Spatially nested niche partitioning between syntopic grazers at foraging arena scale within overlapping home ranges

Abstract

Abstract. Niche separation among species with similar resource requirements can be expressed at various spatiotemporal scales, from the resource components selected at feeding sites to habitat and home range occupation and ultimately geographic distribution ranges. African large herbivores present a challenge to niche theory because multiple species commonly overlap both spatially and in vegetation components consumed. Aided by GPS telemetry, we investigated the space use patterns of two large grazers that are frequently associated in mixed-species aggregations. Specifically, we compared a generalist grazer with hindgut fermentation (plains zebra) with a similar-sized grazing ruminant (blue wildebeest) in west-central Kruger National Park, South Africa. We found that herds of the two species overlapped substantially in the home ranges that they occupied, but exploited spatially distinct foraging arenas for periods lasting several days or weeks within these ranges. Moreover, wildebeest and zebra differed in duration of settlement, extent of areas occupied during settlement, consequent exploitation intensity per unit area, proportion of time spent within foraging arenas relative to roaming interludes, and movement rates while within these arenas. In particular, wildebeest herds concentrated within small areas for prolonged periods, while zebra herds used more foraging arenas but exploited them for briefer periods. Both species overlapped substantially in habitat use, although wildebeest more strongly favored gabbro uplands and sodic sites presenting short grass lawns while zebra made greater use of areas with a taller grass cover. Hence resource partitioning was expressed mainly through behavioral distinctions in patch exploitation at foraging arena scale rather than in home range or habitat separation. Although zebra may have been partially excluded from the grasslands kept short by wildebeest, these sites formed only a small part of the wider ranges utilized by zebra, thereby restricting the competitive consequences. Hence spatially nested resource partitioning of this form contributes to the coexistence of these two grazers, and may be a mechanism enabling niche separation among other species.

Habitat segregation between brown bears and gray wolves in a human‐dominated landscape

“…Habitat segregation has been studied at different scales for many coexisting species, from spiders (Thompson, Ball, & Fitzgerald, ) to a variety of mammals, including ungulates (Darmon et al., ; Owen‐Smith, Martin, & Yoganand, ) and medium‐sized and large carnivores (Broekhuis et al., ; May et al., ; Pereira, Alves da Silva, Alves, Matos, & Fonseca, ). However, evidence of interspecific competition between sympatric large carnivores with fine‐scale data (e.g.…”

“…The patterns observed at different spatial scales (Ordiz et al, 2015 and this study) show that the result of biotic interactions might be visible at several scales and might act as a key mechanism allowing the coexistence between apex predators. Because most of the observed interactions between wolves and bears occur at carcasses (Ballard et al, 2003), fine-scale movements around carcasses might be an additional mechanism used to reduce the risk of encoun- Habitat segregation has been studied at different scales for many coexisting species, from spiders (Thompson, Ball, & Fitzgerald, 2015) to a variety of mammals, including ungulates (Darmon et al, 2012;Owen-Smith, Martin, & Yoganand, 2015) and medium-sized and large carnivores (Broekhuis et al, 2013;May et al, 2008;Pereira, Alves da Silva, Alves, Matos, & Fonseca, 2012). However, evidence of interspecific competition between sympatric large carnivores with fine-scale data (e.g.…”

The distribution of plant consumption traits across habitat types and the patterns of fruit availability suggest a mechanism of coexistence of two sympatric frugivorous mammals

“…Preferred foods are consumed whenever they are available, while fallback foods are consumed when preferred foods are scarce (Yamagiwa & Basabose, ). A few studies have considered the abundance of resources (Brown, ; Kotler & Brown, ; Steinmetz, Garshelis, Chutipong, & Seuaturien, ) or their diversity (Kleynhans, Jolles, Bos, & Olff, ; Kotler & Brown, ), but without taking into account the intrinsic value of each resource to the animal consumers, or considering food resource quality at the community level (Owen‐Smith, Martin, & Yoganand, ; Steinmetz et al, ). A study by Vélez, Espelta, Rivera, and Armenteras () investigated how the distribution of preferred fruits influenced habitat use by lowland tapirs ( Tapirus terrestris ), but did not evaluate the implications for coexistence with closely related species.…”

Space use patterns of a large mammalian herbivore distinguished by activity state: fear versus food?

“…The PFRs occupied by the wildebeest herds during early morning and late afternoon periods coincided with the open habitats with comparatively short grass identified by Yoganand & Owen‐Smith () as representing either gabbro uplands, favoured during the wet season, or seep zones in granitic landscapes, occupied during the dry season. PFRs occupied by individual wildebeest herds remained consistent from 1 year to the next, and overlapped little or not at all with those of neighbouring herds (Owen‐Smith et al ., ). While providing high quality grazing, the PFRs also presented low cover for predators, making it difficult to separate these two influences on habitat occupation during these times of day (Yoganand & Owen‐Smith, ).…”

“…Furthermore, wildebeest showed shorter residence times and moved more frequently between foraging patches in the late dry season when movements to and from surface water became necessary. Owen‐Smith, Martin & Yoganand () described how wildebeest herds exploited particular foraging arenas covering 1–3 km 2 for periods of several weeks within their home ranges, before relocating to a new area, while zebra ( Equus quagga ) herds showed shorter settlement durations and more frequent relocations. Following encounters with lions taking place mainly at night, wildebeest tended to remain within their preferred open habitat rather than moving elsewhere as zebra did (Martin & Owen‐Smith, ), and Traill, Martin & Owen‐Smith () showed that moon phase did not influence the nocturnal activity of wildebeest unless lions were nearby.…”