A fifteen month experiment was conducted to study the pattern of utilization of Lehmann lovegrass by cows during different seasons at three stocking rates on four patch types (grazed, open; grazed, under-mesquite; mowed, artificial; and ungrazed control) at the Santa Rita Experimental Range. The purpose of the research was to determine the influence of standing biomass, proportion of green material and nutrient content of patch types on the relative time cattle grazed patch types. Cattle biting rate on patch types was also measured. Height of leaves and flowers, dry biomass (kg/ha and %), green biomass (kg/ha) and total biomass were greater on ungrazed patches. Proportion of green was greater in grazed than ungrazed patches. Protein, phosphorus, Calcium and IVDMD were higher in green and complete samples of grazed than ungrazed patches. Cattle concentrated grazing upon upland, open grazed patches and under-mesquite canopy. These selected areas were higher in proportion of green biomass and nutrient value and lower in total standing crop and total green biomass than ungrazed areas. Nutrient density, rather than biomass appeared to govern cattle grazing.

Foraging party and territory size of Heterotermes aureus (Snyder) were investigated on the Santa Rita Experimental Range south of Tucson, Arizona. A comparison of three techniques for delineating territorial extent suggested that the release and recapture of dyed termites was most useful, while agonistic behavior among termites may reflect past as well as current associations. Spatial and temporal patterns of termite attack on baits proved to be unreliable. Data obtained via the release and recapture of dyed termites indicated that most territories encompassed an area of several hundred to thousand square meters. These data sharply contrast with those obtained via spatial and temporal patterns of termite attack, which provided an estimate of 9.2 m² for average territory size. Although agonistic responses were useful for differentiating H. aureus colonies, the lack of this behavior among termites did not necessarily imply a current relationship, as they may have been from subgroups that previously had budded off from each other. These groups may be headed by neotenic reproductives, which were found for the first time under field conditions for this species. Data on foraging party size obtained via a mark-release-recapture technique indicated that many H. aureus colonies contained from ca. 50,000 to 300,000 foragers. However, the validity of these estimates is suspect because several of the assumptions of this technique were not met, i.e., marked individuals did not completely mix in the population, but their numbers tended to be more concentrated near release sites, and colonies may have represented open populations. However, exhaustive trapping data also indicated that colonies may contain tens or hundreds of thousands of foragers. As many as 100,000 foragers in a single colony were removed from fiberboard traps during a 1.5-year period. The average foraging party consisted of 1,456 individuals, of which 8.6% were soldiers.

A 15-month study was conducted on the Santa Rita Experimental Range to evaluate the factors influencing both plants and cattle in southern Arizona. Forage biomass, nutrient value, botanical composition, and ground cover were greater in the growing season than in the dormant season. Moderate and heavy pastures had lower plant parameters than very heavy pasture, except for forage biomass and Lehmann lovegrass proportion, forage fiber and ground cover. Slopes and washes had a higher forage nutrient content and lower biomass and ground cover than the uplands. Lehmann lovegrass was more abundant on the uplands and in the washes than on the slopes and the reverse was true for native grasses and shrubs. Understory forages contained greater nutrients and forbs than open forages and the opposite occurred for shrubs and ground cover. Grazing activities, drinking, salting, defecation, urination and rumination were greater in the growing seasons, but standing and idling were greater in winter. There were no differences among pastures in major activities, but walking, drinking and salting were greater on very heavy pasture than on moderate and heavy pastures. Most grazing activities were on the uplands and resting activities were in the washes. Biting rates were similar among topographic areas. Upland and wash defecation and urination frequencies were similar and higher than slope frequencies. Grazing activities were greater in the open than under canopy and the reverse was true for resting activities. Open and canopy areas were similar in defecation and urination frequencies and biting rates. Except for resting activities, major and minor activities were more intense in the afternoon than in the morning. Morning and afternoon biting rates were similar. The weather index was the most important predictor of all cattle activities, except for the defecation frequency which mostly depended on the proportion of green forage. The forage nutrients and green proportion were the second and third important predictors of cattle activities, respectively. In conclusion, plants and animals interact and both react to environmental conditions. The recommendations for best management of a grazing land ecosystem should consider these conditions.

Studies were conducted on the dynamics of live, standing recent dead, and standing old dead herbage for a desert grassland site in the southwestern United States. Data were collected at eleven sample dates from August 24, 1979 to October 18, 1980. Coefficients of variation for biomass data for most species exceeded 400% with only the most abundant species sampled with coefficients of variation less than 100%. Coefficients of variation generally were less than 80% for the perennial grasses as a group. The mean rate of transfer of biomass from live herbage to standing recent dead herbage was 0.21% per day for 203 days when expressed as a percentage of the peak live herbage. A rate of transfer of 0.53% per day of live herbage to standing dead for 109 days for perennial grasses in the desert grassland was found during early vegetative growth. A high proportion of leaves to culms was present during this period as compared to the summer growing season. Heavy precipitation in the early part of September accelerated growth of live herbage, and also accounted for losses of standing recent dead and standing old dead herbage to the surface litter component. The loss of dry leaves from standing grass culms due to rainfall impact contributes to an underestimate of net primary production. Standing old dead biomass accumulated following the depression in September. Transformation of the recent dead herbage to an appearance of old dead late in the summer also contributed to underestimating of current year production based on peak crop method due to the identification of recent dead herbage as the old dead component. Summation of growth increments by sample periods provided the highest estimate of aboveground net primary productivity when compared to estimates based on peak standing crop, summation of species peaks, and summation of significant growth increments by sample periods. Estimates of net productivity were 186% of the estimate at peak standing crop. Estimates of net production based on significant growth increments by sample periods yield the lowest value for net production, because poor precision of samples restricted data to few significant values. Based on the peak periods for standing biomass of lifeform groups, a minimum of four sample dates are recommended to estimate aboveground net primary production for semidesert grassland in southeastern Arizona. These sample dates include: (1) late April to sample spring peaks by perennial grasses, annual forbs and annual grasses; (2) late June to capture the spring trough; (3) late September to sample peak crops of perennial forbs, and half-shrubs; and (4) mid to late October to sample the fall peak for perennial grasses. Net production estimates by the peak crop method for perennial grasses varied from 18.7 g/m² in 1979 to 86.1 g/m² in 1980. This variability was attributed to the differences in the amount of rainfall in 1979 and 1980. This factor, therefore, largely influenced the repeatability of biomass estimates from one year to another. The large amount of time (approximately 644 man-hours) needed to sample and separate live and dead components by species for 20 quadrats at each harvest date, together with the year-to-year variability and the need for a minimum of four sample dates to effectively sample the desert grassland community, makes biomass data impractical for general use as a data base in land-use planning. However, this effort should be looked at from the standpoint of research studies describing the dynamics of range systems based on temporal characteristics and transfer functions to provide data which can help design management strategies for these range ecosystems.

No description available.

No description available.

A study of the coyote in southern Arizona was initiated to gain insight into basic ecological relationships and to provide a basis for more detailed future studies. The behavioral portion of the study was conducted on the Santa Rita Experimental Range (SRER), where apparent minimum home ranges for 6 radio-tracked coyotes ranged in size from 0.5 to 7.9 square miles, and averaged 4.2 square miles. The relatively small home ranges may have reflected high coyote density and abundance of food during the period of study. Females tended to occupy larger areas than did males. Home ranges appeared to be a composite of foraging ranges, each of which had its own center of activity. Generally home ranges exhibited the property of linearity. Coyotes typically became active before dusk and remained so until midmorning of the following day, with cooler weather extending activity periods. Based upon annuli counts from canine teeth of 378 coyotes, the age distribution within the general population was as follows: 0-1 year old, 32.8%; 1-2, 14.3%; 2-3, 15.3%, 3-4, 12.2%; 4-5, 11.4%; 5-6, 5.0%; and over 6 years, 9.0% of the sample. The average age was 3.2 years (s.d. 2.4), with one animal reaching just under 14 years of age. Subsamples representing different years, causes of death, and counties had significantly different age class distributions. Also, coyote age class structures from various regions of North America exhibited highly significant variations. Of 273 known-sex coyotes, the ratio was 154 males: 119 females. Males tended to outlive females; for coyotes over 5 years of age males significantly outnumbered females. The control practices of trapping and poisoning killed a highly significant majority of male coyotes. Hypothetically, disproportionate sex ratios were part of a mechanism whereby coyote populations maintained a balance with their environment. Reproductive tracts from 22 males and 20 females were examined. Males produced spermatozoa from January to June. There was no evidence of breeding among juvenile females. Over 100 coyote specimens were examined for parasites. Information on the occurrence of ectoparasites tended to be of qualitative value. The species identified were Pulex simulans, Echidnophaga gallinacea, Thrassis arizonensis, Heterodoxus spiniger, and Otobius megnini. The 15 species of helminths recovered consisted of 5 cestodes, including Taenia pisiformis (56% infection rate), T. multiceps (22%), T. macrocystis (6%), T. hydatigena (1%), and Mesocestoides sp. (6%); 8 nematodes, including Ancylostoma caninum (38%), Filaroides osleri (3%), Toxascaris leonina (43%), Physaloptera rara (51%), P. sp. (1%), Rictularia cahirensis (3%), Mastophorus numidica (1%), and Dirofilaria immitis (2%); and 2 acanthocephalans, including Oncicola canis (46%) and Pachysentis canicola (1%). Pups and females were subject to greater collective endoparasite burdens. Variations in incidence and intensity of infection were also noted with year, season, and county. A general picture of food habits was obtained by examining 101 coyote stomachs. By percentage of overall volume, stomach contents were: larger mammel, 25.4%; smaller mammal, 35.0%; bird, 16.4%; reptile, 0.1%; invertebrate, 6.4%; and vegetable matter, 16.2%. Much of the larger mammal material was carrion. Statistical analyses revealed that there were significant differences in the diets of pups and females versus adults and males, respectively, while variations in diet between years, seasons, and counties did not appear significant. By percentage of organic weight, contents of 619 coyote scats from the SRER were: larger mammal, 15.8%; smaller mammal, 49.9%; bird, 0.8%; reptile, 0.2%; insect, 5.4%; and vegetable matter, 27.9%. Variations in recovered weights of the major food categories between seasons were highly significant. The proportion of native fruits and insects in the scats increased greatly in summer and fall, and appeared responsible for moderating predation upon smaller mammals for several months.

No description available.

No description available.

Thesis (M.S. - Renewable Natural Resources)--University of Arizona. / Includes bibliographical references.