Interspecific interference competition at the resource patch scale: do large herbivores spatially avoid elephants while accessing water?

Abstract

Animals may anticipate and try to avoid, at some costs, physical encounters with other competitors. This may ultimately impact their foraging distribution and intake rates. Such cryptic interference competition is difficult to measure in the field, and extremely little is known at the interspecific level. We tested the hypothesis that smaller species avoid larger ones because of potential costs of interference competition and hence expected them to segregate from larger competitors at the scale of a resource patch. We assessed fine-scale spatial segregation patterns between three African herbivore species (zebra Equus quagga, kudu Tragelaphus strepsiceros and giraffe Giraffa camelopardalis) and a megaherbivore, the African elephant Loxodonta africana, at the scale of water resource patches in the semi-arid ecosystem of Hwange National Park, Zimbabwe. Nine waterholes were monitored every two weeks during the dry season of a drought year, and observational scans of the spatial distribution of all herbivores were performed every 15 min. We developed a methodological approach to analyse such fine-scale spatial data. Elephants increasingly used waterholes as the dry season progressed, as did the probability of co-occurrence and agonistic interaction with elephants for the three study species. All three species segregated from elephants at the beginning of the dry season, suggesting a spatial avoidance of elephants and the existence of costs of being close to them. However, contrarily to our expectations, herbivores did not segregate from elephants the rest of the dry season but tended to increasingly aggregate with elephants as the dry season progressed. We discuss these surprising results and the existence of a trade-off between avoidance of interspecific interference competition and other potential factors such as access to quality water, which may have relative associated costs that change with the time of the year.

The impact of camel visitation on native wildlife at remote waterholes in arid Australia

“…Thus, competition for a limited resource, such as water in dry times, can lead to high niche overlap (Gotelli & Ellison, 2013) and not the low niche overlap expected for species that can coexist by partitioning their resources (Connell, 1980). Similarly, Ferry et al, (2016) found that smaller herbivores spatially avoided elephants at the beginning of the dry season, but not later, even though elephant usage of waterholes increased as the dry season progressed.…”

Heterogeneity of water physico-chemical characteristics in artificially pumped waterholes: do African herbivores drink at the same locations and does it lead to interference competition?

“…For example, Valeix et al (2007) showed a temporal avoidance of African elephants Loxodonta africana by several other herbivores species. However, a recent study revealed that when zebras Equus quagga, and to a lesser extent kudus Tragelaphus strepsiceros, co-occur with elephants around pumped waterholes at the end of the dry season, they tend to all aggregate in the same specific sections of the waterhole area (Ferry et al 2016). One hypothesis suggested to explain this unexpected result is that it is not only the presence or the quantity of the resource that matters but its quality.…”

Influence of temperature on intraspecific, unbalanced dyadic contests between crabs

“…Animal conflicts are common across many taxa (e.g., Bonacci et al, 2006; Ferry et al, 2016; Robins, 2008; Robinson, 2014; Souza, Ilarri & Rosa, 2011; Tierney, Godleski & Massanari, 2000) and can be either inter or intraspecifically orientated. Bouts over food resources and territorial disputes are common inter and intraspecific interactions (e.g., Dröscher & Kappeler, 2014; Souza, Ilarri & Rosa, 2011), while disputes for mates, protection of offspring and social hierarchy inside a given population are exclusive intraspecific interactions (e.g., Lee, Yang & Curley, 2018; Sato & Nagayama, 2012; Souza & Ilarri, 2014).…”