The power of odour cues in shaping fine-scale search patterns of foraging mammalian herbivores

Abstract

Foraging by mammalian herbivores has profound impacts on natural and modified landscapes, yet we know little about how they find food, limiting our ability to predict and manage their influence. Mathematical models show that foragers exploiting odour cues outperform a random walk strategy. However, discovering how free-ranging foragers exploit odours in real, complex landscapes has proven elusive because of technological constraints. We took a novel approach, using a sophisticated purpose-built thermal camera system to record fine-scale foraging by a generalist mammalian herbivore, the swamp wallaby ( Wallabia bicolor ). We tested the hypothesis that odour cues shape forager movement and behaviour in vegetation patches. To do this, we compared wallaby foraging in two odour landscapes: Control (natural vegetation with food and non-food plants interspersed) and +Apple (the same natural vegetation plus a single, highly palatable food source with novel odour (apple)). The +Apple treatment led to strongly directed foraging by wallabies: earlier visits to vegetation patches, straighter movement paths, more hopping and fewer stops than in the Control treatment. Our results provide clear empirical evidence that odour cues are harnessed for efficient, directed search even at this fine scale. We conclude that random walk models miss a key feature shaping foraging within patches.

Konzentrierte Nahrungssuche bei Magellanspechten: Die Bedeutung von Baumalter, Waldzusammensetzung und Offenhabitaten

“…The assessment of ARS behavior has been, for instance, carried out in marine species, including sharks [14], seals [15], whales [16], dolphins [17], sea turtles [18], pu ns [19], boobies [20] and albatross [21]. Although the ARS behavior has been tested in terrestrial species like carnivores [22], [13], small mammals [23], marsupials [24], lizards [25] and spiders [26], less attention has been paid to study it in woodpeckers. Determining habitat conditions under which forest specialized woodpeckers adopt an ARS behavior may contribute to sustainable landscape planning and forest management intended to increase habitat quality and connectivity.…”

Ring‐tailed lemurs (Lemur catta) use olfaction to locate distant fruit

“…As the ability to navigate to distant food is critical for survival, animals tend to use multiple sensory systems to encode locations (Wiener et al, 2011). Animals as varied as carnivores (Gittleman, 1991), frugivorous bats (Korine & Kalko, 2005), herbivorous wallabies (Orlando et al, 2020), and seabirds (Nevitt, 2000) rely on olfaction to navigate their environments. The few studies investigating navigational olfaction among primates have focused on humans.…”

Modeling mycorrhizal fungi dispersal by the mycophagous swamp wallaby (Wallabia bicolor)

“…Spatial and temporal patterns of fecal pellet deposition are related to feeding behavior and movement patterns. Swamp wallaby feeding behavior is not random nor evenly distributed across a landscape; Orlando et al (2020) found that swamp wallaby foraging patterns were shaped by odor shown to defecate at a greater rate while feeding than while resting, and rates vary with age, sex, and season (Johnson et al, 1987;Southwell, 1989;Warner, 1981). These findings are likely also true for swamp wallabies, and pellet deposition would vary spatially, temporally, and among individuals; thus, spore dispersal is not even across their home range.…”

“…Swamp wallaby feeding behavior is not random nor evenly distributed across a landscape; Orlando et al. (2020) found that swamp wallaby foraging patterns were shaped by odor cues. Tammar wallabies ( Macropus eugenii ), eastern gray kangaroos ( M. giganteus ), and red‐necked wallabies ( M. rufogriseus ) have all been shown to defecate at a greater rate while feeding than while resting, and rates vary with age, sex, and season (Johnson et al., 1987; Southwell, 1989; Warner, 1981).…”