Effects of Northern Bobwhite Habitat Management Practices on Red Imported Fire Ants

Management practices that create early successional plant communities through disturbance (discing and prescribed fire) often are prescribed for restoration of declining northern bobwhite (Colinus virginianus) populations. Because disturbance may facilitate invasion of exotic flora and fauna such as red imported fire ants (RIFA, Solenopsis invicta), we hypothesized that habitat management practices commonly used to enhance bobwhite habitat might have the unintended consequence of increasing local abundance of RIFA. During 1999, we tested effects of 4 treatments (spring discing, spring prescribed burning, spring mowing, and no management), in a randomized complete block design (n = 10) on RIFA abundance in Conservation Reserve Program (CRP) fields in central Mississippi. We surveyed RIFA abundance using 3 measures: 1) mound density, 2) a population index based on worker ant and brood estimates, and 3) foraging activity as indexed by attraction to protein bait cups. During May 1999, mound density (P = 0.0136) and population index (P 0.0078) differed among treatments, with abundance values greatest in plots treated with fire, and lowest in disced plots. The index of foraging activity did not differ among treatments (P = 0.6637). During October 1999, mound density (P = 0.0334) and population index (P = 0.0451) differed among treatments with abundance values greatest in plots receiving fire and disc treatments, and lowest abundance in control plots. The index of foraging activity did not differ among treatments (P = 0.9079). Disturbance tools such as prescribed fire and discing are essential to maintain plant communities to which bobwhite are adapted; however, they may have the unintended consequence of facilitating invasion of RIFA and increasing local RIFA populations

Impacts of human hunting on spatial behavior of white-tailed deer (Odocoileus virginianus)

This study was funded by The Samuel Roberts Noble Foundation, Inc., and the Department of Wildlife, Fisheries and Aquaculture at Mississippi State University.Predators can influence populations through top-down effects, but most large predators have been extirpated from the white-tailed deer’s (Odocoileus virginianus) range. Hunters have filled this predatory role, but also can indirectly influence prey species. Indirect behavioral responses can include altered resource selection, space use, or movement patterns. Herein, we developed a controlled study that contained both temporal and spatial risk levels to assess how deer behavior changes in space relative to temporal periods of risk. Total distance travelled (m) and micro-range area (m²) were calculated over two-day periods to determine the general effects of hunting season on deer spatial behavior. Generally, distance travelled, micro-range area, and exploratory behavior decreased during the course of the study, with the greatest decrease occurring during the active 16-day hunting period. Despite potential risk and disturbance from hunters, deer maintained site fidelity to previously established ranges and did not expand micro-range areas. These data indicate that deer recognize threats from humans on the landscape and adapt behavioral strategies by minimizing movement and exhibiting high residency times in well-established ranges, factors known to influence harvest susceptibility. This information can be used to assess potential impacts from hunting for management purposes, but also to test the adaptive ability of animals to risk.Publisher PDFPeer reviewe

The Non-Indigenous Ant, Solenopsis invicta, Reduces Loggerhead Shrike and Native Insect Abundance

The red imported fire ant (Solenopsis invicta Buren) is an aggressive, non-indigenous species that is a threat to native biota in the southeastern United States. We determined the effect of S. invicta on loggerhead shrike (Lanius ludovicianus L.) abundance and investigated a possible mechanism of impact, which is a reduction in insect prey availability. We used a fire ant bait (hydramethylnon) to reduce fire ant populations on one randomly chosen member of each of five pairs of 202-ha study areas in the Texas coastal Bend region, and also measured shrike relative abundance and a volumetric index of insect biomass on the study areas. Loggerhead shrike relative abundance was assessed at five counting stations established along 3.2-km transects through prairie habitat on each study area during the fall of 1992 and 1993. We sampled non-S. invicta invertebrates with 13.3-L capacity UV light traps and found that insect volume, species richness, and diversity were greater on treated sites. More shrikes were observed on areas where S. invicta populations had been reduced. Both insect biomass and shrike abundance were negatively correlated to the level of S. invicta infestation. Our data suggest that shrikes may avoid areas on wintering habitats that have been invaded by S. invicta and that this avoidance may result from reduced insect availability

Does Human Predation Risk Affect Harvest Susceptibility of White-Tailed Deer During Hunting Season?

Large carnivores are considered a primary source of mortality for many ungulate populations, but harvest by hunters is the primary means of population management. However, research is needed to evaluate how human predation risk influences observability (a surrogate to harvest susceptibility) of ungulates. We determined how hunting intensity and duration influence observation rates of white-tailed deer (Odocoileus virginianus) and how deer behavior (i.e., movement rate and resource selection) affects observation rates. We sampled 37 adult (≥2 yr) male deer at 2 levels of risk (i.e., low-risk = 1 hunter/101 ha; and high-risk = 1 hunter/30 ha) during 3 exposure periods (i.e., first, second, and third weekend of hunting) on a 1,861-ha property in Oklahoma, USA, during the 2008 and 2009 rifle deer-seasons. Observation rates (collared deer/hunter-hr/day) were greatest during the first weekend in both the low- and high-risk treatments, but declined each weekend thereafter in both treatments. Immediately prior to hunter observation, movement rate of observed collared deer was greater than that of unobserved collared deer, but only when hunting risk was high. Greater movement rates of deer in the high-risk treatment also led to a greater probability of observation. Hunters also had a greater probability of observing collared deer at higher elevations. Overall, deer modified their behavior to avoid detection by hunters. These results can be used to explain decreased observation rates to hunters and to modify harvest rates by altering timing and intensity of human predation risk during the recreational hunting season to help achieve population management goals through harvest

Short-Term Fire Effects on Small Mammal Populations and Vegetation of the Northern Chihuahuan Desert

Fire is an important ecological factor in semidesert grass-shrub community dynamics, but there is a lack of designed field experiments documenting effects on vegetation and small mammals. We document effects of June prescribed fire on vegetation and small mammals on 20, 25-ha study areas in the Northern Chihuahuan Desert of Southern New Mexico, USA one month and one year posttreatment. Canopy cover of shrubs and grasses recovered to 68 and 27% of the preburn canopy cover, respectively, after one year. Prescribed burns during June enhanced short-term forb production by reducing competition from grasses and shrubs. Thirty thousand trap-nights yielded 1744 captures of 766 individuals of 15 small mammal species. Burns did not affect small mammal species richness and species diversity. Relative abundance of Merriam's kangaroo rats (Dipodomys merriami) was 91% greater on burned sites than on control sites one year postburn. Silky pocket mouse (Perognathus flavus) relative abundance was 221% greater on burned sites one year postburn. Chihuahuan Desert pocket mice (Chaetodipus eremicus) responded negatively to the fire, with relative abundance 170% greater on control sites (=.080). Burning produced short-term benefits for two heteromyids, Merriam's kangaroo rats and silky pocket mice

Efficacy of Aluminum Phosphide for Black-Tailed Prairie Dog and Yellow-Faced Pocket Gopher Control

The efficacy of aluminum phosphide was tested on a total of 300 active black-tailed prairie dog (Cynomys ludovicianus) mounds and 68 active yellow-faced pocket gopher (Pappogeomys castanops) tunnels during June-August, 1986 on the southern Great Plains in Lubbock County, Texas. Efficacy of aluminum phosphide was higher than controls (P \u3c 0.001) for both species. Efficacy was higher for black-tailed prairie dogs (94.7 - 96.0%) than for pocket gophers (61.5 - 85.7%). Soil porosity and moisture appeared to influence efficacy for yellow—faced pocket gophers

RED IMPORTED FIRE ANT IMPACT ON WILDLIFE: AN OVERVIEW

We reviewed the past 50 years of literature concerning red imported fire ant impacts on wildlife species. The red imported fire ant has had a negative impact on numerous species of wildlife. However, experimental evidence of population-level impacts is meager. We discuss potential fire ant perturbations and suggest research directions that may settle the long-standing controversy concerning the impact of imported fire ants on native vertebrates and the ecosystems they have invaded

RED IMPORTED FIRE ANT IMPACTS ON NORTHERN BOBWHITE POPULATIONS

The stability of Northern Bobwhite (Colinus virginianus) populations in Texas, where high density polygyne red imported fire ants (Solenopsis invicta) account for \u3e50% of all (S. invicta) colonies, has been cited as a reason to repudiate impacts by this exotic species on Northern Bobwhite. We used two approaches to investigate the relationship between red imported fire ants and Northern Bobwhite. In the first approach, we used correlation analysis to compare Northern Bobwhite abundance trends, determined from Christmas Bird Count data in 15 Texas counties, before and after fire ant infestation. Before red imported fire ant infestation, no significant trend in Bobwhite abundance existed (r = -0.355, P = 0.314). After fire ant infestation, Northern Bobwhite abundance declined and was highly negatively correlated with years of infestation (r = -0.867, P \u3c 0.001). Bobwhite populations from 16 uninfested counties in Texas revealed no trend over a 27-yr (1966-1992) period (r = -0.081, P = 0.688). In the second approach, red imported fire ant populations were reduced on five 202-ha study areas in the Texas Coastal Bend; autumn Northern Bobwhite densities were monitored for 2 yr on those reduced areas and five untreated areas. By the 2nd yr, Bobwhite autumn density was higher (P = 0.028) on areas where red imported fire ants were suppressed. We concluded that polygyne red imported fire ants were negatively impacting Northern Bobwhite in this region of Texas

EFFECTS OF RED IMPORTED FIRE ANTS ON RECRUITMENT OF WHITE-TAILED DEER FAWNS

We investigated the effect of red imported fire ants (RIFA; Solenopsis invicta) on an index of whitetailed deer (Odocoileus virginianus) fawn recruitment (doe:fawn ratio) on 10 200-ha plots in the Texas Coastal Prairie during 1991-93. Five of the plots received treatments of the fire ant bait AMDRO© (Am. Cyanamid Co., Wayne, N.].) during April and October 1991 and May 1992 to reduce RIFA populations. The remaining 5 plots served as untreated comparison areas. Populations of RIFA were reduced (P \u3c 0.10) on treated study areas during deer fawning periods in 1991-92. Fawn recruitment was higher on treated areas during 1991 (P = 0.037) and 1992 (P = 0.069), with recruitment about twice as high on treated areas. In 1993, after 1 year of RIFA reinfestation, fawn recruitment did not differ between treated and untreated plots (P = 0.443). We conclude that high density RIFA infestations reduced white-tailed deer fawn recruitment