Bobwhite Nests Research Articles

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.

Mesopredator predation risk limits northern bobwhite nesting habitat

AbstractPredators can significantly limit the amount of available habitat for vulnerable prey. Encouraging spatial segregation of predators and prey through habitat management prescriptions may be a useful tool to increase productivity and abundances of prey species of conservation concern. We estimated the total area of low‐risk nesting habitat by interacting predator habitat selection models with northern bobwhite (Colinus virginianus) nest‐site selection models. We used trail cameras, transect sampling, spotlighting transects, and incidental tracking to survey and map occurrences of mesopredators at a site in western Oklahoma, USA. We created broad‐scale resource selection function models for bobwhite nest‐site and mesopredator habitat selection using generalized linear models to create maps of occurrence probability in ArcGIS. Bobwhite nests were more likely to be depredated in areas of high selection by coyotes (Canis latrans) and striped skunks (Mephitis mephitis) compared to areas with low mesopredator selection. Approximately 392 ha of bobwhite nesting habitat (17%) had low probabilities of selection by both coyotes and striped skunks. Our results demonstrate the need for incorporating species' interactions into estimations of available habitat. Based on the total area of highly selected cover by northern bobwhite, approximately 29% of the study area would have been deemed suitable for nesting. However, only 5% of that area is predicted to have a low predation risk.

Nest Hatch Chronology of Northern Bobwhite and Implications for Management

Managers in Missouri, USA, and in other Midwestern states have long operated under the belief that the peak of nest hatching for northern bobwhite (Colinus virginianus; hereafter, bobwhite) is 15 June. Though it is widely understood that bobwhite nests hatch throughout the summer, many management decisions are made based on the accepted peak. Fully understanding the dynamics behind bobwhite nest timing is critical, as management activities in nesting cover during summer are common. To better understand nest chronology, we used radio-telemetry to monitor nest incubation initiation, hatch date, and renesting rate on 6 conservation areas in southwestern Missouri from 2014 to 2018. Nest hatch date varied by area and year, but only 8.5% of nests hatched on or before 15 June. The 7-day interval during which the most nests hatched was 15–21 June, but we also saw high numbers of nests hatch in early July and mid- to late August. The median hatch date across all 5 years of the study was 17 July. Our results suggest that the entire summer is critical for bobwhite nesting activities, with late summer being just as important as the early summer months. We encourage bobwhite managers and conservation program policymakers across the Midwest to rethink previously held constructs of bobwhite nest timing. We also recommend that summer disturbances to nesting cover be kept to a minimum when the goal is to maximize bobwhite reproductive output.

Northern Bobwhite Response to Control of Red Imported Fire Ants in the Gulf Coast Prairie of Texas

The population decline of northern bobwhite (Colinus virginianus; hereafter, bobwhite) on the Texas Gulf Coast Prairie, USA is largely attributed to habitat loss. However, red imported fire ants (Solenopsis invicta) occur throughout the region and are considered a possible contributing factor to the bobwhite decline. The objectives of our study were to determine the influence of red imported fire ants on bobwhites by comparing bobwhite nest success, survival, and density between sites treated with fire ant bait (treatment) and reference (control) sites. Our study was conducted on 3 private ranches in Goliad and Refugio counties, Texas. Each ranch contained 2 paired experimental units that consisted of a treatment and control site (500 ha each). The treatment sites received an aerial application of fire ant bait (Extinguish® Plus) during April 2018, whereas the control sites were not treated. We estimated mound density by counting fire ant mounds using distance sampling. We used radio-telemetry to monitor bobwhite nest success and survival, and we estimated bobwhite densities using distance sampling via helicopter surveys. Fire ant mound density decreased through time on both treatment and control sites. However, fire ant mound density was lower on treatment sites than control sites, indicating the insecticide was effective at decreasing fire ant mound density. Bobwhite survival, nest success, and density did not statistically differ between control and treated sites either pre-treatment (2017) or post-treatment (2018), but survival and nest success metrics were numerically higher in treated units. Bobwhite survival remained relatively stable in the treatment units 4 weeks after application but decreased in the control units. Following treatment, apparent nest success in the treated units increased by 37.4% while nest success in the control units decreased by 35.2%. Bobwhite populations were low in this ecoregion, which influenced our ability to trap and monitor many bobwhites or monitor many nests. In addition, it may be possible that repeated, annual treatments for fire ants are necessary for a benefit to accrue and be observed in bobwhites. Our results indicate that there may be potential benefits to bobwhites from fire ant reduction that deserve further research attention.

Impacts to Quail Space Use and Demographics from Oil and Gas Development

Southern Texas contains some of the last relatively unfragmented habitat for northern bobwhite (Colinus virginianus; hereafter, bobwhite) and scaled quail (Callipepla squamata) in the United States. Development of the Eagle Ford Shale hydrocarbon formation in this region could negatively impact quail and their habitat. Our objective was to examine the indirect effects of oil and gas activity (traffic and noise) on bobwhite and scaled quail on 2 private ranches in southern Texas. In 2015 and 2016, we radio-marked bobwhite and scaled quail in 2 areas where oil and gas activity was occurring (disturbed treatment) and 2 areas where little oil and gas activity occurred (undisturbed treatment). We measured vehicle passages and modeled noise propagation from oil and gas infrastructure at 2 biologically relevant frequencies (250 Hz and 1,000 Hz) in our study area to quantify oil and gas disturbance and examine its effects on quail space use (site selection and home range size) and demographics (survival, nest success, and density). Bobwhite and scaled quail selected areas 0–200 m and >425 m, respectively, from the primary, high-traffic roads in the disturbed treatment. In the undisturbed treatment, bobwhite and scaled quail selected areas 0–425 m and 0–300 m from primary roads, respectively. Bobwhite and scaled quail selected areas with sound levels 0–1.6 and 0–2.2 dB above ambient levels at the 250-Hz frequency level, respectively. At 1,000 Hz, bobwhite and scaled quail selected areas with sound levels 0–2 and 0–3.2 dB above ambient levels, respectively. We found no evidence that disturbance variables affected bobwhite and scaled quail home range size, survival, or density. We found bobwhite nest success decreased as sound levels (dB) at 250 Hz increased; we found no relationship between nest success and disturbance for scaled quail, possibly as they avoided major oil and gas disturbances. In calculations of the total footprint of quail habitat loss, indirect loss due to oil and gas activity needs to be considered in addition to direct loss due to conversion of rangeland to oil and gas infrastructure.

Effects of Prescribed Fire on Northern Bobwhite Nesting Ecology

ABSTRACTRepeated prescribed fire can create and maintain areas with sparse overstory tree cover and a dense grass‐forb‐shrub understory, providing habitat for northern bobwhite (Colinus virginianus; hereafter, bobwhite). Despite potential benefits of prescribed fires for conserving bobwhite habitat, burning during the nesting season may destroy bobwhite nests and reduce available nesting cover. We monitored radio‐transmittered bobwhite (n = 104) from 2016 to 2018 to describe nest‐site selection and determine the risk of nest destruction on a 17,000‐ha North Carolina military installation, Fort Bragg, managed with rotational growing‐season and dormant‐season prescribed fires on an approximate 3‐year return interval. We located 48 nests, of which 8 (16%) were in areas burned the same year, 9 (19%) were in one‐year post fire, 25 (52%) were in 2‐years post fire, and 6 (13%) were in ≥3‐years post fire areas. We compared vegetation composition and structure at nests to nearby random locations and determined bobwhite selected nest sites with greater woody understory and wiregrass cover, lower basal areas of pines and hardwoods, and less distance to the nearest road. Two nests (6.7%) were destroyed during prescribed fires, but success of incubated nests was high (67%). We calculated the overall risk of nest destruction by prescribed fire as the proportion of active nests in areas with ≥3 years since last fire multiplied by the proportion of the study area burned each week. Overall, 11% (weekly = 0.75%, range = 0–3%) of the study area was burned during the 2016 nesting season (3 June to 3 September), 4% (weekly = 0.31%, range 0–2%) of the study area was burned during the 2017 nesting season (5 June to 2 September), and 7.5% (weekly = 0.58%, range 0–5%) of the study area was burned during the 2018 nesting season (3 June to 31 August). We estimated that no more than 0.75% of bobwhite nests across the study site were exposed to fire annually. Most growing‐season fires occurred before the bobwhite nesting season, which limited direct effects of prescribed fire on bobwhite nest survival. However, shifting prescribed fires to later in the growing season to better match the historical lightning season (i.e., after 1 June) would increase the risk of nest destruction. Because bobwhite used older roughs (i.e. areas 2 years since fire) for nesting, shortening the fire return interval to less than 3 years would increase the proportion of nests exposed to fire. Additionally, a shortened fire return interval would decrease available nesting cover, especially in regions with low soil fertility where vegetation change following fire is less rapid than on more productive soils. © 2021 The Wildlife Society.

High-intensity short-duration grazing during spring is not an effective habitat management tool for Northern Bobwhites in Colorado

Abstract Many wildlife species, like Northern Bobwhite (Colinus virginianus), are reliant on periodic environmental disturbance to maintain heterogeneity in vegetation patterns. The Northern Bobwhite is a species of conservation concern requiring different vegetation types for nesting and brood-rearing stages, as well as for protection from predators and extreme weather. In northeastern Colorado, there are few management options to increase disturbance, other than domestic livestock grazing, to manage Northern Bobwhite habitat. As high-intensity short-duration grazing has shown promise as a mode of disturbance to manage Northern Bobwhite habitat in other regions, I used a randomized block design to test the effect of spring high-intensity short-duration grazing on Northern Bobwhites and their habitat in northeastern Colorado from 2016 to 2019. Specifically, I monitored Northern Bobwhite nest and brood survival and habitat selection in relation to grazing treatments over 3 years. I found that grazing had no effect on nest or brood survival or brood habitat selection, but Northern Bobwhites selected against grazed plots for nesting. Nest survival was negatively influenced by percent litter around the nest, and Northern Bobwhites selected nest sites with more grass cover and less bare ground. Broods selected habitat with less bare ground and more woody vegetation. Grazing affected vegetation immediately after grazing, but these effects weakened or disappeared by the end of the growing season. One exception to this overall pattern was forbs, which tended to be more abundant on grazed plots throughout the growing season. Overall, I found neutral effects of grazing on Northern Bobwhite nest and brood survival and habitat selection and neutral to positive benefits to the vegetation. Spring high-intensity short-duration grazing does not appear to be an effective tool to manage Northern Bobwhite nest or brood habitat in northeastern Colorado.

Partial meso‐mammal predator removal positively affects northern bobwhite reproduction

Perceived changes in predator—prey dynamics along with documented declines of northern bobwhite Colinus virginianus have created a renewed interest from biologists and managers about the role meso‐mammals play in shaping bobwhite population trajectories. Therefore, we evaluated the efficacy of meso‐mammal trap and removal (MMTR) at reducing meso‐mammal activity and increasing bobwhite reproductive success; thus testing the predation limitation hypothesis. During 1999–2006, we monitored bobwhite reproduction on 11 sites in three states across the southeastern United States. Combined, there were 37 site—year combinations when MMTR occurred and 20 combinations when it did not occur. We conducted 57 predator surveys and calculated an index of meso‐mammal activity (i.e. predator index), for each site, as the average number of station visits per night by raccoons Procyon lotor, nine‐banded armadillos Dasypus novemcinctus, Virginia opossums Didelphis virginiana, bobcats Lynx rufus and foxes Vulpes vulpes, Urocyon cinereoargenteus. The average predator index (predator visits per trap night) across sites was 0.13. We collected bobwhite reproductive information from a total of 3935 radio‐tagged bobwhites resulting in 2499 nests. We used generalized linear mixed models to evaluate the relationships between MMTR, predator activity, and bobwhite reproduction. The mean predator index for non‐trapped sites was 0.21 (95% CLs: 0.18, 0.24) compared to 0.10 (95% CL: 0.07, 0.13) for trapped sites. Bobwhite nests were 1.33 times (Odds ratio, 95% CL: 1.09, 1.62) more likely to be successful on trapped sites than non‐trapped sites. Meso‐mammal trap and removal had a positive effect on nests per hen (βtrapped= 0.25 ± 0.06; 95% CL: 0.13, 0.37), broods per hen (βtrapped = 0.37 ± 0.08; 95% CL: 0.21, 0.53), and chicks per hen (βtrapped = 1.09 ± 0.52; 95% CL: 0.07, 2.11). Our results show that MMTR reduces meso‐mammal activity and positively affects bobwhite reproduction.

Extrapair paternity and nest parasitism in two sympatric quail

ABSTRACT We conducted a comparative study of 2 closely related and sympatric species, Northern Bobwhite (Colinus virginianus) and Scaled Quail (Callipepla squamata), to explore the drivers of interspecific variation in alternative reproductive strategies. Specifically, we used parentage analyses to determine rates of extrapair paternity and intraspecific brood parasitism for each species, and evaluated possible mechanisms for explaining variation in these rates between the 2 species. During 2013–2014, we genotyped hatched (n = 388 for Northern Bobwhite and n = 214 for Scaled Quail) and unhatched (n = 32 for Northern Bobwhite and n = 9 for Scaled Quail) eggshells from 34 Northern Bobwhite and 22 Scaled Quail nests in western Oklahoma, USA. Extrapair paternity occurred in 85% of Northern Bobwhite nests and 9% of Scaled Quail nests. The number of sires for each nest was greater in Northern Bobwhite nests (x = 2.29 ± 0.14 SE sires per nest) than in Scaled Quail nests (x = 1.09 ± 0.06 sires per nest). Intras...

Parental Risk-Taking at Natural Northern Bobwhite Nests

Parental risk-taking at the nest is critical to examining the trade-offs between current and future reproduction. Using Northern Bobwhites ( Colinus virginianus) at camera-monitored nests in the natural environment, we examined how parental and offspring characteristics, predator community, and predator type affected flush distance of incubating birds to approaching predators. During 1999–2006, we monitored 118 predation interactions at nests at two pairs of study sites in southern Georgia and northern Florida, USA where mesomammalian predators were experimentally reduced or not reduced. The results showed that incubating parent birds allowed closer approaches by predators that typically only consumed eggs ( e.g. Nine-banded Armadillos Dasypus novemcinctus, Virginia Opossums Didelphis virginiana, and snakes) than by predators that could harm the adults (including Bobcats Lynx rufus and Raccoons Procyon lotor) prior to flushing from the nest. Our data did not support the hypotheses that parent-offspring characteristics and predator community affect parental risk-taking at the nest. Our findings suggest that parent birds incorporate information about predator identity over parental and offspring characteristics or predator community into anti-predator decisions at the nest in systems with high predation risk.

Macrohabitat Composition Surrounding Successful and Depredated Northern Bobwhite Nests

Relationships among macrohabitat and depredation of northern bobwhite (Colinus virginianus) nests are poorly understood. Yet, macrohabitat composition may influence the nest predator community and, therefore, the vulnerability of northern bobwhite nests to depredation. We determined if macrohabitat composition surrounding bobwhite nests influenced nest placement, nest success, and which predators were responsible for depredating nests. We characterized macrohabitats at 2 scales, 8 and 16 ha, by surrounding both bobwhite nests, and an equal number of random locations, with a circular buffer. Random points were placed within the area used by bobwhites on our study area. We then determined the acreage of each macrohabitat category within each circular buffer to determine the macrohabitat composition. Macrohabitat categories included hardwood forested drains, upland pine forests burned in March of the same calendar year, upland pine forests burned in March of the previous calendar year, and fields. We documented nest predators using infrared video cameras placed at the nest site. We monitored 104 bobwhite nests on Tall Timbers Research Station (TTRS) during 1999 and 2000. Size of the circular buffer around nests did not qualitatively affect results. Area (ha) of upland pine forests and fields were similar at depredated nests, hatched nests, and random locations. However, there was an average of 81% and 56% more area of hardwood drain in the circular buffers associated with random locations than at successful and depredated nests, respectively. Area of upland pine forests and fields were similar for nests depredated by raccoon (Procyon lotor), armadillo (Dasypus novemcinctus) and snake (Elaphus spp.). However, there was an average of 6.1 and 3.3 times more area of hardwood drain surrounding nests that were depredated by snakes relative to nests depredated by raccoons and armadillos, respectively. While our sample sizes were low, bobwhites exhibited a tendency to place nests in landscapes with less hardwood drain than were generally available on the study area. Macrohabitat surrounding nests influenced the type of nest predator to depredate nests. To minimize depredation of bobwhite nests by snakes, we suggest nesting cover should be developed away from drain edges.

Depredation Patterns of Northern Bobwhite Nest Predators in Virginia

Little information exists that can be used to accurately identify predator species responsible for destruction of northern bobwhite (Colinus virginianus) nests. We used remotely-tripped cameras to photograph nest predators at 25 wild bobwhite nests that were continually filled with eggs from pen-raised quail. Data describing depredation events were collected to characterize species-specific damage patterns. Seven species of nest predators were photographed 1,797 times from June to October 1996. We describe depredation patterns for opossums (Didelphis marsupialis), striped skunks (Mephitis mephitis), raccoons (Procyon lotor), gray fox (Urocyon cinereoargenteus), and domestic dogs (Canis familiaris). These descriptions should help researchers identify the predator species responsible for destroyed bobwhite nests.

Landscape Features Affecting Northern Bobwhite Predator-Specific Nest Failures in Southeastern USA

Nest predation is a critical component in avian productivity and typically is the leading cause of nest failure for most birds. Several landscape features are thought to drive the behavioral interaction between northern bobwhite (Colinus virginianus; e.g., nest placement) and their predators (e.g., search methods for food acquisition). In order to understand habitat characteristics influencing predation, we studied bobwhite nests using 24-hour near-infrared video cameras. We monitored 675 bobwhite nests with cameras on 3 properties in northern Florida and southern Georgia, USA, during 2000–2006. To test the association between nest failures and specific failure causes with landscape structure, we calculated a suite of landscape metrics and examined these at 3 spatial scales (3.1 ha, 19.6 ha, and 50.3 ha). We found increased probability of nest success with greater proportions of, and proximity to, fallow and annually disked fields at larger scales (50.3 ha), but we found no landscape metrics to be important predictors of bobwhite nest failures at small scales (<20 >ha). Fallow and disked fields may provide alternative prey items (e.g., rodents) important in buffering nest predation. Relative to meso-mammal predation, we observed increases in proportion of the landscape in field to be related to lower incidental nest failures at the smallest scale (3.1 ha). Nests closer to feed lines were more likely depredated by meso-mammals than ants at the 2 larger spatial scales. Interestingly, the fate of a nest was independent of the fate of neighboring nests, suggesting bobwhite nest predation may be primarily incidental.

Testing the Value of Prickly Pear Cactus as a Nest-Predator Deterrent for Northern Bobwhite

Recent research indicates that northern bobwhites (Colinus virginianus) in Texas commonly nest in prickly pear cactus (Opuntia sp.) instead of conventional bunchgrass habitat. We hypothesized that bobwhites nested in prickly pear because it served as a deterrent to nest predators thereby increasing probability of nest success (nest-protection hypothesis; Slater et al. 2001). We experimentally tested the nest-protection hypothesis by providing 50 wild-caught, captive raccoons (Procyon lotor) with combinations of simulated, bobwhite nests. Nest combinations included either 1 nest in bunchgrass (e.g., little bluestem [Schizachryium scoparium]) and 1 nest in prickly pear cactus (partial [75%] or full [100%] protection), or 2 separate nests in prickly pear (partial and full protection). Raccoons depredated 97%, 33%, and 14% of simulated nests constructed of bunchgrass (n = 35 nests), partial protection prickly pear (n = 30 nests), and full protection prickly pear (n = 35 nests), respectively. Prickly pear nests that provided full protection exhibited better survival against raccoon depredation than other nest types. Our study provides support for the nest-protection hypothesis regarding why northern bobwhite possibly nest in prickly pear cactus.

Impacts of Red Imported Fire Ants on Northern Bobwhite Nest Survival

Invasive species are a large management issue because of extensive environmental and economic damage. The red imported fire ant (RIFA, Solenopsis invicta) is an invasive species of growing concern in wildlife management in the United States because of its increasing distribution, difficulty to suppress, and aggressive predation on native invertebrates, herpetofauna, birds, and small mammals. Managers of the northern bobwhite (Colinus virginianus) have questioned the direct impact of RIFA on bobwhite nest success, particularly the factors that might influence the level of nest predation. We hypothesized that RIFA predation on northern bobwhite would vary by location and correlate with drier weather conditions. To test our hypothesis we analyzed bobwhite nest data gathered from 3 properties in the southeastern United States. The nest data are part of a larger research effort on bobwhites, collected by Tall Timbers Research Station and the Albany Quail Project using radiotelemetry from 1992 to 2015. Over these 23 years we tracked bobwhites and located nests (n = 3,207) daily to determine nest fate (success or failure) based on field sign and evidence attributed to specific causes of mortality. We used the nest-survival model in Program MARK to estimate nest survival. Average nest survival varied annually for the Albany and Tall Timbers study areas, respectively. The overall effect of RIFAs on nest survival was generally small, with an average annual loss in Albany of 5.13% (range = 0–15.59%) and 2.17% in Tall Timbers (range = 0–5.83%), but in some years was as high as 15.6%. Greater losses occurred late in the breeding season when it was typically drier and the loss rate in general was higher on the drier of the 2 study sites. Despite the relatively small direct impact on nesting success demonstrated, indirect effects of RIFAs on bobwhite populations are poorly understood at present. Quantifying the influence of indirect factors, such as soil type and habitat disturbance, on RIFA abundance and the subsequent impact on bobwhites, will provide additional insight to the ecological interaction with a highly pervasive and expanding invasive species and help inform management options.

Northern Bobwhite Nest Site Selection in Field Borders

Field borders are used to supplement early successional habitat critical for northern bobwhite (Colinus virginianus) nesting that is lost to modern intensive agricultural practices. The suitability of field border habitat for nesting may be affected by microhabitat characteristics at the site and patch scale and placement relative to various land-cover types at the landscape scale. We sought to determine whether bobwhite select nest locations at site, patch, and landscape scales. We collected microhabitat data (stem density, percent cover, and ground composition) and distance to land-cover type data (woody edge, crop, ditch, and road) from 26 bobwhite nests and 26 control sites in field borders in North Carolina, USA, during 2010 and 2011. We modeled nest site selection by comparing nests with random locations using conditional logistic regression at the site scale and logistic regression at the combined patch–landscape scale. We performed model selection using the small sample Akaike’s Information Criterion (AICc). The top site-scale model showed that bobwhite selected for the presence of woody cover and avoided open soil at the nest. There was no clear top model at the combined patch–landscape level. In an agriculture-dominated landscape, managers should focus on microhabitat characteristics of field borders to improve suitability for bobwhite nesting.

Use of Extinguish Plus™ to Reduce Red Imported Fire Ants and Increase Northern Bobwhite Abundance

Populations of northern bobwhite (Colinus virginianus) have been declining throughout Texas since at least the 1970s. The red imported fire ant (RIFA, Solenopsis invicta) was introduced from South America and reached Texas by the 1950s. Previous studies have documented the negative effects of RIFA on northern bobwhite populations through both direct predation and indirect reduction of small invertebrates. In 2013, 2014, and 2015, large areas (1,490 ha in 2013 and 2,380 ha in 2014 and 2015) of the 3,744-ha portion of the Attwater Prairie Chicken National Wildlife Refuge (APCNWR) in Colorado County, Texas, were aerially treated with Extinguish Plus™, a chemical pesticide and reproductive inhibitor that targets ants. Our study took place on APCNWR and our objectives included evaluation of the impacts of RIFA treatment on 1) RIFA abundance, and 2) northern bobwhite nest success and brood survival. We trapped, banded, and radiocollared northern bobwhites in areas treated and not treated with Extinguish Plus from May 2014 through August 2016. We also collected RIFA abundance data using baited Petri dishes on areas treated and nontreated areas during these periods. Treatment reduced RIFA presence on the refuge by 73.4% during 2014 and 2015, but did not reduce RIFA presence during 2016 possibly because of displacement of RIFA colonies due to heavy flooding on the refuge. We detected a difference (χ21 = 11,009, P = 0.0009) in the number of females sighted with and without broods between treated (19.5% F with broods) and nontreated areas (35.7% F with broods). We also found a difference (t12 = 2.51, P = 0.027) in mean number of chicks per brood sighted within treated (4.7) versus nontreated (9.3) areas for 2014 and 2014; but in 2016, we found no difference (t12 = 0.32, P = 0.754) in mean number of chicks per brood sighted within treated (7.7) and nontreated (8.4) areas, which was possibly due to extensive flooding in the nontreated area in April that destroyed most first nests. Our data suggested treatment with Extinguish Plus did not increase northern bobwhite abundance on the APCNWR during the 2014, 2015, and 2016 bobwhite nesting seasons. Our results differ from previous studies, possibly because of time since treatment and differences in environmental factors between treated and nontreated areas such as ecological site, vegetation composition, and predator abundance.

Effects of Growing Season Fire on Northern Bobwhite Nest Site Selection and Survival

Restoration and management of longleaf pine (Pinus palustris) communities necessitates frequent prescribed fire. Prior to human colonization of the southeastern United States thousands of years ago, longleaf pine forests burned primarily during the growing-season as a result of lightning-ignited fires. Growing-season prescribed fire may suppress woody vegetation and promote herbaceous groundcover better than dormant-season fire. Despite the potential ecological benefits of growing-season fire, many land managers use only dormant-season prescribed fire to avoid destruction of ground nests, including those from northern bobwhite (Colinus virginianus). Our objective was to determine bobwhite nest survival and nest-site selection in the presence of early, growing-season prescribed fire on a 3-year return interval. We compared vegetation composition and structure at nest sites and paired random sites to identify important predictors of nest-site selection and to evaluate the effects of habitat covariates on nest survival. We captured bobwhite and attached radio transmitters. Radio-marked individuals were tracked to locate nests and determine nest survival. We documented 2 nests that burned during a growing-season prescribed fire. All 14 nests were located within units that were burned at least 2 years prior, putting these nests at a greater risk for being destroyed by prescribed fire that occurred on a 3-year return interval. We suggest that restricting early, growing-season prescribed burning to April through early June should limit an overlap between prescribed burns and the peak of northern bobwhite nesting season, which occurred mid-July at our study site. Additionally, longer fire return intervals may be needed to allow development of woody understory structure selected by bobwhites for nesting, especially on poor soils like those on our study site in the Sandhills physiographic region.

Depredation Patterns and Northern Bobwhite Nest Success in Field Borders

Northern bobwhite (Colinus virginianus) populations have declined because of habitat loss and fragmentation. Field borders provide additional habitat for northern bobwhites and other wildlife that depend on early-succession habitat. However, their proximity to woods as well as other edge types may result in increased bobwhite nest depredation. We examined if northern bobwhite nest survival in field borders decreased with increasing proximity to edges such as woods, crop fields, ditches, and roads; effects of year, camera presence, and field border width also were considered. We examined if snakes are the primary nest predator with 24-hr video camera surveillance. We searched for and monitored northern bobwhite nests on ~ 77 ha of field borders in southeast North Carolina during summers 2010 and 2011. We found 26 nests and monitored them every 3–4 days. Fourteen nests were monitored with cameras. We built nest survival models using the covariates of distance to nearest woody edge, crop field, ditch, and road as well as year, camera effect, and field border width. The most explanatory model was constant northern bobwhite nest survival with an estimated daily nest survival 6 SE of 0.9512 6 0.0119 (AICc weight 1⁄4 0.23). Models with covariates suggested similar daily nest survival rates. Four snake and two mammalian predation events were recorded on camera. Distance to edge types and field border width did not appear to influence the outcome of nests in an agriculture-dominated landscape. Thus, landowners and managers in an agriculture-dominated landscape may have flexibility with field border placement and distance to edge type as they relate to nest success.

Effects of Micro-Habitat, Macro-Habitat, and Predator Space-Use on Success of Northern Bobwhite Nests (Poster Abstract)

Northern bobwhite (Colinus virginianus) exhibit high reproductive potential allowing populations to rapidly respond to newly created habitat and recover from high annual mortality. However, they experience low individual nest success, ranging from 16–50%. Survival of nests, particularly first nests, is an important demographic parameter that influences overall population performance and participation in alternative reproductive strategies such as renesting, double-clutching, and male-incubation. As bobwhite populations continue to decline, old paradigms regarding the relationships among habitat characteristics, predator abundance, and bobwhite productivity are being reexamined. A new emerging paradigm hypothesizes that habitat structure, landscape context, and predator context interact in a complex manner to influence fate of individual nests. Vegetation characteristics at nest sites, and components of bobwhite nesting habitat have been described, but few studies have shown relationships between vegetation characteristics and nest success. In contrast, several studies have demonstrated relationships between landscape structure and nest success, and ongoing research in the southeastern United States is demonstrating relationships between predator context and productivity. Although numerous studies have estimated nest success, no study has simultaneously examined effects of vegetation structure, landscape structure, and predator context on survival of bobwhite nests. We use incubated nests (n = 104) of radiomarked bobwhite on a managed area in east-central Mississippi from 1996–00 to examine effects of micro-habitat, macro-habitat, and predator space-use on nest survival. At each nest we characterized microhabitat by measuring vegetation height, density (Robel Visual Obstruction Reading), grass canopy coverage, forb canopy coverage, litter coverage, litter depth, and % bare ground. Within 50-, 200-, and 400-m concentric circles around nest sites we characterized landscape context using measures of patch richness, patch diversity, and interspersion/juxtaposition indices, and habitat specific measures of patch density, patch shape index, edge density, and % of landscape. We used year-specific harmonic mean utilization distributions of radiomarked raccoons to construct cumulative raccoon utilization distributions to measure intensity of space use by an important bobwhite nest predator. We used logistic regression on nest fate (hatched/failed) to develop predictive models of nest success as a function of micro-habitat, macro-habitat, and predator space-use. We constructed a set of candidate models that hypothesized nest fate as a function of micro-habitat, macro-habitat, predator space-use, micro and macro habitat, microhabitat and predator space use, macrohabitat and predator space use, and a global model that included all 3 groups of predictor variables. We used information theoretic approaches for model selection and inference.