DOI: 10.5061/dryad.w6m905qx5
title: Dietary niche variation in an invasive omnivore: the effects of habitat on feral pig (Sus scrofa) resource use in Hawaiʻi

description: Invasive omnivores may have profound impacts on ecological communities
 through diet selection, particularly when their functional roles differ
 from those in their native range. While the threat of feral pigs (Sus
 scrofa) to native plant communities in Hawai‘i is well known, their
 trophic dynamics and the drivers of variation in their diet remain
 understudied. We investigated the feral pig trophic niche on Hawai‘i
 Island using stable isotopes (13C and 15N) and Bayesian mixing
 models to identify drivers of variation in resource use. We also
 reconstructed intra-individual variability for six subsampled individuals
 to understand temporal variation in resource use and individual diet
 specialization. Our results revealed feral pigs on Hawai‘i Island exhibit
 a broad trophic niche characterized by diverse diets, with substantial
 overlap in resource use across districts and habitats. Differences in
 dietary composition in the transition from forest to open habitat were
 driven primarily by a decline in invertebrates and an increasing reliance
 on resources enriched in 15N, which may reflect a shift in protein sources
 with habitat. Pigs in forested areas exhibited a smaller trophic niche
 than those in open habitats, largely driven by differences in feeding
 strategies and resource availability. Diets for subsampled individuals
 varied little, suggesting feral pig resource-use strategies in Hawai‘i
 tend to be relatively stable through time. Individual niche-width was
 relatively narrow compared to that of feral pigs in Hawai‘i at large,
 indicating the relatively wide feral pig dietary niche is characterized by
 substantial intraspecific diet specialization, likely as a result of
 strong intraspecific competition. Understanding the drivers of feral pig
 resource use offers key information for management strategies aimed at
 mitigating their ecological impacts in imperiled systems like Hawai‘i.
description: Resources were collected around Hawai‘i island in the districts
 noted in the dataset raw.data_sources.csv. All tail hair samples were
 cleaned using 2:1 chloroform:methanol solution, sectioned,
 and <sup>13</sup>C and <sup>15</sup>N were
 quantified using accelerator mass spectrometry at the University of New
 Mexico’s Stable Isotope Laboratory (Albuquerque, NM). 3-mm sections of the
 most recent hair (closest to the skin) was used for
 raw.data_sampled.indiviuduals.csv. Hairs from six individuals were
 subsampled 12 - 16 times in the data file
 raw.data_subsampled.individuals.csv.
description: # Dietary niche variation in an invasive omnivore: the effects of habitat
 on feral pig (Sus scrofa) resource use in Hawaiʻi
 [https://doi.org/10.5061/dryad.w6m905qx5](https://doi.org/10.5061/dryad.w6m905qx5) ## Description of the data and file structure raw.data_sources.csv contains d13C and d15N values for resources used in the mixing models, along with concentrations of N and C. raw.data_sampled.individuals.csv contains d13C and d15N values for individuals with the most recent 3-mm segments of hair sampled used to investigate spatial variation in resource use. raw.data_subsampled.individuals.csv contains d13C and d15N values for the six subsampled individuals used to investigate individual diet specialization. ID provides a unique code specifying each individual, while length gives the mm-mark for each segment (starting at 0 for 0-3mm). Sex, age, district, and habitat information also given. ### Files and variables #### File: raw\.data\_sources.csv **Description:** Contains d13C and d15N values for resources used in the mixing models, along with concentrations of N and C. ##### Variables * Sample ID: Unique identifier for each resource * d15N : d15N * d13C: d13C * %N: N concentration (%) * %C: C concentration (%) * Type: Resource category (invertebrates, C3, C4) * Tissue: Primarily differences in plant tissues (leaves, roots, fruits) * District: District where sample was collected #### File: raw\.data\_sampled.individuals.csv **Description:**  Contains d13C and d15N values for individuals with the most recent 3-mm segments of hair sampled used to investigate spatial variation in resource use. ##### Variables * ID: Unique identifier for each sampled individual pig * District: Capture district * Habitat.: Capture habitat * Sex: Sex * Age..yr: Estimated age from dentation * Weight..Lbs.: Weight in lbs * d15N: d15N  * d13C: d13C #### File: raw\.data\_subsampled.individuals.csv **Description:** Contains d13C and d15N values for the six subsampled individuals used to investigate individual diet specialization. ID provides a unique code specifying each individual, while length gives the mm-mark for each segment (starting at 0 for 0-3mm). Sex, age, district, and habitat information also given. ##### Variables * Sample ID: Unique sample ID * ID: Unique ID for each individual * length: mm-mark for each segment (e.g. 0 = 0 - 3 mm, 9 = 9 - 12 mm, etc.) * d15N : d15N * d13C: d13C * sex: sex * age: age estimated by dentation * district: capture district * habitat: capture habitat ## Code/software All files are csv files, and all analysis was run using R.