Cone-billed tanager (Conothraupis mesoleuca): Rediscovered rarity at risk

The cone-billed tanager (Conothraupis mesoleuca) is a rare and elusive bird species endemic to Brazil. First described in 1939, it remained undetected for 65 years before its rediscovery in 2003 in Emas National Park, Goiás. Additional populations have since been identified, but its distribution remains highly fragmented. Due to habitat destruction and limited known populations, it is classified as endangered.

male cone-billed tanager (Conothraupis mesoleuca)
Male cone-billed tanager | Photo by Rodrigo Conte
Common nameCone-billed tanager
Scientific nameConothraupis mesoleuca
OrderPasseriformes
FamilyThraupidae
GenusConothraupis
IdentificationMale: black with white underparts, bluish-grey bill; female: olive-brown, darker bill
RangeCentral Brazil (Goiás, Mato Grosso, Pará); three disjunct populations
MigrationNon-migratory
HabitatGallery forests, flooded areas, riparian zones
DietInsects, seeds (bamboo, exotic grasses)
Conservation statusEndangered

Discovery

The cone-billed tanager was first discovered on August 25, 1938, by Dr. Alphonse Vellard in the Alto Rio Juruena region of Mato Grosso, Brazil. The only known specimen, an adult male, was preserved in the Paris Museum. In 1939, Jean Berlioz formally described the species in the Bulletin of Ornithology, initially placing it in a newly proposed genus Rhynchothraupis, citing its stout, icterine-shaped bill as unusual for a tanager. Due to the lack of additional specimens or observations, the species’ systematic position remained uncertain, and its status in the wild became a mystery.

For 65 years, no additional records were documented, leading to speculation that the species might be extinct. However, in 2003, it was rediscovered in Emas National Park, Goiás, in a gallery forest habitat. The following year, B. A. Carlos independently confirmed its presence at the same location, verifying that the species persisted in the wild. In 2006, a second population of approximately 100 individuals was discovered along the Alto Rio Juruena in Mato Grosso, about 900 km from the Emas National Park site. This discovery significantly expanded the known range of the species and provided new opportunities for study.

Identification

The cone-billed tanager is a medium-sized passerine, measuring approximately 14 centimeters (5.5 inches) in length. The male is distinguished by its deep black plumage, with a contrasting white patch on the middle of the breast and belly. The vent, thighs, and undertail coverts are mixed black and white. It has a short, rounded tail and a thick, conical, bluish-grey bill.

female cone-billed tanager
Female cone-billed tanager | Photo by E. Santos

The female, first described in 2006, has dark greyish-brown upperparts, lighter auriculars, a brown throat, dark brown breast and flanks, and a light yellowish-brown belly. The bill and tarsi are dark brown. Juveniles have not been extensively documented, but their appearance is presumed to be similar to adult females.

Vocalization

The vocalizations of the cone-billed tanager are now better documented following recent field studies. Males produce a loud, structured song, often responding aggressively to playback, which suggests strong territorial behavior. The typical vocalization pattern starts with a series of low notes, followed by a trill, described as: “Tche, tche, tche, tche, tche, tcherrrrrrrrrrrr, tcherrrrrrrrr, tiiiiiiiiiiiiiiiiiiiiiiiiii.”

The species is most vocal during the early morning hours, with males singing from elevated perches within riparian forests. Unlike males, females are significantly less responsive to playback, indicating potential differences in communication behavior between sexes. Further studies are needed to analyze the function of these vocalizations in courtship and territory defense.

Range and habitat

The cone-billed tanager is currently known from three isolated populations in the Brazilian states of Goiás, Mato Grosso, and Pará. It inhabits gallery forests, seasonally flooded areas, and dry forests along rivers, showing a strong dependence on riparian zones. Field observations confirm that the species is almost always found near water sources, reinforcing its reliance on flooded habitats for survival.

In Mato Grosso, it has been recorded in seasonally flooded forests and grasslands, particularly in the Chapada dos Parecis region, where it is commonly associated with moriche palms (Mauritia flexuosa). Surveys in this area have identified key populations along the upper Juruena River, which appears to be a major stronghold for the species. In Emas National Park, Goiás, it favors gallery forests and appears to require permanently or seasonally flooded environments. The species is also present in the transition zone between the Amazon rainforest and the cerradão (closed-canopy cerrado), where it inhabits bushy vegetation in dry forests.

Due to its strict reliance on water-associated habitats, the cone-billed tanager is particularly vulnerable to deforestation, agricultural expansion, and hydropower developments. The fragmentation of riparian forests, combined with the increasing conversion of land for soy cultivation, has led to significant habitat degradation. The planned hydroelectric projects in the Alto Juruena basin could further reduce its already limited habitat, putting additional pressure on the species’ survival.

Migration

This species is non-migratory but may engage in local movements in response to seasonal changes in water levels.

Behavior

The cone-billed tanager is believed to be territorial, with males displaying strong responses to playback, suggesting that song plays a role in territory defense. It is most vocal during the early morning hours, often singing from elevated perches within riparian forests. Unlike males, females are significantly less responsive to playback, which may indicate differences in behavior between sexes. Individuals are typically observed singly or in pairs, reinforcing the possibility of monogamous behavior.

Conothraupis mesoleuca in its habitat
Conothraupis mesoleuca in its habitat | Photo by Sylvia Wright

The species primarily forages by sallying from perches to catch insects mid-air, a strategy frequently used near water sources. Males have been observed returning to the same perch after capturing prey, suggesting site fidelity in foraging behavior. It is active at various heights, foraging both in the understory and upper canopy, demonstrating a degree of feeding flexibility. The species’ strong association with riparian and seasonally flooded habitats further emphasizes its reliance on these environments for both foraging and territorial activities.

Breeding

Very little is known about the breeding ecology of the cone-billed tanager. Courtship behavior, nesting sites, and clutch size remain undocumented due to the rarity of observations. No confirmed nests have been recorded, making it unclear whether the species prefers trees, shrubs, or riverbanks for nesting. Given its strong association with riparian habitats, it is likely that breeding is influenced by seasonal changes in water levels and habitat availability. Further research is needed to determine the breeding season, incubation period, and parental care strategies.

Diet

The cone-billed tanager is primarily insectivorous but also consumes seeds, including those from bamboo and exotic grasses (Brachiaria species). It uses rapid sallies to catch small flying insects, particularly in the upper Rio Juruena region of Mato Grosso. The species forages at both low vegetation and canopy levels, showing flexibility in food acquisition. Its reliance on insects and seeds suggests that seasonal fluctuations in food availability could influence its movements and population dynamics.

Conservation

The cone-billed tanager is currently classified as endangered by the International Union for Conservation of Nature (IUCN), with an estimated population of 250 to 999 mature individuals. Once thought to be extinct for over 60 years, the species was rediscovered in 2003 in the Cerrado biome of Brazil. However, its population remains highly fragmented and continues to decline due to habitat loss.

The species is heavily dependent on gallery forests and seasonally flooded areas, particularly along the upper Juruena River and within Emas National Park. Its habitat is increasingly threatened by deforestation for agriculture, particularly soybean cultivation, which has led to significant reductions in available forest cover. The expansion of farmland has not only reduced suitable habitat but has also contributed to fragmentation, isolating remaining populations.

Another major threat is the construction of hydroelectric projects in the Alto Juruena basin, which could result in the flooding of critical habitats, potentially affecting a significant portion of the remaining population. The species’ reliance on riparian forests means that any modifications to water systems, whether through dams, land conversion, or increased mechanized farming, can have a severe impact on its survival.

Conservation efforts

The cone-billed tanager benefits from some level of protection within Emas National Park, but enforcement is inconsistent, and private lands surrounding the park remain largely unregulated. Expanding protected areas and improving habitat management strategies are key to preventing further population declines.

Conservation organizations have emphasized the need for detailed population surveys to identify additional locations where the species may persist and to assess habitat connectivity. Collaboration with private landowners is also essential, as much of the Cerrado biome is under agricultural use. Encouraging sustainable land management practices that preserve riparian forest corridors could mitigate habitat destruction. Further legal protections against deforestation and hydroelectric expansion in sensitive areas are also necessary to ensure the long-term survival of this species.

Although rediscovered in the 21st century, the cone-billed tanager remains one of the rarest birds still found in the wild, and without urgent conservation action, its future remains uncertain.

Similar species

The black-and-white tanager (Conothraupis speculigera) is the only other member of the genus Conothraupis and the closest known relative of the cone-billed tanager. While both species share a black-and-white plumage pattern, they differ in range, habitat, and certain morphological features. The black-and-white tanager is found in southwestern Ecuador and northwestern Peru, primarily in scrub, woodland, and forest borders at elevations ranging from 100 to 1,800 meters. In contrast, the cone-billed tanager is restricted to lowland gallery forests and seasonally flooded areas in central Brazil.

male black-and-white tanager (Conothraupis speculigera)
Male black-and-white tanager | Photo by Nick Athanas

In addition to habitat differences, the black-and-white tanager has a longer bill, a white wing-speculum, and lacks the distinctively stout, bluish-grey bill of the cone-billed tanager. The female black-and-white tanager is also olive-colored with faint yellowish underparts, whereas the female cone-billed tanager is uniformly brownish-grey. Behaviorally, the black-and-white tanager is known to form small flocks at times, while the cone-billed tanager is mostly observed alone or in pairs. Despite their shared taxonomy, the two species occupy very different ecological niches and are unlikely to overlap in the wild.

Future outlook

At Planet of Birds, we have been closely following the cone-billed tanager’s rediscovery and conservation efforts since it was first sighted again in 2003. Given its status as one of the world’s rarest birds, the need for continued research and protective measures remains urgent.

Members of our team in Brazil are actively engaged in monitoring developments related to the species and are likely to participate in future conservation projects aimed at preserving its fragile habitat. As new surveys are conducted and additional data emerges, we will continue to update our findings and contribute to the global effort to safeguard this enigmatic bird.

For those interested in supporting or learning more about conservation initiatives for the cone-billed tanager, we encourage collaboration with local organizations, researchers, and habitat preservation programs in the Cerrado and Alto Juruena regions. Protecting this species requires a concerted effort, and every contribution helps secure its future in the wild.

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Updated: February 13, 2025 — 7:39 am

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