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Articles 3331 - 3360 of 3529

Full-Text Articles in Physical Sciences and Mathematics

Inbreeding In Rainbow Trout (Salmo Gairdneri): Analysis Of Lethal Temperature Tolerence, Jospeh L. Mangiardi Jan 1979

Inbreeding In Rainbow Trout (Salmo Gairdneri): Analysis Of Lethal Temperature Tolerence, Jospeh L. Mangiardi

Electronic Theses and Dissertations

Inbreeding in rainbow trout (Salmo gairdneri) was evaluated in relation to an altered environment (upper lethal temperature 29 C), at four levels of inbreeding. At each level of inbreeding mean time to death for inbred, female-outbred half-sib, male-outbred half-sib and outbred families were evaluated. In all cases inbreds were less resistant to lethal temperature than were respective outbred families. Analysis of variance 9Snedecor’s F) and multiple range analysis (Tukey’s “w” procedure) provided inference limitations. Inbred fish were 82% less resistant to lethal temperature as comared to the respective outbred family at 50% inbreeding and 19% less resistant at 25% inbreeding. …

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Expectation Of Genetic Alteration Of Muscle Composition And Growth Traits In Rainbow Trout (Salmo Gairdneri), George W. Partelow Jan 1979

Expectation Of Genetic Alteration Of Muscle Composition And Growth Traits In Rainbow Trout (Salmo Gairdneri), George W. Partelow

Electronic Theses and Dissertations

The breeding of farm animals to produce superior organisms has been extensively applied to many parts of the world. Much of the research has been concerned with the manip0ulation of muscle protein and fat in muscle tissue for the purpose of catering to human needs (Kielanowski 1972; Dinkel and Busch 1973; Olson et. al. 1976). Though fishes are able to convert food to quality protein more efficiently than most animals, they have been underutilized as a protein source in the United States. Until recently, genetic manipulation through selection to enhance their quality has not been extensively applied (Smith and Rumsey …

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Pheasant Use Of Wetlands During The Winter And Application Of Landsat Imagery For Assessing Winter Habitat, Signe Sather-Blair Jan 1979

Pheasant Use Of Wetlands During The Winter And Application Of Landsat Imagery For Assessing Winter Habitat, Signe Sather-Blair

Electronic Theses and Dissertations

This study was designed to investigate 1) vegetative factors influencing ring-necked pheasant (Phasianus colchicus) use of wetlands during the winter, 2) the relationship of land use practices adjacent to wetlands and the use of such wetlands as winter cover by pheasants, and 3) the feasibility of assessing wetlands as pheasant winter habitat through the use of remote sensing data. Fifteen wetlands in Windsor Township, Brookings County, South Dakota, were randomly selected for study to estimate their use by pheasants. Use of cover types was analyzed by using multiple regression, chi-square, and t-tests. Correlation matrices were generated to locate significant relationships. …

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Non-Game Bird Habitat Associated With Haul Roads And Surface Mining For Bentonite Clay, Tim A. Schaid Jan 1979

Non-Game Bird Habitat Associated With Haul Roads And Surface Mining For Bentonite Clay, Tim A. Schaid

Electronic Theses and Dissertations

A 2 year study was conducted to investigate possible differences in density and diversity of birds in relation to distance from mining haul roads and various aged mine spoils. Winter bird surveys and breeding bird counts were conducted during 1977 and 1978. Bird density and diversity were estimated and compared between the following habitat areas: old spoils (mined ≥20 years ago, unreclaimed), new spoils (mined ≤20 years ago, reclaimed) and unmined areas. Within unmined areas density and diversity of birds 100m, 300m, 500m, and 900m from a mining haul road were compared to detect differences in density and diversity with …

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The Modification And Use Of An Electron Paramagnetic Resonance Spectrometer For Data Collection At Liquid Nitrogen Temperature, Vernon Lee Baumberger Jan 1979

The Modification And Use Of An Electron Paramagnetic Resonance Spectrometer For Data Collection At Liquid Nitrogen Temperature, Vernon Lee Baumberger

Electronic Theses and Dissertations

The scope of this study includes the modification of an EPR spectrometer for acquisition of low temperature data. The modification involved adaptation of the system for use with a cylindrical cavity specifically designed for low temperature operation. This modification increased the capability of the present system for data collection at liquid nitrogen temperature and gave such greater stability than the rectangular cavity previously used. A comparison was made of signal to noise for the two cavities. This study showed a somewhat greater signal to noise ratio for the low temperature cylindrical cavity. Operation at low temperature also allowed the observation …

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Population And Productivity Of A Flock Of Giant Canada Geese In Northeastern South Dakota, Ted A. Clausing Jan 1979

Population And Productivity Of A Flock Of Giant Canada Geese In Northeastern South Dakota, Ted A. Clausing

Electronic Theses and Dissertations

Population and productivity studies of giant Canada geese (Branta canadensis maxima) were conducted in northeastern South Dakota in 1976 and 1977. One hundred ninety-three of 436 randomly selected sample quarter sections on the 5,459 km2 area contained potential goose nesting habitat in 1976. Forty-six pairs, 6 indicated pairs, and 6 single geese were found on these 193 quarter sections during the 1977 nesting season. The population was estimated to be 1,880 geese. Recommendations were to continue aerial surveys in the spring and late summer and to supplement them with annual searches of the sample quarter sections used in this study. …

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The Taxonomic Status Of Coyotes From Western South Dakota, Susan E. Lauzon Jan 1979

The Taxonomic Status Of Coyotes From Western South Dakota, Susan E. Lauzon

Electronic Theses and Dissertations

Expansion of the range of the coyote (Canis latrans) has been accompanied by numerous instances of hybridization with domestic dogs (C. familiaris). Recent studies have found a hybrid element in some wild coyote populations. The objectives of this study were to identify the taxonomic status of coyotes in western South Dakota, and to determine the degree of hybridization, if any, that is occurring between coyotes and domestic dogs in the state. Animals were collected from three areas in western South Dakota from September 1976 through January 1978. Skulls of 289 wild canids were cleaned; of these, 167 skulls from adults …

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Special Reflectance Of Hydrophytes, Robert G. Best Jan 1979

Special Reflectance Of Hydrophytes, Robert G. Best

Electronic Theses and Dissertations

Identification of hydrophytes will improve the delineation and classification of wetlands on remotely sensed imagery. Spectral reflectance measurements of 10 species of hydrophytes were made with an Exotach radiometer during three phenological stages, flowering and early seed, senescence, and early emergent. Reflectance data were analyzed to determine significant (≥.95) reflectance differences between species in each of four spectral regions during each phenological stage. Eight species had significantly (≥.95) different reflectances during the flower and early seed stage. Only one species could not be spectrally separated during at least one phenological stage. The results indicate that films sensitive to both visible …

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Winter Limnological Conditions In A Prairie Pothole And The Application Of Molecular Oxygen, Richard A. Fike Jan 1979

Winter Limnological Conditions In A Prairie Pothole And The Application Of Molecular Oxygen, Richard A. Fike

Electronic Theses and Dissertations

The physical, chemical, and biological conditions in Round Lake, Oakwood Lakes State Park, South Dakota were monitored during the 1977-1978 winter, and reaeration utilizing molecular oxygen was evaluated as a practical method to prevent winterkill. Ice and snow conditions after 20 December, 1977 allowed little light penetration, and phytoplankton numbers (6174/ml to 1668/ml) and chlorophyll concentration (46.6 mg/L to 14.1 mg/L) decreased throughout the winter. Aquatic bacteria and fungi comprised from 87.0% to 93.7% by number of the total cells identified (phytoplankton, bacteria, and fungi) in the lake water under ice. Dissolved oxygen declined to anoxic conditions after 19 January, …

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Nesting Chronology Of South Dakota Ducks, Stephen A. Tessmann Jan 1979

Nesting Chronology Of South Dakota Ducks, Stephen A. Tessmann

Electronic Theses and Dissertations

Duck broods were censused on 476 randomly selected plots in South Dakota during July of the years 1973 through 1976. Broods were also censused on wetlands located off the study plots both in July and August of these years, except in 1976 when no August counts were made. Hatching and nest initiation dates were determined by back dating from brood age classes. Early nesting species were mallards (Anas platyrhynchos) and pintails (A. acuta). Northern shovelers (A. clypeata), redheads (Aythya americana), and canvasbacks (A. valisineria) were intermediate nesters while blue-winged teal (Anas discors), gadwalls (A. strepera), and American wigeons (A. americana) …

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Catfish Cage Culture In A South Dakota Power Plant Cooling Reservoir, Gary P. Wheeler Jan 1979

Catfish Cage Culture In A South Dakota Power Plant Cooling Reservoir, Gary P. Wheeler

Electronic Theses and Dissertations

Studies were conducted to evaluate the Big Stone Power Plant cooling reservoir in northeastern South Dakota as a site for cage culturing channel catfish (Ictalurus punctatus) for market and sport fishery stocking. Temperatures suitable for catfish culture (21-32 C) were present in the reservoir from mid-March through mid-September 1978 and from mid-October through 4 November 1978, the end of the study period. Mean values of chemical parameters analyzed included dissolved oxygen - 8.8 mg/1, total available chlorine- 0.13 mg/1, pH - 8.6, specific conductance - 2228 micromhos/cm, total hardness - 1128 mg/1 as CaC03, calcium hardness - 570 mg/1 as …

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Breeding Waterfowl Use Of Intermittent Streams, Mchenry County, North Dakota, Daniel E. Hubbard Jan 1979

Breeding Waterfowl Use Of Intermittent Streams, Mchenry County, North Dakota, Daniel E. Hubbard

Electronic Theses and Dissertations

Thirty-three 425 m segments of 4 intermittent streams in north central North Dakota were censured for breeding pairs of waterfowl in 1977 and 1978. Pair count data were available for 1976. Emphasis of this study was placed on the narrow meandering portions of the streams. High dabbling duck (Anas spp.) densities were observed in 1977 and 1978; 6.11 pairs per ha and 5.60 pairs per ha, respectively, for the first census of each year. Accepting blue-winged teal (A. discors), numbers of dabbler pairs were similar in 1976 and 1978. Dry conditions in 1977 caused lower numbers of all species of …

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Habitat Preferences And Censusing Of Waterfowl Broods On Stock Ponds In South Central South Dakota, Mark A. Rumble Jan 1979

Habitat Preferences And Censusing Of Waterfowl Broods On Stock Ponds In South Central South Dakota, Mark A. Rumble

Electronic Theses and Dissertations

Waterfowl broods on stock ponds in south central South Dakota were surveyed in 1977 and 1978 to compare flush and observation techniques for censusing broods and to determine waterfowl brood habitat preferences. Results indicated that 72-8% of the broods present were censused by either technique alone. No differences were indicated between the 2 techniques when analyzed by species. For total brood counts, a significant (P<0.05) difference was indicated for 1 of the 4 sample periods. Differences were found between the 2 techniques for certain age-classes of species and age-classes overall. Visibility correction factors were calculated for each species based on the percentage of known broods censused by each technique. Brood habitat preferences were examined using multiple regression and discriminant analyses of 33 pond and upland variables. Ponds were selected in a limited size range (0.71-2, 70 ha) to reduce variation in numbers of broods per pond due to pond size. However, variables indicative of pond size were significantly and positively associated to brood use of ponds in 8 of 9 analyses. Potential brood escape cover such as Polygonum spp. and Eleocharis spp. were positively associated with mallard (Anas platyrhynchos), (A. strepera), northern shoveler (A. clypeata) and class 1 broods. Large differences in numbers of broods on study ponds between the 2 years were likely due to increased nesting cover provided by yellow sweet clover (Melilotus officinalis). Study ponds with higher pH and more submersed aquatic vegetation had more brood use.

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Bird Utilization Of Woodland Habitat In The Eastern Quarter Of South Dakota, John M. Emmerich Jan 1978

Bird Utilization Of Woodland Habitat In The Eastern Quarter Of South Dakota, John M. Emmerich

Electronic Theses and Dissertations

Bird utilization of narrow, riparian woodland; riparian; block-like, tree claim; and linear, single-row windbreak habitats in the eastern quarter of South Dakota were studied during the spring migration, reproductive, and winter seasons. The relative importance of these three habitats and multi-row shelterbelt habitat was evaluated using bird species diversity (BSD), bird population density, and habitat preferences of individual bird species. Cluster analysis delineated distinctive vegetation cover types in each of the three habitats studied. Bird communities associated with each cover type were tabulated for comparison purposes and predication capabilities. Multiple regression analysis predicted physical and vegetation features of each habitat …

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Effects Of Grazing Systems On Sharp-Tailed Grouse Habitat, Samuel N. Mattise Jan 1978

Effects Of Grazing Systems On Sharp-Tailed Grouse Habitat, Samuel N. Mattise

Electronic Theses and Dissertations

Effects of grazing systems on sharp-tailed grouse (Pedioecetes phasianellus jamesi) nesting and brooding habitats in the Little Missouri National Grasslands of southwestern North Dakota were evaluated. Three grazing allotments with deferred-rotation grazing systems and three allotments with season-long grazing systems were randomly selected for study. Fifty measurements of vegetation were taken using the height-density pole on line transects in each of three range sites; rolling grasslands, upland grasslands and lowland draws. Vegetation was sampled in late spring, summer and fall of 1976 and early spring of 1977. Average height-density of vegetation for the season-long grazing system was significantly greater than …

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Evaluation Of Fish Stocking In Southeastern South Dakota Ponds, Paul J. Peeters Jan 1978

Evaluation Of Fish Stocking In Southeastern South Dakota Ponds, Paul J. Peeters

Electronic Theses and Dissertations

A mail survey was sent to owners of 220 ponds which had received hatchery fish. Based on 187 pond owner responses, at most 45 (24%) of the ponds still contained the fishes stocked. Pond dryness and/or winterkill attributed to the failure of 121 (65%) of the ponds. A subsequent field survey of 30 ponds identified fish populations of recreational value. Attempts were made to identify important pond parameters that contributed to successful fish populations. Aᵼ (percent harvestable fish), F/C (forage to carnivore ratio), balance (in or out), and a scale of balance were the dependent variable used to describe successful …

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Wildlife Habitat In The James River Valley, South Dakota, L. Paul Schneider Jan 1978

Wildlife Habitat In The James River Valley, South Dakota, L. Paul Schneider

Electronic Theses and Dissertations

A wildlife habitat inventory was conducted on the 12 485 ha study area of the James River floodplain in north-eastern South Dakota. Included were vegetation mapping, small mammal trapping, waterfowl breeding pair counts, waterfowl brood counts, bird census routes, and general observations. Natural vegetation consisted of 3181 ha of grassland, 2002 ha of woodland, 1115 ha of savannah, and 392 ha of marshland. Small mammal trapping revealed low densities of mostly white-footed mice (Peromyscus spp.). No vegetation type was more valuable to small mammals than any other. Waterfowl breeding pairs, mostly mallard, blue-winged teal, and wood duck, numbered 244 in …

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Specificity Of Antisera Against Hordeum Vulgare Ribonuclease And Serological Quantitation Of The Enzyme In Tissue Extracts, Steven Bryan Hawthorne Jan 1978

Specificity Of Antisera Against Hordeum Vulgare Ribonuclease And Serological Quantitation Of The Enzyme In Tissue Extracts, Steven Bryan Hawthorne

Electronic Theses and Dissertations

Specific rabbit antisera against purified seedling RNase I from both a hardy (Dicktoo) and less-hardy (Tennessee Winter) cultivar of winter barley was obtained using a 1 mg injection schedule. Both antisera formed a single precipitin band on double immunodiffusion and immunoelectrophoresis when reacted with the homologous crude tissue extract. RNase antigen from either cultivar was highly cross-reactive with both antisera. Passive hemagglutination inhibition was used in an attempt to distinguish purified RNase from both cultivars. A consistent difference in anti-RNase serum specificity between cultivars was shown, but the difference observed by this method was not sufficient to conclude structural differences …

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Diversity And Density Of Shelterbelt Bird Communities, Thomas E. Martin Jan 1978

Diversity And Density Of Shelterbelt Bird Communities, Thomas E. Martin

Electronic Theses and Dissertations

The number of bird species and the density of each species were monitored in 69 shelterbelts in eastern South Dakota during spring migration and breeding seasons in 1976 and 1977. A total of 44 different species of birds were found during breeding and 68 species during spring migration. Approximately 60 to 80% of the species in a shelterbelt eat insects as part of all of their diet. Most of these bird species are territorial. Usually only 1-2 pairs of a territorial species will reside in any one shelterbelt. This low density is caused by the limited habitat area that shelterbelts …

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Diet And Nutrition Of The Pronghorn Antelope, Norman C. Messenger Jan 1978

Diet And Nutrition Of The Pronghorn Antelope, Norman C. Messenger

Electronic Theses and Dissertations

Pronghorn antelope (Antilocapra americana) in northwestern South Dakota consumed at least 32 different plants species. Major forage plants were big sagebrush (Artemisia tridentate), silver sage (A. cana), yellow sweet clover (Meliotus officinalis), gold aster (Chrysopsis villosa), and blue grama (Bouteloua gracilis). Cultivated small grain crops were not a major food source of pronghorn. Differences in diet composition, plant groups, plant groups and time of use and plant group, area, month interaction were significant. Average in vitro digestion of 31 food plants was 51 percent. Mean digestion of grasses was 57 percent, forbs 42 percent, and shrubs 55 percent. Yearling male …

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Breeding Biology And Prey Selection Of Ferruginous Hawks In Northwestern South Dakota, Charles L. Blair Jan 1978

Breeding Biology And Prey Selection Of Ferruginous Hawks In Northwestern South Dakota, Charles L. Blair

Electronic Theses and Dissertations

A study of the breeding biology and prey selection of ferruginous hawks (Buteo regalis) was conducted in northwestern South Dakota during 1976 and 1977. Twenty four pairs were located in 1976 and 18 pairs attempted to nest; 17 pairs located in 1977 attempted to nest. The ecological density of breeding pairs was approximately one per 100 km2. Young fledged per nesting attempt averaged 1.89 in 1976 and 2.29 in 1977. All but one nest were located in unbroken, lightly grazed prairie and all were situated on hills, buttes, or river cutbanks. General nest orientation was toward the south and west. …

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Fungal Control Methods, Diets And Water Temperatures Used To Culture Paddlefish, Polydon Spathula, Ronald L. Brandt Jan 1978

Fungal Control Methods, Diets And Water Temperatures Used To Culture Paddlefish, Polydon Spathula, Ronald L. Brandt

Electronic Theses and Dissertations

Studies were conducted at Gavins Point National Fish Hatchery, South Dakota, in 1976 and 1977, to evaluate the effects of diet and water temperature on growth and survival of paddlefish, Polyodon spathula, young, and the effects that fungicides have on hatching success and fry survival. The W-7 cool water diet was fed hourly and three times daily while the Liv commercial diet was fed hourly to paddlefish young for 40 days after swim-up. Average survival rate and total length of paddlefish fed W-7 hourly were 16.0% and 30 mm, those fed W-7 three times daily were 10.0% and 23 mm, …

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Non-Game Birds In Relation To Habitat Variation On South Dakota Wetlands, Michael J. Weber Jan 1978

Non-Game Birds In Relation To Habitat Variation On South Dakota Wetlands, Michael J. Weber

Electronic Theses and Dissertations

Non-game birds on South Dakota wetlands were surveyed on 476 quarter sections representing the major portion of South Dakota excluding the Missouri River and its impoundments and the Black Hills. Two surveys were conducted, one in May and a second in June, in both 1975 and 1976. The distribution of 13 non-game species was analyzed by physiographic strata and wetland classification: red-winged blackbird {Agelaius phoeniceus), yellow-headed blackbird (Xanthocephalus xanthocephalus), Wilson's phalarope (Steganopus tricolor), black tern (Chlidonias niger), lesser yellowlegs (Totanus flavipes), sora {Porzana carolina), marbled godwit (Limosa fedoa), willet (Catoptrophorus semipalmatus), American avocet (Recurvirostra americana}, American bittern {Botaurus lentiginosus), great …

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Nucleophilic Substitution At Phosphorus In Six-Membered Ring Phosphate Esters, Mike Bauman Jan 1978

Nucleophilic Substitution At Phosphorus In Six-Membered Ring Phosphate Esters, Mike Bauman

Electronic Theses and Dissertations

From these results the following conclusions may be drawn: 1. The stereochemistry of nucleophilic substitution at phosphorus is influenced by the basicity of the leaving group with the more basic leaving group favoring retention. 2. Lithium ion diverts the reaction to retention by forming an intimate ion-pair with the nucleophile which then attacks phosphorus. This associated ion is less reactive than the unassociated nucleophile. 3. For the retention mechanism the leaving group participates in the rate determining step. 4. The mechanism for retention entails a more sterically unfavorable configuration than for inversion.

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Studies On The Gas Given Off By Yeast When It Goes From An Anaerobic To Aerobic Metabolism, David C. Potts Jan 1978

Studies On The Gas Given Off By Yeast When It Goes From An Anaerobic To Aerobic Metabolism, David C. Potts

Electronic Theses and Dissertations

Several investigators have observed that when yeast cells (yeast) go from a strictly anaerobic environment to an aerobic oner and glucose is added a negative value is recorded on the manometer. This phenomenon indicates that a gas has been given off by the yeast. The purpose of this research was to identify the gas and determine how it arises.

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Molybdenum(V) Solutions In Hydrobromic Acid, Edwin Charles Perley Jan 1978

Molybdenum(V) Solutions In Hydrobromic Acid, Edwin Charles Perley

Electronic Theses and Dissertations

Interest in the coordination chemistry of molybdenum has increased greatly in recent years because of the discovery that molybdenum plays an active role in several redox enzymes. Model systems have been devised to gain insight into the function of molybdenum in these enzymes. Most model systems are believed to contain an oxomolybdate(V) dimer in equilibrium with a redox active monomer or dimer. A relatively simple system that shows important similarities to model systems is a molybdenum(V) solution in hydrobromic or hydrochloric acid. As in the model systems, these solutions are believed to contain monomers and dimers in equilibrium. The equilibria …

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Factors Affecting Waterfowl Brood Use Of Stock Ponds In South Dakota, Gene D. Mack Jan 1977

Factors Affecting Waterfowl Brood Use Of Stock Ponds In South Dakota, Gene D. Mack

Electronic Theses and Dissertations

A July waterfowl brood survey was conducted from 1973 to 1976 on stock ponds located within four physiographic strata in South Dakota. Information was collected on weather, stock pond characteristics, land use and the condition of other wetlands located within the quarter section (64.8 ha) study plots. Multiple regression and multiple discriminant analyses were sued to determine the importance of these variables in influencing brood use of stock ponds. Vegetation type, distribution of emergent vegetation and pond size were important in determining if broods of any particular species utilized a pond or not. Shoreline distance was particularly important in explaining …

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Variables Associated With Breeding Waterfowl On South Dakota Stock Ponds, Jay A. Roberson Jan 1977

Variables Associated With Breeding Waterfowl On South Dakota Stock Ponds, Jay A. Roberson

Electronic Theses and Dissertations

Use of stock watering ponds by indicated breeding pairs of waterfowl was measured in the western two-thirds of South Dakota from 1973 to 1976. Multiple regression and discriminant analyses were used to describe the habitat associated with pairs of each species. Habitat variables explained 35-47 percent of the variation in pairs having small home ranges and 26-35 percent of the variation in pairs having large home ranges. Shoreline distance account for more variation in mallard (Anas Platyrhmchos) and blue-winged teal (A. discors) pairs than any other single variable. Ponds used by these pairs and shoreline distances that averaged 590 m …

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Population, Home Range, And Dispersal Of Red Foxes In East-Central South Dakota, James D. Sweeting Jan 1977

Population, Home Range, And Dispersal Of Red Foxes In East-Central South Dakota, James D. Sweeting

Electronic Theses and Dissertations

The population, dispersal movements and summer home range of red foxes (Vulpes vulpes) were studied in east-central South Dakota during 1974 and 1975. The spring population density of foxes on a 23,319 ha study area declined from 9.2 families/township in 1974 to 7.6 families/township in 1975. Fifty-four percent of 130 foxes tagged in spring, 1974 and 1975 were recovered during the first year following tagging. Hunting and trapping accounted for 18.0 and 77.8 percent, respectively. Recoveries revealed that dispersing juvenile male foxes were more mobile than juvenile females; juvenile foxes traveled a mean distance of 39 km for males and …

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Cover Use And Activity Time Budget Of Blue-Winged Teal, Mallard, And Pintail Broods, James K. Ringelman Jan 1977

Cover Use And Activity Time Budget Of Blue-Winged Teal, Mallard, And Pintail Broods, James K. Ringelman

Electronic Theses and Dissertations

Blue-winged teal (Anas discors), mallard (A. platyrhynchos), and pintail (A. acuta) broods were observed on 17 days between 25 June and 30 July, 1976. Brood activities and cover uses were recorded continuously from first light until dark. Observations of 269 broods from three wetlands were evaluated by species and brood age-class. Activity time budgets revealed significant (p<.01) age specific differences in total feeding time and visibility among age-classes of all species combined and age-classes of blue-winged teal broods. Feeding modes also varied among age-classes. Daily patterns of cover use varied among brood age-classes and species. Morning and evening feeding peaks became more pronounced, and overall visibility increased, with brood age. Interspecific differences in daily activity patterns were observed among broods of the same age-class. Duration of active periods increased with age in blue-winged teal broods. Active periods recurred at regular intervals in all broods throughout the day, suggestive of polycyclic behavior patterns similar to those of adult ducks. A progressive increase in brood visibility was attributed primarily to seasonal changes in brood age structure and to wetland water loss. Temperature and wind speed influenced brood visibility during most observation days. Climatic conditions favorable to nighttime brood activity influenced brood behavior during the following day. Accuracy of present brood inventory techniques could be improved if considerations were made for brood behavior patterns and environmental factors which alter brood cover use.

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