Data from: An integrated population model for bird monitoring in North America

Integrated population models (IPMs) provide a unified framework for
simultaneously analyzing data sets of different types to estimate vital
rates, population size, and dynamics; assess contributions of demographic
parameters to population changes; and assess population viability.
Strengths of an IPM include the ability to estimate latent parameters and
improve the precision of parameter estimates. We present a hierarchical
IPM that combines two broad-scale avian monitoring data sets; count data
from the North American Breeding Bird Survey (BBS) and capture-recapture
data from the Monitoring Avian Productivity and Survivorship (MAPS)
program. These data sets are characterized by large numbers of sample
sites and observers, factors capable of inducing error in the sampling and
observation processes. The IPM integrates the data sets by modeling the
population abundance as a first-order autoregressive function of the
previous year's population abundance and vital rates. BBS counts were
modeled as a log-linear function of the annual index of population
abundance, observation effects (observer identity and first-survey-year),
and overdispersion. Vital rates modeled included adult apparent survival,
estimated from a transient Cormack-Jolly-Seber model using MAPS data, and
recruitment (surviving hatched birds from the previous season + dispersing
adults) estimated as a latent parameter. An assessment of the IPM
demonstrated it could recover true parameter values from 200 simulated
data sets. The IPM was applied to data sets (1992-2008) of two bird
species, gray catbird (Dumetella carolinensis) and wood thrush (Hylocichla
mustelina) in the New England/Mid-Atlantic coastal Bird Conservation
Region of the USA. The gray catbird population was relatively stable
(trend 0.4% yr−1), while the wood thrush population nearly halved (trend
-4.5% yr−1) over the 17-yr study period. IPM estimates of population
growth rates, adult survival, and detection and residency probabilities
were similar and as precise as estimates from the stand-alone BBS and CJS
models. A benefit of using the IPM was its ability to estimate the latent
recruitment parameter. Annual growth rates for both species correlated
more with recruitment than survival, and the relationship for wood thrush
was stronger than for gray catbird. The IPM's unified modeling
framework facilitates integration of these important data sets.