Jon C. Boren

Relationship between protein nutritional status and immunocompetence in northern Bobwhite chicks

ABSmAcr.-We investigated the effects of dietary protein quality on the development and functioning of the immune system in four-week-old Northern Bobwhite (Colinus virginianus) chicks. Chicks were fed isocaloric diets containing 8, 15, or 33% protein over a three-week period. Significant reductions in the rate of body growth were evident in chicks receiving 8 and 15% protein. Development of the bursa of Fabricius and spleen was significantly depressed in the 8% protein group compared to the other two treatments. Lymphocyte yields from dissociated lymphoid organs of chicks fed 8% protein were substantially reduced compared to birds fed higher levels of protein. In vitro lymphoproliferative responses of cultured splenocytes to mitogenic stimulation (concanavalin A, pokeweed mitogen, and Salmonella typhimurium), white-blood-cell counts, and in vivo measures of humoral immunity did not differ among dietary treatments. Cell-mediated immune function, as measured by an in vivo hypersensitivity response to an intradermal injection of a T lymphocyte-dependent mitogen (phytohemagglutinin), was significantly suppressed in the 8% protein group compared to the other two treatments. Several measures of immune-system development and function were significantly correlated with body mass change during the trial. Results indicated that four-week-old Northern Bobwhite chicks fed an 8% protein diet for three weeks may have difficulty expressing a competent immune response to pathogenic challenge in the wild. Received 30 January 1992, accepted 25 November 1992.

Land use change effects on breeding bird community composition.

We identified land uses, vegetation cover types, and landscape patterns associated with avian community diversity in 2 rural landscapes in a hardwood forest-tallgrass prairie ecotone that differ with regard to human population density. We obtained long-term (24 years) changes in avian community composition through records from the North American Breeding Bird Survey. We obtained historical and present land use, vegetation cover types, and landscape structure of both landscapes from high-resolution aerial photography. Avian community composition in the low density rural population landscape was primarily related to the amount of land in deciduous forest and land treated with fire or herbicides. In contrast, avian community composition in the high density rural population landscape was primarily related to the amount of land in deciduous forest, native grassland, and roads. Changes in vegetation cover type were related to changes in the avian community composition by increasing prairie habitat associated species in the low density rural population and generalist habitat associated species in the high density rural population landscapes. Loss of neotropical migrants and increased number of generalist species in the high density rural population landscape was related to decreased native vegetation, road development, and increased landscape fragmentation. Biologists and conservationists in this region should focus attention on preserving biological diversity of rural ecosystems by maintaining native plant communities.

Vegetation cover type and avian species changes on landscapes within a wildland-urban interface

Abstract Probability of occurrence of selected avian species was modeled as a function of modeled changes in landscape cover types in two landscapes to test whether (1) exotic and generalist avian species will continue to increase in an high density rural population landscape; and, (2) native grassland avian species will continue to increase in a low density rural population landscape. Landscape cover types were modeled with logistic regression based on temporal changes between 1966 and 1990. Demographic-economic regression models also were used to predict landscape cover types in year 2014 based on selected independent variables. Logistic regressions were used to model probability of occurrence of selected avian species based on predicted area of landscape cover types in year 2014. Model output of vegetation cover types suggests the continued use of intensive agriculture management practices in the high density rural population landscape while extensive agriculture management practices will maintain the native vegetation component in the low density rural population landscape. Our models suggest continued intensive agriculture practices associated with the high density rural population landscapes will adversely affect native grassland bird species to a greater magnitude than extensive ranching practices in the low density rural population landscapes.

Landscape structure and change in a hardwood forest-tall-grass prairie ecotone.

Temporal changes in land use, vegetation cover types, and landscape structure were examined in a hardwood forest-tallgrass prairie ecotone in northern Oklahoma using a Geographic Information System. Our objective was to examine relationships between human activity, changes in land use and vegetation cover type, and landscape structure in rural landscapes between 1966 and 1990. Cover types in most of the high density rural population landscape in this study require more intensive inputs and management, which resulted in a landscape with lower diversity, higher homogeneity, and greater patch fragmentation compared to the low density rural population landscape. Both native grasslands and forests were less fragmented in the low density rural population landscape whereas forests were increasingly fragmented in the high density rural population landscape. Native grasslands were less fragmented than forests for all years in both the low density rural population and high density rural population landscapes. Our study suggests conservationists should focus their concerns on fragmentation and losses in biological diversity that accompany increased human activity in densely populated rural landscapes that surround urban centers. Extensively managed landscapes dominated by native vegetation that are under less pressure from expanding human influence are in less peril.

Amino acid concentrations in seed of preferred forages of bobwhites.

Nutritional factors have been hypothesized to regulate gallinaceous bird populations such as the Northern Bobwhite (Colinus virginianus). Although protein is considered one of the most important and limiting nutrient categories in wild animal populations, we lack a complete understanding of the availability of essential amino acids in foodstuff protein. Seed grains comprise a major component of the annual diet of bobwhites throughout its geographic range. We investigated the concentration of 17 amino acids in seed of 4 highly preferred forages of bobwhites from central Oklahoma. The total nitrogen content of seed was composed of 28-43% nonamino nitrogen of limited nutritional value. We provide evidence that crude protein may grossly overestimate true protein. Amino acid content of forages in lieu of crude protein may better describe the nutritional ecology of quail and other gallinaceous birds and provide new insights into the role of nutrition in regulating animal populations.

Limitations of Amino Acids in Diets of Northern Bobwhites (Colinus virginianus)

Northern bobwhite (Colinus virginianus) populations fluctuate widely in den- sity, which may be due to changing nutritional conditions. High requirements for protein in the diet of bobwhites for reproduction and growth and the low quality of protein in many cereal grains led us to hypothesize that dietary limitations in certain essential amino acids may occur in wild bobwhite populations in western Oklahoma. We explored this hypothesis by examining seasonal changes in the amino acid composition of bobwhite diets and com- paring observed levels in their diets to known requirements of a closely related species, Japanese quail (Coturnix coturnix japonica). Bobwhites were harvested seasonally (summer, autumn, winter 1989-1990) on three ranches from supplementally fed ( 900 m from supplemental food). Bobwhites used supplemental food for >15% of their diet in only 1 of 6 seasons. Supplemental food did not appreciably influence body condition indices (body mass, organ masses, carcass com- position), but did influence the diets of bobwhites, as evidenced by significant differences in concentrations of fat and essential amino acids in crop digesta. Although crude protein requirements apparently were met in all seasons, levels of ?one essential amino acid in diets of reference and supplemented bobwhites were below recommended levels for growth or breeding in Japanese quail. The sulfur-containing amino acids, methionine + cystine, were consistently the most limiting nutrients in the diet, with seasonal means ranging from 0- 53% below recommended levels for growth or breeding in Japanese quail. These observa- tions support our hypothesis that selected essential amino acids may be seasonally limiting in diets of bobwhites. Dietary requirements of bobwhite for suspected limiting amino acids should be determined in feeding trials to identify more accurately the magnitude of these apparent deficiencies.

Long-term effects of woody vegetation management on seasonal body condition of northern bobwhites.

We investigated effects of season and brush management on body condition of northern bobwhites (Colinus virginianus) in the Cross Timbers ecosystem of central Oklahoma. Quail were collected seasonally and body condition assessed by necropsy and analysis of percent fat, protein, and ash in the carcass. Brush management by herbicide, herbicide + fire, and mechanical removal had minimal long-term effects on body condition. However, we found significant seasonal differences in weights of the gizzard, gizzard fat, liver, and lipid reserves (body and gizzard fat). With respect to condition, we concluded that northern bobwhites derived no long-term benefits from brush management programs in the Cross Timbers ecosystem of central Oklahoma.

Profiles of Serum Amino Acids to Assess Condition of Cotton Rats (Sigmodon hispidus)

We investigated the use of concentrations of blood-serum amino acids to assess status of dietary proteins of juvenile cotton rats ( Sigmodon hispidus ). Eighteen juvenile animals were randomly assigned to isocaloric diets containing 4 or 16% crude protein, and serum concentrations of amino acids were determined by high-pressure liquid chromatography on days 30 and 45 of a 45-day feeding trial. Concentrations of methionine, threonine, tryptophan, valine, hydroxyproline, and branch-chain amino acids (BCAA) were depressed, whereas histidine and proline were elevated among low-protein-fed cotton rats. The glycine/(leucine + valine) and phenylalanine/tyrosine ratios were greater in serum of cotton rats fed low-protein diet, whereas the tyrosine/neutral amino acids (NAA) and tryptophan/NAA ratios were depressed. Concentration of several free amino acids in serum of juvenile cotton rats differed between 30- and 45-day samples. Because diet × sample interactions were significant for only tryptophan and hydroxyproline, temporal changes probably were a reflection of age-related alterations in developmental physiology and not effects of diet. Our results indicate that clinical profiles of selected amino acids in serum can provide a useful technique for assessing protein nutritional status and quality of diet in small mammals.