<trp-post-container data-trp-post-id='359730'>Chestnut-backed Tanager

En bref

• Scientific Name: Stilpnia preciosa
• Spanish Name: Tangara dorsicastaña
• Famille : Thraupidae
• Known Nicknames: Chestnut-backed Tangara, Precious Tanager
• Longueur moyenne : 13–14 cm / 5,1–5,5 pouces
• Average Weight: 18–22 g / 0.63–0.78 oz
• Envergure : N/A
• Key Feature: Rich chestnut back contrasting with bright blue head and black mask
• Régime alimentaire principal : Principalement frugivore
• Range: Southeastern Brazil, eastern Paraguay, and northeastern Argentina
• Habitat: Atlantic Forest, montane evergreen forest, and forest edges
• Social Structure: Social, often in mixed-species flocks
• Nesting/Breeding: Cup-shaped nest in tree fork
• Statut de conservation : Préoccupation mineure (LC)
• Évolution démographique : En baisse

The Chestnut-backed Tanager (*Stilpnia preciosa*) is a dazzling jewel of South America’s Atlantic Forest, easily recognized by its striking contrast of a deep, rich chestnut-brown back against a brilliant turquoise-blue head, throat, and underparts. A unique characteristic is the male’s iridescent, almost metallic sheen on its blue plumage, which can flash a vivid violet in certain lights, while females are slightly duller but retain the same bold pattern. Its stout, dark bill is perfectly adapted for plucking small fruits and berries, and it often forages in noisy, mixed-species flocks, adding a flash of color to the canopy. This tanager’s most special feature is its preference for high-altitude, mossy forests, where its vibrant hues stand out against the muted greens, making it a highly sought-after sight for birdwatchers.

Faits amusants

The Chestnut-backed Tanager has a quirky habit of following army ant swarms to snatch up insects and small vertebrates fleeing the chaos, acting like a feathered bodyguard for the ants. It also engages in "anting," where it rubs ants or other acidic creatures onto its feathers to use the formic acid as a natural insecticide and feather conditioner. Males perform a unique "flutter-flight" display during courtship, rapidly beating their wings while hovering in place to show off their vivid chestnut back and blue-black hood.

Habitats et répartition

The Chestnut-backed Tanager is primarily found in the Atlantic Forest region of southeastern Brazil, extending into adjacent parts of northeastern Argentina (Misiones) and eastern Paraguay. Its habitat consists of humid lowland and montane forests, including both primary and mature secondary growth, often near watercourses. It is also known to inhabit forest edges, clearings with tall trees, and selectively logged areas, but generally avoids open and heavily degraded landscapes. The species occurs at elevations ranging from sea level up to about 1,200 meters, with a distribution centered on the coastal mountain ranges from Bahia south to Santa Catarina.

Comportements & Reproduction

The Chestnut-backed Tanager is typically observed in small, loose flocks of up to a dozen individuals, often associating with mixed-species foraging groups. Their social structure appears fluid, with no strong evidence of permanent pair bonds outside the breeding season. Mating is thought to be monogamous during a given reproductive cycle, with courtship involving mutual preening and the male performing a short, fluttering display while singing to the female. The species constructs a cup-shaped nest of plant fibers and moss, usually placed in a tree fork. Females lay a clutch of two to three eggs, and both parents share incubation duties for about two weeks. A notable reproductive strategy is the frequent reuse of old nests or nest materials from previous seasons, which may conserve energy and reduce construction time. After fledging, the young remain dependent on the parents for several weeks before joining juvenile flocks.

Alimentation

The Chestnut-backed Tanager is primarily a frugivore, with fruits, especially small berries and soft pulpy fruits from trees and shrubs, forming the bulk of its diet. It supplements this with a significant amount of arthropods, including insects like beetles, caterpillars, and ants, as well as spiders, which it actively gleans from leaves and branches while foraging in the mid to upper canopy. An interesting aspect of its feeding behavior is its tendency to join mixed-species foraging flocks, allowing it to exploit food sources more efficiently by following other birds to insect flushes or fruiting trees. This tanager also occasionally visits bird feeders offering fruit, and it has been observed consuming nectar from flowers, adding a minor but notable sugar source to its otherwise fruit-and-insect-based menu.

Couleurs

The Chestnut-backed Tanager features a striking chestnut or rich reddish-brown back and wings, contrasting with a pale blue-gray head, throat, and underparts. Its most unique marking is a bold black mask that extends from the bill through the eyes, framed by a narrow white supercilium. The wings and tail show subtle black edging, and there is no camouflaged adaptation, as this vivid coloration is for display in forest canopies.