Dissertation/Thesis Abstract

Population Dynamics of Northern Cardinal and Carolina Wren in an Urban Forest Fragment: Safe Refuge or Ecological Trap?
by Karmacharya, Binab, M.S., University of Louisiana at Lafayette, 2015, 42; 10002466
Abstract (Summary)

Conserving bird populations in urban landscapes often depends on interactions between extinction, recolonization, and survival in remnant habitat patches such as small nature preserves. Thus, determining the ecological value of small nature preserves to birds is a necessary step towards an informed conservation strategy. As such, I conducted a year round capture-mark-recapture study from April 2010 to March 2014 to examine population dynamics of Northern Cardinals (Cardinalis cardinalis) and Carolina Wrens ( Thryothorus ludovicianus) in a 41.7-ha nature preserve embedded in an urban matrix. More specifically, we examined variation in survival, recruitment, and realized population growth rates relative to year, season, sex, age, and wing length (as a proxy for body size) to investigate attributes that affect individual survival and to assess whether the reserve served as a population source or sink. The overall annual apparent survival rate of Northern Cardinals (0.520 ± SE 0.050) was higher than that of the Carolina Wrens (0.349 ± 0.050), and estimates in both species were similar to regional baseline estimates. The survival rates for adults were significantly higher than for immatures in both species, with body size having a positive influence on survival. Seasonal variation in survivorship was evident only in Northern Cardinals, being highest in the winter and lowest during the breeding season. Average annual population growth rate was slightly greater than 1.0 for both species, indicating stable or perhaps modestly increasing populations. These results represent the first published full annual cycle estimates of survival and population growth relative to age, sex, and body size for non-migratory passerines. Our results suggest that urban forests can provide the necessary resources to sustain growing populations of locally common birds. Furthermore, our demographic estimates derived from two healthy bird populations can serve as target values for other species of conservation concern within human-modified landscapes.

Indexing (document details)
Advisor: Duke-Sylvester, Scott M.
Commitee: Klerks, Paul L., Neigel, Joseph E.
School: University of Louisiana at Lafayette
Department: Biology
School Location: United States -- Louisiana
Source: MAI 55/03M(E), Masters Abstracts International
Subjects: Wildlife Conservation, Wildlife Management, Ecology
Keywords: Avian ecology, Conservation, Habitat, Population growth rate, Recruitment, Survival
Publication Number: 10002466
ISBN: 9781339419749
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