DOI: 10.5061/dryad.qz612jmn0
title: Survival of juvenile Florida Scrub-Jays is positively correlated with month and negatively correlated with male breeder death

description: Juvenile survival in birds is difficult to estimate, but this vital rate
 can be an important consideration for management decisions. We estimated
 juvenile survival of cooperatively breeding Florida Scrub-Jays (Aphelocoma
 coerulescens) in a landscape degraded by fire suppression and
 fragmentation using data from marked (n = 325) and unmarked juveniles (n =
 1,306) with an integrated hierarchical Bayesian model. To assess the
 combined analyses, we also analyzed these datasets separately, with a
 Cormack–Jolly–Seber model (marked) and a young model (unmarked). Our data
 consisted of monthly censuses of territorial family groups from Florida
 Scrub-Jay populations in East Central Florida collected over a 22-year
 period. Juvenile survival was estimated from July when young Florida
 Scrub-Jays begin developing independence to March when they become
 first-year individuals and grouped according to the habitat quality class
 of their natal territory that were based on shrub height (with
 intermediate shrub heights being optimal and short and tall shrub heights
 being suboptimal) and the presence of sandy openings (the preferred open
 having many sandy openings; closed not having enough). Parameter estimates
 in the combined analysis were intermediate to the separate analyses.
 Notable differences among the separate analyses were that suboptimal
 habitat survival was lower in the unmarked analysis, the unmarked analysis
 showed a linear effect of time not seen in the marked analysis, and there
 was an effect of male breeder death in the marked but not unmarked
 analysis. The combined data analysis provided more inference than did
 either dataset analyzed separately including juveniles in optimal-closed
 territories unexpectedly had higher survival than those in optimal-open,
 survival increased through time, and male breeder death had a negative
 effect on survival. This study suggests that optimal-closed habitat may
 play an important role in juvenile Florida Scrub-Jay survival perhaps by
 providing better cover from predators and warrants further investigation
 for management implications.
description: Habitat quality within territories was classified annually by
 overlaying territory maps on digital orthorectified aerial photography.
 Visual classification specified textures that corresponded to vegetation
 height (Breininger and Carter 2003); we binned territories into the
 defined habitat classifications. Sociobiological covariates for each
 territory were quantified from annual demographic data. Helper count was
 taken in March (at beginning of breeding season), sibling count and cohort
 count were taken in July (at beginning of capture history). Male death and
 female death that occurred between March and the following July was coded
 as binary (1 = death during year). Two types of survival data were
 utilized. In the first type (hereafter the marked dataset), all nestlings
 were banded 11 days after hatching using a numbered metal leg band and a
 unique combination of color bands allowing identification of individuals.
 The marked dataset was collected from 1988 to 2009 as part of a long-term
 demographic monitoring effort of the scrub-jay population  occurring on
 Merritt Island National Wildlife Refuge/John F. Kennedy Space Center
 (MINWR/KSC). During this period, the populations under study were
 intensively monitored, and we attempted to locate all nesting attempts
 before the penultimate egg was laid, and thus clutch size and age of
 nestlings were known (Carter et al. 2011). Nests were visited weekly to
 determine status and count eggs or nestlings until failure or fledging.
 Thereafter, we conducted a monthly census within each territory to record
 observations of banded birds. In the second data type (hereafter the
 unmarked dataset), young were not banded in the nest, but a monthly census
 like that for the marked dataset was conducted within each territory to
 observe the total number of unmarked young alive with the family group.
 The unmarked dataset was collected from 1988 to 2014 as part of a larger
 and less intensive monitoring effort (i.e. no nest monitoring) of the
 scrub-jay metapopulation in East Central Florida (Breininger et al. 1995)
 and on MINWR/KSC (Figure 1).
description: Bayesian models were fit using Markov Chain Monte Carlo (MCMC)
 methods using the program JAGS 4.3.0 implemented in R (R Core Team 2020)
 with the package jagsUI and visualized using R packages coda, ggmcmc, and
 bayesplot.