Niche partitioning among mule deer, elk, and cattle: Do stable isotopes reflect dietary niche?

Stewart, Kelley M.; Bowyer, R. Terry; Kie, John G.; Dick, Brian L.; Ben‐David, Merav

doi:10.1080/11956860.2003.11682777

Cited by 113 publications

(105 citation statements)

References 29 publications

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“…Under such conditions, animals will often forego areas with high-quality forage and consume less nutritious foods (Werner et al 1983, Holbrook & Schmitt 1988, Werner & Hall 1988, Ibrahim & Huntingford 1989. Stewart et al (2003) observed that mule deer Odocoileus hemionus in Oregon were displaced by North American elk Cervus elaphus and free-ranging cattle Bos taurus and, as a result, foraged on a higher diversity of lower quality plants in xeric habitats. Alternatively, under heightened competition or predation risk, sexual and age segregation of habitat use and diet can occur (Werner et al 1983, Corti & Shackleton 2002.…”

Section: Introductionmentioning

confidence: 99%

Evidence of bottom-up control of diet driven by top-down processes in a declining harbor seal Phoca vitulina richardsi population

Herreman¹,

Blundell²,

Ben‐David³

2009

Mar. Ecol. Prog. Ser.

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Two mechanisms of population control dominate most biological systems: bottom-up and top-down regulation. It is possible, however, that top-down mediation may lead to bottom-up control of a population if predators simultaneously compete for the same prey. Harbor seal Phoca vitulina richardsi populations in Glacier Bay (GB) and Prince William Sound (PWS), Alaska, have declined drastically since the 1970s, with PWS recently stabilizing and GB continuing to decline. Hypotheses for the declines include both bottom-up and top-down processes. We hypothesized that increased competition and predation risk are causing harbor seals in GB to forage on lower quality prey. We combined analyses of prey remains in scat and stable carbon and nitrogen isotope ratios in blood and hair to compare seal diets in these areas. Seal diets in GB and PWS varied spatially and temporally due to changes in resource availability and sexual segregation. Adults showed clear divergence in diet during specific times of the year in both areas. Sexual segregation of diet in GB was most prevalent during spring and fall, while in PWS segregation was greatest during late summer. Diet of seals in PWS showed annual variation not found in GB, likely following prey cycles. In GB during summer, all seals switched to a diet with a lower fat content, including more intertidal/ demersal species such as rockfish and sculpin. This switch coincided with an increase in competitors and predators entering GB. The change in diet, combined with higher emigration of harbor seals out of GB, suggest that increased competition and risk of predation may contribute to overall population declines.

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Section: Introductionmentioning

confidence: 99%

Evidence of bottom-up control of diet driven by top-down processes in a declining harbor seal Phoca vitulina richardsi population

Herreman¹,

Blundell²,

Ben‐David³

2009

Mar. Ecol. Prog. Ser.

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“…Stable isotope analysis of carbon (C) and nitrogen (N) can be used to reconstruct diets (Kelly, 2000), with isotopic signatures of herbivore tissues reflecting the stable isotope ratios of plants assimilated (Stewart et al, 2003). Isotopic signatures can be used to separate plants into broad categories based on such qualities as photosynthetic pathway or carbon source (e.g., aquatic macrophytes from terrestrial plants; LaZerte and Szalados, 1982;Keeley, 1998;Cloern et al, 2002;.…”

Section: Stable Isotope Analysismentioning

confidence: 99%

The role of forage availability on diet choice and body condition in American beavers (Castor canadensis)

et al. 2013

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“…Many studies on food interactions among sympatric ungulates have already been carried out in temperate and Afro-tropical large mammal assemblages (VeseyFitzgerald 1960;Gwynne and Bell 1968;Bell 1970;McNaughton 1979;Jarman and Sinclair 1979;Jenkins and Wright 1988;Gordon and Illius 1989;Putman 1996;Johnson et al 2000;Voeten and Prins 1999;Mysterud 2000;Woolnough and du Toit 2001;Stewart et al 2003;du Toit 2003;Gayot et al 2004). However, few studies have compared the diets of wild sympatric herbivores in the Asian subtropics (Dinerstein 1980;Martin 1982;Johnsingh and Sankar 1991;Bagchi et al 2003;Steinheim et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Dry season diets of sympatric ungulates in lowland Nepal: competition and facilitation in alluvial tall grasslands

Wegge

Shrestha

Moe

2006

Ecological Research

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Based on microhistological analyses of faecal material, we compared the early dry season diets of greater one-horned rhinoceros Rhinoceros unicornis, swamp deer Cervus duvauceli and hog deer Axis porcinus, which inhabit the same alluvial grassland habitat complex in lowland Nepal. Their diets were quite similar, both at the forage category level and within subcategories of graminoids and woody plants. Early successional tall grasses, especially Saccharum spontaneum, were the dominant food of all three species, underlining the key role of the threatened alluvial floodplains in large mammal conservation in South Asia. The two deer species ate significantly more graminoids (>66.5%) than did rhino (45.5%), and although they did not differ in proportions of graminoids, swamp deer ate significantly more late successional tall grasses (Narenga porphyrocoma and Themeda spp.) and short grasses (mainly Imperata cylindrica) than hog deer. The two deer consumed almost equal proportions of woody browse (ca. 10%), significantly less than that of rhino (33.0%). The prediction of the Jarman-Bell hypothesis, that large-bodied herbivores are less selective and subsist on lower quality graminoids than smaller ruminants, was not supported by the data. Based on this and previous studies in the same area we propose a conceptual model where the larger megaherbivores (rhino and elephant Elephas maximus) facilitate the smaller swamp deer and hog deer during the monsoonal growing season, while the smaller and more selective deer species outcompete the larger during the dry season when food is more limited. Owing to the all-year sprouting ability of S. spontaneum, facilitation may occur also in the dry season with low numbers of megaherbivores, thus accentuating competitive exclusion at higher deer densities.

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Niche partitioning among mule deer, elk, and cattle: Do stable isotopes reflect dietary niche?

Cited by 113 publications

References 29 publications

Evidence of bottom-up control of diet driven by top-down processes in a declining harbor seal Phoca vitulina richardsi population

Evidence of bottom-up control of diet driven by top-down processes in a declining harbor seal Phoca vitulina richardsi population

The role of forage availability on diet choice and body condition in American beavers (Castor canadensis)

Dry season diets of sympatric ungulates in lowland Nepal: competition and facilitation in alluvial tall grasslands

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