Article by Tony Silva
Carolus Linnaeus (Linné) published the 10th edition of his systematic list in 1758. His Systema Naturae gave order to the species concept, with a generic and a subspecific name—the so-called binominal nomenclature; the tenth edition is regarded as the starting point of zoological nomenclature. This concept allowed scientists worldwide to recognize the same individual by the same name; the use of common names typically proved tremendously erring, as different countries then as they do now use different common names for the same species. This scientific principal unquestionably advanced science tremendously and is still in use today.
Linné named on page 101 of Systema Naturae a bird, Psittacus aestivus, the generic name identifying it as a parrot and the species as a bird whose color reminded him of summer; the modern aestiva is the feminine form of the Latin adjective aestivus; the generic Psittacus at the time contained all psittaciformes. The species was identified as originating from “America” and was named from either a depiction in a painting or a bird imported by a mariner for a pet. No type specimen was assigned and thus we will never know what formed the basis for the description.
The Latin entry on page 101 of Systema Naturae reads as follows:
Habitat in America.
Corpus magnitudine Columbae, viride, dorso adsperso pennis luteis. Facies flava. Frons caerulea. Vertex albidus. Rectrices virides apice pallidiores: 1.2.3. bafi interior rubrae; at I et am lutere exterior caerulea. Humeri fulvi s. sanguinei. Remiges primores nigrae apice caerulescentes, latere exterior virides; secundariae anteriores latere extensive versus bafin rubrae. Rostrum nigrum.
The description has one sentence of specific interest: the Latin Humeri fulvi s. sanguinei translates to red shoulders with yellow. These few words are relevant to this article as discussed later.
Nearly two hundred years after Linné, the type range was assigned as “southern Brazil” by C.E. Hellmayr in his Catalogue of the Birds of the Americas. This is the second important point.
The type specimen is the individual used for naming of a species and is used as the reference for all other work involving that species and its taxonomy. What Linné identified was a bird whose plumage was green, had yellow and blue in the head and red and yellow at the bend of the wing. The color of the bend of the wing has become the single identifying feature that has separated the nominate (or first named) form from the subspecies described in 1896 by Berlepsch as Chrysotis aestiva xanthopteryx. (The generic Chrysotis was subsequently replaced by Amazona in J.L. Peters Check-list of the Birds of the World, in 1937.) Berlepsch named the bird xanthopteryx as a result of the presence of yellow feathers at the bend of the wing. The type for xanthopteryx originated from Bueyes in the Beni, Bolivia.
Subsequent ornithological work refined the distribution: nominate aestiva had a range centered in the north-eastern Brazilian states of Pará, Tocantins, Piauí, Bahía, Minas Gerais, Goiás and Mato Grosso, with some also including as part of the range São Paulo and Paraná; and xanthopteryx occupying the area south and west of nominate aestiva, extending from south-western Brazil to eastern Bolivia, through Paraguay to northern Argentina. Within this large range one would expect variability in color, especially in the extent of blue and yellow. The problem is that reality does not come close to the postulated concept of two distinct, easily separable subspecies. Instead one finds birds with features of xanthopteryx within deep in the range of aestiva and vice versa, as well as a broad contact zone. There is also the issue of the description given by Linné, which clearly refers to birds from the contact zone—a fact reaffirmed by Hellmayr decades later when he assigned the range for aestiva as falling within the contact zone of the two subspecies. The widely accepted red (and only red) bend at the end of the wing used to distinguish aestiva does not seem tenable in lieu of Linné´s description.
The vernacular name has also been fraught with problem. In theory, aestiva should be called the Blue-fronted Amazon and xanthopteryx the Yellow-winged Amazon, a direct translation of xantho = yellow and pteryx = wing. Aviculturists have often struggled to identify the subspecies and typically call all birds in English Blue-fronted Amazon.
In this article I attempt to give clarity to a rather difficult subject. First let me identify the existing problems, so that they can be discussed:
- Since the specimen used by Linné cannot be examined, we really have no idea of the extent of red and yellow on the bend of the wing and, especially, the morphology of the bird (as will be discussed later). Linné´s description clearly rules out the form called Bahia in Europe and Auá (pronounced A-wah) in Brazil, which has a red bend of the wing, has a slimmer, more muscular body, exhibits sexual dimorphism (males have red bases to the throat feathers) and has an almost constant color scheme: the yellow (which forms a variable bib) is golden, the blue is pale and the plumage is a paler green. Here I refer to this form as Auá, which is the most common native Brazilian name for it; Bahia (as it is called in Europe) is a state in the north-east of Brazil and refers to only part of a broader distribution area for this distinctive form. Was the bird that Linné used (as suggested by his description) a hybrid from the contact zone, given the description of red and yellow and the subsequent assignment of the type locality to southern Brazil?
- The form called Auá has both isolated populations (i.e., Serra das Capivaras and Serra dos Confuçoes, Pauí) and populations that come in contact with typical aestiva, with which it hybridizes readily. Is the core population of Bahia sufficiently distinct to justify being separated as a distinct species or subspecies? Does molecular genetics suggest it is distinct from other forms of aestiva?
- The contact zone between aestiva and xanthopteryx is broad and even within the northernmost range of aestiva one finds individuals with yellow at the end of the wing, as specimens from Belém do Pará and Aragarças, Caldas Novas, Araguacema and Nova Roma in Goiás and held in the archives of the Museu Nacional in Rio de Janeiro and the Museo de Zoologia de São Paulo and also individuals confiscated by the authorities from trappers in Bahia, Brazil show. Does this mean that this species is so variable that it is impossible to separate the forms and that a single species concept applies?
- Is there constancy in appearance in specific geographic areas, or is there variability in all populations in the extent of yellow and blue on the head and also in the presence of red and yellow or both colors on the bend of the wing?
- What is the occurrence of individuals of blue-faced birds that lack almost all (if not all) traces of yellow from the face and found in parts of southern Brazil? Are they distinct from individuals from the Sierra de Santa Bárbara in the Argentine provinces of Salta and Jujuy? Do they also represent an undescribed subspecies?
- Finally, how does one address the apparent incorrect nomenclature where Linné´s aestiva describes a bird whose features approximates that of xanthopteryx?
My attempts to clarify the taxonomic status of Amazona aestiva has taken me into the archives of museums in Brazil, the US and Europe and has resulted in the examination of specimens in the field and housed as pets in situ across all parts of the range. I have also contacted and received the valuable opinion of Antonio Chacón in Argentina, who for over 45 years has traded in wild and captive bred individuals, and the extremely knowledgeable Brazilian aviculturist Renato Costa, who specializes in Amazona aestiva. My current view as expounded here is not etched in stone and is likely to change in the future, but represents data gathered over a period of 30 years.
- From the early 1600s to the 1700s, Brazil´s chief exports were sugar, which left from the port of Salvador in Bahia, and sugar and mining from Rio de Janeiro; Salvador was Brazil´s capital until 1763, when it moved to Rio de Janeiro, whose significance by then had grown. On the shipping boats carrying sugar and the products of mining, other items left the country, including live birds. In the Archives of Indies in Seville, Spain there are shipping manifests containing the lists of the personal items of mariners visiting the tropics and some of these lists mention live parrots as personal articles. It is thus safe to assume that the parrot used by Linné was brought to Europe by a mariner, who sold it for a pet; the bird was then either painted with its owner (as was common at the time) and thus used to describe the species or seen alive or as a skin by Linné, who documented its appearance. Whatever the source, it is not available for examination, but it is likely the bird originated from the southern part of the range or more likely the contact zone (as the bird identified in Linné´s description suggests and as assigned by Hellmayr), which would have been close to the exporting port of Rio de Janeiro.
- The Auá is in my opinion the most striking, separable form. It is more proportionate in shape and invariably has pale blue on the forehead followed by golden yellow, which forms a bib; its color scheme is like that found in the Cuban Amazon Amazona leucocephala, with the white being blue and the red in the throat being replaced by yellow. In the core range the birds are carbon copies of one another. Males typically have reddish bases to the throat feathers. The range centers on a line that extends from Goiás to Bahia, Tocantins and Piauí, possibly extending to southernmost Maranhão, where I have seen multiple caged birds.Does this distinctness allude to the Auá being a separate species or is a separable subspecies?Based on current taxonomic principals, for Auá to be regarded as a valid and distinct species from aestiva, it would have to come in contact with aestiva and not hybridize. As an example, Amazona ochrocephala and Amazona farinosa come in contact within parts of their range but they are clearly separate species because they do not hybridize. Subspecies, however, are allowed to cross when they come in contact with each other.For years I thought that Auá did not hybridize with the typical aestiva but I have seen individuals in the wild at the periphery of the range where they come in contact with aestiva that did not have the defined yellow bib; indeed the birds clearly displayed features that suggested a cross between Auá and aestiva. Data from molecular genetics studies suggests that the true Auá are genetically different. This form also seems to nest terrestrially in termitaria, though much more research needs to be conducted. This concept of ground nesting may seem ludicrous, but the same skepticism surfaced when in Psittaculture (1991) I indicated that Alipiopsitta xanthops bred in terrestrial termitaria and was not an Amazon parrot; it was at the time known as Amazona xanthops. Now it is widely accepted that xanthops commonly nests terrestrially and that it is a member of a separate genus (Alipiopsitta).
My hypothesis is that the Auá is a distinctive form that will eventually be classified as a subspecies. That it hybridizes with aestiva is as pointed out acceptable at a subspecies level.
- The contact zone between aestiva and xanthopteryx is very broad. Throughout much of central and southern Mato Grosso and Paraná, Brazil, the two forms integrate freely; some populations also appear to hybridize with Amazona ochrocephala and this will eventually result in a restructuring of the species we currently regard as distinct or allied. Birds from these zones, even from the same clutch, can display predominately red or an equal distribution of red and yellow from the bend of the wing. The intergradation is acceptable at a subspecies level and thus does not impugn the validity of a subspecies.
- Within Brazil, one finds tremendous variability in the amount of yellow and blue on the head, but there is constancy if one examines a large enough series of birds. In general terms, birds from Brazil north of southern Mato Grosso, Mato Grosso do Sul and São Paulo have limited amounts of yellow on the head; it rarely extends beyond the ear coverts and typically extends just past the rear part of the periophthalmic ring. The blue is restricted to the forehead and forecrown. South of these three states, one finds birds with much more color. I have found individuals at Bonito in Mato Grosso do Sul, Poconé in Mato Grosso and Itapetininga in São Paulo that had yellow extend beyond the ear coverts to the latter part of the crown and throat. These individuals occurred in populations of less colorful individuals.
Brazilian specimens from the north-east are larger and longer than those from Mato Grosso and São Paulo but smaller than xanthopteryx from the Chaco.
Individuals from Bolivia, Paraguay and Argentina also show tremendous color and size variation. Birds from eastern Paraguay and most of Formosa province in adjacent Argentina tend to be smaller and duller compared to those from the Chaco region, which are more colorful (sporting more yellow on the head and the bend of the wings), are larger, possess a longer tail, have hints of yellow to the thighs and have lighter green underparts, often bluish hinted. Individuals slightly smaller than those from the Chaco and possessing less yellow to the head, more blue on the head, more red to the bend of the wing and a darker green underside occur in western and north-western Salta and Jujuy in Argentina, central Paraguay and central Bolivia.
Individuals with an equal amount of yellow and blue to the head, the blue being lighter, and about the same amount of red and yellow to the wing occur in Santiago del Estero and Tucumán in Argentina. In size they resemble Chacoan birds.
The Chacoan form appears to nest at a different time than the other types. As an example, within the Argentina range, which extends from Juan José Castelli in Chaco Province to the city of Joaquín V. Gonzalez in Salta and south to Santiago del Estero, the young fledge up to a month after the other types.
- Individuals with significant blue in the face (the yellow being restricted to the periophthalmic region) occur in all populations, but in Brazil appear to be concentrated to the southern states of São Paulo, Rio de Janeiro, Paraná and Rio Grande do Sul. Some of these populations are likely introduced. These birds possess both red and yellow in the wings.
The Brazilian blue-headed birds differ significantly from the individuals found in the Sierra de Santa Bárbara in the Argentine states of Salta and Jujuy. These individuals display an opaque green color, completely green bend of the wing and green heads with sometimes a blue wash but no yellow. They are small in size and are slim in build. In many ways they resemble an Amazona mercenaria. This population seems isolated and thus would appear to be genetically distinct. Attempts to study it have not been carried out. Aviculturally speaking this form may be novel but its dull coloration would not make it coveted.
- The bird currently called Pyrrhura perlata perlata was once called Pyrrhura rhodogaster, until evidence surfaced that in fact the skins used to name the red bellied form were in fact perlata, the Pearly Conure, another species. I believe that the same has occurred with Amazona aestiva: the form named by Linné was in fact the form subsequently identified by Berlepsch as xanthopteryx, leaving the red wing form without a name and making Berlepsch´s xanthopteryx invalid. This leaves open this species to name changes.
To summarize my perception of the races of Amazona aestiva requires that a principal from herpetology or the aquarium hobby to be borrowed: geographic variants. Snake breeders often refer to a form by its geographic distribution. The form of the Corn Snake Pantherophis guttatus from the Okeetee Hunt Club in Florida, for example, is called the Okeetee Corn Snake and the African cichlid Tropheus duboisi from the Kigoma side of Lake Tanganyika is called Tropheus duboisi “Kigoma” to differentiate it from other color forms of the species from other parts of the lake. I believe that our increasing knowledge of parrots in the field justifies borrowing this concept. It allows certain distinct, localized forms to be identified, even though they have not been formally described as a valid subspecies. This is already the case with the form Auá referred to in Europe as ´Bahia´. For the short term this is acceptable, though in this case I believe that this form should be named as a subspecies. I favor the use of Auá over ´Bahia´ in the vernacular simply because this form is not isolated to a small area but rather a swatch that stretches across at least four Brazilian states.
The Chacoan bird also deserves to be identified as different by scientific name. It not only has a distinct appearance but nests after the typical, less colorful form.
The nomenclature also needs to be reviewed, as the name aestiva clearly references the form subsequently described by Berlepsch.
The new nomenclature would require that the red winged, Sierra de Santa Bárbara, Auá and Chacoan forms be named, with the elimination of the apparently invalid (because of duplication) xanthopteryx.
Finally, because one deals with so much color variation in Amazona aestiva, I favor pairing like birds. This insures that at least localized forms be kept similar through generations of breeding. With this parrot this is difficult but it is not impossible. Special attempt, in particular, needs to be given to Auá to insure that breeding with birds from a contact zone does not occur. Maintaining form purity is important for this very attractive form.
Now to aviculture. As aviary birds, Amazona aestiva is the most commonly bred member of the genus, being established worldwide. It is also one of the few Amazons that is reared in commercial numbers for the pet trade; their “talking” ability is recognized worldwide and creates a demand that seems to invariably exceed production. Their willingness to nest, propensity for producing viable eggs (infertility is probably the most common problem I hear about in this genus) and reliability as a breeder contributes to the success.
I have bred five generations of this species and have visited some of the larger breeding facilities worldwide. Marcia Weinzettl has shown me several collections in Brazil where this parrot is reared in commercial numbers. The combined information does provide a manual for success:
- Pairs should be flighted in same sex groups outside the breeding season or the pairs can be left in their cage but any visual barrier removed, to allow the males to see each other through the start of the breeding season. The introduction of a pair into a breeding cage or the ability to display to males in an adjacent enclosure has a stimulating effect.
- At the onset of breeding season, a visual barrier should be erected to prevent males from agitating each other to the point where they may aggress their mates.
- The diet should be enriched at the approach of the breeding season. We feed our aestiva pellets as the sole diet for 8 weeks prior to the onset of the breeding season, when the diet is supplemented with considerable fruits (mainly papaya, guava, mango and other tropical fruits—I limit the feeding of cultivated fruits which have been produced for the human palette and contain an inordinately high amount of sugar), vegetables (principally steamed carrots, sweet potatoes and pumpkin, which are high in beta-carotene, but also cooked broccoli, thawed corn, peas and lima beans, and Moringa leaves), sprouted seeds and pulses (various types of peas, mung beans, lentils, small sunflower, safflower and more) and a cooked mixture that is based on whole grain pasta. The intention is to enrich the food and bring about reproduction. After breeding, we eliminate the sprouted seeds but feed fruits, vegetables and pasta mix until eight weeks prior to breeding, when they receive the austere diet. The abrupt change from a dry to a primarily wet diet seems key in inducing breeding.
- Being seasonal nesters, Amazons produce a single clutch if they are allowed to incubate their eggs and rear their young to full term. Experimentation over many years—the intention was to apply the findings to endangered species requiring high numbers of young to be produced relatively quickly—has shown that it is possible to maximize production. This is achieved by removing the first three eggs as they are laid. They are incubated artificially. The hen is then allowed to continue to lay and incubate the next eggs, or the completion of the clutch, for less than 15 days; in aestiva the ideal time is 12 days. In most pairs there is only a slight hiatus between the laying of the first three and the remaining three or four eggs in the clutch. These eggs are removed for artificial incubation after the oldest is 12 days old. Most hens will then produce a third clutch. This clutch can start from 21-33 days after the eggs are removed. These eggs should be left under the pair, which will generally rear them through fledging; Amazons tend to be in my opinion reliable parents. If eggs are removed as they are laid, the number produced is never as high as when the above technique is applied.
In aestiva the incubation period is 26-28 days. I have found that the descendants of birds that I personally collected many decades ago in the area around Tres Isletas in the Argentina Chaco have an incubation period that is 27-28 days while individuals from Formosa, also in Argentina, consistently hatched at 26 days. The young are easily hand-reared. Sexual maturity is reached by 3 years of age. Rearing the young in groups and allowing natural pairing seem to contribute positively towards early breeding. Force pairing can have a delaying factor.
The Blue-front in all its forms is a stunning and esteemed species as a pet and aviary bird that justifies its cherishes position in aviculture worldwide. They have always attracted a special interest and have been the focus of extensive field research on my part. They have and will always hold a special place in my collection. So if they become available, do not pass this gem up, as they will surely soon capture a special place in your home or aviary.