Browsing by Subject "habitat selection"
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Item Influences of Personal Information, Public Information, and Extra-pair Paternity on Breeding Site Fidelity in a Songbird(2012-10-19) Campomizzi, Andrew JamesI investigated the role of extra-pair paternity on use of public information and the interaction between public information and personal information for patch fidelity decisions. It is unknown if songbirds use public information about the number of conspecific fledglings for patch fidelity decisions when extra-pair paternity is uncommon. I tested if probability of patch fidelity was associated with (1) number of fledglings in adjacent territories (public information), and (2) number of fledglings raised with a social mate (personal information). I used logistic regression to predict probability of patch fidelity of males and females based on the 2 uncorrelated predictor variables (Spearman?s rank correlation, S = 21895.28, n = 50, P = 0.723, r = ?0.051). I monitored patch fidelity of 107 territories, counted the number of fledglings in each territory, and assessed parentage of 102 young from 36 nests for white-eyed vireos (Vireo griseus) from 2008?2010 in a 100 ha patch of woodland in central Texas, USA. I excluded the social male as the father of 3 of the 102 young and did not exclude any of the social females as the mother with parentage analysis using 6 microsatellite loci. The number of fledglings in adjacent territories was not a good predictor of probability of patch fidelity for males (beta 1 = 0.166, df = 35, P = 0.247, Nagelkerke?s R2 = 0.054) or females (beta 1 = 0.121, df = 17, P = 0.670, Nagelkerke?s R2 = 0.016). The number of fledglings raised with a social mate was also not a good predictor of probability of patch fidelity for males (beta 1 = ?0.296, df = 43, P = 0.360, Nagelkerke?s R2 = 0.029), whereas it was a good predictor for females (beta 1 = 1.281, df = 21, P = 0.048, Nagelkerke?s R2 = 0.409). The dominant ecological concepts for explaining site fidelity in songbirds, win-stay lose-switch (based on personal reproductive success with a social mate) and public information, did not predict probability of patch fidelity well for male white-eyed vireos. The win-stay lose-switch model, but not public information was a good predictor of probability of patch fidelity for females. My results suggest that use of public information may depend on frequency of extra-pair paternity. Males may primarily use other information for patch fidelity decisions beyond reproductive success of conspecifics for patch fidelity decisions in some circumstances. My results support the need to ensure high levels of nesting success for females to return and maintain populations in areas managed for breeding songbirds for conservation efforts to be successful.Item Nocturnal Movements and Distributions of Bobcats, Coyotes and Raccoons during Quail Nesting Season(2013-04-16) Jhala, SheshNorthern bobwhites (Colinus virginianus) are a valued game species that have seen massive population declines in the last few decades. This decline has been attributed to many factors including predation, the topic of this study. I examined the habitat selection, nocturnal movement and potential rate of encounter with quail nesting locations by coyotes (Canis latrans), bobcats (Lynx rufus), and raccoons (Procyon lotor) at the Rolling Plains Quail Research Ranch, a private 19 km2 ranch in the Rolling Plains ecoregion of west Texas. My study had 2 objectives: (1) to compare the habitat use of mesopredators in the Rolling Plains to the nesting habitat of bobwhites, and (2) to characterize the nocturnal paths of these mesopredators and measure their overlap with quail nesting locations. I placed GPS collars on 4 bobcats, 7 coyotes and 11 raccoons during the quail nesting seasons of 2009-2011. I used the chi-square test as well as a modified version of the Ivlev?s Electivity Index (1961) to calculate habitat selectivity. I also measured the proximity of the mesopredators and quail nesting locations to roads, water and quail feeders on the ranch. I used fractal analysis to calculate length and tortuosity of nocturnal paths and assessed potential risk to quail nests by determining the intersection rates of mesopredator paths with quail nesting locations. I found that a large difference existed in selectivity of habitat between bobwhite nesting locations and the bobcats and raccoons. Bobwhites selected for the upland grasslands and shrubs and against rocky ridges. Bobcats selected for riparian zones, while raccoons selected for both riparian zones and rocky ridges, neither of which were selected for by nesting quail. Bobcats and male raccoons additionally showed a propensity for road travel, which quail often nested close to. Coyotes selected strongly for grasslands, utilized their home ranges comprehensively and showed a preference for road usage, and thus had the greatest potential encounter rate with quail nest sites. However, coyotes also showed the most linear and direct movement pattern, potentially reducing their efficiency in finding quail nests. This study indicates that coyotes potentially present the largest threat to the nests of quail and female raccoons the least. Management decisions such as the levels of management needed for the 3 species of mesopredators are discussed.Item Use of social information for habitat selection in songbirds(2012-07-16) Farrell, Shannon LeighHabitat selection research has focused on the role of vegetative and geologic habitat characteristics or antagonistic behavioral interactions. Conspecifics can confer information about habitat quality and provide positive density-dependent effects that may result in improved fitness, resulting in positive behavioral responses to conspecifics as a habitat selection strategy. I conducted 3 replicated, manipulative experiments to investigate use of conspecific cues in habitat selection for the golden-cheeked warbler (Dendroica chrysoparia) using simulated conspecific vocalizations during pre-settlement and post-breeding periods, across a range of woodland canopy cover. I measured territory density, pairing, and fledging success in paired treatment and control units. Territory density was >2 times higher in treatment units across the range of canopy (P = 0.02). Pairing success was positively correlated with territory density (P = 0.008). Territory density response was higher for pre-settlement than post-breeding treatment (P = 0.004). I found pre-settlement and post-breeding conspecific cues influence golden-cheeked warbler habitat selection, inducing settlement in previously unoccupied areas, and producing aggregations within areas of similar vegetative characteristics. Better understanding of social information use in habitat selection can improve our understanding of species distributions, yielding more accurate predictive distribution models; improve our ability to predict impacts of habitat changes on habitat use, survival, reproduction, and ultimately fitness; and provide a potential tool for attracting individuals to restored or managed sites.