Yellow-sided Warbler

 

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For more information about native warblers, see this post.

Yellow-sided Warbler, Setophaga solilateralis L 13-15 cm, WS 19-23 cm, Family: Parulidae

 

IUCN Conservation Status: Least concern (LC)

 

Description:    

Small, active songbird, large for a warbler, with large head and sturdy bill. Upperparts steely gray with a streaked back, black cheeks, a white eyering, two white wingbars and white spotting in wings and tail. Throat and lores yellow, with yellow flanks and white belly. Large, triangular breast spot and streaking along flanks. Non-breeding plumage brownish and duller, and females similar but duller overall, lacking the breast spot, streaking, and their throat and flanks are pale to white.

Voice:

Song is a series of slow, clear whistles rising and falling in pitch like waves, usually lasting around 3 seconds. The rising, falling, and rising again pattern and steady rhythm are distinct among native warblers. Eastern populations tend to sing shorter songs. A variety of calls include a common, diagnostic chek and softer chips and seets.

Range and Habitat:    

During breeding, can be found across Novasola, including Kosatka and the Francis Islands. In winter, many birds migrate to Oregon and California, but many others remain on Novasola year-round and spend the winters at low elevations along the island’s southern coasts and the Twin River Basin. Breeding habitat consists of mature forest ecosystems, especially conifer or mixed conifer-deciduous forests with Coopers-fir, spruce, hemlocks, firs, cedars, pines, redwoods, alder and willow, but they may also be found in lower numbers in deciduous forests, especially of maple. Can be found at high elevations, up to the tree line, and as low as sea level. During winter they can be found in more varied environments and prefer open habitats with a dense shrub layer like meadows, fields, riparian zones, and orchards or plantations. Common in residential or developed areas.

Discussion:      

Possibly the most common warbler on Novasola, rivaled by the Black-eared Yellow Warbler, the larger Yellow-sided Warbler is a common sight across the island and the only warbler to remain through winter. These bold little birds are quite versatile and may be seen in a wide array of ecosystems and forage using many differing methods. They are still among the easiest native warblers to observe given their numbers and less strict requirements, and their habit of perching on exposed branches. They are common to backyard feeders and the backcountry, coasts and mountain peaks alike.

Variable foragers, Yellow-sided Warblers mainly eat insects and other invertebrates which they pick from foliage like the undersides of leaves, pick from bark, or catch on the wing. They will even feed off the ground. Their preferred food sources include caterpillars, flies, gnats, beetles, moths, aphids, and spiders. They also eat many bark beetles and other wood-boring insects which they pick from crevices in the bark or from woodpecker holes. Active foragers, they move quickly from food source to food source, but they spend more time perched still than the Ricci’s Warbler. They may also fly out to catch insects on the wing, called “sallying”. They supplement their diet with fruits, especially in the winter when fruit makes up the bulk of their diet, especially berries. The Yellow-sided Warbler’s winter dependance on fruits is what allows them to remain on Novasola through the winter, and its also why they are commonly seen in developed areas like orchards, plantations, vineyards, and residential backyards.

Yellow-sided Warblers breed across Novasola, and while most birds migrate to the coasts of British Columbia, Washington, and Oregon, and small but significant portion of the population remains on the island year-round and spends the winter at low elevations along in the south, especially around Fairweather and Charlotte sounds and the Twin River Basin. Males usually arrive at their breeding territories in late April and leave in September. Males sing to defend territories from neighbors and to attract mates. It is common to hear multiple neighboring males singing back and forth over one another in a sort of vocal fight called counter-singing. These warblers form monogamous pairs, but often pair with new individuals each breeding season. The female will build the nest while the male brings her materials and food. Most nests are built in conifers on horizontal limbs, but they may occasionally use deciduous trees like maples or oaks. Outside the breeding season they will forage in flocks, including mixed-species flocks, and some autumn flocks can be quite large by warbler standards. The largest recorded Yellow-sided flock had at least 104 individuals.

The Yellow-sided Warbler was originally described in 1865 by Spencer Fullerton Baird based on a specimen he acquired for the Smithsonian Museum from a farmer in Cape George, though the original genus Dendroica was later merged with Setophaga. By 1902 and the NRC expeditions, numerous other specimens have made their way into several collections.  

Though warblers can be difficult to tell apart, especially when they move so quickly through the vegetation, they often give clues to their ID. The Yellow-sided Warbler can best be distinguished by its clear song and call notes, and by its yellow throat and white belly. They are shorter distance migrants than other warblers as well, and many even winter on Novasola, where they become much more visible, often visiting backyard feeders.

“This sharp little bird, smartly dressed in a most vibrant sunburst yellow, is one of the more common warblers and inhabits any of the island’s diverse country, from the cottonwoods of prairie gullies to the heath of mountain tundra, but is especially comfortable in the shelter of mature forests and evergreen woodlands. Hardy and robust, the Yellow Sided Warbler persists in the Fastwaters through the cold months unlike so many of its more seasonal brethren. In April I have observed males in their fresh spring plumage along the Kusasha, and in July I have encountered countless birds in the forests of the upper Chidkayook, outnumbering most other songbirds. More still have I observed in the Georgian foothills, especially in Autumn when the birds abandon their northerly sites and migrate south. The mountains there are then saturated with warblers just as they arrive to reap the berry crop. It is impossible to explore the Georgian region without the company of this warbler, and it is from this area Mr. Baird’s specimen originates, though his was of the less brilliant winter plumage.

…

The song of the Yellow Sided Warbler is one of clear and musical whistles, meandering up and down the scale, speedy but even. It is fairly easy to distinguish and the only warbler’s song which culminates in a rising, questioning pitch. For this reason many of my fellow Corpsmen quickly learned to recognize its sound, such that they would know not to excite me upon hearing it thinking it a new discovery.” – Native Birds of Novasola, 1912