Pectoral sparrow

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Pectoral sparrow
Arremon taciturnus Pectoral Sparrow (male); Rio Formoso, Pernambuco, Brazil.jpg
Male pectoral sparrow in Rio Formoso, Pernambuco, Brazil
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Passerellidae
Genus: Arremon
Species:
A. taciturnus
Binomial name
Arremon taciturnus
(Hermann, 1783)
Arremon taciturnus map.svg
Synonyms
  • Tanagra taciturna Hermann, 1783

The pectoral sparrow (Arremon taciturnus) is a small species of bird in the family Passerellidae, first described in 1779. It is found in Bolivia, Brazil, Colombia, French Guiana, Guyana, Peru, Suriname, and Venezuela. Its natural habitat is subtropical or tropical moist lowland forests.

Contents

Taxonomy

The pectoral sparrow was described in 1779 by French polymath Georges-Louis Leclerc, Comte de Buffon in his Histoire Naturelle des Oiseaux under the French name "L'Oiseau Silencieux". [2] [3] It was also illustrated in a hand-colored plate that was produced to accompany Buffon's book. [4] Buffon did not use binomial names but in 1783 the French naturalist Johann Hermann coined the name Tanagra taciturna. [5] The specific epithet taciturnus is the Latin word for "silent" or "quiet". [6] The species is now placed in the genus Arremon that was erected by the French ornithologist Louis Pierre Vieillot in 1816 with the pectoral sparrow as the type species. [7] [8]

Two subspecies are recognized: [8]

The yellow-mandibled sparrow (Arremon axillaris) was formerly considered as a subspecies. [8]

Description

The pectoral sparrow is sexually dimorphic, and, as the name implies, sparrow-sized, at 15 cm (5.9 in) in length and 24 g (0.85 oz) in weight. [10] [11] Its upperparts are pale green, becoming yellow near the bend of the wing. The head is black, with white on its throat and as stripes on its crown. Its underparts are white or creamy, with males also having a broad black band going across their breast. The beak is also black, roughly 14–15 mm (0.55–0.59 in) long for both males and females. Tails are 58–60 and 64–67 mm (2.3–2.4 and 2.5–2.6 in) and wings are 74–75 and 76–80 mm (2.9–3.0 and 3.0–3.1 in) for males and females respectively. Its iris is brown, and its tarsi and toes are pinkish gray. [9] [10]

Male and female plumage is distinctly different, with females having dull olive upperparts instead of bright yellow, a grayish pectoral band, and greyer, darker underparts. [9]

The pectoral sparrow is fairly unique in its habitat, as a result, it is usually the only small forest sparrow with a striped head in its range. They can be differentiated from the orange-billed sparrow, which they border distribution with in eastern Columbia, by the namesake orange bill, as well its inverted throat colors (black throat with a white stripe). [9]

Distribution and habitat

Pectoral sparrows can be found everywhere in the Amazon Basin east of the Andes except for the western parts between the Negro and Purus rivers. [12] Besides the Amazon jungle, it is found in eastern and north-eastern Brazil. [13] They occupy altitudes up to 1,500 m (4,900 ft) in southern Venezuela, 1,000 m (3,300 ft) in southeastern Peru, and 1,300 m (4,300 ft) in Bolivia. [9] They do not migrate. [9] They occupy the lowland undergrowths of humid evergreen forests or secondary forests, and infrequently in lighter woodlands or coffee plantations, often when near humid wooded ravines. [9]

Behavior

The pectoral sparrow is socially monogamous, however much of its breeding behavior is not well studied. [9]

Breeding

Nests are spherical, bulky, and roofed, with an entrance on the side, around 12.1 cm × 13.2 cm × 12.4 cm (4.8 in × 5.2 in × 4.9 in) in length, width and height respectively, and 48 g (1.7 oz) in weight. They consists of 2 layers — the outer layer, which is composed of dried bamboo, leaves, roots, and twigs, totaling around 35 ± 25 g (1.23 ± 0.88 oz) in weight. The inner layer is much lighter, at 12.9 ± 3.2 g (0.46 ± 0.11 oz), and is composed of leaves(20%) and pale brown rootlets(80%). [9] [14] Eggs are on average 23.6 mm × 17.4 mm (0.93 in × 0.69 in) in length and width and weighing 3.5 g (0.12 oz). All nests studied had 2 eggs per clutch. Egg markings are highly variable; some were completely white, others speckled with varying amounts of brown spots. [14]

Incubation is thought to take 15–17 days, with the female observed acting as the sole incubator. Incubation was done in periods, averaging 71 minutes (ranging from 8 to 323 minutes). Females averaged 7.4 trips outside the nests per day, each averaging 46 minutes, however trips increased in frequency as the eggs neared hatching, going from 61% of daylight spent incubating during days 4–10 to only 55% during days 11-15. Fecal sacs were solely removed by males. [14]

The phenology of the pectoral sparrow is unknown, however a 2011 study by Valdez-Juarez et al. found recently laid eggs across the entire period of the study, from late August to early December. [14] [9] Additionally, out of the 15 nests studied, only 2 eventually hatched, the remaining having been abandoned or predated upon. [14]

Feeding

Feeding behavior is not well studied. [9] They have been observed mainly eating insects and seeds, and to a lesser extent various fruits. Studies on stomach contents in Brazil and Suriname showed various beetles, true bugs and ants, along with other insects and a small amount of grass and seeds. Adults have been observed bringing insect limbs to the nest for feeding. [9] [14]

Conservation

According to BirdLife International, the pectoral sparrow is a least-concern species due to its large range of 9,910,000 km2 (3,830,000 sq mi) and large population size not meeting the criteria for vulnerable. The population size is declining at an estimated rate of 5–9% over the 2016–2026 period. [15]

References

  1. ↑ BirdLife International (2016). "Arremon taciturnus". IUCN Red List of Threatened Species . 2016 e.T103771491A94709610. doi: 10.2305/IUCN.UK.2016-3.RLTS.T103771491A94709610.en . Retrieved 17 November 2021.
  2. ↑ Buffon, Georges-Louis Leclerc de (1780). "L'Oiseau Silencieux". Histoire Naturelle des Oiseaux (in French). Vol. 7. Paris: De l'Imprimerie Royale. pp. 429–430.
  3. ↑ Paynter, Raymond A. Jr, ed. (1970). Check-List of Birds of the World. Vol. 13. Cambridge, Massachusetts: Museum of Comparative Zoology. p. 182.
  4. ↑ Buffon, Georges-Louis Leclerc de; Martinet, François-Nicolas; Daubenton, Edme-Louis; Daubenton, Louis-Jean-Marie (1765–1783). "Tangara, de la Guiane". Planches Enluminées D'Histoire Naturelle. Vol. 8. Paris: De L'Imprimerie Royale. Plate 742.
  5. ↑ Hermann, Johann (1783). Tabula affinitatum animalium olim academico specimine edita, nunc uberiore commentario illustrata cum annotationibus ad historiam naturalem animalium augendam facientibus. Argentorati [Strasbourg]: Impensis Joh. Georgii Treuttel. p. 214, note.
  6. ↑ Jobling, James A. (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. p. 377. ISBN   978-1-4081-2501-4.
  7. ↑ Vieillot, Louis Pierre (1816). Analyse d'une Nouvelle Ornithologie Élémentaire (in French). Paris: Deterville/self. p. 32.
  8. 1 2 3 Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (February 2025). "New World Sparrows, Bush Tanagers". IOC World Bird List Version 15.1. International Ornithologists' Union. Retrieved 21 March 2025.
  9. 1 2 3 4 5 6 7 8 9 10 11 12 13 Valdez-Juárez, Simón Octavio; Schulenberg, Thomas S.; Jaramillo, Alvaro; Billerman, Shawn M.; Kirwan, Guy M.; Boesman, Peter F. D. (2025). "Pectoral Sparrow (Arremon taciturnus), version 2.0". Birds of the World. doi:10.2173/bow.pecspa3.02. ISSN   2771-3105.
  10. 1 2 Willard, D. E.; Foster, M. S.; Barrowclough, G. F.; Dickerman, R. W.; Cannell, P. F.; Coats, S. L.; Cracraft, J. L.; O’Neill, J. P. (1991). "The birds of Cerro de la Neblina, Territorio Federal Amazonas, Venezuela". Fieldiana Zoology.
  11. ↑ Ridgely, Robert S.; Tudor, Guy; Brown, William L. (1989). The birds of South America. World Wildlife Fund (U.S.) (1st ed.). Austin: University of Texas Press. ISBN   978-0-292-70756-6.
  12. ↑ Buainain, Nelson; de Assis, Claydson P.; Raposo, Marcos A. (2017-07-01). "Geographic variation and taxonomy of the Arremon taciturnus (Hermann, 1783) species complex (Aves: Passerellidae)". Journal of Ornithology. 158 (3): 631–650. doi:10.1007/s10336-016-1421-8. ISSN   2193-7206.
  13. ↑ Brazilian name and distribution
  14. 1 2 3 4 5 6 Valdez-Juarez, Simon O.; Londoño, Gustavo A. (2011). "Nesting of the Pectoral Sparrow ( Arremon taciturnus ) in Southeastern Peru". The Wilson Journal of Ornithology. 123 (4): 808–813. doi:10.1676/11-010.1. ISSN   1559-4491.
  15. ↑ "Pectoral Sparrow Taciturnus Species Factsheet". BirdLife DataZone. Retrieved 2026-01-26.
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