Professor Marcelo Gordo, Universidade Federal do Amazonas
The Project
Habitat loss and fragmentation are major problems for biodiversity conservation. Fragmentation of habitats affects different animal and plant groups in different ways and may generate loss of biodiversity, changes in community composition and population density, invasion by opportunistic species and interference with gene flow. It may have a negative effect on the more specialized species or groups in certain environments or resources and a positive one on generalist and invasive species (Laurence & Bierregaard, 1997; Bierregaard et al., 2001; Rambaldi & Oliveira, 2005).
Figure 1. Saguinus bicolor,
the pied tamarin.
Callitrichidae have long been known for their tendency to efficiently colonize disturbed and marginal forest environments (Eisenberg, 1978; Garber 1980; Sussman & Kinzey, 1984). Generally, they prefer the dense vegetation of the lower strata of disturbed and peripheral habitats, where they prey on insects, especially orthopterans (Ferrari, 1993). But even callitrichids, which often behave as opportunist species, colonizing altered and fragmented environments (Ferrari, 1993), may have serious problems with fragmentation, isolation and degradation of environments, which may fragment and isolate populations, reducing their effective number and often subjecting them to suboptimal environmental conditions (see review in Cerqueira et al., 2005).
As the available area for a given population decreases through fragmentation and loss of habitats, total number of individuals also tends to decrease, even if population density increases in some cases. As a result, the risk of local extinction grows, as many factors cause natural oscillations in population size which, in the case of small populations, may be decisive. Some studies estimating population viability (Minimal Viable Populations – MVP) of different taxonomic groups concluded that, to be viable in the long run, vertebrates require populations numbering thousands of individuals (Shaffer et al., 2002; Reed et al. 2003; Reed & Hobbs, 2004). Populations in that size range are typical of some neotropical primate species, which have been seriously affected by fragmentation and loss of habitats in different biomes (Chiarello & Melo, 2001; Ferrari et al., 2003; Rambaldi & Oliveira, 2005), including Saguinus bicolor (personal observation).
This fragmentation, associated to ongoing exploitation, causes a series of transformations in the processes and ecological functions of the standing forest (see Shaffer, 1990), including break-up of the genetic flow between remaining, previously continuous populations, reducing genetic variability of the metapopulation (Martin & von Segesser, 1996). The main importance of conserving genetic parameters is to maintain the capacity to respond to environmental changes (Franklin, 1980; Frankel & Soulé, 1981; Hedrick, 1996; Lynch, 1996; Moritz, 2002). In other words, loss of genetic variability or the accelerated overall changes in genetic parameters may decrease the capacity of a given population to respond to environmental changes and pressures.
With the expansion of logging, crops and cattle ranching, the Amazon forest is being lost or transformed into a mosaic of fragments and altered areas at an alarming rate (Fearnside, 2005). Of the eleven species of Amazonian primates that figure in the Threatened Brazilian Species List (Machado et al., 2005), at least six are affected mainly by fragmentation and loss of forests.
Among them is the pied tamarin, Saguinus bicolor (Figure 1), listed as Endangered in the IUCN Red List (IUCN, 2008) and as Critically Endangered in the Threatened Brazilian Species List (Gordo, 2008). Different from most species in this genus, which ranges over a good part of the Amazon River basin and neighboring areas in northwest South America (Emmons, 1997), Sanguinus bicolor has a very reduced range, endemic to the Manaus region (encompassing part of Manaus, Rio Preto da Eva and Itacoatiara rivers).
The pied tamarin’s range is bound by the Cuieiras and Negro rivers in the west, by the Amazon River in the south, and by the Urubu River in the east; to the north it extends 50 kms from the Amazon River (Figure 2). The first surveys mention the presence of S. bicolor east of the Urubu River, with the Uatumã river acting as a barrier (Hershkovitz , 1966, 1977; Ayres et al., 1980, 1982; Egler, 1983). In a more recent review, Subirá (1998) and Röhe (2006) suggest that there has been a reduction in the original range, currently bound by the Urubu River. They also suggest that this reduction is due to competition with Saguinus midas, a parapatric species ranging widely east of the Negro River, a hypothesis previously proposed by Ayres et al. (1980).
Destruction and fragmentation of the forest in the area of occurrence of Sanguinus bicolor are the main threats to preservation of the species, especially in the Manaus urban area and along the roads radiating from this area (Figure 2). Regions boasting large human densities pose a special threat to endangered species (Harcourt & Parks, 2003) due to the intensification of the negative factors associated to fragmentation.
Figure 2. Geographic range of Saguinus bicolor.
Manaus is growing at a fast and disordered pace, and has lost more than half of its green areas in the last ten years. In the remaining fragments there is intense exploitation for wood, fruits, etc, and poaching. Pied tamarins suffer from road kills, electric shocks from high tension lines, attacks by domestic animals, mishandling and capture by people living around fragments. It is common to find groups of Sanguinus bicolor surviving in highly degraded and small fragments (from two to ten hectares), i.e., below the minimum conditions apparently needed to sustain a healthy group (Egler, 1986, pers. obs.).
Previously, few studies focused on the ecology of the species in more detail. Egler (1986; 1991a,b, 1992, 1993) monitored a social group in a fragment of secondary forest in Manaus. Other papers (Vidal, 2003; Vidal & Cintra, 2006) assessed the influence of forest structure variables on demographic parameters of the Sanguinus bicolor population living in a continuous forest in the Ducke Reserve, north of Manaus. Some studies on behavior, management and social interactions were conducted in captivity (see review in Wormell, 2000) and only one cognitive ecology study was made recently, focusing on a single group (Azevedo, 2006).
Overall, the available data are insufficient to yield reliable and definitive subsidies for management and conservation of the remaining populations of the species. Since 1999 a team led by Professor Marcelo Gordo from Universidade Federal do Amazonas has been conducting studies on the genetics, ecology and behavior of groups in isolated forest fragments and in continuous forest. From 2002 to 2004 the project “Ecological and genetic studies for the conservation of the Saguinus bicolor monkey” (Pied Tamarin Project) was carried out, supported by PROBIO (Ministry of Environment) - Endangered Species Edict, 2001. From 2004 to the beginning of 2009 the Project was supported by FNMA (Ministry of Environment) and various European zoos, the Philadelphia Zoo (USA), WCS-Brazil and CI-Brazil. These studies have proved essential in supplying subsidies for management and conservation of this species.
The project has already yielded valuable results for conservation of the species (Gordo et al., 2002), and a preliminary analysis of genetic parameters (Santos, 2005) indicates an imbalance in populations isolated for longer periods. We recorded and mapped many groups in isolated backyards and tiny fragments, and several deaths by road kills, dog attacks, hunger, electrocution on power lines and even killing by local people. Follow-up studies of some of these fragments harboring tamarins have shown a clear reduction in number of individuals.
Present Goals and Objectives
The Pied Tamarin Project’s goal is to raise pertinent data for the conservation of the primate Saguinus bicolor (Callitrichidae) and to implement emergency actions to rescue individuals and groups in imminent danger of extinction.
Our objectives are:
- To estimate population densities of Sanguinus bicolor in forest areas deemed important by their size or potential for being made into Protected Areas.
- To estimate populations and densities within the already existing Protected Areas, assessing the conservation status of these areas to enable a discussion on their effectiveness in protecting the species.
- To perform a preliminary land survey of these more relevant areas so we can devise more specific actions for each case.
- To rescue or monitor tamarin groups living in urban forest fragments which will be totally or partially deforested to build housing developments, avenues, etc.
Bibliographic references
GORDO, M . Saguinus bicolor. In: Angelo Barbosa Monteiro Machado, Gláucia Moreira Drummond, Adriano Pereira Paglia.. (Org.). Livro vermelho da fauna brasileira ameaçada de extinção. 1 ed. Brasília: MMA, 2008, v. 2, p. 750-751
MAIA DA SILVA, F ; NAIFF, R ; MARCILI, A ; GORDO, M. ; DAFFONSECANETO, J ; NAIFF, M ; FRANCO, A ; CAMPANER, M ; VALENTE, V ; VALENTE, S . Infection rates and genotypes of Trypanosoma rangeli and T. cruzi infecting free-ranging Saguinus bicolor (Callitrichidae), a critically endangered primate of the Amazon Rainforest. Acta Tropica, v. 107, p. 168-173, 2008.
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