Performing Department
Biological & Environmental Sci
Non Technical Summary
Cerulean Warbler (Setophaga cerulea) (CERW), one of the fastest declining songbird species in North America, has lost 70% breeding population since 1960s. One of the major factors contributed to this fast decline is the loss of suitable forested habitat. Northern Alabama historically represented CERW's southern-most breeding range where they were common, now is the place of the greatest conservation need of the species. An isolated population has persisted at Bankhead National Forest (BNF). Little is known about why the species occurs there, less is known about species' population status, breeding success, habitat use, and the effect of forest composition, structure, and management. Wildlife management agencies called for CERW studies in Alabama to provide more accurate population estimates and breeding information; forest resource managers including the staff at BNF are seeking scientific bases for effectively managing their forests for the CERW. This project is in response to these requests with the objective of gaining better knowledge of the breeding ecology and habitat association of CERW and the effect of forest management practices, including tornado-created forest openings. Our specific goals are to 1) have a better knowledge of the population status of CERW at BNF, 2) examine avian community associations of the CERW to facilitate a better understanding of the interactions of CERW with other species, 3) identify landscape and microhabitat conditions related to forest composition, structure, and vegetation features that best explain CERW occurrence, and 4) examine if forest openings created by natural disturbrance and forest management provide suitable habitat for CERW. The project will help us to have a better understanding of the impacts of forest habitat change on wildlife and how the collective changes in forest structure due to forest management practices and natural disturbances affect population dynamics of a threatened and conservation priority species and ultimately, biodiversity. The study results will address current knowledge gaps that are particularly important for the best management practices of forest resources that will benefit the conservation of wildlife species and forest ecosystem. This project will also provide training opportunities for the next generation of natural resources and environmental sciences workforce, particularly for minorities.
Animal Health Component
50%
Research Effort Categories
Basic
60%
Applied
40%
Developmental
0%
Goals / Objectives
Our specific goals of this project are to 1) have a better knowledge of the population status of CERW at BNF, 2) examine avian community associations of the CERW to facilitate a better understanding of the interactions of CERW with other species, 3) identify landscape and microhabitat conditions related to forest composition, structure, and vegetation features that best explain CERW occurrence, and 4) examine if forest openings created by tornados and forest management provide suitable habitat for CERW.
Project Methods
Study Site. This study will be at the BNF, located in Lawrence, Winston, and Franklin Counties of northwestern Alabama. The BNF is a 72,800 ha multi-use forest located along the highly dissected portion of the southern Cumberland Plateau (Gaines and Creed 2003). The Sipsey Wilderness in the BNF is the largest wilderness area east of the Mississippi.Mixed forests of this region tend to be dominated by oak-hickory forest (McWilliams 1991) except in areas where pines, such as Loblolly Pine (Pinus taeda) were actively planted for commercial purposes. Beginning in the mid-1990s, Southern Pine Beetle (Dendroctonus frontalis) infestations caused large die-offs of P. taeda throughout the southeast and have produced large numbers of standing dead trees and increased fuel loads, including the BNF.Bird Surveys. We will survey ceruleans using point count following the protocol of Hamel et al. (1996) and our earlier studies (Carpenter et al. 2011, Carpenter and Wang 2018) from May to June during the breeding seasons of 2022 to 2024. The areas to be surveyed include the locations where the birds were reported previously (data provided by Allison Cochran, Wildlife Biologist of BNF and Eric Soehren, Wildlife Ecologist & Manager of Alabama Department of Conservation and Natural Resources) such as the floodplains and adjacent slopes along Flannigan and Borden creeks in BNF; point counts will also be performed at locations where no cerulean occurrence was reported previous, with a focus on ridges, upper slopes, and near areas of local relief with stratification of canopy trees within deciduous/mixed mature forest within BNF. Point count locations will be determined at random locations and during each encounter with a cerulean. Before beginning, Global Positioning System (GPS) coordinates will be recorded while allowing all birds to settle. Every bird observed during three-time intervals (0-3 min, 4-5 min, and 6-10 min) will be mapped in the proper direction and distance interval (<25 m, 25-50 m, 50-100 m, >100 m, and flyover). Counts will be centered at the cerulean's original position when detected, and location may vary on subsequent visits throughout the season due to the foraging and territorial nature of birds. If a cerulean is detected at a random point, counts will be conducted at both the pre-determined and under the individual's original locations. Behaviors and locations of all ceruleans will be documented using our protocol develop for this species (Carpenter et al. 2011). Once a cerulean is within discernible range, the bird's relative vertical and horizontal position will be estimated using instantaneous sampling (Hejl et al. 1990). This will be accomplished by counting to five and recording measurements at the instant the count reaches its apex. If a cerulean leaves the vicinity before counting is finished and cannot be relocated, measurements will be taken from the last known position. Additional data will consist of: tree species, tree height, tree diameter at breast height (DBH), tree crown class (dominant, co-dominant, intermediate, and suppressed), GPS coordinates, weather, aspect, gender, and descriptions of any territorial and breeding activities performed. All heights will be estimated with a clinometer and DBH with a logger's tape.Mist-netting, Banding, and Radio Telemetry. Banding and radio telemetry efforts will take place once a week from early May to late June following our protocol (Carpenter and Wang 2018) and (Delancey and Islam 2020). Banding will distinguish individuals from adjacent neighbors and assist in estimating territory size and determining site-fidelity. Radio tracking will aid in nest searching, estimating territory size, and monitoring post-breeding movements. Ceruleans will be lured into a mist-net using a wooden decoy and conspecific song centered in a triangular net design (Carpenter et al. 2011). Every cerulean captured will be ringed with a single aluminum USFWS band on the right tarsus and a plastic colored band on the left and/or right tarsus. Once banded, each bird will be sexed, aged, weighed, and measured according to Pyle (1997). Transmitters weighing approximately 0.35 g (5% of body weight) will be attached to ceruleans using adhesives (Kenward 2001).Forest habitat quantification. Forest habitat will be assessed once nesting has consummated in 2023 and 2024 using the method of our earlier studies (Carpenter et al. 2011, Carpenter and Wang 2018) and other researchers (Delancey and Islam 2020, Wessels and Boves 2021). The 0.04 ha (11.25 m radius) circular plots will be established in "used" and "unused" habitat and at all nest sites. The "used" habitat is regarded as GPS coordinates of cerulean encounters, whereas "unused" habitat is random points where ceruleans are not detected. A supplementary habitat plot will be centered in territories when sufficient information is available to delineate its boundaries. Habitat variables selected for measurement include: species and number of trees ≥ 3 cm DBH, number of saplings and shrubs < 3 cm DBH, number of standing snags ≥ 7.5 cm DBH, percent canopy cover, canopy height, log and tree dispersion, distance to and size of canopy gaps, basal area, tree/basal area ratio, slope, and aspect. Saplings, shrubs, and canopy cover will be measured along two right-angle transects set in the cardinal directions. Total number of woody stems < 3 cm intercepted by out-stretched arms will estimate sapling and shrub density per acre (James and Shugart 1970). Percent canopy cover will be determined by 40 densitometer readings (twenty along each transect) of the presence of vertical vegetation. Canopy structure will be quantified by assigning each plus reading to a height interval (<2 m, 2 to <5 m, 5 to <15, 15 to <25 m, and ≥25 m). Canopy heights of each plot will be averaged from measurements of several trees. Log and tree dispersion will be estimated by measuring distances to and DBH of the nearest tree and distance to, DBH and length of nearest fallen log ≥1.5 m in length and ≥8 cm DBH (Noon 1981). Basal area for each tree will be calculated as BA=0.00545DBH2 (Ashley 1991), and ratio of basal area to tree density as total BA/number of trees ≥ 3 cm (Jones and Robertson 2001).