Spix's Macaw (Cyanopsitta spixii), also known as the Little Blue Macaw, is a Brazilian macaw and the only small blue macaw. It is a member of Arini tribe in the subfamily Arinae (Neotropical parrots), part of the family Psittacidae (the true parrots). It was first described by German naturalist Georg Marcgrave, when he was working in the State of Pernambuco, Brazil in 1638 and it is named for German naturalist Johann Baptist von Spix, who collected a specimen in 1819 on the bank of the Rio São Francisco in northeast Bahia in Brazil.

The species inhabited riparian Caraibeira (Tabebuia aurea) woodland galleries in the drainage basin of the Rio São Francisco within the Caatinga dry forest climate of interior northeastern Brazil. It had a very restricted natural habitat due to its dependence on the tree for nesting, feeding and roosting. It fed primarily on seeds and nuts of Caraiba and various Euphorbiaceae (spurge) shrubs, the dominant vegetation of the Caatinga. Due to deforestation in its limited range and specialized habitat, the bird has been rare in the wild throughout the twentieth century. It has always been very rare in captivity, partly due to the remoteness of its natural range.

The IUCN regard the Spix's Macaw as critically endangered and possibly extinct in the wild. Its last known stronghold in the wild was in northeastern Bahia, Brazil and the last known wild bird was a male that vanished in 2000. The species is now maintained through a captive breeding program at several conservation organizations under the aegis of the Brazilian government. It is listed on CITES Appendix I, which makes trade illegal except for legitimate conservation, scientific or educational purposes.

The Brazilian government department of natural resources (ICMBio) is conducting a project Ararinha-Azul with an associated plan to restore the species to the wild as soon as sufficient breeding birds and restored habitat are available.

Taxonomy [edit]

Spix's Macaw is the only known species of the genus Cyanopsitta. The genus name is derived from the Latin cyano and psitta (a shortened form of psittacus), which are in turn are derived from the Ancient Greek kuanos meaning "blue" and psittakos meaning "parrot".^[2] The species name spixii is a Latinized word derived form of the surname "Spix", hence Cyanopsitta spixii means "blue parrot of Spix".^[2] The genus Cyanopsitta is one of six genera of Central and South American macaws in the tribe Arini, which also includes all the other long-tailed New World parrots. Tribe Arini together the Amazonian parrots and a few miscellaneous genera make up subfamily Arinae of Neotropical parrots in family Psittacidae of true parrots.^[3][4]

In 1638 Georg Marcgrave was the first European naturalist to observe and describe the species; however, it is named for Johann Baptist von Spix, who collected the type specimen in May 1819 in Brazil, but misidentified it as a Hyacinth Macaw.^[5] Spix's mistake was noticed in 1832 by German professor of zoology Johann Wagler, who realized that the 1819 specimen was smaller and a different color than the Hyacinth Macaw and he designated the new species as "Sittace spixii". It wasn't until 1854 that naturalist Prince Charles Bonaparte properly placed it in its own genus, designating the bird Cyanopsitta spixi [sic],^[6] based on important morphological differences between it and the other blue macaws.^[7] It was listed as Cyanopsittacus spixi [sic] by Italian zoologist Tommaso Salvadori in his 1891 Catalog of the Birds in the British Museum.^[8]

Naturalists have noted the Spix similarity to other smaller members of tribe Arini based on general morphology as long ago as Rev. F.G. Dutton, president of the Avicultural Society U.K. in 1900: "it's more like a conure".;('conure' is not a defined taxon - in Dutton's time, it referred to the archaic genus Conurus; today those would be among the smaller non-macaw parakeets in Arini).^[9] Brazilian ornithologist Helmut Sick stated in 1981: "Cyanopsitta spixii...is not a real macaw".^[10] (Sick's remark was in the context of an article on Lear's Macaw, a larger blue macaw. He recognized, as Spix had not 150 years before, that C. spixii is notably different from the larger macaws).

The morphology-based taxonomy of C. spixii, intermediate between the macaws and the smaller Arini, has been confirmed by recent molecular phylogenetic studies. In a 2008 molecular phylogenetic study of 69 parrot genera,^[11] the clade diagrams indicate that C. spixii split from the ancestral parakeets before the differentiation of the modern macaws. However, not all of the macaw genera were represented in the study. The study also states that diversification of the Neotropical parrot lineages occurred starting 33 mya, a period roughly coinciding with the separation of South America from West Antarctica. The author notes that the study challenges the classifications of British ornithologists Nigel Collar and Ian Rowley in the encyclopedic Handbook of the Birds of the World, volume 4 (1997).^[12][13] A 2011 study by the same authors which includes key genera of macaws further elucidates the macaw taxonomy: the clade diagram of that study places C. spixii in a clade including the macaw genera which is sister to a clade containing the Aratingas and other smaller parakeets. Within the macaw clade, C. spixii was the first taxon to diverge from the ancestral macaws; its nearest relatives are the Red-bellied Macaw (Orthopsittaca manilata) and the Blue-headed Macaw (Primolius couloni).^[14]

Description [edit]

A juvenile in captivity. Note white stripe along top of beak and pale-grey bare facial skin

Spix's Macaw is 55–57 cm (21.5–23.5 in) long with a tail length of 26–38 cm (10.2–15 in), weighs 318 gm (11.4 oz) (males), 288 gm (10.2 oz) (females)^[15] and has a wingspan of 64 cm (25.2 in). It is various shades of blue, including a pale blue head, pale blue underparts, and vivid blue upperparts, wings, and tail.^[16] The underside of the wings and tail are black. In adults there is a bare area of grey facial skin and the legs and feet are almost black. In adults the beak is entirely grey-black and the irises are yellow.^[17] The species is easy to identify being the only small blue macaw and also by its grey bare facial skin.^[17] The external appearance of the male and female are identical.^[17] In common with many parrots, they have zygodactyl feet with two forward facing and two rearward facing toes.

Juveniles are similar to the adults, but they have a white stripe along the center of the top of the beak (along the culmen), which is also seen in juvenile Red-bellied Macaws. In juveniles the bare facial skin is pale grey and the irises are brown.^[17]

Its lifespan in the wild is unknown; the only documented bird (the last wild male), was older than 20 years. The eldest bird in captivity died at age 34 years.^[15]

Behavior [edit]

Diet [edit]

In the wild, the most commonly mentioned seeds and nuts consumed by Spix's were from Pinhão (Jatropha pohliana var. mollissima) and Favela (Cnidoscolus phyllacanthus). However these trees are colonizers, not native to the bird's habitat, so they couldn't have been historical staples of the diet.^[18]

Its diet also includes seeds and nuts from Joazeiro (Ziziphus Joazeiro), Baraúna (Schinopsis brasiliensis), Imburana (Commiphora leptophloeos or Bursera leptophloeos), Facheiro (Pilosocereus piauhyensis), Phoradendron species, Caraibeira (Tabebuia caraiba), Angico (Anadenanthera macrocarpa), Umbu (Spondias tuberosa) and Unha-de-gato (Acacia paniculata). Reports from previous Spix's Macaw researchers seem to add another two plants to the list: Maytenus rigida and Geoffroea spinosa. Combretum leprosum may also be a possibility.^[15]

Reproduction [edit]

Juveniles reach sexual maturity in seven years (captive specimens). It is suspected that late maturity in captivity may be an artifact of inbreeding or other artificial environmental factor, as other parrots of similar size reach sexual maturity in two to four years. In the wild, mating involves elaborate courtship rituals, like feeding each other and flying together. This process is known to possibly take several seasons in other large parrots, and it may also be the case for the Spix's. They make their nests in the hollows of large mature Caraibeira trees, and reuse the nest year after year. The breeding season is November to March, with most eggs hatching in January to coincide with the start of the Caatinga Jan.-Apr. rainy season. In the wild, Spix's were believed to lay three eggs per clutch; in captivity, the average number is four eggs, and can range from one to seven.^[15] Incubation period is 25–28 days and only the female performs incubation duties. The chicks fledge in two months and are independent in five months.

The mating call of Spix's Macaw can be described as the sound "whichaka". The sound is made by creating a low rumble in the abdomen bringing the sound up to a high pitch.^[15] Its voice is a repeated short grating. It also makes squawking noises.

Distribution and habitat [edit]

Spix's Macaw was most recently (1974–1987) known in the Río São Francisco valley, in northeastern Brazil, principally in the basins on the south side of the river in the State of Bahia. In 1974, ornithologist Helmut Sick, based on information from traders and trappers, extended the possible range of the Spix's Macaw to embrace the northeastern part of the state of Goias and the southern part of the state of Maranhao.^[19] Other ornithologists reporting the bird in various parts of the state of Piaui further extended the range to a vast area of the dry interior of northeast Brazil.^[18]

Study of the lone bird discovered at Melância creek in 1990 revealed substantive information about its habitat. It had been previously assumed that the Spix's Macaw had a vast range in the interior of Brazil embracing several different habitat types, including buriti palm swamps, cerrado, and dry Caatinga. But the evidence collected in Melância Creek indicated that the Spix's Macaw was a specially adapted inhabitant of the disappearing woodland galleries. Ornithologist Tony Silva mentions that "where craibeiras have been felled, as in the Pernambuco side of the São Francisco River, the species has disappeared".^[20] Previous observations of the birds elsewhere were attributed to birds migrating between possibly isolated areas of habitat, birds displaced from older habitats by deforestation, or birds expansively hunting for scarce nesting sites.

Other recent evidence has shown that anthropic changes that occurred on the northern shore of the São Francisco River, such as a broad scale conversion into agricultural lands and flooding following the construction of Sobradinho dam starting in 1974, have changed the flora structure and displaced the Spix's Macaw away from that portion of its original range.^[21]

Much remains uncertain about the extent of the bird's original range, because most of its woodland habitat was cleared before naturalists observed either the birds or the Caraiba nesting sites. The historical range is now believed to have encompassed portions of the states of Bahia and Pernambuco in a 50 km (31 mi) wide corridor along a 150–200 kilometres (93–120 mi) stretch of the Rio São Francisco between Juazeiro (or possibly Remanso) and Abare.^[22]

The caatinga vegetation of northeastern Bahia (which hosts the Spix habitat) is stunted trees, thorny shrubs and cacti, prevailed by plants of the family Euphorbiaceae. This macaw lived in the hottest and driest part of the "Caatinga" within Caraiba, or Caribbean Trumpet Tree (Tabebuia caraiba) woodland galleries. The Caraibeira woodland galleries constitutes a microclimate within the Caatinga. The existing galleries are fringes of unique woodland extending a maximum of 18 metres (Bad rounding here59 ft) to either side along a series of seasonal waterways at least 8 m wide in the Rio São Francisco drainage basin.^[18] All T. caraiba woodland was recorded in the middle and lower levels of the creek system where fine alluvial deposits were present. The character of the galleries is tall (8m) evenly spaced Caraibeira trees, ten per hundred meters, interspersed with low scrub and desert cacti. Large mature trees of this species (and apparently no other) provided the nesting hollows of the Spix Macaws, as well as shelter and their seedpods, food for the species.

Notable among the seasonal waterways are Riacho Melância watershed 30 km south of Curaçá, where the last known wild Spix's Macaw nest was located, adjacent Riacho Barre Grande, and Riacho Vargem to the north all in the State of Bahia south of Rio São Francisco. In 1990, these were all that remained of what was once believed to be a vast filigree of creekside Caraibeira woodland extending 50 km into the Caatinga on either side of the Rio São Francisco along a significant stretch of its middle reaches.^[23] There is also one confirmed site, since cleared, on the north shore of Rio São Francisco in Pernambuco. Caraiba grows very slowly; most of the trees are 200–300 years old, and there has not been any regenerative growth for the last 50 years.

In addition, 45% of the Caatinga dry forest in which the woodland galleries are embedded has been cleared for farms, ranches and plantations. Climate change resulting in desertification of significant parts of the Caatinga has permanently reduced the potential reclaimable habitat.^[24]

History [edit]

Plate from Spix's 1824 description. It has the bill of a juvenile

The species appears to have been seen and described ("larger than a Psittacus[ African Grey Parrot ], the entire plumage is grey-blue") by the German naturalist Georg Marcgrave when he worked in Pernambuco in 1638.^[25]

Spix's Macaw is named for German naturalist Johann Baptist von Spix, who collected the first specimen in May, 1819 on the bank of the São Francisco River near Juazeiro in Brazil. Spix wrote: "The bird is gregarious and very rare."

The next reported sighting of the bird wasn't for 84 years, in 1903 by Othmar Reiser of the Austrian Academy of Sciences, 400 kilometres (250 mi) west of Juazeiro at Lagoa de Parnaguá (lake at Parnagua) in the State of Piaui. (What we now know about its habitat and probable range casts doubt on this observation^[26]) Reiser had also seen one in captivity at a railway station in Remanso. These observations resulted in an early supposition of a vast potential range for the species in the dry interior of the northeast. .

A trickle of Spix's appeared in captivity starting in the late 1800s. The earliest known specimens were three held by the London Zoological Society between 1878 and 1902. The bird remained rare and highly coveted. The first captive breeding occurred in the 1950s in Brazil, in the aviaries of the late Alvaro Carvalhaes, an aviculturist from Santos. He hatched numerous chicks, some reports say as many as 24, one of which ended up at the Naples Zoo (Italy), where it remained alive until the late 1980s. Most of his birds died of poisoning in the 1970s. Some of these birds were the likely source of rumored Brazilian Spix owners in the 1960s and 1970s.

With the passage of the Brazil Wildlife Protection Act in 1967, Brazil forbid the export of its wildlife, and in 1975 became a party to the CITES treaty. These actions barely impacted the illicit bird trade, but Spix owners were forced underground (consequently complicating the later effort to initiate a captive recovery program).

The bird was not studied in the wild until the 1970s. As recently as 1980, R. Ridgely stated that "there is no available evidence indicating a recent decline in numbers." Beginning around 1980, at the very height of the illegal bird trade, traders and trappers removed dozens of Spix's from the wild, and by the early 80s, it was generally believed to be extinct in the wild.

Three Spix's were re-discovered in the Curaçá region in 1986. Two of the birds were captured for trade in 1987. A single male, paired with a female Blue-winged Macaw, was discovered at the site in 1990. A female Spix's Macaw released from captivity at the site in 1995 was killed by collision with a power line after seven weeks. The last wild male disappeared from the site in October 2000.^[16] The species probably became extinct in the wild late in 2000, when the last known wild bird was no longer seen.^[16] No sightings of this macaw have been made in the wild since 2000. While the IUCN Red List views its status as Critically Endangered and possibly extinct in the wild,^[1] ornithologist Nigel Collar of Birdlife International, the authority for the IUCN Redlist of birds now calls this bird extinct in the wild.^[26]

Conservation and threats [edit]

In the middle 1980's, by the time fieldwork to locate and understand the habitat of the Spix was completed, it was apparent that the situation of the species in the wild was dire. Conservationists realized that a captive breeding program would be necessary to preserve the species. At a meeting in 1987 of captive Spix holders and conservationist groups including IUCN at Loro Parque (one of the original Spix holder's) in Tenerife, Canary Islands, only 17 captive Spix macaws could be located. Without the involvement of the Brazilian government, little was accomplished.

In 1990, the Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis (IBAMA, Brazilian Institute of Environment and Renewable Natural Resources) established the Permanent Committee for the Recovery of Spix's Macaw, called CPRAA, and its Ararinha Azul Project (Little Blue Macaw Project) in order to conserve the species. At that time, the known captive population of Spix's stood at 15, and one in the wild. Two birds had died since the time of the Tenerife accord. Early 1990 was the low point for conservation of the Spix. Several exchanges of birds based on DNA sexing were made between institutions and individuals to create new breeding pairs. In 1991, another holder, Dr. Hamnerli of Switzerland came forward holding three birds,and brought the captive total to 18.

By late 1999, the captive population of Spix's stood at 60, including large collections at Birds International in the Philippines and the Swiss aviaries of Dr. Hammerli.

In Oct. 2002, a Spix named Presley was discovered in Colorado, and repatriated to Brazil. It was the last Spix ever to be discovered, which had not been among those known in 1987.

The Permanent Committee was dissolved in 2002 due to irreconcilable differences between the parties involved. In 2004 a committee was re-formed and re-structured under the title of "The Working Group for the Recovery of the Spix's Macaw".^[15]

Between 2001 and 2004, most of the de Dios and Hammerli collections were purchased by His Excellency Sheikh Saoud bin Muhammed bin Ali Al-Thani of Qatar and became Al Wabra Wildlife Preservation. Under the Sheikh were instituted exemplary standards of animal keeping, veterinary care, animal husbandry and stud book records for the conservation of the Spix's.

In the early 2000s, two other organizations, Association for Conservation of Threatened Parrots (ACTP) in Berlin, Germany and Lymington Foundation in state of Sao Pauo, Brazil, each holding a pair of Spix's, joined the ICMBio breeding program.

In 2007 and 2008, two farms totalling 2780 hectares (6870 acres) in Curaçá, State of Bahia, Brazil were purchased by the Lymington Foundation (with contributions from ACTP and Parrots International) and Al Wabra. These compose a small but important part of the natural habitat of the Spix, in the vicinity where the last known wild Spix nest existed. Efforts to clear the habitat of introduced predators and restore the natural Caraibeira seedlings are ongoing.^[15]

A research collaboration between the Loro Parque Fundación of Tenerife, Canary Islands (Spain) and the University of Giessen in Germany is using a new artificial insemination technique to help the recovery of the Spix's Macaw. It was first attempted in the 2009–2010 breeding season and was unsuccessful. The procedure involves electro-ejaculation for collection of sperm, cryopreservation of the sperm, and artificial insemination of the hen, or possibly in-vitro fertilization of an otherwise infertile egg. The technique would be useful not only to increase the number of potential hatchings, but also to create genetic crosses that can't be done "naturally" because of the choosiness of parrots. It can also preserve the genetic heritage of elderly or unpaired cocks among the original wild caught birds (for example Presley at The Lymington Foundation).^[27]

In May, 2012, Brazil's ICMBio formulated and published a 5-year National Action Plan (PAN) for conservation and reestablishment of the species in the wild.^[21] Highlights of the plan are to increase the captive population to 150 specimens, build a breeding facility in Brazil within the Spix's native habitat, acquire and restore additional portions of its range, and prepare for its release into the wild between 2013 and 2030.

Threats [edit]

The bird was already rare by the time of Spix' discovery of it in 1819 following 100 years of intensive burning, logging and grazing of the caatinga. Centuries of deforestation, human encroachment and agricultural development along the Rio Sao Francisco corridor following European colonization of eastern Brazil preceded its precipitous decline in the latter part of the 20th century. Naturalists surveying its native habitat in the Curaçá region have estimated that it could have supported no more than about 60 birds at any time in the last 100 years.^[28] Other accounts relate that the birds were more common in Pernambuco than in Bahia through the 1960s but not later.^[22]

Contributing factors were the anthropic introduction of invasive and predatory species of black rats, feral cats, mongooses and Marmoset monkeys which prey on the eggs and young, and goats, sheep and cattle which destroy the regenerative growth of the woodland trees, particularly the Caraibeira seedlings.

The final decline of the species in the 1970s and early 80s is attributed to hunting and trapping of the birds, unsustainable harvesting of the Caraíba trees for firewood, the construction of the Sobradinho Dam above Juazeiro starting in 1974 that submerged the basin woodlands under an artificial lake, and the northward migration of the Africanized bee, which competes for nesting sites.^[23]

Captive population [edit]

The existing captive population is descended from just 7 wild caught founder birds,^[29] which are believed to have all come from just two wild nests that existed post 1982:^[18] pairs originally owned by Antonio de Dios, Dr. Hammerli, and Wolfgang Keissling (Loro Parque), and a male from the São Paulo Zoo.^[29]

In the years since 1987 when naturalists, conservationists and later IBAMA/ICMBio started tracking the Spix, only two sets of birds unknown in 1987 have ever been discovered: Dr. Hammerli's in 1991, and a single male bird in Colorado in 2002. There is no evidence that any others not known in 1987 still exist (though see a cryptic reference to black market dealing in the birds in 1995.)^[30]

As of May, 2012 there are approximately 96 Spix's Macaws in captivity. 80 of these are participating in an international breeding program managed by the Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio), the Natural Heritage Branch of the Brazilian Government.^[29] 60 of these are managed at Al Wabra Wildlife Preservation (AWWP), State of Qatar, which took over the population of Birds International and most of the birds in Dr. Hammerli's Swiss collection. Other Spixs are located at Loro Parque, Tenerife, Canary Islands, Association for the Conservation of Threatened Parrots (ACTP) in Berlin, Germany, the São Paulo Zoo and Lymington Foundation in Brazil. At these five conservation organizations, a captive breeding program is guiding Spix's Macaw a step closer to re-establishment back to its natural habitat in Brazil.^[31] Approximately 13 Spixs are in the hands of private owner(s) in Switzerland.^[29] The status and locations of 3 other Spixs lost from Dr. Hammerli's Swiss collection in 1999 are unknown but presumed to be still alive.^[32]

Note: table data based on Al Wabra ICMBio Spix Presentation Jan. 2012

The captive population suffers from very low heterozygosity^[33] - the original wild caught founder birds were few, closely related in the wild and intensively inbred in captivity - resulting in infertility, and high rate of embryo deaths (at AWWP, only one in six eggs laid is fertile; only two-thirds of those hatch).^[29] The AWWP population is also afflicted by Proventricular Dilatation Disease (PDD), an invariably fatal condition,^[34] as well as a number of serious avian viruses and congenital disorders.^[33]

The sex of all captive birds has been determined using non-invasive DNA testing of plucked feathers.^{[citation needed]} The sex of chicks is not determined until they have featheration (one to two months).^[35]

For unknown reasons, originally suspected to be bloodline related, captive specimens have delayed sexual maturity. The youngest pairs to lay fertile eggs were 10 years of age.^[33]

All or nearly all hatched chicks in the breeding program are hand raised by experienced staff, to reduce the risk of losing a scarce live chick (only about one out of ten viable eggs laid hatch).^[15] No chick has been lost through weaning.^[29] These hand raised birds are strongly imprinted on humans, and this will present a significant issue for their ultimate release into the wild.

Other captive breeding issues are that, possibly because of inbreeding, many more hens than cocks are hatched, at least twice as many. Also, parrots choose their own mates, so the best genetic pairings may not be possible. Artificially created "pairs" may groom and associate with each other as if they were a pair, but in fact are not mates, and it may take several seasons to determine this. An additional complication is that infected birds are not paired with uninfected birds, because of the risk of spreading viral diseases.^[29]

Aviculture [edit]

Illustration of Glaucous Macaw (foreground) with Spix's Macaw in Hamburg, 1895

The bird was exceedingly rare in aviculture, the few being held by wealthy collectors rather than privately as pets. Bates & Busenbark say that the bird was intelligent and affectionate, talked some, and had no worse proclivity for screaming than Amazons. They also noted that the Spix were spiteful to other birds.^[36]

Due to its CITES Appendix I conservation status^[37] and lack of private breeders, there are now no sources from which the bird may be obtained for the pet trade.

The Spix is one of the "four blues", the four species of all blue macaws formerly seen in captivity together including the Hyacinth Macaw, Lear's Macaw, and Glaucous Macaw (extinct).^[38]

Popular culture [edit]

In the animated TV series Noah's Island, the "Born to be Wild" episode focuses on Noah, the main character, bringing a breeding pair of Spix's Macaws to his island from the Amazon rainforest, in the hope that they will breed. At first, the two Macaws are both very aggressive and fight with each other, but they eventually make up and fall in love.^[39]

In the opener of the Gorgo episode of Mystery Science Theater 3000, Crow finds that his head crown has become a nesting spot for two Spix's Macaw eggs. Later in the episode he reveals that the eggs have been taken away by Egg Protective Services after he accidentally made an omelet in front of them.^[40]

In the 2011 animated movie Rio, the main characters Blu (Jesse Eisenberg) and Jewel (Anne Hathaway) are the supposed last pair of Spix's Macaws in the world (although they are referred to as Blue Macaws). The movie even references their extinct-in-the-wild status and at one point ornithologist Túlio Monteiro mentions the species' scientific name.^[41]

See also [edit]

• List of macaws

References [edit]

Cited texts [edit]

• Forshaw, Joseph M. (2006). Parrots of the World; an Identification Guide. Illustrated by Frank Knight. Princeton University Press. ISBN 0-691-09251-6. 

Further reading [edit]

A note on the references. There are only about a dozen original ornithological research papers devoted exclusively to the Spix written in the last 40 years. Most are collected at www.bluemacaws.org. A comprehensive natural and conservation history through late 2002 is available in Juniper's Spix Macaw book. More recent information is available in periodic reports issued by Loro Parque and Al Wabra. Most other material is derived.

• del Hoyo, et al.(eds) (1997) Handbook of the Birds of the World, vol.4, Family Psittacidae (Parrots), N.J. Collar, pp-280-479, Lynx Edicions, Barcelona, Spain ISBN 84-87334-22-9
• Donald, Pain, Marsden & Collar (2010) Facing Extinction: the World's Rarest Birds and the Race to Save Them T. & A. D. Poyser ISBN 0-7136-7021-5
• Juniper, Tony (2003) Spix's Macaw : The Race to Save the World's Rarest Bird ISBN 0-7434-7550-X
• Sick, Helmut (1993) Birds in Brazil, A Natural history. Princeton University Press ISBN 0-691-08569-2
• Sick, Helmut (1997) (Portuguese Edition) Ornithologia Brasileira. Editora Nova Fronteira ISBN 85-209-0816-0
• Silva, Tony (1993) "A Monograph of Macaws and Conures" ISBN 1-895270-00-6