Coyotes fed upon agricultural carrion at feedlots operated by the Farmer's Investment Company (FICO) and Roisland Farms. Agricultural carrion was not available in the Whetstone area. The FICO feedlot stopped operating in May 1976, and carrion was not available there after that time. Coyotes were trapped and shot at the FICO feedlot from November 1975 through March 1976, from June through August 1976, and from May through August 1977. Coyotes were trapped at Roisland Farms in July and August 1976 and January and February 1977. A trapper collected coyotes in the Whetstone area from January through March 1976 and from November 1976 through February 1977. I operated a scent station line on the Santa Rita Experimental Range on a monthly basis from October 1975 through June 1976, from September 1976 through June 1977, and in December 1977. From data on the visitation of scent stations by coyotes, lagomorphs, and small mammals I calculated indices of monthly relative abundance for each animal group. There were no differences among the age distributions, weights, ovulation rates, and litter sizes of coyotes from the 3 study areas. The mean weights of all adult-sized male and female coyotes collected during this study were 11.1 and 9.3 kg, respectively. The overall mean ovulation rate and mean litter size were 4.1 and 3.4, respectively. At FICO and Roisland, 70 to 90% of yearling and adult females bred, but only 20% bred in the Whetstone area. There were more male than female coyotes at FICO, but sex ratios were not different from 1:1 at Roisland and Whetstone. The visitation rates of coyotes, lagomorphs, and small mammals fluctuated greatly during this study. Monthly visitation rates of coyotes differed significantly, but annual and daily rates did not. The visitation rates of both lagomorphs and small mammals were significantly different between years and among months, but not among days. Lagomorph and small mammal visitation increased significantly after the trapping of coyotes and the end of the FICO carrion supply in the summer of 1976. Coyote visitation appeared to decrease after the summer of 1976. Prior to the summer of 1976, the visitation rates of coyotes and lagomorphs were positively correlated, but the rates of coyotes and small mammals were not correlated. After the summer of 1976, coyote visitation was negatively correlated with both lagomorph and small mammal visitation. The distribution of coyote and lagomorph visits along the scent station line did not change after the summer of 1976. Small mammal visitation, however, increased in the distant section of the line after the summer of 1976. Coyotes visited stations located on the upwind side of the road more frequently than they stopped at stations on the downwind side. Lagomorphs showed no preference for either side of the road, but small mammals visited more stations on the downwind side of the road than on the upwind side. The breeding rate at FICO did not decrease after the carrion supply ended. It seems unlikely, therefore, that the high breeding rate at FICO was caused by feeding on carrion. The scent station technique has potential as a means of monitoring the monthly relative abundance of coyotes and certain prey groups. Unfortunately, visitation is a function of animal numbers and activity. Further research is required to quantify the relationship between visitation and abundance for each animal group.

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.