Game Bird – Ecology and Management

Contributed Oral Presentations

SESSION NUMBER: 19

Contributed paper sessions will be available on-demand for the duration of the conference, then again at the conclusion of the conference.

 

Small Populations Lose Overall Genomic Diversity But Can Maintain Adaptive Potential
Samarth Mathur; James Andrew DeWoody
Populations are rapidly declining world-wide and creating targeted conservation strategies for at-risk species is a priority for wildlife managers. In principle, populations with higher genetic diversity and larger effective sizes have greater evolutionary capacity (adaptive potential) to respond to ecological stressors. Small isolated populations tend to lose genetic diversity rapidly due to the detrimental effects of drift and inbreeding via genetic erosion. We analyzed individual whole genome sequences from different populations of the Montezuma Quail (Cyrtonyx montezumae), a small ground-dwelling bird that is sustainably harvested in some portions of its range but is of conservation concern elsewhere. We find that small Montezuma Quail populations in the U.S. have mean genome-wide heterozygosity comparable to other threatened or endangered birds. Our results indicate that smaller and isolated Texas population is significantly more inbred than the large Arizona and the intermediate-sized New Mexico populations. We provide evidence that small populations are able to maintain adaptive potential by exhibiting higher genic heterozygosity despite a reduction in overall genomic diversity. We show that smaller populations carry significantly less proportion of deleterious mutations (“potential load”) in their genome than their larger counterparts. As most deleterious mutations are recessive, larger populations carry them as heterozygotes whereas they are homogenized by genetic erosion and are exposed in smaller populations (“realized load”). Collectively, our results highlight that smaller, isolated populations are at higher risk of inbreeding depression and conservation strategies should focus on minimizing inbreeding for long-term population persistence. We are currently implementing forward-time simulations to determine whether efforts like periodic translocations would improve the overall adaptive potential of these small isolated populations. Ultimately, our population genomics study of Montezuma Quail should yield insights to help wildlife managers conserve this species and act as a roadmap for devising targeted management strategies for other species facing extinctions or local extirpations.
Comparative Genomic Structure Within Alaskan Galliforms
Robert Wilson; Sarah Sonsthagen; Sandra Talbot
In Alaska, resident avian species such as ptarmigan and grouse possess unique ecological traits and likely corresponding genomic variation, allowing them to thrive year-round in Arctic and sub-Arctic ecosystems. Specialization to synergistic effects of thermal and day-light regimes typified by the Arctic may have resulted in narrow response windows in resident species, potentially rendering them more (or differentially) impacted than migratory species to environmental change. We collected reduced representation genomic (ddRAD) data for ptarmigan (rock, willow, white-tailed) and grouse species (spruce, ruff, and sharp-tailed) sampled along a latitudinal gradient (60-70°N) within Alaska. Our goals were to examine levels of genomic diversity and gene flow, and simultaneously identify loci in that may signal local adaptation to Arctic environments. Genomic diversity within Alaskan galliforms is arrayed differentially: weak to no genetic structure in rock ptarmigan (ΦST = 0.012; 0.009 within subspecies) and sharp-tailed grouse (ΦST = 0.012); isolation by distance in willow (ΦST = 0.023) and white-tailed (ΦST = 0.021) ptarmigan; and northern and southern clusters in spruce (ΦST = 0.036) and ruff (ΦST = 0.042) grouse. Patterns of genomic diversity coincide with physiogeographic features (e.g., mountain ranges) and highlight the importance of these environmental and ecological barriers shaping how genomic diversity is arrayed across the landscape. Lack of concordance in spatial patterns of genetic variation among certain species, and the presence of species-specific patterns, however, indicate that species behavior (movement, breeding, etc.) and habitat affinities still play key roles in driving the contrasting patterns of genomic structure among Alaska gallids. These findings highlight the importance of considering disparities in species’ life history traits when evaluating the influence of topographic features on the distribution of genomic diversity across the landscape in comparative analyses.
Influence of Spring Cover Crops on Ring-Necked Pheasant Populations in Kansas
Alixandra J. Godar; Adela Piernicky; David Haukos; Jeff Prendergast
Across the Midwest, agriculture has changed the landscape. Efficient farming practices allow farmers to plant more land and harvest more efficiently, fragmenting and degrading wildlife habitat. Many wildlife species, including the ring-necked pheasant (Phasianus colchicus), have experienced significant population declines coinciding with the landscape changes. Pheasants persist in a variety of agricultural landscapes and tend to be tolerant of human activity. In western Kansas, landscapes supporting pheasants include a mosaic of corn, sorghum, and winter wheat. Winter wheat is alternated with corn or sorghum, leaving the field fallow every other summer. The common practice is chemical fallow, using herbicide to terminate all vegetation growth in the field until the next planting. Alternatively, planting cover cropping may increase beneficial plant species, promoting soil health and wildlife use. Cover crops have increased wildlife presence, but the influence on pheasant populations is poorly understood. We evaluated the effect of spring cover crops on pheasants from 2017 – 2019 in western Kansas. Study fields were divided into 4 treatments consisting of 3 cover crop seed mixes and a chemical fallow control plot. We monitored adult hen survival, nest survival, brood survival, and hen resource selection. Cover crops emerged in mid-May, after initiation of the majority of nests (0.928 daily survival, SE = 0.009). Timing of cover provided the most potential to impact brood survival (n = 22 broods). Female breeding season survival was estimated at 0.46 (SE = 0.05). Hens selected for cover at locations and Conservation Reserve Program land for cover type throughout the breeding season but, disproportionately, ~25% of brood locations were in cover crops and hens selected for a variety of vegetation characteristics including cover of forbs and bare ground. Cover crops are used by pheasants, primarily as alternative brood habitat.
Roles of Vegetation and Age in Nest Site Selection by Wild Turkeys
Andrea R. Litt; Michael J. Yarnall; Chadwick P. Lehman
Selecting a nesting location that provides sufficient concealment is essential to reduce the risk of predation, the most common cause of nest failure in gallinaceous birds. Older birds with more reproductive experience may be better able to recognize and select nest sites that are less vulnerable to predation, resulting in higher nest survival. We captured and radio-marked female Merriam’s wild turkeys (Meleagris gallopavo merriami) in 2016 and 2017 in the Northern Black Hills, SD, monitoring signs of nesting activity for at least 40 juvenile and 40 adult hens each year. To characterize nest site selection, we quantified visual obstruction, total cover, and canopy cover at the nest site, as well as at a paired random location. Most adult female turkeys (83%) and relatively few juveniles (26%) nested; we analyzed vegetation characteristics for 74 nests from adults and 25 nests from juveniles. Using an information-theoretic approach, we compared 14 conditional logistic regression models that included combinations of the three vegetation covariates, both with and without age class. Female turkeys selected nest sites with more visual obstruction compared to random locations (mean difference = 14.2 Robel pole increments of 1.27 cm, SE = 1.2). Although we tracked substantially more nests of juvenile turkey hens than previous studies, we were unable to detect differences in selection between adults and juveniles. Mammals are common nest predators in this region, such that lateral vegetation and guard objects (characterized by visual obstruction) surrounding nests might be most important to conceal turkeys while incubating. Selecting locations on the landscape with greater visual obstruction has important fitness implications, given that we previously documented higher daily survival rates for turkey nests with greater visual obstruction. If juvenile and adult hens select similar characteristics for nesting locations, age-based differences in nest survival also could result from variation in nest attendance.
Nest and Poult Survival of Eastern Wild Turkeys in South-Central Tennessee
Lindsey M. Phillips; Vincent M. Johnson; David A. Buehler; Craig A. Harper; Roger Shields; Roger D. Applegate
Eastern wild turkey (Meleagris gallopavo silvestris) are an important game species across the eastern United States. However, many southeastern states, including Tennessee, are experiencing a decrease in spring harvest rates in portions of the state. To determine what may be driving this decline, eastern wild turkey reproduction was documented in five focal counties in south-central Tennessee. From 2017-2019, we tagged eastern wild turkey hens (n = 201) with VHF and GPS transmitters. We tracked hens throughout the nesting season each year and monitored nest locations every other day once incubation began. We trapped poults before 7 days old and fitted them with VHF transmitters. We monitored poult survival every day until 7 days old, and every other day until 28 days old. We performed flush counts at two and four weeks post-hatch. We used Program MARK to calculate daily survival rates for nests and poults. Average initial nesting rate was 74%, with an average daily survival rate (DSR) of 0.96 and average success rate of 23%. Average renesting rate was 33%, with an average DSR of 0.95 and average success rate of 21%. Average clutch size of initial nests and renests was 9.4 and 7.3 eggs, respectively. Based on transmittered birds, average poult survival was 11% for the 28-day period, with an average DSR of 0.88. Based on four-week flush counts, average poult survival was 28%. Estimates of the reproductive parameters in our study are lower than those of other studies conducted on stable or increasing populations using similar methods. We attribute reduced fecundity as the primary factor related to the decrease in harvest numbers in the counties we studied. Currently, we are conducting hen-specific habitat management experiments to determine if focused nest and brood habitat management strategies can improve productivity sufficiently to counter the apparent population decline.
Density Estimates of Male Wild Turkeys on Public Access Areas in Arkansas
Douglas C. Osborne; Clay M. Walters
Season structure and bag limits for eastern wild turkey (Meleagris gallopavo silvestris) are determined annually by state wildlife agencies and are often modified in response to perceived change in population abundance. Currently, state agencies rely on indices such as total annual harvest and spring poult counts, which exhibit high levels of uncertainty, to guide harvest management decisions. Management decisions based on data uncertainties can be problematic for understanding the direct effects of changing season structure and bag limits on population dynamics. Conversely, reliable data sources outside the current indices are challenging to obtain and currently undeveloped. Thus, we investigated camera trap surveys in a partially marked wild turkey population to estimate abundance and density on public lands in Arkansas. We marked 51 male wild turkeys with alphanumeric color leg-bands and satellite transmitters across 3 wildlife management areas (WMA) in Arkansas during Jan-Mar, 2018 and 2019. We used spatially-explicit mark-resight (SMR) models and landcover covariates to generate density estimates and evaluate the factors influencing density heterogeneity across the landscape. We observed spatial resightings of 11 individual male turkeys from camera traps, and incorporated telemetry location data to bolster the estimation of the spatial parameter sigma (σ). Mean density estimate across sites was 0.316 male wild turkeys per square kilometer (SE=0.059) and ranged from densities of 0.165-0.401 male wild turkeys per square kilometer. Sigma estimates suggests that home range sizes were similar at Bearcat Hollow (σ=1784.7 m) and Muddy Creek (σ=1807.0 m) WMAs and smaller at Gene Rush (σ=929.2 m) WMA. Camera trap surveys and SMR provides the robust statistical framework necessary to assess annual change in abundance and could be used to evaluate population response to change in harvest regulations. With further development, the approach could be used to launch an adaptive harvest management approach to setting annual harvest regulations.
Integrating Survival and Harvest Rates to Estimate Wild Turkey Population Size Across Maine
Matthew Gonnerman; Stephanie Shea; Kelsey Sullivan; Pauline Kamath; Erik Blomberg
Wild turkey populations have steadily grown since their reintroduction in the 1970s. In Maine, this has led to need for resource managers to balance maintaining quality turkey hunting while decreasing potential for human-wildlife conflicts. Due to harsh winter conditions, turkeys in Maine often associate with areas where anthropogenic food subsidies are available, which has prompted concerns over property damage and spillover of disease into domestic livestock. The Maine Department of Inland Fisheries and Wildlife set out to develop a rigorous monitoring program to better inform harvest regulations for turkeys to meet the needs of both hunters and Maine’s citizens. Our objective was to provide MDIFW with a tool to estimate region-specific turkey abundance that better informs management plans. In Winter 2018-2020, we banded 848 turkeys across Maine. We used these data to estimate harvest rates using the Seber parameterization of a dead recovery model. Estimates of harvest rates for these models and total reported harvest for each hunting season were combined in a Lincoln estimator to estimate population size for management districts. To account for mortality of turkeys between banding and hunting seasons, we estimated weekly survival rates in a nest survival framework using information from individuals fit with VHF radio transmitters (n = 262). Estimated weekly survival rates differed by management district (0.970 – 0.985) and month of the year (0.949 – 0.993). Harvest rates also varied by wildlife management district; 0.119 – 0.228 for adult males and 0.046 – 0.178 for juvenile males. Estimated statewide turkey populations were 18,932 (± 9,264 SE) adults males and 13,764 (± 3,361) juvenile males in 2018 and 21,132 (± 10,341) adults males and 12,477 (± 3,046) juvenile males in 2019. These estimates of population size can be incorporated into a harvest management tool to better inform turkey management according to desired objectives.
Using Citizen Science Data to Estimate Distribution and Abundance of American Woodcock in Rhode Island
Erin R. Harrington; Scott McWilliams
The American woodcock (Scolopax minor) population has been declining in Rhode Island roughly 1.2% per year for the past four decades, and this decline is due in part to the loss of early successional forests. To estimate population trends and better understand this decline on a national scale, the US Fish and Wildlife Service (USFWS) conducts an American Woodcock Singing-ground Survey (SGS) every year. However, the current survey methodology used to estimate this decline has multiple limitations. To address these shortcomings, we designed and conducted point count surveys throughout Rhode Island and used occupancy modeling to estimate state-wide distribution. From April-May of 2018-2020 citizen scientists conducted four SGSs on ~120 different driving routes. We used occupancy modeling to assess factors associated with occupancy and detection probability, and to delineate habitat characteristics associated with woodcock distribution and abundance in Rhode Island. We then compared the distribution and abundance estimates from the SGS and occupancy modeling approach to that from a complimentary resource-selection radiotelemetry study. We predicted that sites with high occupancy will be comprised of wetland forests and deciduous or mixed upland forests that are closer to streams, agricultural openings, and upland young forests. Information from this study will help local agencies develop better informed state-specific forest management plans.
Stopover Habitat Selection and Site Use of Fall Migrating American Woodcock in the Eastern Management Region
Clayton Graham; Tanner Steeves; Alexander Fish; Dr. Erik Blomberg; Dr. Scott McWilliams
Habitat selection during migration of eastern management region American Woodcock (Scolopax minor) is poorly known. As part of a large multi-state collaborative project, we used satellite transmitters to track 161 woodcock during fall migration 2018 and 2019 as they moved from breeding to wintering areas. We identified stopover locations using the moveHMM package in R and used a step-selection function to quantify the strength of habitat selection in relation to the following covariates: distance to wetlands, distance to hydric soil, distance to streams, distance to agricultural fields, distance to corn, distance to soybeans, and forest type (conifer, mixed or deciduous). Woodcock selected upland mature coniferous, deciduous, and mixed forest as stopover sites. A predictive LASSO model was used to identify sites most likely to be used as stopover sites by American Woodcock during fall migration. Such information about key stopover sites and migratory routes used by Woodcock enhances our ability to effectively manage habitat for Woodcock in this eastern region.
Quantifying Detection Probability of Nesting American Woodcocks on Transects Sampled with Handheld Thermal Technology
Luke F. Gray; Darin J. McNeil Jr.; Jeffery L. Larkin
Developing effective population monitoring techniques are central to wildlife management and critical for species of conservation concern. Although, for many birds, counts of singing males are useful for assessing relative abundance, data on nests provide a better metric of habitat quality as they afford insight into habitat-specific productivity. With that in mind, locating and monitoring nests is challenging, especially for cryptic species. One developing technology, handheld thermal monocular, may hold promise for locating avian nests but researchers have only just begun exploring the potential of this technology to survey for ground-nesting birds. To better understand the merit of handheld thermal technology for avian nest detection, we quantified the detection probability of nesting American Woodcock (Scolopax minor) in nesting habitats across central Pennsylvania. We conducted 40 line transects within two types of woodcock nesting habitat: old fields (n = 20) and regenerating timber harvests (n = 20). Along each transect, one observer searched with a thermal monocular for a random number of artificial nests (0-20 m perpendicular distance), each of which consisting of a mounted American Woodcock skin containing hand-warmers to simulate body heat. We also collected data on vegetation conditions at each site. Although our simulated nests strongly resembled live incubating woodcocks we observed in the field, detection probability was imperfect, especially within dense vegetation. Still, most of our simulated nests were detected by observers, highlighting the potential merit of handheld thermal technology for American Woodcock nest detection. Our detection probability models suggest a need for researchers using thermal technology to survey ground-nesting bird populations to explicitly consider habitat-specific detection probability for nests and adjust density estimates accordingly using methods like distance sampling. Future research should focus on using thermal-based transects to sample other sedentary cryptic species.
Behavioral Modifications Lead to Disparate Demographic Consequences in Two Sympatric Species
Evan P. Tanner; Jeremy P. Orange; Craig A. Davis; Dwayne Elmore; Samuel D. Fuhlendorf
Life‐history theory suggests species that typically have a large number of offspring and high adult mortality may make decisions that benefit offspring survival in exchange for increased adult risks. Such behavioral adaptations are essential to understanding how demographic performance is linked to habitat selection during this important life‐history stage. Though studies have illustrated negative fitness consequences to attendant adults or potential fitness benefits to associated offspring because of adaptive habitat selection during brood rearing, equivocal relationships could arise if both aspects of this reproductive trade‐off are not assessed simultaneously. To better understand how adaptive habitat selection during brood rearing influences demographics, we studied the brood survival, attendant parental survival, and space use of two sympatric ground‐nesting bird species, the northern bobwhite (hereafter: “bobwhite”; Colinus virgininanus) and scaled quail (Callipepla squamata). During the 2013-2014 breeding seasons, we estimated habitat suitability across two grains (2 m and 30 m) for both species and determined how adult space use of these areas influenced individual chick survival and parental risk. We found the proportion of a brood’s home range containing highly suitable areas significantly increased bobwhite chick survival (β = 0.02, SE = 0.006). Additionally, adult weekly survival for bobwhite was greater for individuals not actively brooding offspring (0.9716, SE = 0.0054) as compared to brooding adults (0.8928, SE = 0.0006). Conversely, brood habitat suitability did not influence scaled quail chick survival during our study, nor did we detect a survival cost for adults that were actively brooding offspring. Our research illustrates the importance of understanding life‐history strategies and how they might influence relationships between adaptive habitat selection and demographic parameters.

 

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