between their breeding ranges. On the wintering grounds there can be some overlap in Mexico and Central America. But the Louisiana tends to be further inland.
Habitat
The habitats these waterthrushes occupy also differ significantly:
Northern Waterthrush
– Breeding: Coniferous and mixed forests with dense undergrowth. Often near water or wetlands. Favors areas with moist soil and leaf litter.
– Migration: Forest and second growth. Also wetlands, fields, parks, and riparian corridors.
– Winter: Mangrove forests, drier coastal woodlands, swamps, fields, plantations.
Louisiana Waterthrush
– Breeding: Mature deciduous forests near swiftly flowing streams. Nest is always near moving water.
– Migration: Forested riparian areas. Also woodland undergrowth and scrub.
– Winter: Forested mountain streams, shaded gullies, wet ravines. Still favors moving water.
The Louisiana waterthrush is more specialized for living around water year-round. The northern occupies a wider variety of wooded habitats.
Behavior
Several behavioral differences exist between these species:
Foraging:
– The northern waterthrush feeds by picking prey from leaves and soil while walking. It teeters its tail while walking.
– The Louisiana waterthrush feeds by picking insects directly from stream rocks, logs, and beds while bobbing its rear end. It actively seeks prey underwater.
Nest placement:
– The northern waterthrush nests on the ground, hidden by plant debris and leaf litter.
– The Louisiana waterthrush nests along stream banks, forming nests behind waterfalls, on ledges, and amongst tree roots.
Territoriality:
– Male northern waterthrushes are not strongly territorial on the wintering grounds. They may flock together.
– Louisiana waterthrushes maintain winter territories around prime stream habitat. Males are aggressive to intruders.
Migration:
– Northern waterthrushes often migrate in larger flocks.
– Louisiana waterthrushes migrate individually or in smaller groups.
Conclusion
In summary, the northern waterthrush and Louisiana waterthrush can be tricky to differentiate by sight alone. Listen for their distinct songs and calls. Also look closely at habitat – northern waterthrushes favor wet woods while Louisianas live right along moving streams. Minor plumage and structural differences exist, but vocalizations and habitat preferences are more useful in telling these birds apart. Understanding their ranges is also helpful – northern waterthrushes breed further north and winter from Mexico to South America, while Louisianas breed in eastern US forests and winter in Central America. With close inspection and awareness of these key differences, birders can confidently identify northern and Louisiana waterthrushes.