Cost-efficient conservation for the white-banded tanager (Neothraupis fasciata) in the Cerrado, central Brazil
Introduction
Developing cost-efficient management strategies for the world’s avifauna is going to become an increasingly important global problem. Of all the bird species in the world 12% are considered threatened and 8% are listed as Near Threatened (Baillie et al., 2004). Most threatened species need to be actively managed to persist in the long term. Some species are restricted to captive populations with low chances of being successfully re-introduced in natural environments. For example, the Spix’s Macaw project in the Caatinga biome (Brazil) failed to save the last wild individual and re-introduction has not been successful so far (Galetti et al., 2002). This species was considered extinct in the wild in 2000 with less than 60 individuals existing in captivity (Galetti et al., 2002). Although captive populations can offer insurance against extinctions, it would be foolhardy to assume that these species can be easily re-introduced back into the wild to form viable populations (Baillie et al., 2004). Additionally, many populations of common bird species are in decline around the world (BirdLife International, 2004). In many cases, habitat protection on its own is not sufficient, and therefore intensive management will be required to stop populations falling to a point where they no longer play their functional role in ecosystems (Redford, 1992).
Population viability analysis (PVA) is a quantitative approach to assessing the viability of populations and the factors that affect that viability (Possingham et al., 1993, Beissinger and Westphal, 1998). The original purpose of PVA was to determine the minimum population size of a viable population (Shaffer, 1981). PVA can be applied to estimate persistence probabilities of populations under different conditions using life history data and knowledge about the influence of environmental factors (Shaffer, 1981, Reed et al., 1998). A PVA model provides the means for assessing the magnitude of changes in parameters such as survival, fecundity and resource availability that precipitate important biological effects (Burgman, 2000). By incorporating elements of uncertainty these models provide a stochastic projection of a population’s fate (Brito and Fernandez, 2000). Although this assessment of extinction risk is useful, authors have questioned this traditional use of PVA arguing that it is generally difficult to accurately predict extinction probabilities (Possingham et al., 1993, Beissinger and Westphal, 1998). Although there are concerns about their predictive power, PVAs can be used to uncover the importance of different model parameters (McCarthy et al., 1995, Brito and Fernandez, 2000), and optimize conservation programmes (Cross and Beissinger, 2001, Morris and Doak, 2002).
PVA can be usefully applied in conjunction with decision support tools to evaluate and compare conservation strategies (Clark et al., 1991, Drechsler and Burgman, 2004). By simulating a range of possible scenarios that a species may face in the future, PVAs can be used to compare alternative management options (Lindenmayer et al., 1993, Lindenmayer and Possingham, 1996, Burgman, 2000). Another benefit of PVA models is that they can help us determine which type of data would be the most useful to collect in the future to reduce uncertainty about our choice of management action (Possingham et al., 1993, Morris and Doak, 2002).
Despite the call to use PVA in conservation decision making, there are few studies where it has been done with realistic economic costs (e.g. Larson et al., 2003, Tisdell et al., 2005). Conserving biodiversity requires significant financial resources and countries with large number of threatened species must spend their limited resources prudently (Baillie et al., 2004). Conservation decisions that ignore costs may be very expensive to implement and draw substantial resources away from other more cost efficient conservation actions (Baxter et al., 2006). By incorporating cost in the decision analysis it is possible to determine the action expected to deliver the best viability within a constrained budget (Noon and McKelvey, 1996, Possingham et al., 2001, Yokomizo et al., 2003, Haight et al., 2004, Yokomizo et al., 2004, Yokomizo et al., 2007).
This paper determines the most cost-efficient management option for populations of a Near Threatened bird species (the white-banded tanager, Neothraupis fasciata) in central Brazil. We assume that the best conservation strategy is the one that maximizes population persistence for a fixed budget. In other words, it achieves the vital rates required for population persistence while minimizing financial costs. In this paper we focus on the economic costs of different management options and consider the efficiency of different strategies for decreasing the chance of extinction.
Brazil has a high diversity of bird species and contains the highest number of threatened bird species of any country in the Neotropics (Collar et al., 1997, Marini and Garcia, 2005, IUCN, 2006). The Cerrado region is the most extensive woodland/savanna region in South America, and also the only biodiversity hotspot that largely consists of savanna, woodland/savanna and dry forest habitat (Mittermeier et al., 2005). It is the second largest South American biome, and one of the most threatened ecosystems in South America (Silva and Bates, 2002, Klink and Machado, 2005). The primary threat to its biodiversity is the accelerated process of conversion to agriculture and a deficiency in the extent and representativeness of the protected area system (Silva et al., 2006). Recent estimates suggest that most of the unreserved natural habitat in the Cerrado will be destroyed by 2030 if the current rate of destruction continues (Machado et al., 2004). Most of the Cerrado’s endemic species can be considered as threatened because of the high rate of habitat loss even though some have not been officially red listed (Garcia and Marini, 2006). This is one region where cost-efficient management strategies are urgently needed for endemic species.
In this paper we: (1) assess the extinction risk of the white-banded tanager population in ‘Estação Ecológica de Águas Emendadas’ using data from three years of field research; (2) determine the management strategy which maximizes viability within a limited budget or minimizes financial costs while reaching the vital rates required for population persistence and (3) identify the most important future research. The study is generalized by assessing the extinction risk of other populations of this species in protected and unprotected areas in the Cerrado.
Section snippets
Study area
The field study that provided information for the PVA was conducted in a 10,547 ha protected area called “Estação Ecológica de Águas Emendadas” (ESECAE) (15°29′–15°36′S and 47°31′–47°41′W), located in Distrito Federal, Brazil. This contains a little over 6000 ha of suitable white-banded tanager habitat (Duca, 2007). ESECAE is one of the most important protected areas in central Brazil, with 301 bird species including 16 Cerrado endemic (Bagno, 1998, Lopes et al., 2005) representing 37% of the
Population persistence
VORTEX simulations suggest that the white-banded tanager population in ESECAE has a very low chance of becoming quasi-extinct in the next 100 years (quasi-extinction probability = 0.038, basic scenario). In spite of the low quasi-extinction probability, the population trend (stochastic growth rate) for all scenarios was negative (Table 2). Decreasing the carrying capacity increases the extinction probability. When the area drops below about 2000 ha, the quasi-extinction probability becomes higher
Population persistence
The sensitivity analysis indicated that fecundity and adult survival have the greatest impact on the population persistence of the white-banded tanager. Variation in adult survival invariably has the greatest impact on persistence probabilities for long-lived vertebrates (e.g. Goldingay and Possingham, 1995, McCarthy, 1996, Lunney et al., 2002, Larson et al., 2002), but intriguingly fecundity appears to be the most important vital parameter for the white-banded tanager in ESECAE. Fecundity was
Conclusion
Our results confirm previous research that stresses the importance of considering costs when making conservation decisions (Possingham et al., 2001, Frazee et al., 2003, Baxter et al., 2006, Wilson et al., 2006). We conclude that the best strategy for the conservation of the white-banded tanager is to increase its fecundity and this goal can be achieved most cost efficiently by doing only fire management and/or nest protection. The amount spent of each activity depends on the budget available
Acknowledgements
This study was funded by the ‘Fundação O Boticário de Proteção À Natureza’. ‘PEQUI – Pesquisa e Conservação do Cerrado’ provided institutional support. We thank the ESECAE/SEMARH for authorization to conduct this study. C. Duca was supported by a fellowship from CAPES/CNPq, and M.Â. Marini is supported by research fellowship from CNPq. We thank all people from ‘Laboratório de Ornitologia’ at Universidade de Brasília during field work. This work has been supported by a Grant-in-Aid for
References (90)
- et al.
Estimating the costs of conserving a biodiversity hotspots: a case-study of the Cape Floristic Region, South Africa
Biological Conservation
(2003) - et al.
Area requirements for viable populations of the Australian gliding marsupial
Biological Conservation
(1995) - et al.
Optimizing reserve expansion for disjunct populations of San Joaquin kit fox
Biological Conservation
(2004) - et al.
A simulation study of the impacts of population subdivision on the mountain brushtail possum Trichosurus caninus Ogilby (Phalangeridae: Marsupialia) in south-eastern Australia
Biological Conservation
(1995) - et al.
Small mammals, habitat patches and PVA models: a field test of model predictive ability
Biological Conservation
(2002) - et al.
A review of the generic computer programs ALEX, RAMAS/space and VORTEX for modeling the viability of wildlife metapopulations
Ecological Modelling
(1995) - et al.
Modelling mammalian extinction and forecasting recovery: koalas at Iluka (NSW, Australia)
Biological Conservation
(2002) Extinction dynamics of the helmeted honeyeater: effects of demography, stochasticity, inbreeding and spatial structure
Ecological Modelling
(1996)- et al.
Sensitivity analysis for models of population viability
Biological Conservation
(1995) - et al.
Assessing the effect of estimation error on population viability analysis: an example using the black-capped vireo
Ecological Modelling
(2002)
Life-history and viability analysis of the endangered Hawaiian stilt
Biological Conservation
Policies for saving a rare Australian glider: economics and ecology
Biological Conservation
Conservation effort and assessment of population size in fluctuating environments
Journal of Theoretical Biology
Multiple-year optimization of conservation effort and monitoring effort for a fluctuating population
Journal of Theoretical Biology
Optimal conservation strategy in fluctuating environments with species interaction: resource-enhancement of the native species versus extermination of the alien species
Journal of Theoretical Biology
Biologia de nidificação de Lathrotricus euleri (Cabanis 1968) (Tyrannidae) em um fragmento de mata de Minas Gerais
Ararajuba. Revista Brasileira de Ornitologia
Nesting biology of the gray-hooded flycatcher (Mionectes rufiventris)
Ornitologia Neotropical
Social system and helping behavior in the white-banded tanager (Neothraupis fasciata)
The Condor
Dieta e táticas de forrageamento de Neothraupis fasciata em Cerrado no Distrito Federal, Brasil (Passeriformes: Emberizidae)
Ararajuba. Revista Brasileira de Ornitologia
Ninhos, ovos e crescimento de filhotes de Neothraupis fasciata
Ararajuba. Revista Brasileira de Ornitologia
Accounting for management cost in sensitivity analyses of matrix population models
Conservation Biology
On the use of demographic models of population viability in endangered species management
Journal of Wildlife Management
State of the World’s Birds 2004 – Indicators for Our Changing World
Influence of habitat quality, catastrophes, and population size on extinction risk of the Scrub-jay
Wildlife Society Bulletin
Evaluation of minimum viable population size and conservation status of the long-furred woolly mouse opossum Micoureus paraguayanus: an endemic marsupial of the Atlantic Forest
Biodiversity and Conservation
Dealing with extinction is forever: understanding the risks faced by small populations
Ciência e Cultura Journal of the Brazilian Association for the Advancement of Science
Differences and congruencies between PVA packages: the importance of sex ratio for predictions of extinction risk
Conservation Ecology
Population viability analysis for bird conservation: prediction, heuristics, monitoring and psychology
Emu
Risk Assessment in Conservation Biology
Effects of fire on savanna birds in central Brazil
Ornitologia Neotropical
Shiny cowbird parasitism in central Brazil
The Condor
Report of workshop on population viability assessment and conservation
Australian Zoologist
Using logistic regression to analyze the sensitivity of PVA models: a comparison of methods based on African wild dog models
Conservation Biology
Combining population viability analysis with decision analysis
Biodiversity and Conservation
Temporal variation in the reproductive success of Cacicus haemorrhous (Linnaeus) (Aves, Icterinae) in an Atlantic Forest reserve in Southeast Brazil
Revista Brasileira de Zoologia
Baixa prevalência de hemoparasitos em aves silvestres no Cerrado do Brasil central
Neotropical Biology and Conservation
Density dependence as related to life history strategy
Ecology
Padrões de riqueza, risco de extinção e conservação dos psitacídeos Neotropicais
Comparative study between the global, national and state lists of threatened birds in Brazil
Natureza & Conservação
Territoriality, adult survival, and dispersal in checked-throated Antwren in Panama
Journal of Avian Biology
Cited by (30)
Rescue of a small declining population of Spanish imperial eagles
2013, Biological ConservationCitation Excerpt :In order to evaluate the ultimate effect of management techniques on the persistence of the population, we conducted simulation analyses. Analyses of population viability as a tool to evaluate management techniques have been used extensively (Nilsson, 2003; Naujokaitis-Lewis et al., 2008; Soutullo et al., 2008; Duca et al., 2009; García-Ripollés and Lopéz-Lopéz, 2011). Here we used the Vortex simulation software (Vortex, version 9.72; Lacy et al., 2005) to compare variation in persistence time before and after the application of the recovery plan, including two scenarios, with and without releases of young eagles by hacking.
Extension of landscape-based population viability models to ecoregional scales for conservation planning
2011, Biological ConservationCitation Excerpt :The ability to model regional population processes such as dispersal and source-sink interactions enables conservation planners to assess how growth in specific geographies (patches) contributes to the overall CHBCR population. Furthermore, because each model is based on habitat suitability, attributes that can be addressed by habitat management can be directly related to population viability as in Duca et al. (2009). Thus, multiple scenarios that strategically call for management in different areas can be created and their impacts on viability evaluated in a decision analysis framework (Maguire, 1986; McCarthy et al., 2010).
Artificial incubation, egg replacement and adoptive parents in bird management: A test with Lesser Elaenia Elaenia chiriquensis
2013, Bird Conservation InternationalEffects of grassland burning on reproductive success of globally threatened Strange-tailed Tyrants Alectrurus risora
2011, Bird Conservation International