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Swynnertonia swynnertoniSwynnerton's robin

By Tanya Dewey

Geographic Range

Swynnerton's robins are known from a few mountain ranges in eastern Zimbabwe, Mozambique, and Tanzania. There are two, sometimes three, recognized subspecies, each occurring on different mountain ranges. Swynnertonia swynnertoni swynnertoni occurs on Chirinda mountain in Zimbabwe and a few smaller mountains bordering Mozambique, including Mt. Gorongosa. Swynnertonia swynnertoni rodgersi occurs in Tanzania in the Udzungwa and East Usambara Mountains. Swynnerton's robins were recently discovered in a pristine forest fragment on Mt. Mabu in Mozambique, documenting their existence in a previously unrecognized portion of their range. (BirdLife International, 2008a; BirdLife International, 2008b; Collar, 2005; Vickers, 2009)

Habitat

Swynnerton's robins are found primarily in tropical montane forests, from 850 to 1800 m elevation, more common at 900 to 1200 m. The population in the East Usambaras Mountains occurs in lowland evergreen forest, from 130 to 550 m elevation. Some populations seem to be associated with a dominant understory plant: Dracaena fragrans. They are typically seen in the forest understory or on the ground, in contrast to Pogonocichla species that co-occur. Swynnerton's robins are generally restricted to forest interiors, typically near streams or seeps. They seem to prefer forests with closed canopies and open understory structure, with plenty of leaf litter on the ground. (BirdLife International, 2008a; Collar, 2005)

  • Range elevation
    130 to 1800 m
    426.51 to 5905.51 ft

Physical Description

Swynnerton's robins are 12 to 13 cm in length, with blue-grey plumage dorsally and a bright orange breast. The orange plumage of the breast becomes lighter on the belly, becoming a buffy yellow and then white at the vent. The head and chin are grey and there is a small white bib bordered by a black line that separates it from the orange of the breast. They have long legs and feet with grayish flesh-colored skin. The feathers on the wing have an olive-green cast to them. The bill is black and there is a light, indistinct white circle around the eyes which is more prominent above the eye. Swynnerton's robins look much like New World robins (Turdus) in overall appearance and habits, they are generally seen foraging on the ground. They hold their tail at a characteristic 45 degree angle. Females are similar to males, but with more olive on the head and lighter cheeks. Juveniles are brown with yellow spotting above and with a lighter orange breast and belly. Subspecies vary somewhat in coloration. (BirdLife International, 2008b; Collar, 2005)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • Range length
    12 to 13 cm
    4.72 to 5.12 in

Reproduction

There is no information on the mating system of Swynnerton's robins. They are generally observed in pairs, so may be monogamous. (BirdLife International, 2008b)

Swynnerton's robins breed from October to January, with generally two clutches each breeding season. Breeding peaks from November to December. Nests are constructed over the course of 7 to 10 days. Nests are cup-shaped, with a wide rim, and constructed of various plant materials and lined with finer fibers. Nests are typically placed 0.3 to 2 meters above ground, often in Dracaena fragrans axils or at the base of a branch. Eggs are shiny and blue-green with brown spots and blotches. Females lay 2, sometimes 3 eggs and begin to incubate with the first egg. Incubation is complete at 15 to 16 days and young fledge within 14 days after hatching. (BirdLife International, 2008a; Collar, 2005)

  • Breeding interval
    Swynnerton's robins lay two clutches each year in the breeding season.
  • Breeding season
    Swynnerton's robins breed from October to January.
  • Range time to hatching
    15 to 16 days
  • Average fledging age
    14 days

Like most Passeriformes, Swynnerton's robins young are likely to hatch in an altricial state and require significant parental investment to survive to fledging. However, there is no specific information on parental care available in the literature.

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female

Lifespan/Longevity

Longevity of Swynnerton's robins in the wild or captivity is not known.

Behavior

Swynnerton's robins are active during the day. They do not migrate. There are no reports that indicate how territorial or social these birds are outside of the breeding season. They are common within suitable forest fragments. (Collar, 2005)

Home Range

Home range sizes are not reported in the literature. Population densities of 75 individuals per square kilometer are reported from secondary forest. In primary forest 4 to 6 pairs per hectare have been reported. (Collar, 2005)

Communication and Perception

Swynnerton's robins use several vocalizations: a "loud song," "warbling song," and several alarm calls. Songs vary slightly across their range. The loud song is characterized as a sweet, whistling phrase: "cha-chii-roo" or "tee ter-wer choo." The warbling song is a soft and musical whistle and is generally heard near ant swarms. When alarmed, these robins use a descending trill call that ends in several raspy squeaks, "trrrrr-wii-twaw-twiii," or a short "siiip." (Collar, 2005)

Food Habits

Swynnerton's robins eat mainly insects. They hunt for insects on the forest floor by tossing aside leaf litter and opportunistically taking what they find. They also accompany army ant swarms and take the insects that are fleeing. Insect prey are diverse, including beetles, ants, wasps, moths, caterpillars, bugs, spiders, flies, and others. They have also been recorded eating small forest frogs (Arthroleptis xenodactyloides) and some fruits. (Collar, 2005)

  • Animal Foods
  • amphibians
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • fruit

Predation

Predation on Swynnerton's robins is not reported in the literature. It is likely that eggs and nestlings are preyed on by small, terrestrial carnivores and snakes and that adults may be taken by small birds of prey or owls.

Ecosystem Roles

Swynnerton's robin nests are sometimes parasitized by red-chested cuckoos (Cuculus solitarius).

Commensal/Parasitic Species

Economic Importance for Humans: Positive

Swynnerton's robins are restricted to native forest fragments and may act as indicators of habitat quality. Because of their rarity, they may attract ecotourism interest.

Economic Importance for Humans: Negative

There are no known adverse effects of Swynnerton's robins on humans.

Conservation Status

Swynnerton's robins have a small range that is highly fragmented and populations are declining. Throughout most of their range they are threatened by forest destruction and degradation resulting from resource extraction. In the East Usambaras it is possible that adventure tourism is threatening local populations and in Zimbabwe forest degradation is resulting from the spread of a non-native ginger, Hedychium. Some populations are found primarily in protected areas, although enforcement of forest protection may be incomplete in some areas. The global population is estimated at from 2500 to 9999 individuals. (BirdLife International, 2008a)

Other Comments

These birds are also known as Swynnerton's forest robins. They are sometimes placed in the genus Pogonocichla. (BirdLife International, 2008a; Collar, 2005)

Contributors

Tanya Dewey (author), Animal Diversity Web.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

References

Beresford, P. 2003. Molecular systematics of Alethe, Sheppardia and some other African robins (Muscicapoidea). Ostrich, 74: 58-73.

Biodiversity Explorer, 2008. "Swynnertonia swynnertoni (Swynnerton's robin)" (On-line). Biodiversity explorer: the web of life in Southern Africa. Accessed February 10, 2009 at http://www.biodiversityexplorer.org/birds/muscicapidae/swynnertonia_swynnertoni.htm.

BirdLife International, 2008. "Species factsheet: Swynnertonia swynnertoni" (On-line). BirdLife International. Accessed February 18, 2009 at http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=6577&m=0.

BirdLife International, 2008. "Swynnertonia swynnertoni" (On-line). IUCN Redlist of Endangered Species. Accessed February 06, 2009 at http://www.iucnredlist.org/details/147426.

Collar, N. 2005. Family Turdidae (Thrushes). Pp. 514-807 in J del Hoyo, A Elliott, D Christie, eds. Handbook of the Birds of the World, Vol. 10. Barcelona: Lynx Edicions.

Seddon, N., J. Ekstrom, D. Capper, I. Isherwood, R. Muna, R. Pople, E. Tarimo, J. Timothy. 1999. The importance of the Nilo and Nguu North Forest Reserves for the conservation of montane forest birds in Tanzania. Biological Conservation, 87: 59-72.

Vickers, H. 2009. "Google earth reveals hidden oasis" (On-line). BirdLife International. Accessed February 06, 2009 at http://www.birdlife.org/news/news/2009/01/mount_mabu.html.

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