Bowerbirds () make up the bird
family
Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
Ptilonorhynchidae. They are renowned for their unique courtship behaviour, where males build a structure and decorate it with sticks and brightly coloured objects in an attempt to attract a mate.
The family has 27 species in eight
genera
Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...
. These are medium to large-sized
passerine
A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped') which includes more than half of all bird species. Sometimes known as perching birds, passerines generally have an anisodactyl arrangement of their ...
s, ranging from the
golden bowerbird at and to the
great bowerbird at and . Their diet consists mainly of fruit but may also include insects (especially for nestlings), flowers, nectar and leaves in some species.
[ The satin and spotted bowerbirds] are sometimes considered agricultural pests
PESTS was an anonymous American activist group formed in 1986 to critique racism, tokenism, and exclusion in the art world. PESTS produced newsletters, posters, and other print material highlighting examples of discrimination in gallery represent ...
due to their habit of feeding on introduced fruit and vegetable crops and have occasionally been killed by affected orchardists.
The bowerbirds have an Australo-Papuan distribution, with ten species endemic
Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
to New Guinea
New Guinea (; Hiri Motu: ''Niu Gini''; , fossilized , also known as Papua or historically ) is the List of islands by area, world's second-largest island, with an area of . Located in Melanesia in the southwestern Pacific Ocean, the island is ...
, eight endemic to Australia, and two found in both. Although their distribution is centered on the tropical regions of New Guinea and northern Australia, some species extend into central, western, and southeastern Australia. They occupy a range of different habitats, including rainforest
Rainforests are forests characterized by a closed and continuous tree Canopy (biology), canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropi ...
, eucalyptus
''Eucalyptus'' () is a genus of more than 700 species of flowering plants in the family Myrtaceae. Most species of ''Eucalyptus'' are trees, often Mallee (habit), mallees, and a few are shrubs. Along with several other genera in the tribe Eucalyp ...
and acacia
''Acacia'', commonly known as wattles or acacias, is a genus of about of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa, South America, and Austral ...
forest, and shrublands. While the females are unequivocally drab, in some species the males have bright golden-yellow and sometimes black markings.[
]
One group with particularly inconspicuous plumage in males as well as females, but loud meowing calls, is known as "catbirds". Note that the ptilonorhynchid catbirds, the grey catbird (''Dumetella carolinensis'') and black catbird (''Melanoptila glabrirostris'') from the Americas
The Americas, sometimes collectively called America, are a landmass comprising the totality of North America and South America.''Webster's New World College Dictionary'', 2010 by Wiley Publishing, Inc., Cleveland, Ohio. When viewed as a sing ...
, and the Abyssinian catbird (''Sylvia=Parophasma galinieri'') from Africa, are only related by their common name; they belong to different families.
Behaviour and ecology
The ''Ailuroedus'' catbirds are monogamous, with males raising chicks with their partners, but all other bowerbirds are polygynous, with the female building the nest and raising the young alone. These latter species are commonly dimorphic, with the female being drabber in color. Female bowerbirds build a nest by laying soft materials, such as leaves, ferns, and vine tendrils, on top of a loose foundation of sticks.
All Papuan bowerbirds lay one egg, while Australian species lay one to three with laying intervals of two days.[Higgins, P.J. and J.M. Peter (editors); '' Handbook of Australian, New Zealand and Antarctic Birds, Volume 6: Pardalotes to Shrike-thrushes'' ] Bowerbird eggs are around twice the weight of those of most passerines of similar size – for instance eggs of the satin bowerbird weigh around as against a calculated for a passerine weighing . Eggs hatch after 19 to 24 days, depending on the species and are a plain cream color for catbirds and the tooth-billed bowerbird, but in other species possess brownish wavy lines similar to eggs of Australo-Papuan babblers. In accordance with their lengthy incubation periods, bowerbirds that lay more than one egg have asynchronous hatching, but siblicide
Siblicide (attributed by behavioural ecologist Doug Mock to Barbara M. Braun) is the killing of an infant individual by its close relatives (full or half siblings). It may occur directly between siblings or be mediated by the parents, and is dr ...
has never been observed.
Bowerbirds as a group have the longest life expectancy
Human life expectancy is a statistical measure of the estimate of the average remaining years of life at a given age. The most commonly used measure is ''life expectancy at birth'' (LEB, or in demographic notation ''e''0, where '' ...
of any passerine family with significant banding studies. The two most studied species, the green catbird and satin bowerbird, have life expectancies of around eight to ten years and one satin bowerbird has been known to live for twenty-six years. For comparison, the common raven, the heaviest passerine species with significant banding records, has not been known to live longer than 21 years.
Courtship and mating
The most notable characteristic of bowerbirds is their extraordinarily complex courtship and mating behaviour, where males build a bower to attract mates. There are two main types of bowers. Prionodura, Amblyornis, Scenopoeetes and Archiboldia bowerbirds build so-called maypole bowers, which are constructed by placing sticks around a sapling; in the former two species these bowers have a hut-like roof. Chlamydera, Sericulus and Ptilonorhynchus bowerbirds build an avenue-type bower made of two walls of vertically placed sticks. Ailuroedus catbirds are the only species which do not construct either bowers or display courts. In and around the bower, the male places a variety of brightly colored objects he has collected. These objects — usually different among each species — may include hundreds of shells, leaves, flowers, feathers, stones, berries, and even discarded plastic items, coins, nails, rifle shells, or pieces of glass. The males spend hours arranging this collection. Bowers within a species share a general form but do show significant variation, and the collection of objects reflects the biases of males of each species and its ability to procure items from the habitat, often stealing them from neighboring bowers. Several studies of different species have shown that colors of decorations males use on their bowers match the preferences of females.
In addition to the bower construction and ornamentation, male birds perform involved courtship displays to attract the female. Research suggests the male adjusts his performance based on success and female response.
Mate-searching females commonly visit multiple bowers, often returning to preferred bowers several times, and watching males' elaborate courtship displays and inspecting the quality of the bower. Through this process the female reduces the set of potential mates. Many females end up selecting the same male, and many under-performing males are left without copulations. Females mated with top-mating males tend to return to the male the next year and search less.
It has been suggested that there is an inverse relationship between bower complexity and the brightness of plumage. There may be an evolutionary "transfer" of ornamentation in some species, from their plumage to their bowers, in order to reduce the visibility of the male and thereby its vulnerability to predation. This hypothesis is not well supported because species with vastly different bower types have similar plumage. Others have suggested that the bower functioned initially as a device that benefits females by protecting them from forced copulations and thus giving them enhanced opportunity to choose males and benefits males by enhancing female willingness to visit the bower. Evidence supporting this hypothesis comes from observations of Archbold's bowerbirds that have no true bower and have greatly modified their courtship so that the male is limited in his ability to mount the female without her cooperation. In tooth-billed bowerbirds that have no bowers, males may capture females out of the air and forcibly copulate with them. Once this initial function was established, bowers were then co-opted by females for other functions such as use in assessing males based on the quality of bower construction. Recent studies with robot female bowerbirds have shown that males react to female signals of discomfort during courtship by reducing the intensity of their potentially threatening courtship. Young females tend to be more easily threatened by intense male courtship, and these females tend to choose males based on traits not dependent on male courtship intensity.
The high degree of effort directed at mate choice by females and the large skews in mating success directed at males with quality displays suggests that females gain important benefits from mate choice. Since males have no role in parental care and give nothing to females except sperm, it is suggested that females gain genetic benefits from their mate choice. However this has not been established, in part because of the difficulty of following offspring performance since males take seven years to reach sexual maturity. One hypothesis for the evolutionary causation of the bower building display is Hamilton and Zuk's "bright bird" hypothesis, which states that sexual ornaments are indicators of general health and heritable disease resistance. Doucet and Montgomerie determined that the male bowerbird's plumage reflectance indicates internal parasitic infection, whereas the bower quality is a measure of external parasitic infection. This would suggest that the bowerbird mating display evolved due to parasite-mediated sexual selection, although there is some controversy surrounding this conclusion.
This complex mating behaviour, with its highly valued types and colors of decorations, has led some researchers to regard the bowerbirds as among the most behaviorally complex species of bird. It also provides some of the most compelling evidence that the extended phenotype of a species can play a role in sexual selection
Sexual selection is a mechanism of evolution in which members of one sex mate choice, choose mates of the other sex to mating, mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex ...
and indeed, act as a powerful mechanism to shape its evolution
Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...
, as seems to be the case for humans. Inspired by their seemingly extreme courtship rituals, Charles Darwin
Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English Natural history#Before 1900, naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all speci ...
discussed both bowerbirds and birds-of-paradise in his writings.
In addition, many species of bowerbird are superb vocal mimics. MacGregor's bowerbird, for example, has been observed imitating pigs, waterfalls, and human chatter. Satin bowerbirds commonly mimic other local species as part of their courtship display.
Bowerbirds have also been observed creating optical illusions in their bowers to appeal to mates. They arrange objects in the bower's court area from smallest to largest, creating a forced perspective which holds the attention of the female for longer. Males with objects arranged in a way that have a strong optical illusion are likely to have higher mating success.
Taxonomy and systematics
Though bowerbirds have traditionally been regarded as closely related to the birds of paradise, recent molecular studies suggest that while both families are part of the great corvid radiation that took place in or near Sahul (Australia-New Guinea), the bowerbirds are more distant from the birds of paradise than was once thought. DNA–DNA hybridization studies placed them close to the lyrebirds; however, anatomical evidence appears to contradict this placement, and the true relationship remained unresolved for long. Cladistic
Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...
analyses in the mid-2010s usually allied bowerbirds with the Australasian treecreepers (Climacteridae), another Sahul endemic
Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
family which is highly adapted to a woodpecker-like lifestyle (woodpeckers being absent from Sahul). This putative superfamily forms part of a large basal radiation
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes:
* ''electromagnetic radiation'' consisting of photons, such as radio waves, microwaves, infr ...
of ancient songbirds, with the lyrebirds being part of a more ancestral branch than the bowerbirds and their DNA-DNA hybridization similarities being due to the phenetic methodology which (unlike cladistic analysis) merely assesses overall similarity without accounting for convergent evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...
.
Many bowerbirds (in particular New Guinean species) are little known and even less studied. But the hypothesized relationships of 3 roughly equally distinct groups and one peculiar species inferred from courtship behaviour and external appearance are by and large confirmed by molecular phylogenetics
Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
, . Some insights from the more recent studies, however, were less expected: The Tooth-billed catbird, with its unique "stagemaker" courtship, was long suspected not to be a true catbird (genus ''Ailuroedus
''Ailuroedus'' is a genus of birds in the bowerbird family, Ptilonorhynchidae, native to forests in Australia and New Guinea. The common name, catbird, refers to these species' "wailing cat-like calls". The scientific name ''Ailuroedus'' is deri ...
''). As it turned out, this is not only correct, but in fact the Tooth-billed catbird is robustly resolved by the mtDNA data as more closely related to the " maypole"-type bower builders than to ''Ailuroedus'', and certainly warrants separation in genus ''Scenopoeetes''. Also, the enigmatic "maypole-builder" genus '' Archboldia'' seems to be merely a '' Amblyornis'' with unusually heavy melanin
Melanin (; ) is a family of biomolecules organized as oligomers or polymers, which among other functions provide the pigments of many organisms. Melanin pigments are produced in a specialized group of cells known as melanocytes.
There are ...
pigmentation as is often found in tropical rainforest
Tropical rainforests are dense and warm rainforests with high rainfall typically found between 10° north and south of the Equator. They are a subset of the tropical forest biome that occurs roughly within the 28° latitudes (in the torrid zo ...
birds. On the other hand, the "avenue-builders" also have a hypermelanic lineage, the satin bowerbird, but this seems well separable as a monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...
genus ''Ptilonorhynchus'', as is the "maypole-building" golden bowerbird (as ''Prionodura''). Interestingly, the widely divergent "avenue-builders" may represent the oldest living lineage, with the monogamous true catbirds, which do not build a bower and were traditionally held to be "primitive", as the most derived group among living bowerbirds – the last common ancestor of the living bowerbirds is hypothesized to have been polygynous, with sexually dimorphic
Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...
plumage – cryptic greenish in the females, and probably dark with a yellow belly in the males. But overall relationships between the true catbirds, the "maypole-builders" and the "avenue-builders" were not definitely resolvable, with only a small outgroup being used and outgroup effects on intra-family relationships not being tested. Even so, it is precisely this uncertainty about inter-group relationships that strongly suggests that the "maypole"/"avenue" bowers are not one ancestral and one derived type, but evolved independent of one another, perhaps from a "clean stage"-type courtship arena which is commonly established by all bower-building species at the start of bower construction, and persists in little-altered form (just adding some remarkable leaves strewn about as decoration) in ''Scenopoeetes'' which almost certainly is the most ancient living lineage of the "maypole-builders". Among the catbirds, the white-cheeked group (''A.buccoides/geislerorum/stonii'') is very likely the most ancient one, which is also in line with the hypothesis that bowerbirds have become more and more drab and inconspicuous as their evolution progressed.[
The ]cladogram
A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...
below showing the relationships between the genera is based on a molecular phylogenetic
Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
study by Per Ericson and collaborators that was published in 2020. The genus '' Archboldia'' was found to be embedded in the genus '' Amblyornis''.
Genera and species
True catbirds
Genus ''Ailuroedus
''Ailuroedus'' is a genus of birds in the bowerbird family, Ptilonorhynchidae, native to forests in Australia and New Guinea. The common name, catbird, refers to these species' "wailing cat-like calls". The scientific name ''Ailuroedus'' is deri ...
''
* Ochre-breasted catbird
The ochre-breasted catbird (''Ailuroedus stonii'') is a species of bird in the family Ptilonorhynchidae. It is found in southern New Guinea. Its natural habitats are subtropical or tropical dry forests and subtropical or tropical moist lowland fo ...
, ''Ailuroedus stonii''
* White-eared catbird
The white-eared catbird (''Ailuroedus buccoides'') is a species of bird in the family Ptilonorhynchidae found on New Guinea and the West Papuan Islands. Its natural habitat
In ecology, habitat refers to the array of resources, biotic fa ...
, ''Ailuroedus buccoides''
* Tan-capped catbird, ''Ailuroedus geislerorum''
* Green catbird, ''Ailuroedus crassirostris''
* Spotted catbird
The spotted catbird (''Ailuroedus maculosus'') is a species of bowerbird (Ptilonorhynchidae) which can be found in north Queensland, the eastern Moluccas and New Guinea.Higgins, P.J., Peter, J.M. and Cowling, S.J. 2006. Handbook of Australian, Ne ...
, ''Ailuroedus maculosus''
* Huon catbird, ''Ailuroedus astigmaticus''
* Black-capped catbird, ''Ailuroedus melanocephalus''
* Northern catbird
The Northern catbird (''Ailuroedus jobiensis'') is a species of bowerbird (Ptilonorhynchidae) which can be found in central-northern New Guinea.
This species was formerly considered a subspecies of the spotted catbird
The spotted catbird (''A ...
, ''Ailuroedus jobiensis''
* Arfak catbird, ''Ailuroedus arfakianus''
* Black-eared catbird, ''Ailuroedus melanotis''
Maypole-builders (including Tooth-billed catbird)
Genus ''Scenopoeetes''
* Tooth-billed catbird, ''Scenopoeetes dentirostris''
Genus ''Archboldia''
* Archbold's bowerbird, ''Archboldia papuensis''
Genus '' Amblyornis''
* Vogelkop bowerbird, ''Amblyornis inornata''
* MacGregor's bowerbird, ''Amblyornis macgregoriae''
* Huon bowerbird, ''Amblyornis germanus''
* Streaked bowerbird, ''Amblyornis subalaris''
* Golden-fronted bowerbird, ''Amblyornis flavifrons''
Genus ''Prionodura''
* Golden bowerbird, ''Prionodura newtoniana''
Avenue-builders
Genus '' Sericulus''
* Flame bowerbird, ''Sericulus ardens''
* Masked bowerbird, ''Sericulus aureus''
* Fire-maned bowerbird, ''Sericulus bakeri''
* Regent bowerbird, ''Sericulus chrysocephalus''
Genus ''Ptilonorhynchus''
* Satin bowerbird, ''Ptilonorhynchus violaceus''
Genus '' Chlamydera''
* Western bowerbird, ''Chlamydera guttata''
* Spotted bowerbird, ''Chlamydera maculata''
* Great bowerbird, ''Chlamydera nuchalis''
** Eastern great bowerbird, ''Chlamydera (nuchalis) orientalis'' (possibly a distinct species)
* Yellow-breasted bowerbird, ''Chlamydera lauterbachi''
* Fawn-breasted bowerbird, ''Chlamydera cerviniventris''
Fossil record
Bowerbirds have a scant fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...
record that nonetheless extends to the Chattian (latest Oligocene
The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...
), with the fossil species ''Sericuloides marynguyenae'' dated to 26 to 23 million years ago. It was found in Faunal Zone A deposits of the White Hunter Site at D-site Plateau of the Riversleigh World Heritage Area. ''S. marynguyenae'' was a tiny member of its family, about the same size as the golden bowerbird. It is known from the proximal end of a right carpometacarpus and the proximal end of a left tarsometatarsus
The tarsometatarsus is a bone that is only found in the lower leg of birds and some non-avian dinosaurs. It is formed from the fusion of several bird bones found in other types of animals, and homologous to the mammalian tarsus (ankle bones) a ...
. The material, though fragmentary, preserves much detail, and is overall more similar to the "avenue-builders" – in particular ''Chlamydera'' – than to the other two main groups. However, the splits between the three main groups of living bowerbirds are presumed to have occurred only in the Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
, some time after ''Sericuloides'' lived. Thus, the fossil species may have belonged to a more basal and now entirely extinct lineage, and/or it may be considered to support the hypothesis that the "avenue-builders" are the most ancient group of bowerbirds and retain many "primitive" features in their anatomy.
Other than ''S. marynguyenae'', as of 2023 only one other prehistoric bowerbird species is known. This has not been named, as it is only known from the distal left ulna
The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...
piece QM F57970 (AR19857), also found on the D-site Plateau of Riversleigh WHA, but in interval 3 of Faunal Zone B at the Ross Scott-Orr site, in late early Miocene (Burdigalian
The Burdigalian is, in the geologic timescale, an age (geology), age or stage (stratigraphy), stage in the early Miocene. It spans the time between 20.43 ± 0.05 annum, Ma and 15.97 ± 0.05 Ma (million years ago). Preceded by the Aquitanian (sta ...
) sediments dated to 16.55 mya. Even though this piece of fossil bone is merely some 16 mm long, it is excellently preserved, and its features are characteristic of a smallish bowerbird the size of a black-eared catbird. Bowerbird ulnae – to the extent they have been studied – differ little between genera and species, but the Miocene fossil is unlike all living members of the family in one detail or another. If anything, it resembles the presumably more advanced groups ("maypole-builders" and true catbirds) more than the "avenue-builders" and given its age it may well have been one of the earliest members of either of the former two groups.
References
External links
Bowerbird videos
on the Internet Bird Collection
Bower bird nest building
{{Authority control
Birds of Oceania
Taxa named by George Robert Gray
Extant Chattian first appearances