Lear's Macaw

Lear's macaw (Anodorhynchus leari), also known as the indigo macaw, is a large all-blue Brazilian parrot, a member of a large group of neotropical parrots known as macaws. It was first described by Charles Lucien Bonaparte in 1856. Lear's macaw is 70–75 cm (27+1⁄2–29+1⁄2 in) long and weighs around 950 g (2 lb 2 oz). It is coloured almost completely blue, with a yellow patch of skin at the base of the heavy, black bill.

Although there are records of the macaw from Britain from the early 1830s, this bird was only generally recognised as an independent species in the late 1970s. It is rare with a highly restricted native range, which was only discovered in 1978, although intensive conservation efforts have increased the world population about thirtyfold in the first two decades of the 21st century. It inhabits a dry desert-like shrubby environment known as caatinga, and roosts and nests in cavities in sandstone cliffs. It mostly feeds on the nuts of the palm species Syagrus coronata, as well as raiding maize from local farmers. Its ecology also appears linked to cattle ranching.

Taxonomy

Lear's macaw was named after the famous poet, Edward Lear, who was also an accomplished artist. In his teens in the early 1830s, Lear published a book of drawings and paintings of live parrots in zoos and collections, Illustrations of the Family of Psittacidae, or Parrots. One of his paintings in his book strongly resembles this species, and although at the time he titled the work as 'hyacinth macaw' — a larger, darker species with a differently shaped patch of yellow skin adjacent to the base of the bill, which it closely resembles — not everyone agreed, and a quarter century later, in 1856, the illustration was given a species description by the French ornithologist and nephew of Emperor Napoleon, Prince Charles Lucien Bonaparte, who chose to commemorate the poet in the specific name. Most authorities, however, were unconvinced of the distinctness of the new taxon. The rarely seen bird was not considered a distinct species until 1978, when German-born, Brazilian-naturalised ornithologist Helmut Sick finally located the wild population.

Description

Lear's macaw is 70–75 cm (27+1⁄2–29+1⁄2 in) long and weighs around 950 g (2 lb 2 oz).

The body, tail, and wings are dark metallic blue with a faint, often barely visible, tinge of green, and the head is a slightly paler shade. It has an area of pale-yellow skin adjacent to the base of its beak, and orange-yellow eye rings. It has a large, blackish beak and dark grey feet.

Lear's macaw is similar to the larger hyacinth macaw and the slightly smaller glaucous macaw. The hyacinth macaw can be distinguished by its darker plumage, lack of greenish tinge, and a differently shaped patch of yellow skin adjacent to the base of the bill. The glaucous macaw is paler and has a more greyish head.

Feeding

The primary diet of Lear's macaw are the nuts (as many as 350 per day) of the palm Syagrus coronata, locally known as licuri, but the seeds of Melanoxylon, Jatropha mollissima, Dioclea, Spondias tuberosa, Schinopsis brasiliensis and Zea mays are also eaten, as well as the flowers of Agave.

The macaw usually forages in groups. They preferentially feed on the palms where they grow in groves, mixed together with taller trees. At least thirty confirmed feeding localities are known throughout the range. A tall tree is selected by the flock as base to carefully inspect the feeding area. First a pair descends to the level of the palms to assess the suitability, the pair then returns to base, and then the entire flock descends to decide if it is worth staying around. If it is, then the macaws generally feed directly at the site, tearing the fibrous pulp off the fruit to obtain the extremely hard and thick-shelled nut. The pulp is discarded. The heavy bills appear to have evolved specifically to crack open the palm nuts with a chisel-shaped edge, being precisely of the correct size and shape. Upon occasion the birds maw fly off to a better perch to consume the nut, sometimes even carrying a branchlet with a few fruit. Such perches are generally a branch of a tall tree or a cliff face, and the ground below such a perch will become littered with piles of cracked palm nut shells, and are thus easily spotted.

A mystery regarding plants in the Neotropics with very large fruit or seeds is which type of animal disperses the seeds. Elsewhere on earth large herbivorous mammals are the dispersal agents for such plants, but these are largely absent in South America today. The prevailing theory is that such mammals once performed these functions, but that Late Pleistocene extinctions of most of these animals had rendered large-fruited plants impotent regarding the spread of their seed, at least until humans introduced livestock. The Syagrus coronata palm, however, may have found a way to avoid such a fate, despite its large nuts. Macaws are very messy eaters, and this species is no different. A study found a significant number of undamaged palm nuts on the ground below the branches or rocks where the birds occasionally carry their harvest.

A method by which the birds may secondarily disperse the nuts is by their habit of coming down to the ground to search out the nuts regurgitated by cattle, which eat the fruit, but usually cough up the large seeds, cleaned of pulp, which often aggregate in areas where the ruminants rest, and some also appear to be viable after this ordeal. Flocks of Lear's macaws will congregate at cattle corrals and walk around on the bare ground of rumination sites. After finding one, the regurgitated nut is often eaten on a high perch elsewhere. Cattle also alter the ecosystem by creating open spaces in the environment. It is thus possible that cattle ranching simulates the original ecology of Bahia, before the native megafauna had been wiped out around the time the Native Americans colonised America. Just 11,000 years ago, perhaps these macaws were commensals to one or some of the giant browsing herbivore species of northeast Brazil which traveled in herds, and the palms depended on this relationship for effective dispersal.

Lear's macaw are somewhat of a pest species, and a major problem caused by the animals is their habit of raiding the plots of local subsistence farmers to consume maize (Zea mays). In order to minimize the chagrin of victims and stop them from shooting at the birds, a scheme was implemented in 2005 to compensate farmers for crops lost to the animals with bags of maize from elsewhere. During the COVID epidemic this scheme was halted, because most of the farmers were elderly, but the macaws were not shot, as COVID restrictions prevented farmers from marketing their corn anyway.

Breeding

The mating season starts at the beginning of the summer rains, at the start of the year, and extends up to May, when the young begin to fledge and leave the nest. A pair of Lear's macaw lay two or three eggs per year. The eggs are incubated for approximately 29 days. Although some pairs produce three chicks, the average survival rate is two per pair. However, not all pairs of birds in the wild population mate often or at all. The young remain with their parents for up to a year. Juveniles reach sexual maturity around 2–4 years of age.

Distribution and habitat

For a century and a half after it had been described, the species was only known from sporadic occurrences in the bird trade, and the whereabouts of the wild population was unknown. A wild population was eventually discovered in 1978 by ornithologist Helmut Sick in Bahia in the interior northeast of Brazil. Until this discovery the birds were thought to be simply a variant form of the closely related hyacinth macaw.

Lear's macaw roosts on sandstone cliffs, which were formed by streams cutting through outcrops. It is known from two colonies at locations known as Toca Velha and Serra Branca, south of the Raso da Catarina plateau in northeast Bahia. In 1995, a roosting site holding 22 birds was located at Sento Sé/Campo Formoso, 200 km (120 mi) to the west.

From these roosts, the macaws travel throughout the region (the municipalities of Campo Formoso, Canudos, Euclides da Cunha, Jeremoabo, Monte Santo, Novo Triunfo, Paulo Afonso, Santa Brígida and Sento Sé), relying on stands of licury palm to find much of their sustenance. This palm stand habitat is thought to have once stretched over 250,000 km2 (97,000 sq mi) in Brazil, but has been much reduced due to clearance for agriculture. Cattle grazing in the palm stands also appear to be damaging and killing the seedlings, thus posing a challenge for the recruitment of new mature palms -such stands were found to have very little young licury palms. In response to this, tens of thousands of palms were propagated and planted in fenced-off areas in the early 2000s.

Lear's macaw also requires pre-existing natural cavities found in the sandstone cliffs in which to nest. The availability of such cavities may eventually limit population growth, and thus one group of conservationists advised that more cavities should be excavated artificially.

Population and conservation status

This species is currently listed as an endangered species (CITES I).

Yamashita, one of the first scientists to study this bird in the wild, in 1987 estimated that the global population numbered just 60 birds in 1983. The estimated global population in 1987 was 70 birds. The wild population was surveyed as some 170 individuals in 2000. Based on this, Birdlife International (BI), which has written the IUCN Red List assessments, gave an estimated population of 150 birds in 2000. BI claimed that the population growth was decreasing, but did not elaborate on their reasoning. The global population was censused at 246 birds in 2001 (Gilardi), 455 in 2003, and the Brazilian Institute of Environment and Renewable Natural Resources (IBAMA) censused 570 wild birds in 2004. In their 2004 assessment, BI gave a much increased population of 246–280 birds, but continued to claim that the population was decreasing, again without reasoning. Barros counted a total wild population of 630 birds in 2006. In June 2007 Fundação Biodiversitas staff counted 751 individuals. Develey counted a total wild population of 960 birds in 2008. In the 2008 assessment BI countered that earlier surveys undercounted the birds, and that the population was not actually increasing. BI estimated a population of 250–500 mature wild individuals in 2008, arguing that because the population was probably increasing, most of the birds counted by in recent surveys were probably juveniles and therefore did not count as to the total population. BI states that if these juveniles mature over the next few years and the population grows from 250–500 to over 250 individuals, the species would need to be downlisted in the future. The population growth was stated to be uncertain, with BI reasoning that because in the 1990s some 40 birds had been trapped for the pet trade, which had represented a "very rapid decline", it was unclear if the increasing population was increasing.