Niche Breadth, Resource Availability, and Inference

Smith, Eric P.

doi:10.2307/1940109

Cited by 163 publications

(125 citation statements)

References 22 publications

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“…where FT is Smith's measure of niche breadth, p j is the proportion of individuals found in resource state j (Σp j = 1.0), and a j is the proportion of resource j is of the total resources (Σa j = 1.0) (Smith 1982). The 95% confidence intervals were calculated using the equation: ,…”

Section: Methodsmentioning

confidence: 99%

Effect of Reproductive Status on the Diet Composition of Wolverines (Gulo gulo) in Boreal Forests of Eastern Finland

Koskela

Kojola

Aspi

et al. 2013

Annales Zoologici Fennici

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Sex differences in foraging ecology have been found in a variety of taxa. We tested the hypothesis that breeding female wolverines (Gulo gulo), probably due to their smaller home ranges and higher energy demands because of gestation and lactation, are forced to rely more on food caches and carrion than other wolverines. The diet composition, as the percentage occurrence, was estimated for four breeding females and six males and non-breeding females by analyzing scat samples, all collected in eastern Finland. The most important food source for breeding female wolverines was human-and wolfkilled moose (55%), while the diet also comprised mountain hare (13%), domestic pig (13%) and grouse (11%). Mountain hare (52%) was the most utilized food source for males and non-breeding females. Moose (22%) and grouse (15%) were also important components of the diet. Our study highlights the importance of human-and wolf-killed carrion for breeding female wolverines in areas where the density of medium-sized ungulates is low.

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Section: Methodsmentioning

confidence: 99%

Effect of Reproductive Status on the Diet Composition of Wolverines (Gulo gulo) in Boreal Forests of Eastern Finland

Koskela

Kojola

Aspi

et al. 2013

Annales Zoologici Fennici

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show abstract

“…and !" has been criticized because these metrics do not account for resource availability (Hurlbert 1978;Smith 1982). Thus, comparing these values among species that occupy different sites, or that are collected at different times, can be the result of spatial and temporal variation in the availability of different resources (Martinez del Rio et al 2009).…”

Section: Levins Macarthur Niches and Isotopic Ecologymentioning

confidence: 99%

Comparative isotopic natural history of two native passerines (Troglodytes cobbi and Cinclodes antarcticus) and the invasive rats (Rattus norvegicus) that extirpate them

et al. 2016

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While several studies have shown that invasive rats can have negative effects on island birds through predation (both direct predation and nest predation), other mechanisms for the effects of invasives on island biota have been given less attention. Here we explore another potential mechanism by which invasive rats can affect native island birds: the competitive use of common resources. We used stable isotope analyses to estimate the fraction of marine and terrestrial sources incorporated into the tissues of two species of passerines (Troglodytes cobbi, Troglodytidae; and Cinclodes antarcticus, Furnariidae) and Norway rats (Rattus norvegicus, Muridae) in the Falkland Islands. These two passerines are absent on islands where rats are present. We found significant incorporation of marine resources in the three species, with the highest incorporation in tissues of T. cobbi. This species appears to be one of the passerines most reliant on marine sources and the most marine member of the family Troglodytidae. We also used the results of these isotopic analyses to estimate the isotopic niche breadth of each of these species and the isotopic niche overlap among them. Rattus norvegicus had a large isotopic niche that overlapped broadly with those of the two passerine species. We propose that different ways of both depicting and estimating isotopic niche widths are complementary rather than alternative.Our results are consistent with the notion that invasive rats might have an impact on these two species of Falkland Island passerines by using common resources, but do not rule out the possibility that part of their effect is through direct predation.

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“…Zero indicates random feeding. Bootstrapping procedure (300 simulations) was conducted on individual bites [keeping resource abundance constant (Smith 1982)] to estimate the confidence limits of electivity values. Ivlev's electivity values were tested against random feeding by looking if the confidence interval included zero or not.…”

Section: Discussionmentioning

confidence: 99%

“…This measure can take values between zero (specialist feeder) and one (generalist feeder). Seasonal difference in niche breadth was tested using Z-test (Smith 1982).…”

Section: Discussionmentioning

confidence: 99%

Limited flexibility in resource use in a coral reef grazer foraging on seasonally changing algal communities

2010

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Feeding ecology of three life phases of the parrotfish Scarus ferrugineus was studied on a southern Red Sea fringing reef by comparing availability and consumption of benthic algae during the monsoon hot and cool seasons. Dominant biota covering dead carbonate substrates were in decreasing order of importance: turfs on endoliths, turfs on crustose corallines, and crustose corallines. On the reef crest and shallow fore reef, composition of the biota changed seasonally. Cover of turfs on endoliths and turfs on crustose corallines was higher during the hot season, while crustose corallines and macroalgae (only on reef crest) increased during the cool season. Biota in the deep fore reef did not show seasonal variation. All life phases used similar resources and showed selective feeding in all zones. Turfs on endoliths, followed by turfs on crustose corallines, was the primary feeding substrate. These two sources represented over 92% of bites during both seasons. Crustose corallines, macroalgae, and living corals were negligible components being strongly avoided at all zones and seasons. Resource use varied seasonally on the reef crest and shallow fore reef, while it remained unchanged on the deep fore reef. Turfs on endoliths were consistently preferred in both seasons but their contribution increased from 45% in the cool to 70% of bites in the hot season. Electivity for turfs on crustose corallines shifted from random feeding in the hot (27% of bites) to selection in the cool season (47% of bites). Feeding pattern changed diurnally with more bites taken from crustose corallines and turfs on crustose corallines during morning. During the rest of the day, bites from turfs on endoliths predominate. S. ferrugineus shows limited capacity to exploit seasonal increases in the biomass of foliose and canopy forming macroalgae, despite indications of energetic limitation during the cool season.

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Niche Breadth, Resource Availability, and Inference

Cited by 163 publications

References 22 publications

Effect of Reproductive Status on the Diet Composition of Wolverines (Gulo gulo) in Boreal Forests of Eastern Finland

Effect of Reproductive Status on the Diet Composition of Wolverines (Gulo gulo) in Boreal Forests of Eastern Finland

Comparative isotopic natural history of two native passerines (Troglodytes cobbi and Cinclodes antarcticus) and the invasive rats (Rattus norvegicus) that extirpate them

Limited flexibility in resource use in a coral reef grazer foraging on seasonally changing algal communities

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