DOI: 10.5061/dryad.f5c50
title: Data from: Quantifying the importance of geographic replication and representativeness when estimating demographic rates, using a coastal species as a case study

description: Demographic rates are rarely estimated over an entire species range,
 limiting empirical tests of ecological patterns and theories, and raising
 questions about the representativeness of studies that use data from a
 small part of a range. The uncertainty that results from using demographic
 rates from just a few sites is especially pervasive in population
 projections, which are critical for a wide range of questions in ecology
 and conservation. We developed a simple simulation to quantify how this
 lack of geographic representativeness can affect inferences about the
 global mean and variance of growth rates, which has implications for the
 robust design of a wide range of population studies. Using a coastal
 songbird, saltmarsh sparrow (Ammodramus caudacutus), as a case study, we
 first estimated survival, fecundity, and population growth rates at 21
 sites distributed across much of their breeding range. We then subsampled
 this large, representative dataset according to five sampling scenarios in
 order to simulate a variety of geographic biases in study design. We found
 spatial variation in demographic rates, but no large systematic patterns.
 Estimating the global mean and variance of growth rates using subsets of
 the data suggested that at least 10-15 sites were required for reasonably
 unbiased estimates, highlighting how relying on demographic data from just
 a few sites can lead to biased results when extrapolating across a species
 range. Sampling at the full 21 sites, however, offered diminishing
 returns, raising the possibility that for some species accepting some
 geographical bias in sampling can still allow for robust range-wide
 inferences. The sub-sampling approach presented here, while conceptually
 simple, could be used with both new and existing data to encourage
 efficiency in the design of long-term or large-scale ecological studies.
description: Mark_recapture_matrix"Mark_recapture_matrix.csv": A file containing capture records for each individual (by row) for each year of the study (1 is captured in a given year; 0 is not captured). Covariates used in the analysis of annual survival are also provided: Species ID (1 for Ammodramus caudacutus, 0 for Ammodramus nelsoni, NA for unknown species identity), Sex (1 is male), First capture (the date of first capture; 1 is 2010, 2 is 2011, etc.), Site (1-21), and Plot size (standardized by subtracting the mean and dividing by two standard deviations).brood_size_MCMC"brood_size_MCMC.csv": A file containing the posterior estimates of the parameters from a regression of brood size (at fledging) by clutch size. Rows are 1000 draws from the posterior distributions for the regression intercept (intercept) and the effect of clutch size (clutch).nest_failure_MCMC"nest_failure_MCMC.csv": A file containing the posterior estimates of the parameters from a regression of daily nest failure probability by site and date. Rows are 1000 draws from the posterior distributions for each site effect (site[1] through site[21]) and site-specific coefficient for the date effect (one coefficient for each site; date[1] through date[21]).renest_prob_MCMC"renest_prob_MCMC.csv": A file containing the posterior estimates of the parameters from a regression of re-nesting probability by latitude and date. Rows are 1000 draws from the posterior distributions for each coefficient: intercept (intercept of the regression equation), latitude (the effect of latitude on renesting probability), and date (the effect of date on renesting probability).annual_survival_MCMC"annual_survival_MCMC.csv": A file containing posterior estimates of adult annual survival, by site (columns). Rows are 1000 draws from the posterior distributions for the log-odds of survival (survival estimates are back-transformed using the inverse logit in the model code in order to take a value between 0 and 1). Sites are identified by a two-letter code and are provided from low to high latitude.