The nominate form of Scarlet Macaw (Ara macao macao), here a male from Bronx Zoo, US. On this specimen you clearly see the large areas of the green color in the different wing coverts, and the greatly reduced number of yellow feathers in the same place, giving a somewhat more variegated impression of the bird. Photo from the Internet.
Patterns of diversification
Fluctuations in the distribution of habitats in response to changes in temperature and precipitation are commonly considered to be
key factors governing the historical biogeography of lowland ecosystems across the Central and South America.
Regional differences in the intensity and duration of population fragmentation and associated demographic changes provide a theoretical framework
to explain patterns of evolutionary divergence within Scarlet Macaws. In the case of Ara macao cyanopterus, the subspecies’ range encircles the Central American landmass, geographically constrained by an extensive system of
central highlands and the coastal waters of the Atlantic and Pacific Oceans. The Scarlet Macaws’ preferred humid lowland habitats are heavily dependent on the availability of fresh water, and thus shifts in distributions would closely follow this critical
resource. The genetic signatures recovered among mtDNA haplotypes may reflect the fragmentation of ancestral Ara macao cyanopterus into allopatric refugia (non-overlapping distribution areas during periods of unfavorable conditions).
The presence of several distinct Ara macao cyanopterus haplogroups appears to increase levels of overall sequence variation, as diversity indices decline for the majority of haplogroups when treated as separate units.
different pattern of genetic variation emerges upon examination of Scarlet Macaw populations across lower Central and South America. Ara macao macao is represented by only two haplogroups, differentiated by two fixed nucleotide bases
and geographically separated by the Andean Mountains.
Conservation implications and threats
Common throughout its global distribution through the ages, populations of Scarlet
Macaws have experienced widespread demographic declines and local extinctions due to capture for the pet trade and habitat destruction. Furthermore, anthropogenic pressures have been most severe in Central America, where high human population densities and
associated resource demands put tremendous strain on the region’s ecosystems. This has resulted in a 22 % reduction in primary forest within a 20-year period from 1990 to 2010 (FAO 2010).
The confirmation of genetic diversity reveals a critical
gap between conservation needs and conservation status for these charismatic parrots. At present, Scarlet Macaws are considered a species of “Least Concern”, given global demographic trends, population size and extent of available habitat are above
designated thresholds for threatened status (IUCN 2015). Splitting Scarlet Macaws into two distinct conservation units, however, immediately transforms the conservation status of this group. Approximately 83 % of preferred lowland habitats are located within
the Amazon Basin, along with the majority of the estimated census population of 20.000 - 50.000 individuals for Ara macao (BirdLife International 2011). Deforestation rates are declining throughout South America, dropping from 0,49
to 0,41 % in the past decade (FAO 2010), with human population growth rates falling in concert from 1,17 % to 1,07 % (CEPAL 2013). Therefore, robust populations of Ara macao macao ranging across the Amazonian lowlands may indeed qualify
for “Least Concern” status.
Opposite, the situation faced by Scarlet Macaws in Central America is far more precarious. Annual human population growth rates are currently 1,59 % and human
densities are 4,2-fold greater relative to South America, putting tremendous strain on the region’s natural resources. Forest area in Central America declined by an average of 1,19 % annually between 2000 and 2010, the highest rate reported
by the United Nations (FAO 2010). The loss of important foraging and nesting habitats, coupled with intense nest poaching for the pet trade, have decimated Ara macao cyanopterus with fewer than 4.000 wild Ara macao
cyanopterus remaining in isolated forest fragments throughout upper Central America. Recovery of five unique mitochondrial haplogroups within the Ara macao cyanopterus lineage highlights the evolutionary
significance of these populations, further advocating that Ara macao cyanopterus should be up listed to “Vulnerable” status.
Rigorous delineation of conservation
targets is needed
The new study also pointed out that current conservation designations may need to be re-evaluated. The use of the term “subspecies” in taxonomy and conservation biology is considered somewhat controversial given
the arbitrary assessment criteria’s and poor connections to evolutionary history. Therefore, rigorous delineation of conservation targets within Scarlet Macaws is needed to create a solid foundation for conservation assessment, management strategies,
ease of daily handling, etc. The new study has helped to create such clarity, and a clear definition of a subspecies provides a unique conservation target, which hopefully may help to save it in its natural habitats in the long run.
As already stated, it is estimated that fewer than 4.000 Ara macao cyanopterus remain in wildlife in Central America, scattered across areas in smaller isolated forest fragments which makes it very vulnerable. In
comparison, BirdLife International estimates that there are 4.300 Hyacinth Macaws (Anodorhynchus hyacinthinus) left in the wild with a much larger range of 2.850.000 km2, and it is categorized as “Vulnerable”.
is my assessment that if Ara macao cyanopterus in the future can become an independent wild conservation subject, the chances for protecting these wonderful birds in the wild will be much better. However, BirdLife International still
only operates with the Scarlet Macaw (Ara macao) on species-level. As the Scarlet Macaw (Ara macao) in general is widely distributed and thought to be relatively tolerant of degraded habitat, the species
is considered of “Least concern” by the IUCN (2016) and BirdLife International though it also is listed under Appendix I of CITES.
In this area, the United States is significantly further ahead; in 2019 Scarlet Macaws (Ara
macao) received protection under the United States Endangered Species Act (ESA). The northern subspecies of the Scarlet Macaw (Ara macao cyanopterus)
has thus been listed as endangered and a distinct population segment
(DPS) of the southern subspecies (Ara macao macao) as threatened. The southern subspecies (and strangely enough subspecies crosses as well) of the Scarlet Macaw are also added to an existing special rule for parrots under section
4(d) of the ESA. This continues to provide needed protections while allowing for interstate commerce and the import and export of certain captive-bred birds provided the requirements of the Wild
Bird Conservation Act and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) are met. So, the Scarlet Macaw is now protected
by both this important U.S. conservation law and by the international conservation agreement.