Browsing by Author "Wiest, Whitney A."
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Item Development of avian metrics to monitor salt marsh integrity(University of Delaware, 2010) Wiest, Whitney A.Salt marshes are dynamic, highly productive ecosystems that have historically experienced a variety of anthropogenic alterations. Such changes have caused a number of endemic species to become high conservation priorities in the United States. Salt marsh condition must be monitored to develop successful management strategies for wildlife conservation. Avian community structure was evaluated and used to create a Marsh Bird Community Integrity Index (BCI) to assess marsh condition at 184 points across nine Northeast national wildlife refuges (NWR) and refuge complexes. Mean refuge BCI was greatest at E.B. Forsythe NWR and mean survey point BCI was significantly different between marshes of different marsh management types (e.g. ditched, tidal restricted, reference) at four refuges. At the local scale, BCI was positively influenced by percent cover of high marsh and negatively influenced by percent cover of open water. At the landscape scale, BCI was negatively influenced by percent cover of forest, development, and palustrine wetland. A BCI scale can be used to monitor temporal and spatial variations in BCI and to attribute condition labels, “Good”, “Caution”, and “Concern”, to refuge marshes. Monitoring plays an integral role in wildlife conservation efforts; however most monitoring programs are fiscally constrained and must determine how to acquire needed information with minimal resources. Monitoring objectives may be achieved by supplementing costlier intensive assessment metrics with appropriate cost-efficient rapid metrics, and by monitoring specific taxa as indicators of ecosystem health. A subset of the 184 points, located at the Coastal Delaware NWR Complex, was used to evaluate differences in rapid versus intensive avian assessment metrics. Overall, occupancy and relative abundance estimations for four tidal marsh obligate species increased as number of visits increased, however there was a greater positive effect of number of visits on differences between relative abundance estimates than occupancy estimates. Comparisons between metrics of a potential indicator species, Seaside Sparrow, resulted in significant positive relationships between the rapid metric relative abundance and intensive avian metrics, nest density, fledgling density, and territory density. This research supports using birds to monitor the ecological condition of the surrounding salt marsh to improve management decisions and maximize conservation gains.Item Tidal marsh bird conservation in the Northeast USA(University of Delaware, 2015) Wiest, Whitney A.Conservation of tidal marsh birds is a high priority in the United States in light of continued habitat loss from anthropogenic impacts, including climate change. The north Atlantic coast of the U.S. is considered a hotspot for accelerated sea level rise, where rates are increasing three to four times faster than the global average. Increased inundation and coastal storm severity and frequency affect tidal marsh habitat quantity and quality and threaten tidal marsh bird populations with rapid declines or extinction. Tidal marsh bird distributions and abundance are relatively unknown, but are critical for developing effective, novel conservation strategies to increase the likelihood of species persistence. I developed a regional monitoring framework to assess the status of the tidal marsh bird community breeding in the Northeast U.S. (Maine to Virginia), and derived a conservation strategy for the state of Delaware. I sampled 1,780 locations during the 2011 - 2012 breeding seasons to estimate species distribution and abundance in tidal marsh habitat patches for five specialist birds: Clapper Rail ( Rallus crepitans ), Willet (Tringa semipalmata ), Nelson's Sparrow (Ammodramus nelsoni ), Saltmarsh Sparrow (A. caudacutus ), and Seaside Sparrow (A. maritimus ). I used the survey estimates to develop Bayesian Network models to predict distribution and abundance in un-sampled habitat patches as a function of patch covariates. Overall, I found the prevalence of Nelson's Sparrow was similar in Coastal Maine and Cape Cod - Casco Bay and the four other species were most common in patches in Long Island (Saltmarsh and Seaside Sparrows), Delaware Bay (Clapper Rail), and Coastal Delmarva (Willet). I estimated 109,758 (±48,505 95% CI) Clapper Rails; 111,021 (±41,566) Willets; 6,640 (±2,750) Nelson's Sparrows; 60,058 (±19,829) Saltmarsh Sparrows; and 234,542 (±119,419) Seaside Sparrows in the Northeast. In Delaware, I used an optimization algorithm to determine the most favorable, yet cost-effective, unprotected tidal marsh parcels for bird conservation; however, greater than 95% of the marsh area on the selected parcels was inundated under all sea level rise scenarios evaluated. Agricultural land was the greatest remaining land cover type, highlighting the need to assess the potential for marsh transgression on adjacent lands. The monitoring framework, baseline species assessments, and modeling approaches presented here, can be incorporated into an adaptive management tool to guide complex decision-making for tidal marsh habitat and bird populations in an increasingly changing landscape.