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

Abstract

Large ground-dwelling Neotropical gamebirds are highly threatened by habitat loss and hunting, but conservationists 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 curassow 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 persistent in forest patches located (1) more distant from settlements, (2) in landscapes with few settlements, (3) in landscapes 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 submodels had a higher explanatory power than habitat quality submodels, (2) final models comprised four hunting pressure variables but only two habitat quality variables, and (3) hunting pressure variables appeared in all models whereas 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.

Regional variation in responses of a vulnerable bird species to land‐use and climate change

“…In addition, conserving a large extent in areas with higher environmental suitability, such as in the Amazon and the Atlantic Forest, can help to maintain both viable populations and good habitat conditions to receive new individuals of C. fasciolata that can disperse from unsuitable areas (Borges & Loyola, 2020;Hole et al, 2011;Rezende et al, 2020). But it is important to emphasize that the Atlantic Forest is highly fragmented due to the agricultural development and urbanization, which reduces landscape permeability (Ribeiro et al, 2009;Rosa et al, 2021) Beyond the concern about habitat loss and climate change as the main drivers of bird extinction, hunting is a strong pressure currently threatening C. fasciolata (BirdLife International, 2016)also observed in other cracids (Bonfim et al, 2018;Brooks, 2006;Rios et al, 2021). In addition, land-use changes at local scale (not evaluated in this study), such as patch isolation and edge effects, strongly threaten many species, as well as C. fasciolata (BirdLife International, 2016), reducing habitat connectivity and resource acquisition, and changing microhabitat conditions (Andrén, 1994;Ewers & Banks-Leite, 2013;Lees & Peres, 2009).…”

“…Beyond the concern about habitat loss and climate change as the main drivers of bird extinction, hunting is a strong pressure currently threatening C. fasciolata (BirdLife International, 2016)—also observed in other cracids (Bonfim et al, 2018; Brooks, 2006; Rios et al, 2021). In addition, land‐use changes at local scale (not evaluated in this study), such as patch isolation and edge effects, strongly threaten many species, as well as C. fasciolata (BirdLife International, 2016), reducing habitat connectivity and resource acquisition, and changing microhabitat conditions (Andrén, 1994; Ewers & Banks‐Leite, 2013; Lees & Peres, 2009).…”

Shifting cultivation and hunting across the savanna-forest mosaic in the Gran Sabana, Venezuela: facing changes

“…Similarly, the other threatened species detected (six Vulnerables and one Nearly Threatened) had also low abundances. Among them, the black curassow and the great tinamou were important for Pemón hunters, generating also concern about the population status in the future (Rios et al, 2020).…”

“…These difference might be due to different relationship between indigenous communities and this bird species (with Piaroa using this species as a pet, while for Pemon is a game species), or different habitat preferences of the species between lowland and highland Amazon. For other species of curassow, the Endangered red-billed curassow (Crax blumenbachii), in Brazil was more persistent in forest patches faraway from settlements, with hunting pressure potentially exerting more influence on population persistence than habitat quality (Rios et al, 2020). Again, more detailed population studies are required to better describe population status of this and other endangered species in Gran Sabana, as well as improve our understanding of landscape transformation and human activities in their population dynamics (BirdLife International, 2016).…”

Ciência cidadã e modelos de distribuição de espécies para a conservação de aves ameaçadas

“…pess.). Fatores relacionados à caça podem ser mais determinantes para a presença ou não de uma espécie que a fragmentação de habitat, como encontrado para o mutum-do-sudeste no sul da Bahia (RIOS et al, 2020).…”