Great Green Macaw

The great green macaw (Ara ambiguus), also known as Buffon's macaw or the great military macaw, is a critically endangered Central and South America parrot found in Nicaragua, Honduras, Costa Rica, Panama, Colombia and Ecuador. Two allopatric subspecies are recognized; the nominate subspecies, Ara ambiguus ssp. ambiguus, occurs from Honduras to Colombia, while Ara ambiguus ssp. guayaquilensis appears to be endemic to remnants of dry forests on the southern Pacific coast of Ecuador. The nominate subspecies lives in the canopy of wet tropical forests and in Costa Rica is usually associated with the almendro tree, Dipteryx oleifera.

Taxonomy

The great green macaw belongs to the genus Ara, which includes other large parrots, such as the scarlet macaw, the military macaw, and the blue-and-yellow macaw.

This bird was first described and illustrated in 1801 by the French naturalist François Le Vaillant for his Histoire Naturelle Des Perroquets under the name "le grand Ara militaire", using a skin deposited at the Muséum national d'histoire naturelle in Paris. Le Vaillant states that it is not certain if the bird is truly a distinct species of parrot, or, as he thinks more likely, it is specific varietal race of the military macaw, but nonetheless, he must mention that its existence merits notice. The bird was subsequently named Psittacus ambiguus by the Thuringian Johann Matthäus Bechstein in the first tome of the fourth volume, published in 1811, of the series Johann Latham's Allgemeine Uebersicht der Vögel, the greatly expanded German translation of the Englishman John Latham's A General Synopsis of Birds. Bechstein mentions le Vaillant's reluctance to consider it as an independent species, but explains that having examined a living bird, he considers it a valid species, mentioning the size difference and enumerating numerous other characteristics he deems distinctive.

After almost 200 years, the binomial name was changed from Ara ambigua to Ara ambiguus in 2004, as it was decided that the word ara was in fact male, despite ending in an -a (see epicene).

There are two subspecies which are geographically isolated at present: Ara ambiguus ssp. ambiguus, which has the largest distribution range (Central and northern South America), and Ara ambiguus ssp. guayaquilensis, which only occurs in Ecuador. The Ecuadorian subspecies is sometimes referred to as Chapman's macaw or Chapman's green macaw. American naturalist Frank M. Chapman shot the type specimen of his proposed new taxon in 1922 on a hill in the Cordillera de Chongon, twenty miles northwest of Guayaquil, Ecuador, and first described the taxon in 1925 in a report on the newly collected bird skins he had brought back to the US from Ecuador.

Due to the morphological variability of ssp. guayaquilensis, with a number of specimens of this taxon being identifiable as the military macaw, in 1996 Berg and Horstman, themselves referencing Fjeldså et al.., mentioned it might best be synonymised with A. militaris, or suggested there might be gene-flow between all three populations. A 2015 study comparing the mitochondrial DNA of different populations of the military macaw and this species found that while these two species are clearly differentiated, as well as different populations of the military macaw in Mexico, no genetic difference between ssp. guayaquilensis and the nominate taxon was found (at least regarding the mitochondria). This indicates that the division of this species into two subspecies is likely not taxonomically valid. It is also possible that the Ecuadorian populations do not all belong to ssp. guayaquilensis.

Description

Great green macaws are the largest parrots in their natural range, the second heaviest macaw species (although they are relatively shorter tailed than other large macaws such as the red-and-green macaw and are thus somewhat shorter), and the third heaviest parrot species in the world. This species averages 85–90 cm (33.5–35.5 in) in length and 1.3 kg (2.9 lb) in weight. They are mainly green and have a reddish forehead and pale blue lower back, rump and upper tail feathers. The tail is brownish-red tipped with very pale blue. The bare facial skin is patterned with lines of small dark feathers, which are reddish in older and female parrots. Juveniles have grey-coloured eyes instead of black, are duller in colour and have shorter tails which are tipped in yellow.

The main morphological distinction with the subspecies guayaquilensis is that this bird has a smaller, narrower bill.

The great green macaw appears superficially similar to, and may easily be confused with, the military macaw where their ranges overlap.

Distribution and habitat

The great green macaw lives in tropical forests in the Atlantic wet lowlands of Central America from Honduras to Panama and Colombia, and in South America in the Pacific coastal lowlands in Panama, Colombia and western Ecuador, where they also occur in deciduous (seasonal), dry tropical forests. In Colombia, where both species occur, it prefers more humid woodlands than the closely related military macaw. The habitat where it breeds in Costa Rica is practically non-seasonal, evergreen rainforest, with rain some ten months of the year, a precipitation of 1,500 to 3,500 mm a year, and an average temperature of 27 °C throughout the year. In Costa Rica the habitats where great green macaws occur during breeding season is dominated by the almendro (Dipteryx oleifera) and Pentaclethra macroloba, with secondarily raffia palms (Raphia spp.) dominated wetlands. It is usually observed below 600 m above sea level in Costa Rica during the breeding season, but disperses to higher elevations to 1000 m after breeding, and can be seen as high as 1500 m in southern Panama.

The population in Ecuador is thought to be split into two disjunct areas in the western coast of the country, the coastal mountain range of the Cordillera de Chongon in southwestern Ecuador, and in the far north bordering Colombia from the west in Río Verde Canton in central coastal Esmeraldas Province, stretching eastwards into Imbabura Province. This bird is very uncommon in Ecuador. In Colombia it is reasonably common in the Darién region and the Gulf of Urabá near the Panamanian border, and is also found in the north of the Serranía de Baudó mountains on the Pacific coast, the West Andes, and found eastwards to the dry forests of the upper Sinú valley near the Caribbean coast. In Panama it is common in some areas such as the Caribbean slope and in parts of Darién National Park such as the famous Cana birdwatching site and across the Alto de Nique mountain and the adjacent border with Colombia. It is also found in Panama in the mountains of the Serranía de Majé near Panama City and the southern Cerro Hoya mountains. In Costa Rica in the early 2000s, the reproductive range of the great green macaw was thought to be restricted to 600 to 1120 km2 of very wet forests in the northeast along the border with Nicaragua. After the breeding season this population disperse in larger groups to higher altitudes both southwards in the central cordillera of Costa Rica as well as northwards to Nicaragua. Another population was known by 2007 in the hills inland between Old Harbour and Sixaola near the northern Panamanian border. In Nicaragua there are populations in the east of the country in the Bosawás, Indio Maíz Biological Reserve and San Juan reserves. It occurs in a number of areas in eastern Honduras such as the Río Plátano Biosphere Reserve, where it is rare.

Historically this macaw had a larger range. For example: in 1924 it was collected in Limón, Costa Rica, in 1904 and 1907 around Matagalpa, Nicaragua and in 1927 in Almirante, Panama.

Introduced range

This is a rare introduced species in Singapore, where it can be seen on Sentosa island and in Ang Mo Kio Town Garden West.

Ecology

To improve the state of knowledge of the natural history the great green macaw in Costa Rica a large study using radio telemetry was launched by George V. N. Powell and conducted by a team of researchers from 1994 to 2000. The main objectives were to determine the home range of A. ambiguus, characterize the habitats that it frequents and learn more about its feeding habits, ecological associations, abundance, and reproduction and nesting habits.

Behaviour

Birds are usually observed in pairs or small groups of up to four to eight birds, very rarely more. In Costa Rica it breeds in the lowlands, but disperses to higher elevations afterwards, gathering together in flocks which migrate in search of food. In Costa Rica these flocks usually consist of up to 18 birds. This species rests and forages in the upper areas of the canopy. In Nicaragua these macaws are notably unwary of humans and when feeding will often allow a person to come quite close to them.

Older residents of the region where Ara ambiguus ssp. guayaquilensis lives relate that until the 1970s or 1980s it would gather together to undertake a daily migration from the mangrove forests at estuaries along the seashore near the village of Puerto Hondo, crossing the Guayaquil-Salinas road in flocks, to the dry hilly woodlands of the Cerro Blanco Forest.

Vocalisation

An extremely loud, raucous "aak, raak" that can be heard at great distances. Captive birds will emit loud squawks and growls, and also make creaking or groaning sounds.

See external links for an example.

Diet

Birds have been recorded feeding on a wide variety of foodstuffs in the wild such as seeds, nuts and fruits, but also including flowers, bulbs, roots and bark. In Costa Rica at least 38 plants are used for food, of which the most important are the seeds or nuts of Dipteryx oleifera (almendro), Sacoglottis trichogyna, Vochysia ferruginea and Lecythis ampla. This macaw is able to crack open larger nuts than the sympatric scarlet macaw. The beak is particularly suited for breaking open large nuts. Within 50m distance from the lagoons in Maquenque National Wildlife Refuge the following plants have been recorded as food plants for the great green macaw: the palms Iriartea deltoidea, Raphia taedigera, Socratea exorrhiza and Welfia regia, the large shrub Solanum rugosum, the emergent trees Balizia elegans and Dipteryx oleifera, and the trees Byrsonima crispa, Cespedesia macrophylla, Croton schiedeanus, Dialum guianense, Guarea rhopalocarpa, Laetia procera, Maranthes panamensis, Pentaclethra macroloba, Qualea paraensis, Sacoglottis tricogyna, Vantanea barbourii, Virola koschnyi, V. sebifera and Vochysia ferruginea. A major source of food in Costa Rica during breeding time is D. oleifera, 80% of the observations of foraging birds in Costa Rica in a 2004 study were in this tree (albeit in an area where this is the most common tree). It will fly large distances to feed on these trees, also going to trees found in pastures and semi-open areas. It feeds on the trees starting in September, while the fruit is still immature, and continues feeding on them until April. In November D. oleifera forms the mainstay of the diet. Sacoglottis trichogyna is the second most important food here in this period, especially when D. oleifera is not available. It feeds on this species from April to August. When these two trees are no longer in fruit after June the macaws feed on many other species. It is theorised that some movements of the local population of this bird may be due to the asynchronous ripening of D. oleifera fruits. Great green macaws use D. oleifera during breeding season for both feeding and nesting. In Unguía, Chocó Department, Colombia, the species was also observed to feed on D. oleifera. After the two most important trees of the breeding season are no longer in fruit the macaws gather together in flocks and begin to migrate away from the Dipteryx forests. Terminalia catappa, the beach almond (locally also known as almendro), is a commonly planted and naturalised tree from the Old World, which these macaws have also been observed feeding on in gardens in Suerre, Costa Rica, between July and September during their migrations – they use fragments of the leaves to help scrape the flesh off the fruits in order to obtain the nuts, and depart after feeding on the trees for 40 minutes. This tree is also one of the most important foods for the scarlet macaw.

A 2007 study conducted on Ara ambiguus ssp. guayaquilensis in southwest Ecuador showed the most important food plant by far was Cynometra bauhiniifolia, producing more food than all other food plants combined. It further revealed that the abundance of food within a habitat is not related to the abundance of macaw, however, the researchers found that there was a link between the abundance of food and the amount of time great green macaws spend at one place. A popular food plant and nesting tree in Ecuador is also Vitex gigantea.

According to BirdLife International a report from central Colombia recorded that a pair of macaws were observed in Ecuador eating orchids. This, however, appears to be utter nonsense, as the work cited reports no such thing.