Data from: Density-dependent habitat selection of spawning Chinook salmon: broad scale evidence and implications

1. An extensive body of theory suggests that density-dependent habitat selection drives many fundamental ecological processes. The ideal free distribution and the ideal despotic distribution make contrasting predictions about the effect of total population size on relative abundances among habitats. Empirical assessment of these habitat selection models is uncommon because data must be collected over large temporal and spatial scales. 2. I ask whether fluctuation in Chinook salmon (Oncorhynchus tshawytscha) spawner population size through time leads to different relative densities over space. 3. Twenty six years of monitoring data on spawning Chinook salmon across the entire coast of Oregon, USA, were used to evaluate models that make contrasting statements about the interactions of a latent population abundance parameter with physical habitat characteristics. 4. There is strong information-theoretic support for models that include terms that allow the spatial variation in density to change as population size changes through time. Analysis of the best model reveals nonlinear isodars, which suggests a “despotic” or “preemptive” distribution of individuals across habitats, indicating that dominant or early arriving individuals exclude others from breeding sites. 5. This finding has implications for genetic dynamics, population dynamics, and conservation metrics of these highly valued fish. The novel application of modeling techniques used here to assess mechanisms of habitat selection from observational data can be used in the emerging field of eco-evolutionary dynamics

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X are the counts. L is the stream survey length in meters. F is the standardized geomorphic flow variable. G is the standardized geomorphic gradient variable. W is the standardized geomorphic width variable. NDflow is the mean flow in November and/or December

Data from: Proxies in practice: calibration and validation of multiple indices of animal abundance

The abundance of individuals in a population is a fundamental metric in basic and applied ecology, but sampling protocols yielding precise and unbiased estimates of abundance are often cost prohibitive. Proxies of abundance are therefore common, but require calibration and validation. There are many ways to calibrate a proxy, and it is not obvious which will perform best. We use data from eight populations of Chinook salmon (Oncorhynchus tshawytscha) on the Oregon coast where multiple proxies of abundance were obtained contemporaneously with independent mark-recapture estimates. We combined multiple proxy values associated with a single level of abundance into a univariate index and then calibrated that index to mark-recapture estimates using several different techniques. We tested our calibration methods using leave-one-out cross validation and simulation. Our cross-validation analysis did not definitively identify a single best calibration technique for all populations, but we could identify consistently inferior approaches. The simulations suggested that incorporating the known mark-recapture uncertainty into the calibration technique added bias and imprecision. Cross validation techniques should be used to test multiple methods of calibrating multiple proxies to an estimate of abundance. Critical uncertainties with the application of calibrated proxies still exist, and cost-benefit analysis should be performed to help identify optimal monitoring designs