Uncovering the vertebrate scavenger guild composition and functioning in the Cerrado biodiversity hotspot

Abstract

Scavenging is widespread among vertebrates, being very important for maintaining certain ecosystem functions. Despite this, the scavenger communities remain poorly known in some biomes, especially in the Neotropics. Our main objective was to describe for the first time the scavenger community and identify the factors affecting scavenging efficiency in the Brazilian Cerrado. We analyzed the effects of vegetation cover, time of carcass placement and carcass weight, on scavenger species richness, individual abundances, carcass detection and consumption times, and carcass consumption rate. We monitored 11 large and 45 small carcasses using automatic cameras. We documented a total of 19 vertebrate scavenging species, four species of vultures and 15 facultative scavengers. We found that carcass size was the most important factor affecting the scavenger assemblage and consumption patterns. Large carcasses were dominated by vultures, whereas small carcasses were consumed mainly by facultative scavengers. We also found differences between large and small carcasses in all carcass consumption variables except for detection time. However, we did not find an effect of vegetation cover or time of carcass placement on scavenging patterns. The negligible role of mammals and non-raptor birds in large carcasses is also noteworthy, probably due to the consumption and foraging efficiency of the vultures, and the more frugivorous habits of the mesocarnivores. Our results show a highly diverse and efficient scavenging vertebrate community in the Brazilian Cerrado,

Scavenging in the realm of senses: smell and vision drive recruitment at carcasses in Neotropical ecosystems

“…This lack of use of social information may also be due to the quick consumption of small carcasses (i.e. the only ones that are consumed by most facultative scavengers), as the first individual to locate the carcass is the one consuming it completely in most cases [31].…”

“…Because differences in community structure and consumption patterns were found between the two carcass sizes [31], we analysed the data for large and small carcasses separately. The use of camera-trap data to model multi-species time-series dynamics is complicated because the images are not taken at regular intervals, but only when a species is present.…”

Scavenger assemblages are structured by complex competition and facilitation processes among vultures

“…Small carcasses were placed at a minimum distance of 150 m and in higher numbers to more realistically simulate the dynamics of a natural system, where smaller organisms are found at higher densities and have higher mortality rates due to their shorter life span (Rossberg et al., 2008; White et al., 2007). The independence of the samples was confirmed by analyzing the spatial autocorrelation between them and confirmed their spatial independence (see Naves‐Alegre et al., 2021 for further details).…”

“…hoary foxes Lycalopex vetulus ), several raptor species (e.g. southern caracara Caracara plancus ) and some reptiles (see Naves‐Alegre et al., 2021 for details on the study area and the scavenger assemblage).…”

“…All cameras were placed approximate 1.5 m from the carcass, tied to a tree and configured to take 2 photographs per trigger with a delay of 30 seconds, as long as there was movement in front of the lens. Since carrion size is one of the factors that most affects the structure and functioning of scavenger assemblages (Moleón et al., 2015; Naves‐Alegre et al., 2021), we placed 56 fresh carcasses during November 2018, distinguishing two sizes: (1) large, that is domestic goats ( Capra hircus ) weighing 20–40 kg ( n = 11), and (2) small, that is entire chickens or chicken fragments ( Gallus gallus ) weighing between 0.075 and 2 kg ( n = 45), (see study area map in the Appendix S1, Figure S1). All carcasses were placed randomly, large ones at a minimum distance of 1.5 km among them (Morales‐Reyes et al., 2017).…”