dc.contributor.advisor | Weckerly, Floyd | |
dc.contributor.advisor | Williamson, Paula | |
dc.contributor.author | Watson, Cynthia Ann ( ) | |
dc.date.accessioned | 2020-10-12T14:36:17Z | |
dc.date.available | 2020-10-12T14:36:17Z | |
dc.date.issued | 2006-08 | |
dc.identifier.citation | Watson, C. A. (2006). Detection probabilities, occupancy and survey effort of golden-cheeked warblers (Dendroica chrysoparia) using detection-nondetection surveys (Unpublished thesis). Texas State University-San Marcos, San Marcos, Texas. | |
dc.identifier.uri | https://digital.library.txstate.edu/handle/10877/12743 | |
dc.description.abstract | Surveys to detect the presence and absence of endangered species may not
consistently cover an area nor account for imperfect detection. We evaluated a revised
detection - nondetection survey method of the federally endangered golden-cheeked
warbler (GCWA, Dendroica chrysoparia). The methodology allows a surveyor to survey consistently among sites and allowed us to estimate probability of detection (the extent of
imperfect detection) and occupancy (proportion of sample units occupied at a site) using
newly developed mark - recapture techniques in the program PRESENCE. From this
information we then determined the survey effort required to estimate occupancy with a
specified precision (coefficients of variation <0.2). Three sites were selected across the
breeding range of GCWA in central Texas. At each site, 28 - 36 detection stations were
placed 200 meters apart. Each detection station was surveyed 9 times during the
breeding season in 2 consecutive years. Surveyors stayed up to 8 minutes at detection
stations recording GCWA detected by sight or sound. We built models to assess the
potential influence of environmental covariates (e.g. slope, aspect, canopy cover) on
detection and occupancy and possible change in occupancy and detection probabilities
within a breeding season, between years, and among sites. Using information - theoretic
model selection procedures we found that detection probabilities and occupancy varied
among sites, between years and within a breeding season. Detection probabilities ranged
from 0.19 to 0.79 and occupancy ranged from 0.52 to 1.0. These estimates were, in turn,
used to determine that 9 surveys of 32 stations at a site will be needed to have estimates
of occupancy with coefficients of variation of 0.2. These findings assume no further
surveys are needed in that breeding year after detection of GCWA at detection stations. | |
dc.format | Text | |
dc.format.extent | 37 pages | |
dc.format.medium | 1 file (.pdf) | |
dc.language.iso | en | |
dc.subject | Golden-cheeked warbler | |
dc.subject | Detection probabilities | |
dc.subject | Bird populations | |
dc.title | Detection probabilities, occupancy and survey effort of golden-cheeked warblers (Dendroica chrysoparia) using detection-nondetection surveys | |
txstate.documenttype | Thesis | |
dc.contributor.committeeMember | Farquhar, Craig | |
dc.contributor.committeeMember | Hatfield, Jeff | |
thesis.degree.department | Biology | |
thesis.degree.grantor | Texas State University--San Marcos | |
thesis.degree.level | Masters | |
thesis.degree.name | Master of Science | |
txstate.access | restricted | |
dc.description.department | Biology | |