66 research outputs found
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
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
Effects of Disking Versus Feed Patch Management on Northern Bobwhite Brood Habitat and Hunting Success
More than 60 years ago, Herbert Stoddard (1931:376) wrote there is little doubt that such methods [i.e., disking and harrowing] are more practical for Southeastern quail preserves than artificial plantings, which are costly on a large scale and not always effective. Incredibly, this statement, and testing it as an hypothesis, has been ignored by the bobwhite research community until the past 10 years. Therefore, we designed a pilot study to compare measures of northern bobwhite (Colinus virginianus) brood habitat (vegetation composition and arthropod biomass) and direct measures of hunting success (covey finds per half-day hunt) to test whether feed patches were really necessary for bobwhite habitat management in southern Georgia and northern Florida. We applied experimental treatments (disk only versus feed patch planting) by using shooting courses (150-250 ha each) on 2 southeastern shooting plantations during 1994, 1995 and 1996. Overall, results were equivocal between the feed patch and disking treatments; no consistent pattern or difference in brood habitat composition or hunting success was observed. One factor responsible for this pattern may be the relatively fine-grained scale (only 1-3% of the shooting courses were planted or disked) at which treatments were applied were insufficient to significantly influence bobwhite abundance. Further research using increased amounts of ground disturbance and planting (5%, 10%, 20%, etc.) will be required before the actual need for agricultural plantings can be determined in the context of their efficacy for bobwhite management. One potential result of these findings is that significant cost savings can be realized by disking rather than planting agricultural crop plants because at least 70% of the costs of planting are a function of seed, fertilizer and cultivation, whereas only about 30% are attributed to disking
Habitat Selection by Northern Bobwhite Broods in Pine Savanna Ecosystems
Habitat for northern bobwhite (Colinus virginianus) broods is a critical component of bobwhite management. Research within pine (Pinus spp.) savannas has provided contradictory results regarding the value of macro-habitats with studies demonstrating selection for annually-disked fallow fields and others showing avoidance of fields and selection for burned pine savannas. Field establishment (up to 30% of a property) is a published management recommendation for bobwhites in pine savannas but there are significant annual costs with fallow-field management; information on factors that influence habitat selection by broods can improve management recommendations and facilitate weighing costs/benefits. We examined 2nd and 3rd order habitat selection by 466 broods on 3 sites during 1999–2009. All sites had similar macro-habitats (e.g., pine savanna, fallow fields, hardwood drains) but differed in soil characteristics and species composition of ground vegetation. Annually-disked fields were preferred by broods in most years on sites with predominantly grass and hardwood scrub ground vegetation. Rainfall mediated use of hardwood drains and burned upland pine savannas; hardwood drains were used more during droughts whereas burned pine savannas were used more with increased rainfall. Burned upland pine savanna was preferred on higher fertility sites in 9 of 10 years at the 3rd order level, fields were avoided or used according to availability in 8 of 10 years, and drains were avoided. Managers should consider how soil, weather, and vegetation community in pine savannas influences habitat use by bobwhite broods when identifying the value of different macro-habitats. Field establishment may or may not provide brood habitat depending on site
Survival and Reproduction of Parent-Reared Northern Bobwhites
Captive-reared and released game birds typically have low reproductive success in the wild which limits their use for restoration of game bird populations. A fundamental problem with captive-rearing techniques is the absence of a mechanism for imprinting. We developed a parent-rearing technique that facilitates pre- and post-hatch imprinting using parent-reared wild strain northern bobwhite (Colinus virginianus) chicks in outdoor pens. Parent-reared chicks were marked with patagial wing tags and recaptured during October and the following March. We radiomarked juveniles captured in March to monitor survival and reproductive success in two separate studies, one in Georgia, and one in South Carolina, USA. Band-recapture survival estimates of parent-reared chicks from release to the following breeding season in Georgia (2005–2007) averaged 0.12 (range 1⁄4 0.06 to 0.25) and was dependent on release period. Radio- marked, parent-reared bobwhites had lower survival than wild bobwhites and produced 0.3 nests per hen for the breeding season versus 1.0 nests per hen for radio-marked wild resident bobwhites. Nesting success and subsequent chick survival did not differ among groups, but sample sizes were small. Radio-marked, parent-reared hens (n 1⁄4 26) in the South Carolina study (2008–2010) produced 0.67 nests per hen for the breeding season versus 0.62 nests per hen for radio-marked wild resident hens. Nesting success and brood-rearing success of parent-reared hens did not differ from that of wild resident hens and breeding season survival was also similar. Survival and reproduction of parent-reared wild strain bobwhites were greater than previously reported for pen-reared bobwhites and may useful for restoring or enhancing bobwhites populations at the local scale
'Interfaces' 4
Issue No. 4 is the first open issue of Interfaces: A Journal of Medieval European Literatures. It contains contributions by Henry Bainton (12th-century historiography), Lucie Doležalová (parabiblical texts and the canon), Máire Ní Mhaonaigh (Irish literary culture in Latin and Irish), Isabel Varillas Sánchez (legends of composition of canonical texts, Septuaginta), Wim Verbaal (letter collections, Bernard of Clairvaux), and Jonas Wellendorf (canons of skaldic poets in the 12th/13th century), preceded by a brief Introduction by the editors
Nuclear Vav3 is required for polycomb repression complex-1 activity in B-cell lymphoblastic leukemogenesis
Acute B-cell lymphoblastic leukemia (B-ALL) results from oligo-clonal evolution of B-cell progenitors endowed with initiating and propagating leukemia properties. The activation of both the Rac guanine nucleotide exchange factor (Rac GEF) Vav3 and Rac GTPases is required for leukemogenesis mediated by the oncogenic fusion protein BCR-ABL. Vav3 expression becomes predominantly nuclear upon expression of BCR-ABL signature. In the nucleus, Vav3 interacts with BCR-ABL, Rac, and the polycomb repression complex (PRC) proteins Bmi1, Ring1b and Ezh2. The GEF activity of Vav3 is required for the proliferation, Bmi1-dependent B-cell progenitor self-renewal, nuclear Rac activation, protein interaction with Bmi1, mono-ubiquitination of H2A(K119) (H2AK119Ub) and repression of PRC-1 (PRC1) downstream target loci, of leukemic B-cell progenitors. Vav3 deficiency results in de-repression of negative regulators of cell proliferation and repression of oncogenic transcriptional factors. Mechanistically, we show that Vav3 prevents the Phlpp2-sensitive and Akt (S473)-dependent phosphorylation of Bmi1 on the regulatory residue S314 that, in turn, promotes the transcriptional factor reprogramming of leukemic B-cell progenitors. These results highlight the importance of non-canonical nuclear Rho GTPase signaling in leukemogenesis.This project was funded by the National Institutes of Health Grants R01-CA273016 (N.N.N. and J.A.C.) and U54-DK126108 (J.A.C.), the Leukemia & Lymphoma Society of North America (J.A.C and N.N.N.; and N.N.N. and J.A.C.), and William Lawrence & Blanche Hughes Foundation (J.A.C. and N.N.)
Genotype x trial interaction and stability across sites in 11 combined provenance and clone experiments with Picea abies in Denmark and Sweden
- …