DOI: 10.5061/dryad.5q136q2
title: Data from: Integrating abundance and diet data to improve inferences of food web dynamics

description: 1. Both population abundances and chemical tracers are useful tools for
 studying consumer-resource interactions. Food web models parameterized
 with abundances are often used to understand how interactions structure
 communities and to inform management decisions of complex ecological
 systems. Unfortunately, collecting abundance data to parameterize these
 models is often expensive and time-consuming. Another approach is to use
 chemical tracers to estimate the proportional diets of consumers by
 relating the tracers in their tissues to those found in their food
 sources. Although tracer data are often inexpensive to collect relative to
 abundances, diet proportions provide little information on the per-capita
 consumption rates of consumers. Here, we show how integrating these data
 sources can be used to better estimate of consumption rates. 2. Our
 modeling approach informs traditional multispecies population abundance
 models using proportional diet data. We used simulations to determine
 whether integrated food web datasets were more informative than
 traditional abundance datasets and demonstrated the use of our integrated
 approach by estimating consumption rates of humpback whales
 (\textit{Megaptera novaeangliae}) in the western Gulf of Alaska using
 abundances coupled with stable isotopes as a tracer. 3. Our simulations
 demonstrated that integrated models improved the ability to resolve
 alternative hypotheses about the functional response and yielded more
 precise parameter estimates relative to standard food web models. The
 integrated data approach was especially informative under low sample sizes
 or high process variance. Our application of the integrated modeling
 approach to humpback whale indicated that fish averaged about 25\% of
 whale diets, though this proportion declined over the course of the study.
 We also found that traditional abundance model estimates of humpback whale
 consumption were non-estimable and that the integrated food web model led
 to estimable consumption rates. 4. Our results show that integrating
 stable isotopes and abundance datasets provides an exciting way forward
 for parameterizing multispecies models in data-limited systems. We expect
 that future developments of these integrated approaches will extend
 current food web theory by allowing ecologists to study predation dynamics
 over seasonal time scales and at the individual level.
description: Estimated abundances and
 diets of whalesThis file contains the
 estimated densities and diets of humpback whales. The abundances tab
 contains abundance estimates of humpbacks and densities of zooplankton and
 fish from 2004, 2005, 2007, 2012, 2013, and 2014. Each estimate has an
 associated standard error.AbundanceDiet_data.xlsxStable isotope dataThis file contains all the information necessary to estimate diet proportions of this humpback whale population using mixture models. Mixture tabs are the observed mixture for each year. Sources tab is the end member measurements, SourcesCD tab is the concentrations used in the analysis, and the DiscrimSD tab are the discrimination errors.SIA_data.xlsxCode to run abundance and integrated modelsThis R code defines and runs the abundance and integrated models for estimating the feeding rates of humpback whales in the western Gulf of Alaska. Requires R and Just Another Gibbs Sampler (JAGS). Requires the AbundanceDiet_data.xlsx file that is in this repository.WhaleMCMC.R