Which is worse for the red-billed curassow: habitat loss or hunting pressure?


E LAIN E RIO S,PHI LI P J. K. MCGOWA N,NIGE L J. COL LAR MAÍRA BENCHIMOL,GUSTA V O R. CANALE,FABIO OLMOS MANOEL SAN T O S -F ILHO and CHRI S TIN E S. S. BERN A RD O


Abstract Large ground-dwelling Neotropical gamebirds are highly threatened by habitat loss and hunting, but conser- vationists rarely attempt to distinguish between these two threats in the management of populations. We used three different types of species records to determine the status (i.e. persistence level) of the Endangered red-billed curas- sow Crax blumenbachii in 14 forest remnants in north-east Brazil, as either persistent, precarious or extirpated. We related these persistence levels to variables measured in a 2-km buffer radius, including variables associated with habitat quality (proportion of forest cover, length of rivers, patch density, distance from rivers) and hunting pressure (proportion of cacao agroforests and farmlands, length of roads, total area occupied by settlements, distance from roads and from settlements). Curassows were more persis- tent in forest patches located (1) more distant from settle- ments, (2) in landscapes with few settlements, (3)inland- scapes with a high incidence of roads, (4) in a mosaic with a high proportion of forest, shaded cacao agroforest and farmland, and (5) more distant from other forest patches. Hunting pressure potentially exerts more influence on persistence than habitat quality: (1) hunting pressure sub- models had a higher explanatory power than habitat quality submodels, (2) final models comprised four hunting pres- sure variables but only two habitat quality variables, and


ELAINE RIOS ( orcid.org/0000-0001-7547-8082) and CHRISTINE S. S. BERNARDO (Corresponding author,


orcid.org/0000-0003-4406-0251) Programa de Pós


Graduação em Genética, Biodiversidade e Conservação, Universidade Estadual do Sudoeste da Bahia, Rua José Moreira Sobrinho, Bairro Jequiezinho, CEP 45206-190, Jequié, Bahia, Brazil E-mail christinesteiner@yahoo.com


PHILIP J. K. MCGOWAN ( orcid.org/0000-0001-8674-7444) School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK


NIGEL J. COLLAR ( Cambridge, UK


orcid.org/0000-0001-9677-3611) BirdLife International,


MAÍRA BENCHIMOL ( orcid.org/0000-0002-1238-1619) Laboratório de Ecologia Aplicada à Conservação, Universidade Estadual de Santa Cruz, Ilhéus, Brazil


GUSTAVO R. CANALE ( orcid.org/0000-0002-3932-282X) Núcleo de Estudos da Amazônia Meridional, Instituto de Ciências Naturais, Humanas e Sociais, Universidade Federal do Mato Grosso, Sinop, Brazil


FABIO OLMOS ( orcid.org/0000-0003-3832-6455) Permian Brazil, São Paulo, Brazil


MANOEL SANTOS-FILHO ( orcid.org/0000-0002-9784-7114) Universidade do Estado de Mato Grosso, Cáceres, Brazil


Received 20 June 2018. Revision requested 10 August 2018. Accepted 10 June 2019. First published online 18 March 2020.


(3) hunting pressure variables appeared in all models where- as habitat quality variables appeared in only one final model. If hunting pressure is driving declines in curassows, regions with low human presence and a high proportion of forest cover are recommended for establishing new reserves.


Keywords Atlantic Forest, Crax blumenbachii, frugivore, gamebird, hotspot, red-billed curassow, settlement, threat- ened species


Supplementary material for this article is available at doi.org/10.1017/S0030605319000711


Introduction


nomenon (Ceballos et al., 2015). The effects of such pressures tend to be worse when several, such as hunting and habitat loss, act together (Brook et al., 2008). Large forest-dwelling gamebirds, including curassows (genera Crax, Mitu and Pauxi of the family Cracidae), are among the vertebrate spe- cies most affected by the combination of hunting pressure and declines in forest quantity and quality (Collar et al., 1997; Thornton et al., 2012; Kattan et al., 2016). Curassows appear to be sensitive to the proximity of human communi- ties (Begazo & Bodmer, 1998; Thornton et al., 2012) and the presence of roads (Martónez-Morales, 1999; Srbeck-Araujo et al., 2012), both of which are associated with hunting pressure.


T Although they can be abundant where not exploited


(Kattan et al., 2016), curassows are highly vulnerable to hunting pressure because of their low productivity (max- imum output of two chicks per female per year; Butcher, 2006). Seven of the eight species of the genus Crax are categorized as threatened on the IUCN Red List: two are Critically Endangered, two are Endangered and three are Vulnerable (BirdLife International, 2018). The red-billed curassow Crax blumenbachii (Endangered; downlisted from Critically Endangered in 2000) is the only representative of the genus in South America’s Atlantic Forest, to which it is endemic. Extensive habitat loss and high hunting pressure are the main threats to the species. It originally occur- red from near the city of Rio de Janeiro to central Bahia, Brazil, in what was once continuous habitat (IBAMA, 2004),


This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. Oryx, 2021, 55(3), 412–420 © The Author(s), 2020. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605319000711


he loss of species to human pressures is a worldwide and, especially in tropical forests, accelerating phe-


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