Breeding Season Survival Research Articles

Nonbreeding season survival of northern bobwhite in northeastern Colorado

Northern bobwhites have experienced population declines in Colorado and range wide. Estimating vital rates can provide clues to factors limiting population growth rate. Although recent estimates of breeding season survival in the northwest corner of the northern bobwhite range are available, there have been no recent studies on nonbreeding season survival. We used radio‐telemetry to estimate nonbreeding season (October–March) survival of northern bobwhites at two study sites in northeastern Colorado during winter 2019–2020 and 2020–2021. Based on our sample of 157 bobwhites, we found that survival was highly variable between years and was negatively affected by colder daily minimum temperatures and deeper snow depths. Seasonal (six‐month) survival during the first year was 0.219 (SE = 0.040) and during the second year was 0.006 (SE = 0.005). We found no evidence that sex, age or study site influenced survival, and very weak support for an effect of body mass. During our study, there were two extreme winter weather events, during which we found unusually high numbers of non‐predation mortality. Overall, northern bobwhite nonbreeding season survival in the northwest corner of their range appears to be generally similar to other regions, except during extreme winter weather events, which resulted in high mortality. We encourage managers to create or maintain vegetation characteristics that will provide shelter from winter weather while also providing abundant food in close proximity.

Northern bobwhite breeding season and nest survival are greater on native grasslands

AbstractNorthern bobwhites (Colinus virginianus) are declining across their range. Population recovery requires a better understanding of the influence of management strategies and land cover on specific demographic components of full annual cycle population dynamics. We used known‐fate daily survival models to relate adult breeding season survival and nest survival to land cover composition, woody cover, and management actions on 5 study sites in southwest Missouri, USA. We collected 3,516 observations of daily nest survival from 364 bobwhite nests for 7,509 exposure days and 34,386 observations of adult survival from 955 bobwhites for 85,225 exposure days during breeding seasons in 2014–2018. The most supported model for nest and adult breeding season survival included environmental covariates for percent native grass and agricultural cover, distance to shrub, and distance to tree. Both nest and adult breeding season survival were positively related to distance to trees. Nest survival was negatively related to percent agricultural crop cover. Areal nest and adult breeding season survival were greater on native grassland sites compared to conservation areas that maintained small units of strip crop and wooded cover. Management to sustain or expand native grass cover and reduce tree cover should benefit bobwhite nest survival and adult breeding season survival in the landscapes we studied.

Demographic effects of a megafire on a declining prairie grouse in the mixed-grass prairie.

Recent studies have documented benefits of small, prescribed fire and wildfire for grassland-dependent wildlife, such as lesser prairie-chickens (Tympanuchus pallidicintus), but wildlife demographic response to the scale and intensity of megafire (wildfire >40,000 ha) in modern, fragmented grasslands remains unknown. Limited available grassland habitat makes it imperative to understand if increasing frequency of megafires could further reduce already declining lesser prairie-chicken populations, or if historical evolutionary interactions with fire make lesser prairie-chickens resilient. To evaluate lesser prairie-chicken demographic response to megafires, we compared lek counts, nest density, and survival rates of adults, nests, and chicks before (2014-2016) and after (2018-2020) a 2017 megafire in the mixed-grass prairie of Kansas, USA (Starbuck fire ~254,000 ha). There was a 67% decline in attending males on leks post-fire and a 57% decline in occupied leks post-fire. Despite population declines as indicated by lek counts, adult female breeding season survival ( ) was similar pre- ( =0.65 ± 0.08 [SE]) and post-fire (0.61 ± 0.08), as was chick survival (pre-fire: 0.23 ± 0.07; post-fire: 0.27 ± 0.11). Nest survival appeared lower post-fire (pre-fire: 0.38 ± 0.06; post-fire: 0.20 ± 0.06), but did not differ at the 95% confidence interval. Nest density of marked females declined 73% in areas burned by megafire. Although lesser prairie-chickens persisted in the study area and we documented minimal effects on most demographic rates, reduced lesser prairie-chicken abundance and reproductive output suggests full recovery may take >3 years. Increased propensity for megafire resulting from suppression of smaller fires, compounded by climate change and woody encroachment, may impose a short-term (3-5year) threat to already declining lesser prairie-chicken populations.

Evaluation of seasonal site-level demography and management for northern bobwhite using integrated population models

Understanding the effects of landscape management on northern bobwhite (Colinus virginianus) population growth requires information on seasonal- and stage-specific demographic parameters linked across the full annual cycle. We evaluated site-level seasonal dynamics and population growth of bobwhites in southwest Missouri and compared differences between three extensively and two intensively managed sites from 2016 to 2019. Extensively managed sites were continuous tracts of native prairie. Intensively managed sites were composed of smaller native and non-native grassland units interspersed with strip crops, food plots, and woody field borders. We radio-marked adults and broods to estimate survival and productivity, conducted spring whistle counts to estimate abundance and developed a two-season, two-stage, two-sex integrated population model to estimate population dynamics. The number of young hatched per female-incubated nest was greater on the three extensively managed sites compared to the two intensively managed sites. Six-month period survival of adults during the breeding season was also greater on the three extensively managed sites compared to the two intensively managed sites. One hundred-day juvenile breeding season survival varied among sites and was highest on Talbot, compared to juvenile breeding season survival on the other four study sites. Six-month, non-breeding season period survival was lowest on the two smallest extensively managed sites, Stony Point Prairie and Shelton Conservation Area compared to non-breeding season survival on the other three study sites. Annual changes in bobwhite abundance were weakly correlated with female fecundity, though this positive relationship was stronger on extensively managed sites. Intensively managed sites exhibited low mean fecundity and breeding season adult survival relative to those that resulted in a stable population. Populations across sites declined from 2016 to 2019 and estimates of annual population growth rates overlapped across sites. Differences between observed changes in bobwhite abundance and estimates of observed demographic rates at some sites suggest unmeasured processes such as movement or bias associated with data and model assumptions influenced estimated vital rates. Overall, our integrated population model was an effective tool for understanding site-level seasonal dynamics and population growth of bobwhites. Based on comparisons of demography between extensively and intensively managed sites, we suggest increased native grassland cover managed with prescribed fire, low intensity grazing, and high mowing may increase bobwhite nesting success and breeding season adult survival, however, achieving stable or increasing rates of population growth may also require increased juvenile breeding season and non-breeding season survival.

Breeding season survival of female Rio Grande wild turkeys in south‐central Texas

AbstractHistorically, Rio Grande wild turkey (Meleagris gallopavo intermedia) density in south‐central Texas has been lower than other regions within the species' Texas range. Within the Oak‐Prairie Wildlife District of Texas, Rio Grande wild turkey harvest regulations are more restrictive for counties in the eastern portion of the district. Due to a perceived increase in turkey density in the eastern portion of the district, Texas Parks and Wildlife Department (TPWD) has considered increasing the spring hunting season harvest bag limit. Because estimates of sex‐specific abundance and male harvest rates are not available, estimates of female driven population parameters such and nest success and female survival can be used to support regulatory decision‐making. Therefore, before a regulation change we evaluated survival of radio‐marked female Rio Grande wild turkeys during the breeding season in 4 counties in the Special 1‐Male zone (hereafter 1‐bird zone) and 2 counties in the South zone (hereafter 4‐bird zone). We captured and monitored breeding season survival for 138 females during 2016–2018, of which 51 were in the 4‐bird zone and 87 were in the 1‐bird zone. Breeding season (1 Mar–14 Aug) naive mortality rate was 23% (19/81) of tagged females in the 1‐bird zone and 32% (14/43) in the 4‐bird zone. The best approximating candidate model for breeding season survival indicated variation in daily survival () was primarily related to daily distance of individual movements ( = 0.998 at average daily distance of 2,471 m). Estimated breeding season survival at the mean daily movement distance was 81% for the 167‐day period. Breeding season survival was similar between the 1‐bird and 4‐bird regulatory zone. Based on our results, female breeding season survival does not seem to be a limiting factor within the Oak‐Prairie Wildlife District of Texas for Rio Grande wild turkeys. We suggest that TPWD focus efforts on supporting landowners to enhance conditions more conducive for reproductive success and suggest future efforts focus on collection of harvest and harvest rate data to estimate population size in lieu of continued monitoring of female reproductive or survival parameters for decision processes.

Novel passive detection approach reveals low breeding season survival and apparent lactation cost in a critically endangered cave bat.

Capture-mark-recapture/resight (CMR) methods are used for survival-rate studies, yet are often limited by small sample sizes. Advances in passive integrated transponder (PIT) technology have enabled passive detection or ‘resight’ of marked individuals using large antennas with greater read-ranges than previously possible. We used passively-detected resight data and CMR models to study survival rates of the southern bent-winged bat Miniopterus orianae bassanii, a critically endangered, cave-dwelling bat. Over three years, we used PIT-tagging to monitor 2966 individuals at the species’ largest breeding aggregation, using daily detection data (> 1.6 million detections) to estimate seasonal survival probabilities, structured by age, sex and reproductive status, and parameterise population projection matrices. This has hitherto been impossible using traditional CMR methods due to disturbance risk and low recapture rates. Bats exhibited lowest apparent seasonal survival over summer and autumn, particularly for reproductive females in summer (when lactating) and juveniles in autumn (after weaning), and high survival in winter. Lowest survival rates coincided with severe drought in summer–autumn 2016, suggesting that dry conditions affect population viability. Under all likely demographic assumptions, population projection matrices suggested the population is in deterministic decline, requiring urgent action to reduce extinction risk. Passively-collected resight data can now be used in combination with CMR models to provide extensive, robust information for targeted wildlife population management.

Breeding Season Survival and Reproduction in a High-Density Bobwhite Population: A case study

The demographic behavior of northern bobwhite (Colinus virginianus; hereafter, bobwhite) populations at high densities could provide important insights into why bobwhite populations fluctuate. Therefore, we documented breeding season demographics of bobwhites to understand how prebreeding density influenced reproductive effort and postbreeding density on an intensively managed property in Leon County, Florida, USA, 2002–2006. We estimated prebreeding bobwhite density each April using multi-observer strip-transects and postbreeding densities each November using covey call grid surveys. We radio-tagged 217 bobwhites in March and located bobwhites at least 5 days/week, 15 April–30 September to determine vital rates. Prebreeding density ranged from 1.5–8.6 birds/ha, peaking in 2002, declining through 2005, then increasing in 2006. Breeding season survival was 0.55, 0.17, 0.20, and 0.59, and nesting rate was 0.47, 0.67, 0.80 and 0.89, 2002–2005, respectively. Postbreeding density ranged from 5.2–13.6 birds/ha, also peaking in 2002 and declining through 2004 before increasing beginning in 2005 and 2006. High breeding season survival and nesting success (>0.55) resulted in greater chick production during periods of population growth. Nesting rate was inversely related to prebreeding density. Declines in bobwhite nesting rate at high prebreeding densities appeared to regulate population growth near population peaks. Lower adult survival and nesting success appeared to cause population declines. We suggest density-dependent intraspecific competition limited population growth at high bobwhite densities by reducing nesting rate while predation of adults and nests explained population fluctuations.

Evaluating Release Strategy for Translocated Northern Bobwhites in Cross Timbers Ecoregion of Texas: A Pilot Study

Northern bobwhite (Colinus virginianus) population decline is largely driven by the loss, fragmentation, and degradation of grassland habitats. Translocation is used to reintroduce or augment populations in fragmented landscapes where natural dispersal is inhibited. Northern bobwhites have been successfully translocated in the southeastern portion of their range, but outcomes of translocations in western ranges have been mixed. Our objective was to conduct a pilot study to test the feasibility of translocating northern bobwhites to a restored, but isolated, habitat in the Cross Timbers ecoregion of Texas, USA and to evaluate the influence of release strategy for improving northern bobwhite site fidelity and survival post-release. The release property was restored through brush management, native species seeding, and proper grazing management. We trapped and translocated 84 northern bobwhites from source populations in the Rolling Plains and Edwards Plateau ecoregions during March 2015. Coveys were assigned to either delayed or immediate release treatment. We radio-collared all hens (n = 40; 11 adults; 29 juveniles) and evenly divided the sample between delayed and immediate releases. Delayed release coveys were held on the release site for 4 weeks in a Surrogator® (Wildlife Management Technologies, LLC). We trapped and radio-collared resident hens (n = 15) in March and monitored all hens through breeding season (March–August; 180 days). We implemented a 2-state (alive or dead) multistate model in Program MARK to analyze survival as a function of the release treatment, resident status, and age. We found no evidence that survival differed between translocated and resident hens (β = 0.48, standard error [SE] = 0.38), release treatments (β = 0.10, SE = 0.40), or age (β = -0.16, SE = 0.54). Daily survival for all hens was 0.99 (SE = 0.009) and breeding season survival was 0.19 (SE = 0.08). Four (20%) immediate, 2 (10%) delayed release, and 0 resident hens dispersed off-property. Translocated and resident hens survived at similar rates, indicating that translocation may be a feasible management strategy for augmenting a northern bobwhite population on restored habitats in the Cross Timbers ecoregion although overall survival was low. We did not find evidence that delayed release improved daily survival post-release, but our small sample size may have prevented us from detecting a difference. However, delayed release birds were effectively sheltered from predation during peak raptor migration. Additional research is needed to fully understand population dynamics and implications of release strategy for translocated northern bobwhite.

Northern Bobwhite Demographics and Resource Selection Are Explained by Prescribed Fire with Grazing and Woody Cover in Southwest Missouri

Understanding the effects of landscape management on northern bobwhite (Colinus virginianus; hereafter, bobwhite) population growth requires information about seasonal- and stage-specific demographic parameters linked across the annual cycle. We review results to date from 3 years (2016–2018) of an intensive field study evaluating drivers of bobwhite population dynamics and resource selection during the breeding and non-breeding season in southwest Missouri, USA using data from adult and juvenile bobwhite fitted with radio-transmitters. Land cover of our study sites ranged from large blocks of native grasslands maintained with prescribed fire and grazing to more traditional management resulting in small patches of grasslands interspersed with food plots, disked idle areas, and woody cover. During the breeding season, relative probability of selection by broods increased in relation to proportion of native grass managed by grazing and burning and proportion of cropland. Brood survival was also greatest on native grasslands burned and grazed within the past 2 growing seasons. During the fall and winter, relative probability of selection by adults increased as woody edge density increased. Fall and winter survival increased as distance from trees increased and decreased as distance to shrubs increased. Our integrated population model indicated that the number of young hatched per female and adult breeding season survival were greatest on sites with the most native grassland managed by prescribed fire with grazing. However, non-breeding season survival was greater on sites with more agriculture or food plots and woody cover. Abundance declined across all sites from 2016 to 2019. Our work suggests that native grasslands managed by prescribed fire with grazing can provide quail habitat superior to traditional management that strived for a mixture of agriculture, woody cover, and grassland. The combination of conservation grazing and fire in native grasslands interspersed with shrubs may provide the greatest chance for bobwhite populations to persist in southwest Missouri and similar landscapes.

Northern Bobwhite Response to Vegetation Management and Recovery in South Texas

The northern bobwhite (Colinus virginianus; hereafter, bobwhite) requires habitat structure and composition with grass cover for nesting, predator avoidance, and thermal refuge and forb cover for feeding on phytophagous arthropods and seeds. During the past 2 decades, many land managers with interest in promoting quail hunting opportunities have reduced or completely eliminated livestock across South Texas, USA, rangelands. Resting the land from grazing allows vegetation—especially grasses and forbs—to recover and thus provide nesting and foraging habitat for bobwhite and other birds. How bobwhite respond to postgrazing vegetation recovery is of keen interest to rangeland quail managers, but this topic is poorly known because case histories with quantitative data are lacking. Our objective was to investigate how bobwhite respond to the vegetation changes following removal of cattle grazing. Our study was conducted on a private ranch in Jim Hogg County, Texas and involved 3 different categories of postgrazing recovery and management: 1 area at 15 years post-cattle grazing where the landscape has been brush-sculpted and is actively managed since removal of cattle, 1 area at 3 years post-grazing with a previous stocking density of 7 ha/animal unit (high stocking density), and 1 area at 3 years post-grazing with a previous stocking density of 14 ha/animal unit (moderate stocking density). We trapped, radio-marked, and located bobwhites from March to September during 2015–2016 on the 3 comparative units. We estimated nest survival, adult breeding-season survival, home range size, and early winter density. We hypothesized that the 15-year postgrazing site would have higher early winter density, higher adult breeding season survival, and higher nest survival along with smaller mean home range size compared to the 2 more recently grazed sites. On average, the probability of a nest surviving the 23-day incubation period was highest on the 15-year postgrazing site at 0.61 ± 0.12 (mean nest survival ± standard error), with estimates of 0.32 ± 0.12 on the 3-year moderate postgrazing site and 0.33 ± 0.12 on the 3-year high postgrazing site. Adult breeding season survival did not differ among the 3 sites, and was instead influenced mostly by month within the season, probably a result of summer heat. An adult bobwhite had a 0.48 ± 0.04 probability of surviving the breeding season. Early winter density, after summer and fall production was complete, increased on all sites from 2015 to 2016 and was consistently highest on the 15-year postgrazing site. Home range sizes on the

Northern Bobwhite Survival and Productivity in Relation to Food Supplementation

Northern bobwhite (Colinus virginianus; hereafter, bobwhite) populations have experienced a 3.4% decline annually nation-wide from 1966 to 2018. Limitations on resources, such as food, can regulate population growth. Supplemental food could alleviate resource limitation by raising carrying capacity, leading to increased survival and breeding productivity. Studies have shown higher survival rates and higher nest production when food is supplemented; however, repeating experiments in different contexts allows for strong inference. Our objectives were to assess how supplemental food influenced survival and breeding productivity of resident and translocated bobwhite during a 2-year study on public lands in Leon County, Florida, USA within the Apalachicola National Forest. In accordance with the food limitation hypothesis, we predicted that provisioning of supplemental food would have a positive influence on survival rates and nest productivity. We split the study site into 4 approximately 400-ha zones and randomly assigned 2 treatment (fed) and 2 control (unfed) replicates. Treatment and control zones were flipped during the second field season. Treatments received approximately 1.75 bushels of milo (Sorghum bicolor)/acre 2 times/month year-round via broadcast spreader. We radio-marked 205 bobwhites (102 treatment, 103 control) from February 2019 through October 2020. Individuals were tracked 3–4 times/week for location and survival via radio-telemetry to estimate the breeding season survival and reproduction rates. We estimated survival rates using the Kaplan-Meier product limit estimator. The survival rate during the breeding seasons was higher on average for treatment zones (x̄ = 0.38, standard error [SE] = 0.040) than for control zones (x̄ = 0.29, SE = 0.045). We also observed that 79% of nests found were located in treatment zones compared to 21% in control zones. Our results suggest that food supplementation can improve survival rates and nest production of bobwhite in a food-limited landscape.

Edge density affects demography of an exploited grassland bird

AbstractHumans modify landscapes for a variety of reasons including agriculture, urbanization, and to facilitate recreation. Landscape modifications can lead to complete loss of existing cover types and/or fragmentation of remaining cover types. Grasslands are one of the ecosystems most heavily impacted by human modifications; however, for many species, an understanding of how fragmentation affects population parameters is lacking. We investigated the influence of landscape fragmentation on survival, reproduction, and density using the northern bobwhite (Colinus virginianus), a facultative grassland species, as our case study. We experimentally manipulated the level of edge density (none, low, and high) of bobwhite management units and estimated seasonal survival, productivity, and autumn densities. Winter survival was lower in edge density treatments, relative to the control. An increase in migratory raptor density during the winter, along with a decrease in thermal refugia, may be contributing to lower winter survival in edge density treatments. Fecundity was higher in the edge density treatments, relative to the control, and was negatively related to winter survival. Similarly, breeding season survival was higher in more fragmented sites. This indicated a density‐dependent relationship, where lower bird densities at the beginning of the breeding season possibly led to greater resource availability, and thus survival and productivity, of the birds that remained. However, a density‐dependent response in breeding season survival and productivity was not enough to offset the negative impact of edges in the low edge density sites. Consequently, autumn density was lower relative to both control and high edge density treatments. Our study demonstrates the importance of capturing the entire life cycle when exploring the relationship between landscape pattern and population parameters.

Greater Sage-Grouse survival varies with breeding season events in West Nile virus non-outbreak years

Abstract Greater Sage-Grouse (Centrocercus urophasianus) is a species of conservation concern and is highly susceptible to mortality from West Nile virus (WNV). Culex tarsalis, a mosquito species, is the suspected primary vector for transmitting WNV to sage-grouse. We captured, radio-tagged, and monitored female sage-grouse to estimate breeding season (April 15 to September 15) survival, 2016–2017. Deceased sage-grouse were tested for active WNV; live-captured and hunter-harvested sage-grouse were tested for WNV antibody titers. Additionally, we trapped mosquitoes with CO2-baited traps 4 nights per week (542 trap nights) to estimate WNV minimum infection rate (MIR). Eight sage-grouse mortalities occurred during the WNV seasons of 2016 and 2017, 5 had recoverable tissue, and 1 of 5 tested positive for WNV infection. Survival varied temporally with sage-grouse biological seasons, not WNV seasonality. Survival was 0.68 (95% CI: 0.56–0.78; n = 74) during the reproductive season (April 1 to September 15). Mammalian predators were the leading suspected cause of mortality (40%), followed by unknown cause (25%), avian predation (15%), unknown predation (15%), and WNV (5%). These results indicate WNV was not a significant driver of adult sage-grouse survival during this study. Three sage-grouse (1.9%; 95% CI: 0.5–5.9%) contained WNV antibodies. We captured 12,472 mosquitoes of which 3,933 (32%) were C. tarsalis. The estimated WNV MIR of C. tarsalis during 2016 and 2017 was 3.3 and 1.6, respectively. Our results suggest sage-grouse in South Dakota have limited exposure to WNV, and WNV was not a significant source of sage-grouse mortality in South Dakota during 2016 and 2017. Based on our finding that a majority of sage-grouse in South Dakota are susceptible to WNV infection, WNV could potentially have an impact on the population during an epizootic event; however, when WNV is at or near-endemic levels, it appears to have little impact on sage-grouse survival.

Breeding Ecology of Mottled Ducks: A Review

ABSTRACTMottled ducks (Anas fulvigula) are endemic to the Gulf Coast of North America, and their range stretches from Alabama to the Laguna Madre of Mexico, with a distinct population in peninsular Florida and an introduced population in South Carolina. As one of the few non‐migratory ducks in North America, mottled ducks depend on a variety of locally available habitat throughout the annual cycle, and threats to these landscapes may affect mottled ducks more acutely than migratory species. Annual population monitoring has revealed declines in mottled duck populations in Texas and Louisiana since 2008, and the genetic integrity of the Florida population has been muddled by the presence of large numbers of feral mallards (Anas platyrhynchos) resulting in hybridization. Similar to other closely related dabbling ducks, mottled duck populations are influenced by recruitment and breeding season survival, so changes in these factors may contribute to population decline. Accordingly, researchers have attempted to address various aspects of mottled duck breeding season ecology and population dynamics since the 1950s. We conducted a literature review on this topic by searching a combination of key terms using Google Scholar, including mottled duck, nesting ecology, habitat use, breeding incidence, nest success, brood, and breeding season survival, and followed citation trees to eventually aggregate information from nearly 50 publications on mottled duck breeding ecology. Our review concluded that mottled ducks use brackish and intermediate coastal marsh, including managed impoundments, and agricultural land during the breeding season. Their nests can be found in pastures, levees, dry cordgrass marsh, cutgrass marsh, spoil banks, and small islands. Nesting propensity and nest success estimates are often lower than other waterfowl species that are characterized by stable or increasing populations. Broods use wetlands composed of a mix of open water with submerged and emergent vegetation. Breeding season survival is higher for the Florida population than the western Gulf Coast population, but adult survival in both geographies is comparable to (or higher than) that of other dabbling duck species. Breeding habitat use, breeding season survival, and nest‐site selection and success have been studied extensively in mottled ducks, whereas information on nesting propensity, renesting intensity, and post‐hatch ecology is lacking. © 2021 The Wildlife Society.

Breeding-Season Survival, Home-Range Size, and Habitat Selection of Female Bachman's Sparrows

Peucaea aestivalis (Bachman's Sparrow) is a declining songbird endemic to the southeastern US, but lack of basic life-history information for females, including a description of habitat selection, limits effective management. We investigated survival, home-range size, and habitat selection of female Bachman's Sparrows during the breeding season at Fort Bragg Military Installation, NC. We attached radio-transmitters to female sparrows between April and June in 2014–2016 and recorded locations of females every 2–4 days. We estimated seasonal survival and home-range size and, in 2016, we modeled habitat selection of female sparrows within their home range. Estimated breeding-season (90 days) survival (0.941) was greater than a published estimate from South Carolina (0.794), and home-range size (1.48 ha, SE = 0.16) was similar to a published estimate for females and multiple published estimates for male sparrows (min–max = 1–5 ha). Females selected habitat patches with greater woody vegetation and intermediate grass densities than at random locations, suggesting that woody vegetation provides escape and nesting cover for female sparrows. Survival, home-range size, and habitat selection of female Bachman's Sparrows did not differ substantially from males in other studies. Therefore, management focused on male sparrows may concurrently conserve habitat requirements for females.

Landscape Connectivity Influences Survival and Resource Use following Long‐Distance Translocation of Northern Bobwhite

ABSTRACTTranslocation is an important component of northern bobwhite (Colinus virginianus) recovery efforts, given the scale of their decline and inability to rapidly recolonize recently restored habitat. Repopulating sites in northern latitudes that are distant from reliable source populations may require long‐distance trap and transport from southern locales, potentially compounding existing obstacles for this renascent population recovery technique. The landscape connectivity hypothesis predicts that site fidelity and survival would be lower if release properties are small and fragmented and home range sizes would be smaller and dispersal distances would be lower if habitat quality at the release site is perceived to be high and the surrounding matrix is of low permeability. We evaluated this hypothesis to determine if northern bobwhite survival, site fidelity, and resource selection following translocation differed between 2 contrasting landscapes in the Mid‐Atlantic region of the United States. We translocated 508 radio‐collared northern bobwhites from northern Florida and southern Georgia, to small, fragmented properties on the eastern shore of Maryland and large, contiguous properties in southern New Jersey, USA. We monitored northern bobwhites via radio‐telemetry from approximately 1 April through 30 September, 2015–2018, 2–7 times a week. Breeding season (182 days after release) survival varied among sites, and was generally higher at the 2 New Jersey release sites than at the 2 Maryland sites, yet an acclimation period is ostensibly required to obtain reasonable breeding survival estimates to elicit population growth. Site fidelity, maximum dispersal distances, and home range sizes were lower at the smaller, fragmented Maryland properties than the larger New Jersey properties. These results support the landscape connectivity hypothesis such that reduced connectivity in our study decreased site fidelity and survival. Temporal variation in survival was potentially an artifact of translocation stress or maladaptive behavior during initial acclimation to the release sites, indicating that higher stocking rates may be needed to provide adequate founder abundance for translocation success. Northern bobwhites used early‐successional cover at all sites, though selection varied based on scale of analysis and landscape context. These vital rate estimates and resource use patterns should be used to guide future translocations within the Mid‐Atlantic, provide perspective for this population restoration technique range wide, and stimulate further investigation into limiting factors. © 2020 The Wildlife Society.

Survival of Sharp‐Tailed Grouse Under Variable Livestock Grazing Management

ABSTRACTLivestock grazing is a predominant land use worldwide and can influence wildlife populations by altering grassland composition, structure, and productivity. Conceptually, rest‐rotation livestock grazing could increase pasture‐level heterogeneity that would allow wildlife to balance the need for resources with the risk of predation. Prairie‐grouse (Tympanuchus spp.) are recognized as important indicator species for grassland ecosystems, so identifying management approaches suitable for prairie‐grouse could have implications for other species. We monitored radio‐collared female sharp‐tailed grouse (T. phasianellus) to evaluate the effects of 3 systems of livestock grazing management on the breeding season survival and habitat‐associated mortality risk of adult grouse in the northern mixed‐grass prairie in eastern Montana and western North Dakota, USA, during 2016–2018. Cumulative breeding season survival was 0.65 ± 0.04 (SE) and annual survival varied from 0.28 ± 0.04 to 0.50 ± 0.05. Grazing management did not have a meaningful influence on any aspect of the cumulative breeding season survival of adult female sharp‐tailed grouse, although the seasonal timing of peaks in mortality risk differed among systems. A 10% increase in cropland increased mortality risk of adult female sharp‐tailed grouse by a factor of 1.27. Overall, our results suggest that strategies that preserve economically viable ranching systems in unfragmented grasslands may have greater benefits for sharp‐tailed grouse survival than prescriptive livestock grazing systems. © 2020 The Wildlife Society.

Relative Importance of Vital Rates to Population Dynamics of Wood Ducks

ABSTRACTThe wood duck (Aix sponsa) is a common and important cavity‐nesting duck in North America; however, we know very little about how changes in vital rates influence population growth rate (λ). We used estimates of fertility and survival of female wood ducks from our nest‐box studies in South Carolina, Alabama, and Georgia, USA, to create a stage‐based matrix population model. We conducted perturbation analyses and ranked elasticity values to examine the relative importance of 17 component vital rates to λ. Female survival is influenced by nest success, so we recognized this female heterogeneity in our analyses. Four vital rates showed the greatest importance to λ. Analytic elasticities were greatest for breeding season and nonbreeding season survival of females that nested successfully, followed by nest success and female recruitment to the breeding population. Differences in female quality were important to λ. Next, we used process variation of vital rates and conducted life‐stage simulation analyses (LSA) followed by variance decomposition to determine the amount of variation in λ explained by each vital rate. Female recruitment to the breeding population explained 57.7% of the variation in λ followed by nest success (11.4%), and breeding and nonbreeding season survival of females that nested successfully (9.3% and 9.4%, respectively). Together these 4 vital rates explained 88% of the variation in λ. Mean asymptotic population growth rate (λ = 0.80 ± 0.08 [SD]) from LSA revealed a declining population. Recruitment of females hatched from nest boxes was insufficient to sustain the nest‐box population. However, including yearling (SY) females that were produced outside of nest boxes (i.e., immigrants) increased recruitment rates 1.5 to 2 times more than when only SY females recruited from nest boxes were included. Future research that examines how emigration and immigration interact with survival and reproduction to influence local population dynamics of wood ducks will be important for identifying the value of nest‐box programs to wood duck conservation and management. © 2019 The Wildlife Society.

Reduction in meso‐mammal nest predators improves northern bobwhite demographics

ABSTRACTNest predation is the major cause of nest failure in northern bobwhites (Colinus virginianus; i.e., bobwhites). Control of mid‐sized mammalian nest predators (i.e., meso‐mammals) is often conducted to increase reproductive success on lands managed for bobwhites. Nest predation by meso‐mammals, however, is only one part of a complex predator‐prey trophic system. There is limited understanding of the effect of nest predators on bobwhite demographics, which creates uncertainty about the efficacy of nest predator control. We quantified demographic effects on bobwhite populations from reducing meso‐mammals on 4 study areas managed for bobwhites in northern Florida and southwestern Georgia, USA, during 2000–2006. After 1 year of pre‐treatment monitoring (2000), we reduced meso‐mammal nest predator abundance through trapping over 3‐year intervals, March to September, on 2 sites using a crossover design. Efficacy of trapping was demonstrated by a 43% reduction in scent station visitation rates of meso‐mammals. Meso‐mammal control increased all demographic metrics including a 30% increase in nesting propensity, a 10% increase in nest success, and a 43% increase in chicks produced. Despite significant regional variation in breeding season survival rates, this equated to an average 18% increase in autumn density on trapped sites. Decision‐makers should weigh the tradeoffs between bobwhite population goals and costs of meso‐mammal control, where those that value maximum bobwhite density and reduced annual variation should likely implement control of meso‐mammals. © 2019 The Wildlife Society.

Temporal Variation in Breeding Season Survival and Cause-Specific Mortality of Lesser Prairie-Chickens

Abstract The lesser prairie-chicken Tympanuchus pallidicinctus has experienced significant declines in distribution and abundance since the early 1900s. A severe and prolonged drought from 2009 to 2013 resulted in further declines in population numbers and despite improved environmental and habitat conditions since 2013, populations of lesser prairie chickens have shown little improvement. To investigate whether breeding season survival of lesser prairie-chickens in eastern New Mexico could be driving this response, we developed the following objectives: 1) estimate male and female breeding-season survival; 2) determine whether male and female survival varies temporally among lekking, nesting, and brood-rearing periods; and 3) determine cause-specific mortality during the breeding season. We captured and radiocollared 76 lesser prairie-chickens (50 male, 26 female) during spring of 2014 and 2015 and estimated their survival throughout the breeding season (15 March–31 August). Male survival was nearly double that of females in both years (0.79–0.81 and 0.38–0.45, respectively). Males had similar survival across all periods (lekking, postlekking, late summer: 0.89–0.95). Females had the greatest period-specific survival during lekking and brood rearing (0.87 ± 0.08 and 0.85 ± 0.10, respectively) relative to the nesting period (0.58 ± 0.11). Mammalian predation was the primary cause of mortality in both years. Our results indicate that in New Mexico 1) lesser prairie-chicken breeding season survival was consistent with geographically similar studies, 2) females have lower survival during the nesting period, and 3) female lesser prairie-chicken survival was lower than male survival regardless of time period. Management actions that provide and protect high-quality nesting habitat may help ensure that female survival is maximized during the nesting period.