Search

We examined how harvest affected natural mortality rates and how the dynamics of northern bobwhite (Colinus virginianus, hereafter bobwhite) covey membership might affect the additive nature of harvest. We conducted repeated searches for coveys and radiomarked all coveys found on 12 259-ha study areas in east-central Kansas, USA. We simulated a harvest in 6 randomly selected areas each year during November-January, 1997-2000, by trapping and removing 60% of bobwhites in each covey. We used flush counts and radiotelemetry to measure harvest effects on natural mortality rates, overall winter survival, covey size, and densities. Observed natural mortality rates of radiomarked individuals were similar between harvested (50.6 ± 4.3%) and unharvested areas (52.1 ± 4.7%). Estimated winter survival was 47.9% on the unharvested areas and 20.9% on the harvested areas. Harvest did not affect the number of coveys, average covey size, or density of bobwhites, indicating that coveys coalesced through local movement. Our results indicate that harvest is additive to natural mortality and suggest that local movement to maintain optimal group sizes can mask the true effect of harvest on observed densities in small areas. [ABSTRACT FROM AUTHOR]

Little is known about how density-independent and density-dependent processes affecting population dynamics vary geographically across species' ranges. To address this problem for three vertebrate species (Northern Bobwhite [Colinus virginianus], Ring-necked Pheasants (Phasianus coichicus], and eastern cottontails [Sylvilagus floridanus]), we examined spatially subdivided, long-term (1966-2001), seasonal (January, April, July, and October), time-series data from the Kansas Rural Mail Carrier Survey, USA. All three species have range boundaries in Kansas, with population abundances declining toward the periphery of their ranges. We quantified the strengths of density-dependent and density-independent processes affecting the dynamics of 10 populations of each species ranging from low (peripheral) to high (central) mean abundance using first-order autoregressive models that incorporate measurement error. For all three species, peripheral populations with lower mean abundance tended to have greater population variability. This pattern could potentially be explained by peripheral regions experiencing either weaker density dependence or greater environmentally driven density-independent fluctuations in per capita population growth rates. In general, density dependence did not vary among geographic regions, although there was a trend for smaller, peripheral populations to exhibit stronger density dependence. Density-independent variability in per capita population growth rates was higher in peripheral populations. Furthermore, density-independent fluctuations in per capita population growth rates were weakly correlated with temperature and precipitation and were highest for the period October through January, identifying fall as the period of greatest environmentally driven variability in population dynamics. Per capita population growth rates fluctuated in moderate synchrony among regions, especially for more abundant, nonperipheral populations in close geographical proximity. The strong density-dependent and stronger density-independent processes in smaller, peripheral populations suggest that the greater variability in peripheral populations' densities is caused by greater population sensitivity to environmental fluctuations. This may make peripheral populations more likely to go extinct and leads to the prediction that, if these species decline to the point of becoming endangered, this decline will be accompanied by a contraction in their geographical ranges. [ABSTRACT FROM AUTHOR]

ABSTRACT Oak ( Quercus spp.) woodlands and savannas throughout the Mid-South, USA have become closed-canopy forests through succession in the absence of fire, contributing to declines in disturbance-dependent avian species. Restoration could ameliorate these trends, but effects of such management practices on avian communities of the Mid-South are poorly understood. We implemented an experiment on the Cumberland Plateau, Tennessee with treatments involving fall (Oct) or spring (Mar) fire with woodland (14 m2/ha) or savanna (7 m2/ha) residual basal area and unmanaged control stands (20 ha each). We conducted fixed-radius point counts 3 times annually (2010-2012) and analyzed trends in naïve occupancy for 41 species. For 20 species with adequate data (10 early-, 10 late-successional), we performed multiple-season, robust-design occupancy modeling and accounted for detection bias. We then used mixed-model polynomial regression to define relationships between occupancy and measures of live and dead basal area, midstory density, and herbaceous groundcover. Restoration substantially altered forest structural characteristics but did not affect the occupancy of most late-successional species. In contrast, the presence of early-successional species increased as live basal area decreased and herbaceous groundcover increased. Only 3 of 41 species (hooded warbler [ Setophaga citrina], ovenbird [ Seiurus aurocapilla], and worm-eating warbler [ Helmitheros vermivorum]) exhibited reduced occupancy as woodland and savanna conditions were approached. The presence of all other species, including 13 regionally and 2 continentally declining, remained constant or increased as restoration progressed. Woodland conditions of 10 m2/ha live basal area and 20% herbaceous groundcover maximized occupancy of early-successional species with little consequences for late-successional species. Proceeding further toward savanna conditions negatively affected species associated with lower strata of mature-forests but further increased the presence of some early-successional species. Midstory density and dead basal area were poor predictors of occupancy and thus may be necessary but not sufficient in promoting early-successional species. Our results suggest implementing oak woodland and savanna management in the Mid-South could benefit disturbance-dependent birds of high conservation priority with minimal negative impacts on the presence of late-successional species. © 2016 The Wildlife Society. [ABSTRACT FROM AUTHOR]

ABSTRACT Grassland birds have declined more than any other guild in the United States because of loss and degradation of native grasslands. The United States Department of Agriculture Farm Bill programs have restored some native warm-season grasses (NWSG), but populations of many grassland bird species continue to decline. Market-based NWSG uses focused on hay, pasture, and biofuel feedstock may be more appealing to landowners, and may still provide grassland bird habitat on the landscape. We examined breeding grassland bird occupancy of 102 NWSG production fields including 5 treatments (control [ n = 37], grazing [ n = 7], hay [ n = 22], seed [ n = 21], and biofuel [ n = 15] production) in Kentucky and Tennessee during 2009-2010 breeding seasons. We used a robust design model in Program MARK to determine occupancy and detection rates for grassland birds. We modeled occupancy differences among treatments and sites (i.e., KY, TN), and included covariates (i.e., field-level vegetation metrics and landscape composition at 3 scales [250 m, 500 m, and 1 km]) for eastern meadowlark ( Sturnella magna), field sparrow ( Spizella pusilla), grasshopper sparrow ( Ammodramus savannarum), northern bobwhite ( Colinus virginianus), and red-winged blackbird ( Agelaius phoeniceus). Covariates that influenced occupancy included treatment (field sparrow, 2009 only), site (eastern meadowlark, grasshopper sparrow, and northern bobwhite), percent NWSG cover (positive, red-winged blackbird), and percent forest cover within 250 m (negative for eastern meadowlark, grasshopper sparrow, northern bobwhite, and red-winged blackbird) or within 1 km (negative, field sparrow). Our results suggest that forest cover in the surrounding landscape negatively influences species occupancy, and species occupancy generally did not differ among NWSG production treatments. These treatments could be an alternative means to provide grassland bird habitat within an agriculture production landscape. © 2016 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Declines in native warm season grasslands have been linked to grassland bird population decline due to habitat loss including conversion to non-native grasses. Rotational grazing (ROT) and patch-burn grazing (PBG) are two possible tools to restore native warm-season grasses (NWSG) on working-lands in the Mid-South USA and thus aid in the recovery of grassland bird populations. This project compares ROT, PBG, and before treatment implementation to assess their effects on grassland-associated bird species. At three research sites between KY and TN, 14–10 ha NWSG pastures were established and randomly assigned 7 pastures each to ROT and PBG treatment and monitored avian relative abundance during the breeding season from 2014 to 2017. Avian call count data and vegetation characteristics were collected in 2014 and treated as a before treatment year. Following 2014, ROT and PBG treatments were implemented across each respective research site. We used the open N-mixture model framework to estimate avian relative abundance related to year, treatments, research site, and landscape and within-field variables. Avian species richness and diversity were calculated for each treatment, research site, and year. Landscape variables, within-field variables, and research sites exerted more influence on relative abundance than ROT or PBG. Grassland-associated bird species relative abundance and species richness/diversity were affected by habitat disturbances (both ROT and PBG) but varied by species and site. Field sparrows [ Spizella pusilla ] had the highest increase in relative abundance (9.68 ± 1.24 birds/point count location or 1.77 ha) while northern cardinals [ Cardinalis cardinalis ] exhibited a significant decrease in relative abundance (3.44 ± 1.54 birds/point count location) following treatment implementation on specific research sites. Species diversity and richness did not differ between ROT and PBG treatments. However, a site and year difference were observed for both estimates. Using ROT and/or PBG to create habitat disturbances can alter within-field variables (i.e., vegetation height) which, taken into context with landscape variables, could impact grassland bird populations and diversity depending on grassland bird species habitat requirements. Our research provided the baseline information for ROT and PBG impacts on grassland birds in the east/southeastern USA. However, we believe future research should focus on breeding and annual fecundity to better understand how populations will change over time and how working lands conservation might aid this conservation effort without a reduction in livestock productivity. • Grassland bird populations decline has been linked to habitat loss. • Utilizing private working-lands management could increase potential avian habitat. • Rotational grazing and patch-burn grazing create vegetation structural diversity. • Increased vegetation structural diversity can benefit avian relative abundance. • Habitat disturbance/landscape can impact grassland bird richness and diversity. [ABSTRACT FROM AUTHOR]

Lesser prairie-chicken (Tympanuchus pallidicinctus) populations have declined rangewide, and one of the principal causes is thought to be low nest success. Little is known about the relationship of vegetation structure and human intrusion to lesser prairie-chicken nest location and success. We conducted our study from 1997 to 2002 in southwestern Kansas, USA, on 2 sand-sagebrush (Artemisia filifolia) prairie areas managed for livestock production. We determined apparent nest success (26%) for 200 of 209 lesser prairie-chicken nests located. Nest sites had taller grass, greater sand-sagebrush density, and higher visual obstruction than random locations in the surrounding prairie. We recorded the distances from nests to 6 anthropogenic features (wellheads, buildings, improved roads, unimproved roads, transmission lines, center-pivot irrigation fields) to determine whether the features were related to nest location and success. Sand-sagebrush habitat around S of 6 features (all except unimproved roads) was avoided for 80 m (wellheads) to >1,000 m (buildings) by nesting lesser prairie-chickens, but distances to the features were not substantial predictors of apparent nest success. Grass height, sagebrush plant density, and sagebrush height were the most important vegetation characteristics influencing nest success. [ABSTRACT FROM AUTHOR]

We derived consequences (realizations of hunter efficiency, relative harvest rates) of fixed, liberal quail (northern bobwhite [Colinus virginianus], Gambel's quail [Callipepla gambelii], and scaled quail [C. squamata]) harvest regulations applied at large scales from time series on quail abundance, total harvest, and hunter participation. Data came from Kansas (1966-2001), Missouri (1983-2001), Oklahoma (1990-2001), north and south Texas (1986-2001), and Arizona (1982-1999), USA, where harvest regulations were liberal (season length 2.5-4 months, daily bag limit 8-15 birds) during the periods of record. For all study regions, hunter-days were expressible as a linear function of quail abundance, and total harvest was expressible as a linear function of hunter-days. These results implied that hunter efficiency (harvest/hunter-day/index bird) declined monotonically and curvilinearly as quail populations increased. Likewise, relative harvest rate declined monotonically and curvilinearly as abundance increased, which implied that harvest was not self-limiting; however, the rate of decline generally was low because harvest rate was the product of an increasing (hunter-days) and a decreasing function (hunter efficiency) of quail abundance. Under fixed, liberal regulations, variations in quail abundance seem to govern harvest rates at the state or regional level; the regulations per se probably are biologically inconsequential. [ABSTRACT FROM AUTHOR]

Presents information on a study which compared invertebrate biomass in areas used and not used by lesser prairie-chicken adults and broods in southwestern Kansas. Study area; Methodology; Results and discussion.

Understanding how livestock grazing strategies of native warm season grasses (NWSG) can impact facultative grassland bird nesting can provide insight for conservation efforts. We compared pre and post treatment effects of rotational grazing (ROT) and patch-burn grazing (PBG) for facultative grassland bird species nest success and nest-site selection on NWSG pastures at three Mid-South research sites. We established 14, 9.7 ha NWSG pastures and randomly assigned each to either ROT or PBG and monitored avian nest-site selection and nest success, 2014-2016. We collected nesting and vegetation data in 2014, before treatment implementation, as an experimental pre-treatment. We implemented treatments across all research sites in spring 2015. We used a step-wise model selection framework to estimate treatment effect for ROT or PBG on avian nest daily survival rate (DSR) and resource selection function (RSF) at the temporal scale and within-field variables. Daily survival rates were 0.93% (SE = 0.006) for field sparrow ( Spizella pusilla ), 0.96% (SE = 0.008) for red-winged blackbird ( Agelaius phoeniceus ), and 0.92% (SE = 0.01) for indigo bunting ( Passerina cyanea ). Model support for PBG treatment and vegetation height were indicated as negative and positive influences for field sparrow DSR, respectively. Red-winged blackbirds' DSR were negatively influenced by ROT while vegetation height positively affected DSR, and DSR for indigo bunting did not differ among treatments. Combined RSF models indicated nest-site selection for all species was positively related to vegetation height and only weakly associated with other within-field variables. We provide evidence that ROT and/or PBG effects vary by species for DSR for these three facultative grassland birds, and vegetation characteristics affected their nest-site selection in the Mid-South USA. A lack of disturbance in Mid-South grasslands can lead to higher successional stages (i.e., mix shrub-grassland), but some combination of ROT, PBG, and unburned/ungrazed areas can provide adequate nesting habitat on small pasture lands (∼1.8 -7.8 ha) for various facultative grassland birds and potentially offer the opportunity to simultaneously maintain livestock production and grassland bird nesting habitat., Competing Interests: The authors declare there are no competing interests., (©2022 Buckley et al.)

There is increasing concern regarding potential impacts of snake fungal disease (SFD), caused by Ophidiomyces ophiodiicola (Oo), on free-ranging snake populations in the eastern USA. The snake cutaneous microbiome likely serves as the first line of defense against Oo and other pathogens; however, little is known about microbial associations in snakes. The objective of this study was to better define the composition and immune function of the snake cutaneous microbiome. Eight timber rattlesnakes (Crotalus horridus) and four black racers (Coluber constrictor) were captured in Arkansas and Tennessee, with some snakes exhibiting signs of SFD. Oo was detected through real-time qPCR in five snakes. Additional histopathological techniques confirmed a diagnosis of SFD in one racer, the species' first confirmed case of SFD in Tennessee. Fifty-eight bacterial and five fungal strains were isolated from skin swabs and identified with Sanger sequencing. Non-metric multidimensional scaling and PERMANOVA analyses indicated that the culturable microbiome does not differ between snake species. Fifteen bacterial strains isolated from rattlesnakes and a single strain isolated from a racer inhibited growth of Oo in vitro. Results shed light on the culturable cutaneous microbiome of snakes and probiotic members that may play a role in fighting an emergent disease.

Babesiosis is an emerging tick-borne zoonotic disease in the United States caused by Babesia parasites. In 2009, the first case of babesiosis was documented in Tennessee. Environmental investigation at the reported site of tick exposure included collection of ticks and specimens from eastern cottontail rabbits (Sylvilagus floridanus) and white-tailed deer ( Odocoileus virginianus ) that were tested for piroplasms by molecular and serologic methods. One hundred and sixty-six Ixodes scapularis ticks and biological samples from 8 rabbits and 5 deer were collected. Ixodes scapularis were PCR positive for Babesia odocoilei (n = 7, 4%) and Theileria cervi (n = 24, 14%). Deer were seropositive for B. odocoilei and PCR positive for T. cervi. Rabbits were seropositive for B. odocoilei and Babesia sp. MO1, and 1 rabbit was PCR positive for Babesia sp. MO1. In summary, zoonotic Babesia sp. MO1 infection in rabbits is reported here for the first time in Tennessee as well as infection of deer and I. scapularis ticks with 2 other piroplasms of veterinary importance.