Calling Rates of Male Bobwhites During Summer in North Florida

The summer call-count survey is a common method used as an index of abundance for male northern bobwhites (Colinus virginianus). Typically, abundance estimates have limited use and transference to other analyses because they lack estimates of detection and availability. Incorporating availability into abundance estimates has not been common because of the difficulty in attaining an availability estimate. We monitored the calling rates of radio-marked northern bobwhites, April–July, to ascertain the proportion of males available for detection within biweekly periods to attain a direct measure of availability. We measured daily and seasonal peaks in calling rates and investigated potential parameters that may influence the calling rate. We used a 5-min survey period and observed a mean calling rate of 0.40, which increased to 0.493 when a 10-min survey period was used. The biweekly calling rates were similar during May and June, but were significantly lower in April and July. Daily call rates within the 4-hr survey time period were consistent for May and June, but were more variable in July. Incorporating availability estimates into standard distance sampling procedures allowed us to produce more robust estimates of summer bobwhite density. Little is known about the variability of male bobwhite calling rates regionally or at different densities and we encourage other researchers to attain availability estimates from other landscapes and population densities

Factors Influencing Northern Bobwhite Hunting Success on Two South Georgia Plantations

Success of wild northern bobwhite (Colinus virginianus) management programs on private lands is most often measured by the rate of coveys pointed during the hunting season. Thus, managers of these properties are keenly interested in factors that influence hunting success. We examined how coveys pointed/hour, a measure of hunting success, was influenced by time of hunting season, time of day, weather parameters, and supplemental feeding on 2 intensively-managed plantations over 4 years. There were significant annual differences in the number of coveys pointed/hour among the 4 study years, but hunting success did not vary during the hunting season. Afternoon hunts had consistently higher success rates than morning hunts; however, the effect size was variable from year to year. The selected weather model indicated an interaction between 12-hr barometric pressure change and starting air pressure; hunting success increased with a rapid pressure increase that resulted in a high pressure value at the start of the hunt. A secondary weather model documented a negative relationship between starting air temperature and hunting success. The number of days since supplemental feed was spread had no significant effect on hunting success in 5 of 6 years for the 2 plantations over 3 years. Knowledge of how these variables influence hunting success should improve hunting and provide realistic expectations of hunt success for a given set of circumstances

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 (\u3e0.55) 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

Age-Specific Nesting Performance by Northern Bobwhites

Greater reproductive productivity of adult versus juvenile northern bobwhites (Colinus virginianus) has been hypothesized as a factor for rapid population growth. Research on bobwhites in the western portions of the species’ range has not supported this hypothesis; however, no effort has been made to investigate age-specific reproduction on population dynamics in the southeast. We measured age- specific reproductive parameters between adult and juvenile bobwhites during 2000–2010. We radio-marked 1,069 females of which 308 were adults and 761 were juveniles. Nests per hens for adults (0.78 nests/hen) was slightly greater than that for juveniles (0.65 nests/hen) (P 1⁄4 0.09). Adult productivity was 1.7 times greater than for juveniles in 4 of 10 years which corresponded to years of population growth. No differences were found in initial clutch sizes or nesting success. Adult hens began incubation earlier than juveniles in all but 1 year suggesting increased nesting may be due to early recrudescence in adults. The magnitude of age-specific reproductive differences in short-lived species like bobwhites is not as great as long-lived species, but has implications for understanding bobwhite population dynamics and harvest

Comparison of Methods to Capture Bobwhites During Summer (Poster Abstract)

Live-capturing northern bobwhites (Colinus virginianus) using baited funnel traps during summer often is inefficient. Previous methods to attract wild bobwhites to a trap site have included bait (typically cracked corn), or use of a pen-raised female bobwhite inside the trap. It has been suggested that playing electronic recordings of the bobwhite’s ‘‘koi-lee’’ call at the trap site may improve trap success, but this idea has never been tested. Therefore, in July 1999, we collected trapping data from farms in Wilson County, North Carolina and Tall Timbers Research Station (TTRS) in Leon County, Florida. Trap sites were randomly assigned each day with 1 of 4 treatments including bait only, bait with electronic calling (bait and call), pen-raised female bobwhite (hen), or a hen with electronic calling (hen and call). Traps were set starting at sunrise and were checked after sunset. We captured 87 males, 10 females, and 3 immature bobwhites in 500 trap nights. At TTRS, number of bobwhites caught per 10 trap nights was 0.5 for bait, 0.2 for bait and call, 4.2 for hen, and 4.4 for hen and call. At Wilson, number of bobwhites caught per 10 trap nights was 1.0 for bait, 0.4 for bait and call, 1.3 for hen, and 3.3 for hen and call. Trap success for the hen only and hen and call treatments varied between sites. At TTRS, use of hens greatly improved capture success compared to using bait, but little difference was observed between hen only and hen and call treatments. Conversely, at Wilson, hen only and bait only treatments had similar capture success, but the hen and call treatment was 2.5 times more successful over the other treatments. Electronic calling appeared to have attracted bobwhites to the trap vicinity and the hen appeared to encourage bobwhites to enter the trap. This circumstance was especially evident at Wilson where the overall bobwhite abundance was low and the distribution was unequal across the landscape. We recommend using pen-raised female bobwhite and electronic calling to maximize trap success during the bobwhite breeding season on areas with low to moderate bobwhite densities

Effects of Supplemental Feeding on Breeding Season Home Ranges and Resource Selection of Northern Bobwhites

Providing supplemental food resources for northern bobwhite (Colinus virginanus) has been a common management practice for decades, but its impact on bobwhite home ranges sizes and space use has been debated. Between 2001 and 2007, we established a 397 ha fed study area on Tall Timbers Research Station, which received grain sorghum biweekly along a 19.5 km feed trail. An adjacent 465 ha area was treated as a control with no supplemental food resources. Radio-tagged wild bobwhites were located 3 – 5 times each week throughout the breeding season and we used these locations to calculate home ranges during early breeding season (15 April – 30 June) and late breeding season (1 July – 1 October). We also determined second and third order selection of a 10-m buffer area surrounding the supplemental feed trail using compositional analyses. In total, 552 and 286 bobwhite home ranges were calculated for early and late breeding seasons, respectively. We observed significantly smaller early breeding season home ranges on the fed area (x̄ = 12.3 ha, 95% CL ± 0.6) relative to the control (x̄ = 17.4 ha ± 1.9). Average length of feed trail within home ranges was 583 m and 710 m for early and late breeding season home ranges, respectively. The feed trail buffer area was 3 to 5% of all home ranges. Home range placement was not random with high selection preference for the feed trail buffer area. However, there was a low selection preference for the feed trail buffer area within home ranges. Average distances to the feed trail for bobwhite locations (x̄ = 64.4 m ± 16.1) was similar to random locations (x̄ = 74.4 m ± 16.9). The effect of supplemental feeding on bobwhite home ranges size and resource use was greatest during the early breeding season when food and useable habitat were likely lower in availability. On our study area, supplemental food resources distributed along a feed trail impacted bobwhites during a critical transition period from the spring prescribed burning season to the early breeding season

Habitat Selection of Northern Bobwhite Coveys on Two Intensive Agriculture Landscapes in Eastern North Carolina (Poster Abstract)

Little information is available for home range size and habitat use of northern bobwhites (Colinus virginianus) on modern agricultural landscapes in autumn. Therefore, we monitored radiomarked bobwhite coveys from September–December 1998 on farms in Wilson and Tyrrell counties, North Carolina. The Tyrrell County farm was a 6084-ha area recently developed for commercial production of corn and soybeans. Dispersed throughout crop areas were forested and fallow blocks at differing stages of succession. The Wilson County farms had small fields (x̄ = 1.8 ha, SE = 0.12) planted in cotton, soybeans, corn, and tobacco and were surrounded by mixed pine and hardwood blocks of differing ages. Mean home range size at the Tyrrell County farm was 33.2 ha (range 4.5–128.5 ha) (n = 10). The two largest home ranges, 70.7 and 128.6 ha, were disproportionately large due to large movements from harvested crop fields to permanent forested cover. Covey home ranges were not established at random (l = 0.124; x2 4= 20.18; P \u3c 0.001). Road and canal edges were selected significantly more than any other habitat followed in rank by soybean fields, corn fields, forested, and fallow blocks. Road and canal edges provided necessary cover for moving between habitat types, especially from forested and fallow blocks to crop fields. Within home ranges, coveys did not allocate their time at random (l = 0.336; x2 4 = 10.89; P \u3c 0.05). Habitats were ranked in the order of forested blocks, fallow areas, soybean fields, road and canal edges, and corn fields, but no significant differences were found between habitats. In Wilson County, average covey home range was 17.4 ha (Range: 4.9–37.6 ha)(n = 11). Coveys did not establish their home range at random (l = 0.407; x22 = 9.87; P \u3c 0.05), selecting forested blocks over crop fields (T9 = 3.02, P \u3c 0.012). Within home ranges coveys did not allocate their time at random (l = 0.1319; x25 = 22.28; P \u3c 0.001), utilizing primarily forested blocks followed by cotton fields, soybean fields, corn fields, and other areas. On both study areas, forested and fallow blocks were the only source of cover to spend time in after crop harvest. Covey use within forested and fallow blocks was concentrated along edges of crop fields, leaving large portions of this habitat type unused. Forested and fallow blocks were primarily used as loafing cover in between feeding periods in adjacent crop fields

Factors Influencing Early Morning Covey Calling in Northern Bobwhites (Oral Abstract)

Data from early morning covey calling may be useful for measuring abundance of northern bobwhite (Colinus virginianus). However, critical assumptions about detection rates, survey timing, and seasonality effects have not been tested. Additionally, the effects of weather and covey density on call rates are unknown. We quantified call rates of 219 radiomarked coveys at 5 sites in 1998 and 2 sites in 1997 and 1999 to monitor calling behavior of bobwhite coveys. First calls for coveys (n = 442) occurred on average 23.4 (SE = 0.5) min before sunrise and averaged 31.4 +- 1.9 calls/covey. Few first calls (13%) occurred after 15 min before sunrise. Across sites, call rates averaged 58% (SE 2.0) (n = 763). Call rates were most variable during September and December biweekly periods and least variable during late October and early November biweekly periods. We developed 15 logistic regression models from data collected in 1998 for predicting the probability of a covey to call. Selected best models were chosen using the Akaike information criterion modified for overdispersion and small sample size. The selected best model included number of adjacent calling coveys, wind speed, cloud cover, and barometric pressure change. Parameter estimates for number of adjacent calling coveys had an odds ratio of 1.4; the 95% CI did not contain 0. A less parsimonious model, which also included biweekly period and interaction terms, was equally as likely (QAICc 0.32) as the selected model. The 16–31 October biweekly period had an odds ratio of 1.8; conditional 95% CI not containing 0. A post hoc analysis was conducted using the same candidate model list, but we replaced number of adjacent calling coveys with deviations of the number of adjacent calling coveys from site means. Results were similar to the previous analysis with the same selected best model, but model fit was improved. Selected best models were tested using observations collected in 1999 from 2 of the 5 sites monitored in 1998. Predicted call rates were relatively precise (observed call rate-predicted call rate \u3c 0.10) for biweekly periods associated with peak call rates, but call rates were less precise (range 0.12–0.27) for other biweekly periods. Constancy of call rates suggests that at bobwhite densities we observed (0.75 and 5 bobwhites/ha), covey call surveys have potential to index fall populations of bobwhites with reasonable accuracy

Effects of Seasonal Fire Applications on Northern Bobwhite Brood Habitat and Hunting Success

Since the early part of the 20th century, land managers have used prescribed fire during February and March to maintain and enhance habitat for northern bobwhites (Colinus virginianus) in southern pine forests. During the past 2 decades, some managers have started to shift their use of fire to mimic more natural lightning-season (April to August) ignitions because these fires encourage flowering of plants in intact native ground cover, and are potentially more effective at hardwood control than winter fires. Therefore, we designed a short-term pilot study to evaluate whether seasonal applications of prescribed fire had any effect on bobwhite brood habitat (as measured by vegetation composition and arthropod biomass) or bobwhite abundance (as measured by hunting success) during the subsequent fall. During the first two years of our study (1994 and 1995), results showed that arthropod biomass and bobwhite hunting success were slightly greater on the shooting course burned during lightning-season (May) than the one burned during February and March. These results indicate that applications of lightning-season fire can be used, at least on a small scale (i.e., management blocks \u3c250 ha) in southern pine forests for hardwood control, and possibly enhancement of native ground cover without short-term negative impacts on northern bobwhites

Value of Private Lands Managed for Wild Northern Bobwhites in the Deep South

Successful northern bobwhite (Colinus virginiaus) management creating huntable bobwhite populations in the southeastern United States is largely practiced on private lands. These properties not only support high density bobwhite populations, they also support biodiversity including many declining or endangered species associated with frequently-burned pine savannas. The private land model has proven sustainable over centuries and has recently increased with \u3e20,000 ha of wild bobwhite lands added in Georgia, Florida, and South Carolina since 2000. The NBCI recognizes private lands are critical to restoration of bobwhites but, despite their conservation value, no studies have quantified areas under wild bobwhite management. We mapped 259 properties totaling ~ 345,614 ha with wild bobwhite management principally in Georgia, Florida, Alabama, and South Carolina, and are completing mapping in Mississippi, Virginia, and North Carolina. Our survey data found management actions were consistent across these properties including maintaining open pine canopy, reducing hardwoods in upland areas, prescribed fire on areas of appropriate sizes and distribution, year- round supplemental feeding, nest predator management, and conservative harvest rates. Adoption of these management practices are a result of long-term research demonstrating their efficacy. Density of bobwhites on a property was related to landscape composition with lower densities on more fragmented sites. Properties in core areas surrounded by other managed properties often achieved bobwhite densities of 5–8 quail/ha. Bobwhite densities on smaller isolated properties densities were ~ 2.5 quail/ha during fall. Aspects of this successful management model may be useful to other private lands as well as public management areas focused on northern bobwhite