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R.L. Lochmiller

Publications and source records attributed to R.L. Lochmiller.

9 recordsLinked to original sources
USGS2005

Impact of food supplementation and methionine on high densities of cotton rats: Support of the amino-acid-quality hypothesis?

Considerable research supports the tenet that quantity and quality of food limit vertebrate populations. We evaluated predictions that increased availabilities of food and the essential amino acid methionine were related to population limitation of the hispid cotton rat (Sigmodon hispidus). Effects of supplemental food and methionine on density, survival, and reproductive parameters of wild cotton rats were assessed in north-central Oklahoma in 1998-1999. Twelve enclosed groups of 16 adult cotton rats each (8 male, 8 female) were randomly assigned to either no supplementation (control), supplementation with a mixed ration that had methionine at slightly below maintenance levels (0.20%), or a methionine-enhanced mixed ration (1.20%). In general, densities of cotton rats were twice as high and were sustained longer with dietary supplementation, and methionine-supplemented populations maintained the highest densities. Treatment effects on survival depended on time of year, with higher survival in supplemented enclosures in October and November. Per capita recruitment was highest with methionine-enhanced food. Treatment effects on proportions of overall and female cotton rats in reproductive condition depended on sampling date, but males were most reproductively active with methionine supplementation. Methionine supplementation resulted in an earlier and longer reproductive season. Density-dependent and density-independent factors no doubt interplay to determine population dynamics of cotton rats, but our results suggest that methionine plays a role in the population dynamics of wild cotton rats, apparently by enhancing overall density, recruitment, and reproductive activity of males.

Journal of Mammalogy↗
USGS2003

Immune function and hematology of male cotton rats ( Sigmodon hispidus ) in response to food supplementation and methionine

We examined effects of supplementation of food quantity and quality (=enhanced methionine) on hematologic and immunologic parameters of wild, but enclosed, adult male cotton rats ( Sigmodon hispidus ) in north-central Oklahoma. Sheet metal enclosures were stocked with a high density of wild-caught cotton rats (160 animals/ha) and randomly assigned a treatment of no supplementation, mixed-ration supplementation or methionine-enhanced supplementation. Aside from small increases in counts of red blood cells and hematocrit levels, most indices of erythrocytic characteristics were not affected by supplementation with the mixed-ration or enhanced methionine. In contrast, platelet counts were highest in mixed-ration and methionine treatments and counts of total white blood cells were highest with methionine supplementation, albeit relative proportions of different leukocytes did not differ among treatments. Immunologically, neither delayed-type hypersensitivity response nor hemolytic-complement activity differed among treatments. Supplementation of food quantity and quality did not broadly affect hematologic parameters and immune function of male cotton rats, but enhanced platelet and leukocyte counts may confer advantages to overall health. Clarification of the role of such effects on population limitation or regulation requires additional research.

Comparative Biochemistry and Physiology, Part A: M↗
USGS2000

Risk factors associated with capture-related death in eastern wild turkey hens

Capture-related mortality has been a notable risk in the handling of eastern wild turkey ( Meleagris gallopavo silvestris ). Our objective was to evaluate how environmental factors influence risk and identify physiological correlates that could be used to identify susceptible birds. During winter (January–March) 1995–97, 130 eastern wild turkey hens were captured in southeastern Oklahoma and radiocollared. Of those, 20 hens died ≤14 days of capture. Serum creatine kinase activity (CK; P < 0.01), body temperature ( P < 0.01), processing time ( P = 0.02), and ambient temperature ( P < 0.01) showed a positive relationship with mortality that occurred within 14 days of capture. Plasma corticosterone concentration ( P = 0.08) and relative humidity ( P < 0.01) showed a negative relationship with mortalities that occurred within 14 days post-capture. Stepwise logistic regression selected CK activity, relative humidity, and ambient temperature as the best predictors of mortality within 14 days post-capture. Our data suggest that susceptible individuals may be identified from CK activity and that capture-related mortality may be minimized by establishing guidelines of when to curtail capture operations based on various weather conditions.

Oklahhoma↗
USGS2000

Using supplemental food and its influence on survival of northern bobwhite (Colinus virginianus)

Biologists have debated the effectiveness of supplemental feeders as a management tool for the northern bobwhite (Colinus virginianus), but few extensive evaluations have been conducted. We examined 783 crops from harvested bobwhites during 1992-1996 to determine effects of climatic stress in winter on use of supplemental feeders and their impact on survival rate in winter. Crops of bobwhites harvested from areas with supplemental feeders contained 28.2% supplemental food compared with 5.5% (P<0.001) for those from areas without supplemental feeders. Winter climate was not a significant predictor of the proportional use of supplemental feeders. Rates of winter survival were greater on areas with supplemental feeders compared with non-supplemented areas in winters 1992-1993 (P=0.001) and 1993-1994 (P=0.002), but in 1994-1995, rates were greater on nonsupplemented areas (P=0.032). Cause-specific mortality rates indicated that supplemental feeders did not predispose bobwhites to hunter harvest or predators. Results suggested that bobwhites can gain nutritional benefits from supplemental feeders during times of severe winter stress.

Wildlife Society Bulletin↗
USGS1998

Diets of hartebeest and roan antelope in Burkina Faso: Support of the long-faced hypothesis

Diets of hartebeest ( Alcelaphus buselaphus ) and roan antelope ( Hippotragus equinus ) were assessed at the Nazinga Game Ranch in southern Burkina Faso, West Africa. Microhistological analysis of feces indicated that dietary overlap was high during the rainy ( X̄ = 73.7%) and cool-dry (68.2%) seasons, low during the hot-dry season (48.2%), and lowest during the last month of the hot-dry season (31.5%). As the hot-dry season progressed and food presumably became less available, diets of the two antelopes diverged. Hartebeest maintained a high percentage of grass in their diet, but roan antelope switched from being predominantly grazers (>95% grass) to mixed feeders (<50% grass). As grass feeders, both antelopes have skeletal features that facilitate acquisition and grinding of highly fibrous diets, but 11 of 12 mass-relative indices of the skull morphology of hartebeest exceeded those of roan antelope. Because of those differences in skull morphology, and in keeping with the “long-faced” hypothesis, hartebeest were apparently more capable than roan antelope of acquiring and masticating scarce regrowth of perennial grasses when availability of forage was lowest. Such divergence within a single foraging class of African bovids, such as grass feeders, should reduce competition and perpetuate coexistence.

Journal of Mammalogy↗
USGS1998

Sensitivity of condition indices to changing density in a white-tailed deer population

The ways in which comprehensive condition profiles, incorporating morphometric, histologic, physiologic, and diet quality indices, responded to changes in density of a white-tailed deer ( Odocoileus virginianus ) population were examined. Changes in these condition indices were monitored in a northeastern Oklahoma deer herd as density declined from peaks of 80 and 72 deer/km 2 in 1989 and 1990 (high-density) to lows of 39 and 41 deer/km 2 in 1991 and 1992 (reduced-density), respectively. Compared to a reference population (6 deer/km 2 ), deer sampled during high-density exhibited classic signs of nutritional stress such as low body and visceral organ masses (except elevated adrenal gland mass), low fecal nitrogen levels, reduced concentrations of serum albumin, elevated serum creatinine concentrations, and a high prevalence of parasitic infections. Although density declined by one half over the 4-yr study, gross indices of condition (in particular body mass and size) remained largely unchanged. However, selected organ masses, serum albumin and non-protein nitrogen constituents, and fecal nitrogen indices reflected improvements in nutritional status with reductions in density. Many commonly used indices of deer condition (fat reserves, hematocrit, total serum protein, and blood urea nitrogen) were not responsive to fluctuations in density.

Journal of Wildlife Diseases↗
USGS1994

Essential amino acids in northern bobwhite foods

Frequent population declines, high dietary requirements for protein, and the low quality of proteins in agricultural grains led us to hypothesize that essential amino acid (EAA) deficiencies were common in northern bobwhite (Colinus virginianus) foods. We analyzed amino acid concentrations of 21 northern bobwhite foods and compared them with dietary requirements to derive values that reflected the foods' ability to meet daily bobwhite requirements of 10 EEAs. Despite adequate concentrations of crude protein, deficiencies of EAAs were detected in seeds of all species analyzed. Legumes offered the best mix of EAA, and grasses the poorest. Deficiencies of EEAs relative to maintenance requirements of adults ranged from 13% in legumes to 98% in grasses. About a third of the total nitrogen pool was composed of nonprotein nitrogen with values ranging from 25% for queensdelight stillingia (Stillingia sylvatica) to 44% for redroot amaranth (Amaranthus retroflexus). Computed biological values (ratio of EEA concentrations in seed protein to respective amounts in whole egg protein) ranged from 69 (netleaf hackberry [Celtis reticulata]) to 93 (erect dayflower [Commelina erecta] and woolly croton [Croton capitatus]). Amino acid profiles indicate forage quality better than crude protein estimates.

Journal of Wildlife Management↗