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Abundance of soaring raptors in the Brazilian Atlantic rainforest
Abstract
18 August-4 September 1998, we conducted 23 3-4 hr point-counts in an Atlantic rainforest area of southeastern Brazil to evaluate the richness and relative abundance of raptors in two adjacent protected areas, Parque Estadual Intervales and the Parque Estadual Turístico do Alto Ribeira. During 88.2 hr, we recorded 334 contacts with raptors, involving 734 individuals of nine species. Contacts per hour and the number of species tallied showed that the counts were higher between 0900-1200 H (Local Standard Time), and that counts of 3 hr were the most cost effective. Reasonable precision for abundance indices was achieved with samples sizes of 20-30 points, but samples of 12 should give satisfactory results for the more common species, as long as counting points are distributed sufficiently in space. We derived abundance indices for species of raptors most commonly seen in the area. In 14 3-hr counts, Black Vultures (Coragyps atratus) were observed in 100% of them, Mantled Hawks (Leucoplernis polionota) in 71 %, Black Hawk-Eagles (Spizaetus tyrannus) in 50%, Turkey Vultures (Cathartes aura) in 29%, Ornate Hawk-Eagles (Spizaetus ornatus) in 21 %, Roadside Hawks (Buteo magnirostris) in 14%, Short-tailed Hawks (Buteo brachyurus) in 14%, Crested Caracaras (Polyborus planeus) in 14%, and Tiny Hawks (Accipiter superciliosus) in 7%. Bat Falcons (Falco rufigularis) and White-tailed Hawks (Buteo albicaudatus) also were reported in the area, but outside the counting periods.
... We adopted the point count methodology for studies of birds of prey according to Mañosa et al. (2003), Loures-Ribeiro and Anjos (2006), Carvalho and Marini (2007), and Granzinolli and Motta-Junior (2010). We selected four point counts, located in neighborhoods near the edge of the city but with wide view over the urban area, with a minimum distance of 1 km between each other (detection radius of each point was approximately 500 m). ...
... Although richness was also similar to studies performed in natural areas, species composition shows that this parameter is not indicative of good environmental quality. In studies carried out in areas of the Atlantic Forest, species with greater sensitivity to environmental changes and species that are naturally rare were recorded, such as: Buteogallus lacernulatus (Zorzin 2011), Pseudastur polionotus (Kaup, 1847) (Mañosa et al. 2003), Geranoaetus melanoleucus (Salvador-Jr and Silva 2009), Spizaetus melanoleucus (Vieillot, 1816) (Salvador-Jr and Silva 2009), Spizaetus tyrannus (Wied, 1820) (Mañosa et al. 2003;Azevedo et al. 2003;Zorzin 2011;Salvador-Jr and Silva 2009), Spizaetus ornatus (Daudin, 1800) (Mañosa et al. 2003) and Micrastur ruficollis (Zorzin 2011). The same was observed in studies conducted in Cerrado areas where one species with high sensitivity and naturally rare was recorded, Buteogallus coronatus (Baumgarten 2007;Benfica 2013;Granzinolli 2009). ...
... Although richness was also similar to studies performed in natural areas, species composition shows that this parameter is not indicative of good environmental quality. In studies carried out in areas of the Atlantic Forest, species with greater sensitivity to environmental changes and species that are naturally rare were recorded, such as: Buteogallus lacernulatus (Zorzin 2011), Pseudastur polionotus (Kaup, 1847) (Mañosa et al. 2003), Geranoaetus melanoleucus (Salvador-Jr and Silva 2009), Spizaetus melanoleucus (Vieillot, 1816) (Salvador-Jr and Silva 2009), Spizaetus tyrannus (Wied, 1820) (Mañosa et al. 2003;Azevedo et al. 2003;Zorzin 2011;Salvador-Jr and Silva 2009), Spizaetus ornatus (Daudin, 1800) (Mañosa et al. 2003) and Micrastur ruficollis (Zorzin 2011). The same was observed in studies conducted in Cerrado areas where one species with high sensitivity and naturally rare was recorded, Buteogallus coronatus (Baumgarten 2007;Benfica 2013;Granzinolli 2009). ...
As urban areas expand, some species of diurnal birds of prey occupy these habitats, and many establish viable populations. The objectives of this study were to: (1) survey the species of birds of prey in the urban area located in the interior of the São Paulo state, Brazil, (2) to verify the proportion of generalist and specialist species in terms of habitat and diet, (3) determine the period that the species are more active during the time period of the point counts, and (4) to evaluate if there is a pattern of seasonality. Samples were collected monthly between October 2014 and September 2016 using the point counts method (four points; 4 hr duration each). We analyzed species richness, habitat and diet, number of contacts and frequency of occurrence, period of greatest activity, and seasonality. We recorded 19 species of birds of prey through 2555 contacts. Most of the registered species (61%) were habitat and diet generalists, and the same percentage of species classified as uncommon or rare. In relation to the period of greatest activity, falconids were more active in the first hour while accipitrids and cathartids were more active in the fourth hour. In addition, we did not observe a seasonal pattern in this community, but Gampsonyx swainsonii showed a seasonal trend. We verified that the urban area of the municipality of Pirajuí has a significant diversity of birds of prey, including specialist species of habitat and diet. This information obtained evidence the importance of urban environments for birds of prey and showed the ability of these species to use this environment. From our results, we suggest that future studies should evaluate the effects of urban areas of different sizes and degrees of urbanization on bird of prey communities.
... These surveys were carried out after GHLT surveys were completed to avoid interference in the behavior and detectability of the tamarins. Sampling was carried out between 06:00 and 12:00 hr, the peak period of activity for most diurnal raptors (Mañosa, Mateos, & Pedrocchi, 2003;Thiollay, 1989), avoiding rainy and windy days (Granzinolli & Motta-junior, 2008). ...
... Most raptors start soaring when thermals are well-formed, so the best period to perform point count techniques is between 09:00 and 12:00 hr (Mañosa et al., 2003;Thiollay, 1989). During this period, we recorded all individuals using visual or vocal cues from a fixed point located on hilltops adjacent to the study area (Mañosa et al., 2003). ...
... Most raptors start soaring when thermals are well-formed, so the best period to perform point count techniques is between 09:00 and 12:00 hr (Mañosa et al., 2003;Thiollay, 1989). During this period, we recorded all individuals using visual or vocal cues from a fixed point located on hilltops adjacent to the study area (Mañosa et al., 2003). At six of the 16 sites where the relief was very flat, we performed two complementary point counts located at~100 m from the edge of the cabruca, separated by mean distances of 690 ± 170 m. ...
Organismal distributions in human-modified landscapes largely depend on the capacity of any given species to adapt to changes in habitat structure and quality. The golden-headed lion tamarin (GHLT; Leontopithecus chrysomelas) is an Endangered primate from the Brazilian Atlantic Forest whose remaining populations occupy heterogeneous landscapes consisting primarily of shade cacao (Theobroma cacao) agroforestry, locally known as cabrucas. This cash crop can coexist with high densities of native tree species and holds a significant proportion of the native fauna, but its widely extolled wildlife-friendly status is increasingly threatened by management intensification. Although this potentially threatens to reduce the distribution of GHLTs, the main determinants of tamarin's occupancy of cabrucas remain unknown, thereby limiting our ability to design and implement appropriate conservation practices. We surveyed 16 cabruca patches in southern Bahia, Brazil, and used occupancy modeling to identify the best predictors of GHLT patch occupancy. Key explanatory variables included vegetation structure, critical resources, landscape context, human disturbance, and predation pressure. We found a negative relationship between GHLT occupancy and the prevalence of jackfruit trees (Artocarpus heterophylus), which is likely associated with the low representation of other key food species for GHLTs. Conversely, cabrucas retaining large-diameter canopy trees have a higher probability of GHLT occupancy, likely because these trees provide preferred sleeping sites. Thus, key large tree resources (food and shelter) are currently the main drivers of GHLT occupancy within cabruca agroecosystems. Since both factors can be directly affected by crop management practices, intensification of cabrucas may induce significant habitat impacts on GHLT populations over much of their remaining range-wide distribution.
... The surveys occurred between August 2014 and May 2015, a period that includes the breeding season for most raptor species in Atlantic Forest (Mañosa et al. 2003, Zorzin 2011, and when these predators are expected to behave more conspicuously, increasing their detectability (Seymour et al. 2010, Monsalvo 2012. Also, according to field records, migratory species such as the Swallow-tailed Kite Elanoides forficatus and the Plumbeous Kite Ictinia plumbea can be found in the study region during the major part of this period (https:// en.wikiaves.com/). ...
... A combination of active search, playback and point-counts were performed in each cabruca site by the same observer with the help of a field assistant. All sampling was carried out in two visits between 06h00 and 12h00, a period during which most species of diurnal raptors are active (Thiollay 1989, Mañosa et al. 2003, avoiding days with rain and strong wind due to a possible decrease in species detectability (Jones 2000). ...
... Most raptors, such as the hawks Buteogallus spp. and the Mantled Hawk Pseudastur polionotus, often start soaring when thermals are well-formed, so the best period to perform the pointcount methodology is between 09h00 and 12h00 (Thiollay 1989, Mañosa et al. 2003. During this period, we recorded all individuals visually or through their vocalisations from a fixed location. ...
Habitat loss and fragmentation, especially due to agriculture expansion, pose the main threats to biodiversity conservation. While some species are able to survive and proliferate in human-modified habitats (winner species), others are highly dependent on well-preserved habitats, being more vulnerable to extinction (losers). Many raptors can be considered loser species due to their high trophic position, large home ranges, and low reproductive rates. Consequently, this group is frequently used to reflect the environmental quality of habitats and the biodiversity status of communities. Here we describe the diurnal raptor assemblages found in shaded-cocoa agroforests ( cabrucas ) of Southern Bahia, Brazil, and the determinants of raptor occupancy in this system. We systematically surveyed diurnal raptors in 16 cabruca sites using complementary sampling methods – active search, playback, and point-count – and modeled species occupancy using covariates related to vegetation structure, landscape, management intensity, and biological traits (body mass, trophic level, and diet specialisation). We found a high number of species (at least 18) as able to use cabrucas and a negative relationship between species occupancy and the degree of diet specialisation. Thus, our results suggest that cabrucas have a high potential to mitigate the effects of forest loss and fragmentation on diurnal raptors, but this system alone may not support complete assemblages of this group. It highlights the need for the maintenance of forest remnants in the landscapes to increase species diversity at a regional scale and to assure the conservation of this group in Southern Bahian Atlantic Forest.
... Las investigaciones sobre rapaces en Sudamérica han sido principalmente en paisajes boscosos y de topografía plana (Ellis et al. 1990, Manosa y Pedrocchi 1997, Manosa et al. 2003, Jensen et al. 2005), e incluye a Venezuela (Mader 1981, 1982, Morales y Fernández 1993, Alverez et al. 1996, Navarro et al. 2007; de hecho, en un inventario realizado en el continente sudamericano, el bioma llanero occidental venezolano arrojó la mayor riqueza y diversidad de rapaces (Ellis et al. 1990). ...
The nesting records in Laughing Falcon (Herpethoteres cachinnans) have been obtained in Venezuela and several latin-american countries. However, we obtained the first known record of nesting by this species in xeric habitat in northeastern península of Araya, state of Sucre. The finding of one nestling and parents took place in april 13, 2009, on an abandoned nest builded in a columnar cactus (Stenocereus griseus). The nest was visited weekly three times. Presumably, nestling did not survive. The number of successful survival nestling seems minimum in H. cachinnans.
... Em 14 transectos, cada qual com 3 h de duração, Mañosa et al. (2003) contactaram a espécie em uma única oportunidade, no Parque Estadual de Intervales (Ribeirão Grande, São Paulo), local onde não é citada por outros autores que inventariaram a avifauna local (Aleixo & Galetti 1997, Vielliard & Silva 2001. Além disso, Aleixo (1999) também obteve um único registro em dois anos de censos mensais na região de Sete Barras (São Paulo). ...
... En total, las areas de los llanos que censamos contuvieron el 52% de todas las especies de rapaces y mils del 70% de los elanios, buteos y subbuteos que habitan en Venezuela. Las diferencias regionales en el n6mero medio por ruta para cuatro de las 14 especies m@BULLETts comunesThiollay 1984, Thiollay 1989, Alverez et al. 1996, Manosa and Pedrocchi 1997, Manosa et al. 2003 ...
The Llanos of Venezuela is a 275 000-km2 freshwater wetland long recognized as an important habitat for waterbirds. However, little information exists on the raptor community of the region. We conducted raptor surveys in the Southwestern and Western Llanos during 2000-02 and detected 28 species representing 19 genera. Overall, areas of the Llanos that we sampled contained 52% of all raptor species and more than 70% of the kites, buteos, and subbuteos known to inhabit Venezuela. Regional differences in the mean number per route for four of the 14 most common species, the Crested Caracara (Caracara plancus), Black-collared Hawk (Busarellus nigricollis), American Kestrel (Falco sparverius), and Osprey (Pandion haliaetus), were significant (P < 0.0018) in relation to the wet or dry seasons. Of the 14 less common species, six were detected in only one season (wet or dry). The Southwestern and Western regions of the Llanos support a rich raptor community composed primarily of nonmigratory wetland-dependent and upland-terrestrial species.
... Silva et al. 2003). Portanto, S. ornatus pode realmente nunca ter ocorrido no Centro Pernambuco, pelo menos depois do ano de 1.500, e o espécime de Marcgrave foi levado até o nordeste a partir de algum local no baixo Amazonas e/ou Maranhão, ou da mata Atlântica mais ao sul do rio São Francisco onde rapineiros de grande porte já foram, ou ainda são observados (e.g., Pinto 1935, Oren 1991, Novaes e Lima 1998, Galetti et al 1995, Mañosa e Pedrocchi 1997, Mañosa et al. 2003, Silveira et al. 2005. ...
In this note we present a historical review and evaluate the current status of Ornate Hawk-Eagle Spizaetus ornatus in the Atlantic forest of northeast Brazil. This species was firstly noted in the region during the 17th century by the German Naturalist J. Marcgrave, and more than 200 years later H. F. Berla sighted the species in Pernambuco. Depending on the validity of Berla's record: 1) S. ornatus is currently locally extinct, or 2) it never occurred in the forests located north of São Francisco river.
... The Short-tailed Hawk Buteo brachyurus occurs from south USA through Central America, and south to northern Argentina and Chile (Thiollay 1994). This species is found to be uncommon, although widespread in large areas of South America (Robinson 1994, Manosa et al. 2003, Blendinger et al. 2004. Buteo brachyurus search for prey while soaring above the canopy, suddenly diving on prey (Ogden 1974, Robinson 1994. ...
... In recent years, studies were published describing nests and breeding biology (e.g., Zilio and Mendonça-Lima 2012 ), diet (e.g., Scheibler 2007), taxonomy (e.g., Amaral et al. 2009), migration (e.g., Cabanne and Seipke 2005 ), and distribution (e.g., Lima et al. 2006; Meller and Bencke 2012 ), but much of the information comes from short-term studies or opportunistic observations. Data at the assemblage level (e.g., distributions , abundances, and habitat associations) are scarce and were usually collected in short-term studies (Azevedo et al. 2003; Mañosa et al. 2003; Loures-Ribeiro and Anjos 2006; Alencar-Carvalho and Marini 2007; Salvador-Jr and Silva 2009). Although species occurrences and distributions in Rio Grande do Sul were well summarized in the work of Belton (1984) in the 1970s and through additional records (Krügel 2003; Albuquerque et al. 2006; Barcellos and Accordi 2006; Joenck and Azevedo 2006; Mendonça-Lima et al. 2006; Meller and Bencke 2012), data regarding abundances are scattered, being found primarily in general bird surveys. ...
Background: Raptor distributions and abundances are poorly known in southern Brazil. Given that raptors have low population densities, methods typically applied to census birds are usually inappropriate for surveying raptors. Roadside surveys allow large areas to be searched at a relatively low cost and are often applied to count raptors. We conducted eight paired roadside surveys (roadside point transects and roadside strip transects of 54.5 ~ 58.6 km long) to assess the species richness and abundance of raptors in two grassland landscapes of southern Brazil and to compare results of the two methods. Results: In total, 1,890 observations of 18 raptor species (118.13 individuals (ind.)/transect) were recorded. Raptor abundances were higher in the altitudinal grasslands (299.25 ± 48.91 ind./transect) than in the coastal plain (86.63 ± 44.04 ind./transect). Abundances were higher when raptors were surveyed with point transects (9.38 ind. · [10 km 2 ] −1 · h −1) than with strip transects (3.55 ind. · [10 km 2 ] −1 · h −1). No significant differences were found in relation to species richness, although five species were exclusively recorded with point transects versus one with strip transects. Conclusions: Roadside point transects may reduce bias due to differences in species detection caused by habitat features and in abundance estimates resulting from survey habitat being disproportional to their availability. Point counts may enhance the quality of the search for raptors in a surveyed area, increasing the detection probability. The choice of survey method depends on the objectives of the study, but our results favor the use of point transects rather than strip transects to survey raptors in open landscapes.
... Silva et al. 2003). Portanto, S. ornatus pode realmente nunca ter ocorrido no Centro Pernambuco, pelo menos depois do ano de 1.500, e o espécime de Marcgrave foi levado até o nordeste a partir de algum local no baixo Amazonas e/ou Maranhão, ou da mata Atlântica mais ao sul do rio São Francisco onde rapineiros de grande porte já foram, ou ainda são observados (e.g., Pinto 1935, Oren 1991, Novaes e Lima 1998, Galetti et al 1995, Mañosa e Pedrocchi 1997, Mañosa et al. 2003, Silveira et al. 2005. ...
The history of the Ornate Hawk-Eagle, Spizaetus ornatus, in the Atlantic forest of northeast Brazil. In this note we present a historical review and evaluate the current status of Ornate Hawk-Eagle Spizaetus ornatus in the Atlantic forest of northeast Brazil. This species was firstly noted in the region during the 17 th century by the German Naturalist J. Marcgrave, and more than 200 years later H. F. Berla sighted the species in Pernambuco. Depending on the validity of Berla's record: 1) S. ornatus is currently locally extinct, or 2) it never occurred in the forests located north of São Francisco river.
We give the results of a raptor survey conducted in August 1994 in the Porque Estadual Intervales, a well preserved area of Atlantic rainforest in southeastern Brazil. Point counts were more effective than transect counts. Ten species of raptors were detected. The presence of a pristine population of Mantled Hawks (Leucopternis polionota), Black Hawk-eagles (Spizaetus tyrannus) and Ornate Hawk-eagles (S. ornatus), gives to the area a remarkable interest for the conservation of birds of prey in Brazil. We also observed Turkey Vultures (Cathartes aura), Black Vultures (Coragyps atratus, Tiny Hawks (Accipiter superciliosus), Roadside Hawks (Buteo magnirostris), Short-tailed Hawks (Buteo brachyurus), Yellow-headed Caracaras (Milvago chimachima), Collared Forest-falcon (Micrastur semitorquatus) and possibly Grey-headed Kites (Leptodon cayanensis).
No reliable method has ever been proposed to census a rain forest raptor community. I investigated 4 methods in primary forest of French Guiana and compared results; 1) Mapping territorial pairs, displaying over canopy and followed from dominant lookouts, gives the most complete data on regularly soaring species (Harpagus, Buteogallus, Spizaetus, Spizastur); 2) mean instantaneous number of birds flying over a definite area in optimum conditions may be a reasonable density estimate for vultures (Cathartidae); 3) mapping of individuals recorded along a regular network of trails in the understory was only successful for the highly conspicuous Red-throated Caracara (Daptrius americanus); 4) density estimates from understory strip transects were consistent with those obtained by other methods for 6 of 8 species. Specific detectability, soaring behaviors and frequencies of display flights varied widely among species and so did time required to assess the existence of a territorial pair (1-7 d). Marking, radiotracking and playback of vocalizations are promising techniques but are very time consuming and more appropriate for a detailed study of particular pairs than for survey of a whole community. Use of an abundance index, with a distinct technique for each species, may avoid biases of density estimates. Birds of prey are notoriously difficult to survey in tropical forests, especially in tall, dense, large un- broken tracts of humid lowland forest. No complete census of a rain forest raptor community, with den- sity estimates over a significant area, has ever been published and no appropriate methodology has even been proposed. However, many rain forest raptors are now threatened by habitat destruction, distur- bance or fragmentation (Thiollay 1985b). Raptors may be suitable indicators of optimum size of a forest reserve, because raptors are likely to require areas larger than most other species. Yet, there is still an urgent need of basic data on natural distribution and density of rain forest raptors because of a concern about the suitability of many reserves or even na- tional parks which may well prove to be too small for long term survival of some raptor species sup- ported originally. As part of a larger study on design of a national park in French Guiana, I assessed the distribution and relative abundance of raptors over the country's 80 000 km 2 rain forest area, and I estimated the density of every species within a representative 100 km 2 sample quadrat (Thiollay 1989). Life history and behaviour of most rain forest raptor species are very poorly known, if at all (Thiol- lay 1985a). Often only scant information comes from marginal habitats, rather open woodlands or edges where a species' biology may be atypical. After 20 yrs of personal experience in both New and Old World tropical forests, I can testify that nests of many species are almost impossible to find in pri- mary forest, except under extraordinarily lucky cir- cumstances. In fact, for many species, the nest has never been described. Several species, including some of the most common neotropical forest raptors, seem to never soar(?) nor even fly over the canopy and very rarely venture outside the understory. Although not particularly shy, most species are very secretive and spend long periods perched motionless. Many are very vocal, but others are usually silent. Density is often low and distribution very patchy, which further decreases rate of encounters.
Cumulative impacts of logging and road building in a previously undisturbed tract of tropical rain forest in French Guiana were assessed by random sampling of the bird community and 1-km2 plot counts of diurnal raptors. Similar surveys were carried out during road construction and 15 years later within 5km of the road and were also compared with the undisturbed bird community of a nearby primary forest. The main disturbance was the change in forest structure brought about by logging and secondarily the road opening, the roadside second growth and the depletion of large vertebrates by hunting pressure. The responses of different bird guilds were highly divergent according to their natural habitat requirements, their diet and their vulnerability to hunting. They resulted in a moderate decrease in overall species richness and equitability. All species pooled, the abundance of 118 species was lowered, that of 45 species did not change appreciably and 89 were favored or even appeared. The guilds most affected were those with large body sizes, from terrestrial foragers to canopy frugivores, mostly by hunting, and the open understorey specialists, notably large insectivores and mixed flock members, because of changes in forest structure after logging. The guilds favored by logging and road opening were many of the hummingbirds, upper canopy frugivores and omnivores, and gap, edge or low secondary growth specialists. Recommendations to minimize the negative consequences of human exploitation in rain forests include reducing the width of deforested roadsides to no more than 10–15m on either side, implementing much more careful logging practices and strongly limiting hunting pressure in newly opened areas.
A density index of every diurnal raptor species (Falconiformes) was obtained on 101 400 ha sample plots distributed among eight natural habitats and five man-made habitats arranged along gradients of increasing forest degradation and fragmentation. The most significant structural parameter affecting species distribution was the tall canopy forest cover. Species richness, diversity and density all decreased with this mature forest cover index. Individual species and overall community densities decreased along the deforestation gradient but the species richness was partly maintained by species turnover. Six groups of species were identified according to their natural habitat preferences. Their distribution along the deforestation gradient was correlated with their natural habitat selection pattern. Thus the community composition of each vegetation or landscape type was predictable. Fifty-six percent of the regional assemblage of species had their optimal density in the primary forest. A third of them were interior forest species highly sensitive to forest disturbance and opening. The other two-thirds were upper canopy, gap or edge species more tolerant to forest fragmentation. The last twenty-one species were associated with various coastal habitats, from dense forest patches to mangrove and savanna. Again, one third of them were strictly restricted to their specialized habitats while the last two-thirds colonized human-altered habitats and progressively replaced primary forest species with increasing deforestation. The maintenance of large areas of every natural habitat was essential for the conservation of (1) the whole population of a third of the total raptor diversity and (2) optimal and presumably potential source populations of most other species surviving in human-modified habitats.
The Brazilian Atlantic forest constitutes a unique biome characterised by a high species diversity and a high level of endemism. A long history of land clearing for crops, pastures, timber and firewood has resulted in over two centuries of widespread destruction. Today, less than 6·8% of the total area of the Atlantic forest of Minas Gerais has any form of forest cover and forests in primaeval state are not far from becoming extinct. The remaining forest patches are small, isolated and unprotected. In order to preserve some of the original diversity of the Atlantic forest, urgent efforts must be channelled toward protecting the remaining forest fragments.
Conservationists are far from able to assist all species under threat, if only for lack of funding. This places a premium on priorities: how can we support the most species at the least cost? One way is to identify 'biodiversity hotspots' where exceptional concentrations of endemic species are undergoing exceptional loss of habitat. As many as 44% of all species of vascular plants and 35% of all species in four vertebrate groups are confined to 25 hotspots comprising only 1.4% of the land surface of the Earth. This opens the way for a 'silver bullet' strategy on the part of conservation planners, focusing on these hotspots in proportion to their share of the world's species at risk.
The mass-extinction episode underway is largely centered on tropical forests, insofar as they contain at least half of all Earth's species and they are being depleted faster than any other biome. But species distributions and depletion patterns are anything but uniform throughout the biome. This paper identifies 10 areas that a) are characterized by exceptional concentrations of species with high levels of endemism and b) are experiencing unusually rapid rates of depletion. While these "hotspot" areas comprise less than 3.5% of remaining primary forests, they harbor over 34,000 endemic plant species (27% of all plant species in tropical forests and 13% of all plant species worldwide). They also feature 700,000 endemic animal species and possibly several times more. Unfortunately, they appear likely to lose 90% of their forest cover as soon as the end of the century or shortly thereafter, causing the extinction of almost 7% of Earth's plant species and at least a similar proportion of animal species, this occurring in only 0.2% of Earth's land surface. By concentrating on such areas where needs are greatest and where the pay-off from safeguard measures would also be greatest, conservationists can engage in a more systematized response to the challenge of large-scale extinctions impending in tropical forests.