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

Abstract

Social information, acquired through the observation of other individuals, is especially relevant among species belonging to the same guild. The unpredictable and ephemeral nature of carrion implies that social mechanisms may be selected among scavenger species to facilitate carcass location and consumption. Here, we apply a survival-modelling strategy to data obtained through the placement and monitoring of carcasses in the field to analyse possible information transmission cascades within a Neotropical scavenger community. Our study highlights how the use of different senses (smell and sight) within this guild facilitates carcass location through the transmission of social information between species with different carrion foraging efficiencies. Vultures with a highly developed sense of smell play a key role in this process, as they are the first to arrive at the carcasses and their presence seems to serve as a visual cue for other species to locate the resource. Our study supports the local enhancement hypothesis within scavengers, whereby individuals locate carcasses by following foraging heterospecifics, also suggesting the importance of the sense of smell in the maintenance of the community structure.

Behavioral interactions are modulated by facilitation along a heterotrophic succession

“…Thus, species with greater competitive ability (either because of their social characteristic or their larger size, i.e., American black and king vultures, respectively; Wallace & Temple, 1987) dominated the middle and final stages of the succession (Dawson et al, 2022; Menéndez & Gutiérrez, 1999). This pattern may also be partly related to local enhancement (i.e., a facilitation process in which pioneer species signal the presence of carrion to other species) previously demonstrated in this community, and not, or not only, by the carcass opening process (Naves‐Alegre, Morales‐Reyes, Sanchez‐Zapata, et al, 2022). Moreover, as expected, the carcass opening also had an effect on species richness and abundance.…”

“…First, we detected a linear decrease in the abundance of individuals as the resource was being consumed, contrary to what has been described for autotrophic succession, in which abundance initially tends to increase when colonization begins (Begon & Townsend, 2020). We did not find an initial increase in abundance, perhaps because scavenger recruitment at carcasses in our study system is very fast (i.e., 10-30 min) (Naves-Alegre, Morales-Reyes, Sanchez-Zapata, et al, 2022). Second, species diversity also varied over time, with a concave-down trend, so the scavenger community reached its highest diversity at the midpoint of the successional sequence.…”

“…Carrion of a certain size allows the consumption of multiple individuals of different species at the same time (Moleón et al, 2015), which implies very high levels of competition, occurring among both conspecific and heterospecific individuals (Moreno‐Opo et al, 2020; Naves‐Alegre, Morales‐Reyes, Sánchez‐Zapata, & Sebastián‐González, 2022; Ruxton & Houston, 2004). Furthermore, different facilitative processes have also been described in scavenger communities, in the provision of carrion by carnivores (Allen et al, 2014), in the location of the carcass (Kane et al, 2014; Kane & Kendall, 2017; Naves‐Alegre, Morales‐Reyes, Sanchez‐Zapata, et al, 2022) and for carcass opening (Naves‐Alegre, Morales‐Reyes, Sánchez‐Zapata, & Sebastián‐González, 2022; Orr et al, 2019; Selva et al, 2003). The process of carcass opening refers to tearing apart the hard ungulate skin, which can only be done by a few scavenger species (e.g., those with the largest body size, or with powerful beaks), and thus giving access to the inside of the carcass for all scavengers.…”

Ecological and evolutionary consequences of selective interspecific information use

“…In Amazonian rainforest, birds and primates share an avian predator and flee more likely when hearing each other's alarm calls than when hearing a common bird call (Martínez et al, 2022). Differences in foraging efficiencies and sensory capabilities can provide opportunities for interspecific information use: for example, in a recent study of foraging choices in mixed‐species flocks, all bird species maintained or increased their foraging overlap with other members of the flock, by selectively choosing flock mates or flexibly adjusting their behaviour (Vander Meiden et al, 2022), and members of scavenger community are attracted to vultures with superior efficiency and sensory capability for finding carcasses (Naves‐Alegre et al, 2022).…”

Intraguild scavenging on carnivore carcasses is delayed enough to allow successful dispersal of maggots for pupation

“…They may also shape species assemblages and the temporal transition (i.e. succession) on carcasses in a non‐random manner (Michaud et al., 2015; Naves‐Alegre et al., 2022; Selva & Fortuna, 2007), thereby ultimately determining carcass persistence (Cunningham et al., 2018; Hill et al., 2018; Olson et al., 2012) and nutritional allocation in ecosystems (Barton et al., 2019; Subalusky et al., 2017). As such, monitoring the use of carcasses by vertebrate scavengers and necrophagous arthropods, as well as their potential interactions, is critical for a better understanding of ecosystem functions and services.…”