Continued Deforestation Could Wipe out Key Ecological Functions of Parrots Before They Are Documented in Madagascar

Abstract

Madagascar is a global biodiversity hotspot, with approximately 90% of all its plant and animal species being endemic, most of them associated with forest ecosystems. This rich biodiversity is threatened by relentless deforestation; in 2014 only about 15% of the national territory retained highly fragmented native forests, and deforestation continues with worrying forecasts for the coming decades. This rapid loss of habitat is not only causing species losses, but also the loss of important ecological functions that may disappear well before the extinction of the species involved. Here we want to draw attention to the three species of parrots endemic to Madagascar, for which there is a lack of systematically collected data on their distribution and population trends. We compiled available evidence, including data derived from citizen science, suggesting that the distribution and abundance of at least two of the three parrot species have declined in recent decades. These declines are likely driven not only by forest loss but also by persecution for the pet trade, crop protection, and hunting for food. There is also evidence, although still scarce, showing that these parrot species not only act as plant antagonists, but also fulfill mutualistic functions such as seed dispersal by different mechanisms, pollination, and maintenance of plant health. We urge researchers to study the current distribution and population size of the Malagasy parrots, as well as the full antagonism–mutualism spectrum of relationships with their food plants. This is needed for assessing their current conservation status, which may be significantly worse than that reflected by the IUCN Red List, and for identifying important ecological functions that may be lost before the disappearance of the species involved, which can be key to the maintenance and regeneration of the forests they inhabit.

1. Deforestation and Biodiversity Loss in Madagascar

Madagascar, with an area of c. 587,000 km², is the fourth-largest island, a biodiversity hotspot and one of the 17 megadiverse countries of the world [1]; https://www.biodiversitya-z.org/content/megadiverse-countries (accessed on 22 October 2025). This rich biodiversity results from the wide variety of ecoregions [2] and habitats [3] that the island harbors today, and from its geological and evolutionary history. Following the breakup of Gondwana, Madagascar split from Africa during the Early Jurassic period (c. 180 million years ago) and separated from the Indian subcontinent during the Late Cretaceous (c. 90 million years ago) [4]. This long-term isolation allowed native plants and animals to evolve in relative seclusion, resulting in approximately 90% of all plant and animal species being endemic [5].

Human activities, such as forest loss by ‘tavy’, a traditional slash-and-burn agricultural practice imported by the earliest settlers around 2350 years ago [6,7], threaten the rich flora and fauna of Madagascar. Further population growth, zebu cattle grazing since its introduction around 1000 years ago, the reliance on charcoal as a fuel for cooking and the expansion of agriculture increased forest loss over the past century [8,9]. Anthropogenic deforestation sharply increased in recent decades, and it has been estimated that forest cover decreased by almost 40% from the 1950s to c. 2000 [8]. Later, since 2005, the annual deforestation rate has progressively increased to reach 99,000 ha/yr during 2010–2014 [10]. Thus, in 2014 only 15% of the national territory retained native forests, and these were highly fragmented, with around half of the forest surface being located at less than 100 m from the forest edge [10]. In addition to agricultural practices, forest conservation is challenged by the illicit harvesting as well as the state-sanctioned harvesting of precious timber within national parks [11,12]. The most recent estimates of deforestation rates and future forecasts are even more worrying. Deforestation has increased from less than 0.9%/yr in 2000–2010 to more than 2%/yr in 2010–2017 [13], increasing the frequency of fires, and resulting in a 25% decrease in forest cover between 2001 and 2021 [14]. Given the current population growth and extreme poverty in Madagascar—currently classified among the world’s ten lowest-income countries—[14], together with bad governance and an unregulated global market, recent models predicted that 38–93% of the forest present in 2000 will have disappeared in 2050 [13].

Deforestation has strong consequences on biodiversity in Madagascar, since around 90% of its species are forest dependent [15,16]. By modeling the distribution of 2243 plant and invertebrate species, Allnutt et al. [15] predicted that 9.1% of species in Madagascar have been committed to extinction from deforestation between 1950 and 2000. In the case of flagship endemic species, such as lemurs, the impacts of deforestation have been studied and are better understood. At least 17 species of lemurs have become extinct, and from the 111 extant species and subspecies—39 of which were described by zoologists between 2000 and 2008 [17]—105 (95%) are threatened with extinction [18]. However, assessing population declines and extinction risk across the entire rich flora and fauna of the island [15] is difficult because information is lacking for most species. This is the case of parrots (order Psittaciformes), a group largely associated with forest environments and whose conservation is closely linked to forest conservation worldwide [19].

2. The Decline of Parrot Populations in Madagascar

Madagascar is home to three endemic parrots widely distributed throughout the island, ranging in size from the smallest gray-headed lovebird Agapornis canus (14 cm length) to the medium-sized black parrot Coracopsis nigra (40 cm) and the largest vasa parrot Coracopsis vasa (50 cm) (Figure 1) [20]. There have been no population estimation studies of these species, and there is a lack of systematically collected data on their distribution and population trends [21,22]. The gray-headed lovebird and the vasa parrot were last assessed by the IUCN Red List in 2018, and were evaluated as Least Concern due to the lack of information that could prove range contractions or population declines [23,24]. Still lacking population and range distribution data, the black parrot was further evaluated in June 2025 and listed as Vulnerable. It has been argued that the species is suspected to be declining at a rapid rate, likely mirroring or exceeding the rate of forest cover loss, which has exceeded 30% over the past 22 years [25].

Between 21 and 28 August 2025, we conducted censuses in central Madagascar using well-established methods for obtaining relative abundances of parrots, such as walking transects and roadside surveys [26]. After surveying 1654 km during 73 h, we only recorded black parrots on 8 occasions (12 individuals in total), vasa parrots on 5 occasions (11 individuals), and gray-headed lovebirds on 2 occasions (3 individuals). All parrot sightings took place only within or in the immediate vicinity of national parks and other protected areas: Andasibe-Mantadia NP and Ranomafana NP on the east coast, and Kirindy Forest reserve on the west coast. These observations, although they may be highly biased by the short spatial and temporal survey scale, may suggest that the three parrot species have become scarce and are now restricted to the remaining patches of well-preserved forests.

In the absence of specific population studies, citizen science data can help infer patterns of species abundance and temporal trends. For example, the eBird platform (ebird.org (accessed on 15 October 2025)) displays online maps of the global distribution—according to user-reported observations—of each bird species in a grid with 20 × 20 km cells. These maps show how frequently the species was observed in each cell (that is, the % of complete lists of observed bird species in which the species was recorded by observers who visited that cell), and the categorized frequencies can be visualized by selecting and grouping years. We used the information provided by observers in 318 cells distributed throughout Madagascar, grouped for the periods 1980–2010 and 2021–2025 (Figure 2). This approach was used to detect recent changes in the abundance of the three parrot species associated with deforestation that occurred in the previous four decades. There were no differences in the percentage of cells where gray-headed lovebirds were observed with different frequencies, ranging from cells where the species was never observed (0%) to cells where it was observed in 41–100% of the surveys, between the two time periods (Figure 2, ꭕ² = 2.13, df = 5, p = 0.546). However, the frequency of observations of black parrots decreased significantly (Figure 2, ꭕ² = 21.72, df = 5, p < 0.001); the percentage of cells where the species was not recorded increased from 48% to 65%, while the percentage of cells where the species was recorded in 41–100% of the surveys decreased from 10 to 2.5%. The changes were even more striking in the case of the vasa parrot (Figure 2, ꭕ² = 58.34, df = 5, p < 0.001). The percentage of cells where the species was not recorded increased from 52% to 72%, while the percentage of cells where the species was recorded in 11–100% of the surveys decreased from 35 to 8% (Figure 2).

Citizen science data analysis has recently shown changes in the distribution of two species of parrots [27,28]. However, the use of citizen science has certain limitations that could produce biased results [29,30]. Particularly, inferences about population sizes obtained from citizen science platforms should be taken with caution, as the data may be biased by spatial differences in sampling efforts [31]. However, in the case of Madagascar, its attractive wildlife has led to a sharp increase in nature-based tourism since the 1990s, which is directed almost exclusively towards protected areas [32] [Authors pers. obs.]. These areas contain the last remaining forests, and thus the likelihood of observing not only target species like lemurs [32], but also any forest species, such as parrots, is greater for tourists in recent years. Therefore, the temporal patterns suggested by Figure 2 could be rather conservative, with recent real changes much more pronounced than those shown. With due caution, these trends support the assumption that forest loss and fragmentation have stronger negative effects on vasa and black parrots [21] than on the much smaller and potentially more resilient gray-headed lovebirds [22]. Moreover, deforestation is not the only threat to these species. All three species have been subject to the international pet trade. While exports of the two parrots ceased to some extent between 1995 and 2005 [21], those of lovebirds continued at least until 2020 [22]. However, the two Coracopsis parrots are much more in demand as pets than lovebirds in the Malagasy domestic market [33,34]. The three species are also subject to legal persecution and hunting due to their consideration as crop pests [21,22], a pressure that may increase as habitat loss increases reliance on agricultural crops [35]. In addition, black and vasa parrots are also hunted for food. In fact, in the Kirindy Forest reserve the numbers hunted for food far exceed those captured for the pet trade [21]. Finally, it should be noted that deforestation in Madagascar began a long time ago, and that it may have produced population declines and contractions in the distributions of the three parrot species several decades before those shown in Figure 2. In fact, even lacking information on population sizes, the gray-headed lovebird was described as ‘very abundant’ 150 years ago, as ‘common’ about 50 years ago, and as ‘uncommon’ in the east and ‘absent’ or ‘scarce’ on the central plateau in recent times [22].

3. The Potential Loss of Parrot–Plant Mutualisms

There is increasing evidence that unsustainable anthropogenic habitat loss and resource extraction have not only led to population declines and extinctions, but also to the disruption of ecological interactions between species, affecting the structural integrity of ecological processes [36,37]. A recent study shows that extinctions of threatened species will alter the functional richness and composition of avian frugivore assemblages across the world, which will substantially diminish the ability of many tropical ecosystems to recover fully after disturbance [38]. Nevertheless, the predictive capacity of research on the role of ecological interactions in ecosystem conservation is hampered by our lack of knowledge of the conservation status of many species, and of their ecological interactions, as is the case of the parrots of Madagascar.

While parrots were considered for decades to be plant antagonists, since they are efficient consumers of seeds and other reproductive structures of plants, recent studies show that they fulfill important ecological functions [39], embracing mutualism–antagonism continuums [40]. Among their mutualistic functions, parrots act as long-distance seed dispersers through endozoochory [41,42], stomatochory [43,44,45], and epizoochory [46]. Notably, on numerous occasions parrots are the main dispersers of plants that are keystone species in the ecosystems they occupy [41,47,48,49,50]. Through food wastage, parrots facilitate access to resources for multiple species that act as secondary seed dispersers [44,51]. Parrots can also pollinate [39] and heal their food plants by consuming their parasites [39]. Through both antagonistic and mutualistic interactions, parrots can exert cascading effects on the plants’ life cycles and shape ecosystems by influencing the spatial distribution and demography of their food plants and vegetal communities [39,40,47].

The trophic ecology of Malagasy parrots has been little studied [52] and, as with other parrots worldwide, these species have mainly been considered as seed predators [53]. However, some mutualistic roles as seed dispersers are now known. When studying the seed dispersal system of the endemic Commiphora guillaumini, which is the dominant canopy tree species in the dry deciduous forest of Kirindy, western Madagascar, Böhning-Gaese et al. [54] found that primary seed dispersal was carried out exclusively by black parrots through stomatochory, while ants were the only secondary seed dispersers. Vasa parrots were observed only consuming these fruits and dropping the intact seeds under the parent tree [54,55], but given their morphological and ecological similarities [52], it is reasonable to expect that they may act as dispersers of this or other tree species. Black parrots have been observed dispersing three plant species by epizoochory [46], when feeding on fruits such as those of the endemic Anthocleista madagascariensis and Ficus trees, as their small seeds become attached to the beak (Figure 1C) and are transported long distances. Black parrots have also been observed feeding on flowers (Figure 1D, [52]), and then they can eventually act as pollinators, as in the case of other parrot species [39]. They also consume insect galls [52], which can be beneficial to plant health [39].

With some 14,000 species, 84% of them endemic, Madagascar is home to a unique and globally important assemblage of plants [56]. As mutualistic relationships of plants with other bird species are still being discovered [57], and even with the much better studied lemurs [58], the detailed study of the trophic ecology of the three parrot species will undoubtedly yield knowledge about many, still unknown ecological functions. Since the diversity of frugivorous birds in Madagascar is markedly depauperate compared to that existing on the African continent [55,59], the potential role of parrots as plant mutualists becomes more important. In fact, as in other parts of the world [47,48,49,60], parrots could be dispersing fruits in Madagascar whose dispersal is attributed to extinct megafauna [61,62]. As for the case of plant–lemur interactions [58], combining research-based observations with ethnobiological data could help to discover new, so far cryptic interactions. Research in that area is urgently needed since the loss of ecological interactions may occur well before the disappearance of parrot species [49], affecting species functionality and ecosystem services at a faster rate than species extinctions [37].

4. Conclusions

There is an urgent need to study the current distribution and population size of the three parrot species endemic to Madagascar, as well as their antagonistic and mutualistic relationships with their food plants. This would not only help to understand their current conservation status, which may be much worse than that assessed by the IUCN Red List, but also to discover important ecological functions that may be lost before the disappearance of the species involved.