Quick Answer
Hume’s warbler and yellow browed warbler are two species of small songbirds found in Asia. The main differences between them are:
- Range – Hume’s warblers are found in central and northern India, Nepal and southern China, while yellow browed warblers are found in Russia and northeast Asia.
- Size – Hume’s warblers are slightly larger than yellow browed warblers.
- Plumage – Hume’s warblers are overall grayish-brown with a white undertail and throat. Yellow browed warblers have olive upperparts, bright yellow superciliums (eyebrows), and yellow undertails.
- Habitat – Hume’s warblers prefer drier foothill forests while yellow browed warblers live in dense understory vegetation.
- Diet – Both eat insects but Hume’s warblers take more fruit.
- Songs – Hume’s warblers have a buzzing trill song, yellow browed warblers have a descending whistled song.
Distinguishing Physical Features
Hume’s and yellow browed warblers can be distinguished from each other by careful examination of their size, plumage, and structural features:
Size
- Hume’s warblers are slightly larger with a length of 4.7-5.3 inches (12-13.5 cm) compared to yellow browed warblers which are 4.3-4.7 inches (11-12 cm) long.
- Hume’s warblers weigh 7-10 grams while yellow browed warblers weigh 5-7 grams.
- The wingspans are similar with Hume’s at 7.5-8.2 inches (19-21 cm) and yellow browed at 7.1-7.9 inches (18-20 cm).
Plumage
- Hume’s warblers are overall grayish brown on the upperparts and whitish on the underparts with some buff or rufous on the flanks.
- They have a distinct white throat and undertail coverts.
- Yellow browed warblers have olive-green upperparts and bright yellow superciliums (“eyebrows”), throat, breast and undertail coverts.
- Their bellies are white or pale yellow.
Structural Features
- Both species have thin pointed bills good for catching insects.
- Yellow browed warblers tend to have longer primary projection beyond the tertials.
- Hume’s have relatively shorter tails compared to yellow browed.
- Leg color differs with yellowish on Hume’s and pinkish-brown on yellow browed warblers.
Geographic Ranges
Hume’s and yellow browed warblers occupy distinct breeding and wintering ranges in Asia:
Hume’s Warbler Range
- Breed in the western Himalayas from northern Pakistan to central Nepal.
- Breed in hills of central India south to northern Maharashtra.
- Winter in northeast India, Bangladesh and Myanmar.
- Vagrants may reach southeast China and northern Thailand.
Yellow Browed Warbler Range
- Breed across northern Asia from western Russia to Korea and Japan.
- Migration route concentrates along the east Asian coast.
- Winter from southeast China through Philippines and Indonesia to New Guinea.
Overlap Zone
- The ranges may overlap in a narrow zone in northeast India, northern Myanmar and southern China where identification must be very careful.
- No overlap in the core breeding or wintering ranges.
Habitat Preferences
The two species occupy different breeding habitat niches:
Hume’s Warbler Habitat
- Foothill forests of oak, rhododendron and pine from 1,200-3,000 m elevation.
- Also in groves along streams and open woodland.
- Prefers relatively drier habitats than yellow browed warblers.
Yellow Browed Warbler Habitat
- Dense understory in coniferous or mixed forests up to 2,100 m elevation.
- Also found in plantations and secondary growth with thick bushes.
- Prefers damp habitats near streams and in wetter soils.
Diet and Feeding Behavior
As small insectivorous birds, Hume’s and yellow browed warblers have broadly similar diets and foraging behaviors but some key differences:
Hume’s Warbler Diet
- Feeds mostly on insects including beetles, moths, ants, bees, bugs and flies.
- Also takes fruit and berries more readily than yellow browed warblers.
- Gleans prey from leaves and branches in understory and middle levels.
- Less likely to feed actively on the ground.
Yellow Browed Warbler Diet
- Feeds almost exclusively on insects including beetles, moths, flies, aphids.
- Rarely eats fruit or berries.
- Gleans insects from leaves but also hawks flies and gnats.
- Frequently feeds on or near the ground.
| Diet Comparison | Hume’s Warbler | Yellow Browed Warbler |
|---|---|---|
| Insects | Primary food source | Primary food source |
| Fruit | Regular part of diet | Rarely eaten |
| Foraging Height | Understory and middle levels | All levels from ground to canopy |
Breeding and Nesting
The breeding biology and nesting habits of Hume’s and yellow browed warblers show some similarities but also key differences:
Hume’s Warbler Breeding
- Breeding season May to July.
- Open cup nest in low bush or on ground concealed by vegetation.
- Nest built with grasses and lined with hair and feathers.
- Clutch of 3-5 eggs.
- Incubated by female for 14-15 days.
- Young fledge in about 14 days.
Yellow Browed Warbler Breeding
- Breeding season June to August.
- Open cup nest 1-4m high in conifer tree or dense bush.
- Nest made of twigs, bark, grass, moss.
- Lays 3-6 eggs.
- Incubation period unreported but likely similar 12-14 days.
- Fledging period unreported but likely about 2 weeks.
| Breeding Comparison | Hume’s Warbler | Yellow Browed Warbler |
|---|---|---|
| Nest Site | On ground or low bush | In tree or bush 1-4m up |
| Clutch Size | 3-5 eggs | 3-6 eggs |
| Incubation | 14-15 days | 12-14 days (estimated) |
| Fledging | About 14 days | About 14 days (estimated) |
Vocalizations
The songs and calls of Hume’s and yellow browed warblers are distinctive:
Hume’s Warbler Vocalizations
- Song is a buzzing trill, “zrrrr”, 1-2 seconds long.
- Call is a thin “seep” sounded during foraging.
- Alarm call is a raspy “tek”.
Yellow Browed Warbler Vocalizations
- Song is a series of whistled notes descending in pitch.
- Call is a rattling trill, “drrrrt”.
- Alarm call is a sharp “tsec”.
Hume’s warbler song. A buzzing trill.
Yellow browed warbler song. A descending whistled series.
Status and Conservation
Both Hume’s and yellow browed warblers have large populations and are categorized as Least Concern:
Hume’s Warbler
- PopulationEstimate: 1-10 million
- Population trend: Decreasing but slowly
- Threats: Habitat loss and degradation
- IUCN status: Least concern
Yellow Browed Warbler
- Population estimate: 10-100 million
- Population trend: Decreasing but slowly
- Threats: Some habitat impacts in parts of range
- IUCN status: Least concern
Conclusion
In summary, Hume’s and yellow browed warblers can be distinguished by their different geographic breeding ranges, habitat preferences, plumage features, vocalizations, and aspects of their natural history like diet and nesting. Hume’s are slightly larger and stockier, with more muted plumage overall. Yellow browed are brighter yellow below with strong superciliums. Both species are currently relatively secure but face some conservation threats from habitat loss. Careful observation is needed to identify them where their ranges overlap.
