Citizen and satellite data establish precise distribution maps for threatened parrots

Conservation projects

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Let’s say that you have a burning desire to see a particular kind of parrot in the wild. After several visits and a lot of effort you still have not seen or heard it, and the frustration is understandable. Perhaps the parrots were present, but you simply had the bad luck not to detect them. On the other hand, maybe they were never present in the places you visited because the existing map of the species’ distribution is inaccurate. Accurate maps of species ranges can not only improve the chances of encountering your target parrot, but more importantly are essential to inform conservation actions for threatened species.

Until now, such maps have been time-consuming to produce, as well as to update in the face of changes in the distributions of species induced by environmental changes, related for example to climate or land use. However, help is at hand. A recent scientific article* describes a new approach to mapping distributions, of 1,151 terrestrial bird species with published ranges less than 125,000 km2 in Central and South America, by computer batch processing utilising widely available stored data. The technique combines existing maps of distribution (from BirdLife International – criteria at: http://datazone.birdlife.org/species/spcdistPOS) with the ever-increasing crowd-sourced eBird data of presences and absences from frequently surveyed locations (https://ebird.org/about/resources/sharing-your-sightings-on-ebird), plus high resolution satellite data on forest cover and elevation to map the Area of Habitat (AOH) available to each species. AOH is the habitat available to a species within its distribution.

The results of applying the new technique show that on average, Areas of Habitat (AsOH) are 12% larger than published distributions. Thus, eBird records are expanding the known distributions of many, but not all, species and revealing substantial differences between threatened and non-threatened species (in the IUCN Red List categories). Approximately 40% of Critically Endangered (CR), 43% of Endangered (EN), and 55% of Vulnerable (VU) species have AsOH larger than their published ranges, compared with 31% for Near Threatened (NT) and Least Concern (LC) (non-threatened) species. Hence, threatened Neotropical bird species are generally more widespread than previously estimated, but what is the situation for parrots?

In the overall data-set, 61 parrot species were initially included, comprising 7CR (including 2 possibly extinct or extinct), 15EN, 16VU and 23 non-threatened. The new analysis of the distributions of these species is of substantial interest to the Loro Parque Fundación, which has been supporting conservation projects for 30 of the species, 83% of which are in threatened categories. Of the original 61 species, 14 were excluded from complete analysis for reasons of taxonomic uncertainty, or having less than 10 (or no) qualifying eBird records, or being extinct. The conservation status of the remaining 47 species was, 1CR, 11EN, 16VU and 19 non-threatened. Table 1 summarises the results of applying the new technique.

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Of the 47 species fully analysed, 25 species, of which 18 (72%) are recognised as threatened with extinction, have their areas of habitat increased by this new analytical approach, whereas 22 species, of which ten (45.5%) are threatened, have their areas of habitat decreased.

In the category of CR, the only species which could be included in the analysis was the Indigo-winged Parrot (Hapalopsittaca fuertesi) of the Central Andes of Colombia, which under this analysis shows a reduction of the AOH to 89% of the previous estimate of 1,413km2. Of the EN species, the largest expansion of AOH, by a remarkable 906% from the previous 596km2, was for the Thick-billed Parrot (Rhynchopsitta pachyrhyncha) of Mexico. Also present in Mexico, the Yellow-headed Amazon (Amazona oratrix) has the largest AOH of an EN category species, 365,147km2, again resulting from a very substantial percentage increase.

Of concern is the Lear’s Macaw (Anodorhynchus leari) of Bahía, Brazil, which now has an estimated AOH of 1,255km2, this being only 17% of the previous range of this species. Also of concern is the Grey-breasted Parakeet (Pyrrhura griseipectus), of north-east Brazil, which the analysis indicates has the smallest AOH of all EN category species, being only 475km2, or 69% of the previous estimate.

Of the VU category species, the largest increase in AOH was to 45,359km² for the Red-browed Amazon (Amazona rhodocorytha) of Brazil’s Atlantic Rainforest region, constituting nothing less than an increase of 1,697%. The foremost shrinkage of area in this category was for the Yellow-faced Parrotlet (Forpus xanthops) of Peru, which is now estimated to have an AOH of 699km², only 30% of the former estimate. The VU species with the largest (increased) AOH, 85,244km², is the Spot-winged Parrotlet (Touit stictopterus), which is found in the east Andean foothills from Colombia to Peru.

Of the parrot species not included in IUCN threatened categories, the Golden-capped Parakeet (Aratinga auricapillus) of south-east Brazil is the species with the largest AOH, being 362,380km² from an increase of 555%. At the other end of the scale, the non-threatened species  with the smallest AOH is the Red-eared Parakeet (Pyrrhura hoematotis) of Venezuela, having only 2,712km² or 43% of the past estimated area. To give perspective to these distribution sizes, the area of London, U.K. is 1,572km².

At least for the parrots, the results of applying this new technique are marginally positive, but they also show that there is no room for complacency in the fight to prevent extinctions.

Author: David Waugh, Correspondent, Loro Parque Fundación

Photos credits:  1,3,4 – Huang et al, 2021; 2,5 – Loro Parque Fundación; 6 – Nortondefeis/CC BY-SA 4.0; Title photo – Sylvio Adalberto/CC BY-SA 4.0

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