Animal Diversity Web

Diversity

Broadbills are placed in the order Passeriformes, suborder Eurylaimi and family Eurylaimidae. There are four subfamilies of broadbills: Smithornithinae (typical African broadbills), Calyptomeninae (Asian green broadbills), Eurylaiminae (assorted Asian broadbills) and Pseudocalyptomeninae (Grauer’s broadbill). There are 9 genera and 14 species of broadbills. They are thought to be closely related to pittas (Pittidae) and asities (Philepittidae).

Broadbills are small to medium sized birds with a big head, a wide bill and often bright coloration (greens, reds, blues, etc.). They are primarily forest birds and live in rainforests of tropical Asia and Africa. Little is known about the mating behavior of this group. Some species are thought to be monogamous, others polygynous and some may be cooperative breeders. During displays, many broadbills make a loud trilling sound with their wings that can be heard up to 60 m away. Most species are gregarious. Some species eat primarily insects while others mainly eat fruit. (Bruce, 2003; ; Dickinson, 2003)

Geographic Range

Broadtails live in the Ethiopian and Oriental regions. They are found mainly in tropical southeast Asia (from the Himalayas, southern China and the Philippines to Indonesia) and Africa. (Bruce, 2003; Campbell and Lack, 1985; ; Sibley and Ahlquist, 1990)

• Biogeographic Regions
• oriental
  • native
• ethiopian
  • native

Habitat

Broadbills are primary and secondary tropical forest species. Many species are found in the forest interior, but some are found in more open areas such as scrub, coastal bush, tree plantations and cultivated areas. They are often found near rivers and streams and live from sea level to 2550 m. (Bruce, 2003; Campbell and Lack, 1985; ; Wells, 1985)

• Habitat Regions
• tropical
• terrestrial

• Terrestrial Biomes
• forest
• rainforest
• scrub forest

• Aquatic Biomes
• rivers and streams

• Other Habitat Features
• agricultural
• riparian

Physical Description

Broadbills are small to medium sized birds; they are 11.5 to 28.5 cm long and weigh 43 to 117 g. They have a large head, a wide, flat, hooked bill, large eyes and a large gape. The structure of the bill depends largely on the species’ diet. Many broadbills have bright coloration (greens, blues, reds and yellows) which actually helps them blend in with the surrounding habitat. Members of Smithornithinae resemble flycatchers and have brown streaky coloration. Members of Calyptomeninae have primarily green plumage with black markings; males have iridescence. They also have loral plumes that extend over their bill making the bill appear smaller. Members of Pseudocalyptomeninae look similar to those in Calyptomeninae but have a longer tail and no loral plumes. The members of Eurylaiminae are variable in their plumage; the wattled broadbills have an eye ring of large blue wattles. Males and females are similar in some species and dimorphic in others. Sometimes males and females have different coloration, but the difference is usually subtle. Where sexual dimorphism exists, females are duller than males. Juveniles look similar to adults but are duller and have shorter wings and tails. (Bruce, 2003; Campbell and Lack, 1985; ; Wells, 1985)

• Other Physical Features
• endothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes alike
• sexes colored or patterned differently
• male more colorful
• ornamentation

Reproduction

Some species of broadbill are thought to be monogamous; others polygynous (with a lek system) and still others may be cooperative breeders. Males of many species perform displays and courtship feeding. Male green broadbills (Calyptomena viridis) have a spinning display; others have displays that involve head bobbing, wing flapping and feather fluffing. Members of Smithorninae have display flights in which their primary wing feathers make a buzzing sound that can be heard from more than 60 meters away. (Bruce, 2003; Campbell and Lack, 1985; ; Lambert and Woodcock, 1996; Wells, 1985)

• Mating System
• monogamous
• polygynous
• cooperative breeder

Generally broadbills prefer to breed in the dry season. However, some may breed year-round. Nests are pear shaped with a side opening and are built hanging from small branches and extend over open areas, often over water. They are from 3 to 30 m above the ground (3 to 10 m on average). This nest placement protects the eggs and young from mammalian and reptilian predators, but makes them vulnerable to strong wind. Nests are made of grass, twigs, leaves, moss and roots, and are lined with green leaves, small roots and grassy fibers. They can have a long dangling tail made of vegetation and are often covered with leaves, moss and other materials; these decorations help camouflage the nest. Nests take from 5 days to 7 weeks to construct. In some species both the males and females help build the nests, in others just the female, and in others there are helpers-at-the-nest. Observations have been made of groups of up to twenty dusky broadbills (Corydon sumatranus) building a single nest. Sometimes nests are built in thorny trees or near wasps and bees that presumably provide some protection to the birds. Broadbills will re-use nests from year to year.

Clutch size ranges from 1 to 8 eggs, but usually only 2 to 3 young are raised per brood. Eggs are 19 to 37 mm by 14 to 25 mm and may range from oval to elongated in shape. They may be glossy to matte, white to pale pink and may or may not have spots. Incubation lasts 17 to 18 days and the chicks fledge in 22 to 23 days. Broadbills are occasionally hosts to parasitic cuckoos (family Cuculidae). (Bruce, 2003; Campbell and Lack, 1985; ; Lambert and Woodcock, 1996; Wells, 1985)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • internal
• oviparous

The roles of the sexes in incubating and raising young are not well known. Incubation lasts 17 to 18 days and the altricial chicks fledge in 22 to 23 days. Adults will feign injury to draw predators away from the nest. Young are fed mainly invertebrates and post-fledgling dependency lasts more than 20 weeks in some species. At least three species are suspected to have helpers-at-the-nest. (Bruce, 2003; Campbell and Lack, 1985; ; Lambert and Woodcock, 1996; Wells, 1985)

• Parental Investment
• altricial
• male parental care
• female parental care

Lifespan/Longevity

Based on banding recaptures, broadbills are estimated to live at least 6 years in the wild. The oldest recorded bird in captivity was 19 years old. (Bruce, 2003; )

Behavior

Broadbills tend to be resident species. However, they commonly make altitudinal movements as seasons change and in dry seasons they may move beyond their normal range in search of food. A few species are nomadic and move around in search of fruiting trees; generally fruit-eating species are more nomadic than insectivores. Broadbills tend to show crepuscular activity patterns.

Although they are frequently found in pairs, broadbills also tend to be quite gregarious and are often found in small feeding flocks. Groups are not normally larger than 25 individuals. Broadbills seem to be territorial during the breeding season and their display flights may serve as both breeding and territorial displays. They may also defend small patches of fruit.

Broadbills often bathe in puddles and streams. (Bruce, 2003; Campbell and Lack, 1985; ; Lambert and Woodcock, 1996; Wells, 1985)

• Key Behaviors
• arboreal
• flies
• glides
• crepuscular
• motile
• nomadic
• sedentary
• solitary
• territorial
• social

Communication and Perception

Broadbills are not known for having melodic or complex songs. They have a variety of calls usually described as whistles, rattles, trills, squeaks or screams. They call most often during the early morning and late afternoon. Calls are used in courtship, as alarm signals and for contact between mates. Broadbills often call more frequently when in groups. Members of the genus Smithornis have stiff outer primary feathers that make a buzzing sound (or wing trill) during display flights. The buzz is often louder than their calls and can be heard from 60 meters away. The wing buzz is used in courtship and territorial defense.

Broadbills also communicate using a variety of mating and territorial displays. Green broadbills (Calyptomena viridis) have a particularly notable spinning display. (Bruce, 2003; Campbell and Lack, 1985; ; Wells, 1985)

• Communication Channels
• visual
• acoustic

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Most broadbills are insectivores. They catch insects while flying, glean them from vegetation or dart out from perches in a manner similar to flycatchers (family Muscicapidae). They are opportunistic feeders, and commonly eat Orthoptera (grasshoppers and relatives), Coleoptera (beetles), Hemiptera (true bugs and relatives), Hymenoptera (wasps, bees and ants) and Isoptera (termites). Less frequently they will also eat Diplopoda (millipedes), Araneae (spiders), snails (Gastropoda), crabs (Decapoda), tree frogs (Anura), lizards (Sauria) and fish (Actinopterygii). Three broadbill species are frugivores and their bill structure reflects the dietary differences. The frugivorous species lack the wide bill of the insectivores, but maintain the wide gape. Because of this modification they are not able to easily manipulate the fruit with their bills and so they are forced to eat relatively soft fruits and/or to swallow the fruit whole. Figs are an important food source for fruit-eating broadbills. Frugivores will often catch insects to feed their young during the breeding season. (Bruce, 2003; Campbell and Lack, 1985; ; Lambert and Woodcock, 1996; Wells, 1985)

• Primary Diet
• carnivore
  • insectivore
• herbivore
  • frugivore

Predation

Nests are built hanging from small branches and extend over open areas, often over water. This is thought to be an adaptation to deter mammalian and reptilian predators. Sometimes nests are also built in thorny trees or near wasps and bees that presumably provide some protection to the birds. Adults will feign injury to draw predators away from their nest. (Bruce, 2003; )

• Known Predators

  • mammals (Mammalia)
  • reptiles (Reptilia)

Ecosystem Roles

Broadbills play an important part in controlling invertebrate populations throughout their range. They also aid in seed dispersal. Broadbills are also hosts to parasitic cuckoos (family Cuculidae). (Bruce, 2003; )

• Ecosystem Impact
• disperses seeds

Economic Importance for Humans: Positive

Broadbills disperse seeds of plants that are eaten by humans. Broadbills themselves are also eaten by humans. Because of their colorful appearance, they are sometimes sold in the pet trade and are sought out in the wild by tourists. They also play an important part in controlling invertebrate populations throughout their range. (Bruce, 2003; )

• Positive Impacts
• pet trade
• food
• ecotourism
• controls pest population

Economic Importance for Humans: Negative

There are no known adverse affects of broadbills on humans.

Conservation Status

Broadbills live in lowland rainforest that is rapidly disappearing. The loss of habitat due to increases in agriculture combined with their poor ability to adapt to disturbance leaves broadbills in a vulnerable position. The IUCN lists three species of broadbill as vulnerable (visayan broadbill (Eurylaimus samarensis), wattled broadbill (Sarcophanops steerii) and Grauer’s broadbill (Pseudocalyptomena graueri)) and three as near threatened (Hose’s broadbill (Calyptomena hosii), green broadbill (Calyptomena viridis) and black-and-yellow broadbill (Eurylaimus ochromalus)). (Campbell and Lack, 1985; IUCN, 2002; Lambert and Woodcock, 1996)

• IUCN Red List [Link]

  Not Evaluated

Contributors

Alaine Camfield (author), Animal Diversity Web.

Kari Kirschbaum (editor), Animal Diversity Web.

References

Bruce, M. 2003. Family Eurylaimidae. J del Hoyo, A Elliott, D Christie, eds. Handbook of the Birds of the World, Vol. 8. Barcelona: Lynx Edicions.

Campbell, B., E. Lack. 1985. A Dictionary of Birds. Vermillion: Buteo Books.

Dickinson, E. 2003. The Howard and Moore Complete Checklist of Birds of the World, 3rd edition. London: Christopher Helm.

Gill, F. 1995. Ornithology, Second Edition. New York: W.H. Freeman and Company.

IUCN, 2002. "The IUCN Red List of Threatened Species" (On-line). Accessed September 19, 2003 at http://www.redlist.org/.

Lambert, F., M. Woodcock. 1996. Pittas, Broadbills and Asities. Sussex: Pica Press.

Payne, R. 2003. "Bird Families of the World" (On-line). Accessed September 19, 2003 at http://www.ummz.lsa.umich.edu/birds/Bird_Families_of_the_World.html.

Sibley, C., J. Ahlquist. 1990. Phylogeny and Classification of Birds, A study in Molecular Evolution. New Haven: Yale University Press.

Wells, D. 1985. Broadbills. Pp. 306-307 in C Perrins, A Middleton, eds. The Encyclopedia of Birds. New York: Facts on File Publications.