Habitat‐specific breeder survival of Florida Scrub‐Jays: inferences from multistate models

Abstract

Quantifying habitat-specific survival and changes in habitat quality within disturbance-prone habitats is critical for understanding population dynamics and variation in fitness, and for managing degraded ecosystems. We used 18 years of color-banding data and multistate capture-recapture models to test whether habitat quality within territories influences survival and detection probability of breeding Florida Scrub-Jays (Aphelocoma coerulescens) and to estimate bird transition probabilities from one territory quality state to another. Our study sites were along central Florida's Atlantic coast and included two of the four largest metapopulations within the species range. We developed Markov models for habitat transitions and compared these to bird transition probabilities. Florida Scrub-Jay detection probabilities ranged from 0.88 in the tall territory state to 0.99 in the optimal state; detection probabilities were intermediate in the short state. Transition probabilities were similar for birds and habitat in grid cells mapped independently of birds. Thus, bird transitions resulted primarily from habitat transitions between states over time and not from bird movement. Survival ranged from 0.71 in the short state to 0.82 in the optimal state, with tall states being intermediate. We conclude that average Florida Scrub-Jay survival will remain at levels that lead to continued population declines because most current habitat quality is only marginally suitable across most of the species range. Improvements in habitat are likely to be slow and difficult because tall states are resistant to change and the optimal state represents an intermediate transitional stage. The multistate modeling approach to quantifying survival and habitat transition probabilities is useful for quantifying habitat transition probabilities and comparing them to bird transition probabilities to test for habitat selection in dynamic environments.

Multistate Mark–Recapture Analysis Reveals No Effect of Blood Sampling on Survival and Recapture of Eastern Kingbirds (Tyrannus tyrannus)

“…Multistate models were originally designed to represent movement and survival among different populations (e.g., Hestbeck et al 1991, Breininger et al 2009) but can be adapted for use with other types of categorical variables that could change over time (e.g., reproductive status or effort; Lescroel et al 2009, Schaub andvon Hirschheydt 2009). The state values in our models indicated whether or not blood was collected from an individual in a year.…”

Determinants of Nest Survival in a Managed Florida Scrub-Jay Population

“…This habitat strueture faeilitates predator deteetion and avoidanee by adult Florida Serub-Jays, whieh use a sentinel behavior (MeGowan and Woolfenden 1989). Adult survival and nest sueeess are greatest in this habitat state (Woolfenden and Fitzpatriek 1984, Sehaub et al 1992, Breininger and Carter 2003, Breininger and Oddy 2004, Breininger et al 2009). Insuffieiently frequent fire allows shrubs to grow taller and openings to disappear, while an exeessive frequeney does not allow shrub regeneration suffieient to provide adequate eover.…”

Integrating Land Cover Modeling and Adaptive Management to Conserve Endangered Species and Reduce Catastrophic Fire Risk

“…The success of prescribed fire programs is often measured as the annual burn acreage rather than by remaining fuel levels or the ecological value of the fires. Extensive fires that produce a large proportion of the short vegetation state within FSJ territories (Table 1) result in poor FSJ fitness, and repeated extensive fires can result in catastrophic population declines [8]. Scrub management guidelines, focused on biological diversity, specify mosaic fires that produce mostly open-medium territories [12].…”

“…In our approach, land cover is characterized by discrete successional stages that represent habitat quality, as defined on a geographic scale (10 ha), representing average territory size and, therefore, relevant to FSJ recruitment and survival (Table 1, [8][9][10]). Table 1.…”

“…Table 1. Habitat states used to quantify landscape units as potential territories (10 ha) of Florida scrub-jays (FSJs) directly related to long-term demographic performance (yearling production rates; breeder mortality rates) and fire history successional patterns (adapted from [8][9][10]). Populations are expected to increase in landscapes dominated by source territories (positive demographic performance) or to decrease in landscapes dominated by sink territories (negative demographic performance).…”