Samuel L. Beasom

Relationships between Predator Removal and White-Tailed Deer Net Productivity

This study was conducted to determine the impact of predation on productivity of whitetailed deer (Odocoileus virginianus) in South Texas by removing predators from one area and comparing the results to a control area. A total of 188 coyotes (Canis latrans) and 120 bobcats (Lynx rufus) were removed during predator removal efforts on the approximately 5,400-acre (2,186-ha) experimental area from 1 February to 30 June 1971 and 1972. Aerial counts in 1971, a severe drought year, revealed a fawn:doe ratio of 0.47 in the experimental predator removal area compared to 0.12 in the control area. In 1972 more favorable climatic conditions led to higher deer productivity in both areas, but the relative difference between the two areas was maintained. The experimental area had a fawn:doe ratio of 0.82 compared to 0.32 on the control area. Counts from roads indicated a decline in fawn:doe ratio with increasing distance from the experimental area. These data indicate that deer populations in this locality could be increased with a very intensive predator control program. To justify such a predator control program on the basis of present information, however, a more intensive hunter harvest would probably be required to hold the deer herd below the density level where starvation, diseases, or other factors begin to take their toll. J. WILDL. MANAGE. 38(4):854-859 Regardless of underlying circumstances, certain canid predators have at times developed a specialization for preying on ungulates to the point of drastically curtailing the population (Errington 1946). Selecting against the young of these conspicuous, relatively slow-breeding forms would be potentially very destructive (Allee et al. 1949:374). That predators can specialize by preying on the young of an ungulate species has been suggested by studies involving the coyote and antelope (Antilocapra americana) in Texas (Jones 1949) and Arizona (Arrington and Edwards 1951), the lynx (Lynx canadensis) and caribou (Rangifer tarandus) in Newfoundland (Bergerud 1971), the black-backed jackal (Canis mesomelas) and blesbok (Damaliscus dorcas phillipsi) in South Africa (du Plessis 1972), and the coyote and whitetailed deer in South Texas (White 1966:83, Knowlton 1968). Recent studies with ear-marked (Knowlto 1964) and radio-tagged (Cook et al. 1971) white-tailed deer fawns on the Welder Wildlife Refuge in South Texas have suggested that coyote predation was responsible for substantial juvenile mortality, and that this was likely the major factor stabilizing the dense and generally healthy deer herd on the refuge. Speculation has arisen concerning the fate of white-tailed deer fawns in other portions of South Texas. On th Ki g Ranch in Kleberg County the deer population is maintained at around 3-6 deer per 100 acres (40.5 ha) (Kiel, unpublished data). On other areas of the Rio Grande Pla n of South Texas an average of 3.5-5.5 deer per 100 acres exists (Harwell and Kierce 1972), whereas on the Welder Refuge pproximately 15-18 deer per 100 acres are fo nd (Cook et al. 1971). The deer population in much of the Central Mineral Region of Texas also approximates 18 per 100 acres (Teer et al. 1965). Teer et al. (1965) found average embryo counts for adult white-tailed deer to range from 0.96 to 1.29, whereas yearlings averaged 0.75. Average embryo counts of adult 1 Research supported by the Caesar Kleberg Research Program in Wildlife Ecology through the Texas Agricultural Experiment Station. 854 J. Wildl. Manage. 38 (4):1974 This content downloaded from 157.55.39.163 on Sun, 20 Nov 2016 04:24:27 UTC All use subject to http://about.jstor.org/terms PREDATOR REMOVAL AND DEER o Beasom 855 deer in South Texas have been found to range between 1.24 and 1.81 per doe (Barron and Harwell 1973). Illige (1951) found an average production of 1.28 embryos per doe (adults and yearlings) in a county adjoining the present study area. Postpartum fawn:doe (including adults and yearlings) ratios in Kleberg County, South Texas, however, are rarely greater than 0.3 (Kiel, unpublished data). Evidence suggests that the relatively low whitetail net productivity is a result of high fetal or early postnatal mortality. This study originated as part of a more intensive study on Rio Grande wild turkeys (Meleagris gallopavo intermedia). It was designed to investigate the effects of predator removal on net productivity of both the turkey and white-tailed deer. Gratitude is extended to W. H. Kiel, Jr., biologist, King Ranch, Inc. who provided advice and assistance throughout the study. The enthusiastic field support of D. A. Stiles, J. C. Hutchinson, W. A. Sandifer, H. H. Haucke, R. G. Sims, R. L. Mitchell, and F. S. Guthery during certain phases of the project is gratefully appreciated. E. D. Ables offered many helpful suggestions on the preparation of the manuscript.

Vegetation responses to 2 brush management practices in south Texas.

Brush management for improving wildlife habitat in South Texas is important because of the economic value of wildlife. We determined vegetation responses to (1) roller chopping of guajillo (Acacia berlandieri Benth.)-blackbrush acacia (A. rigidula Benth.)-dominated rangeland and (2) heavy discing of whitebrush (Aloysia lycioides Cham.)-dominated rangeland to improve white-tailed deer (Odocoileus virginianus Raf.) habitat. Canopy cover of vegetation was estimated seasonally during August 1988 to April 1990. Both treatments reduced brush canopy cover, but herbaceous response depended on rainfall. Mean herbaceous cover was 65 and 136% higher on roller chopped sites than on untreated sites when averaged across all sampling dates. Heavy discing reduced relative canopy cover of whitebrush but increased cover of spiny hackberry (Celtis pallida Torr.), an important browse species. Forb species richness was higher on roller chopped and disced sites than on untreated sites, but species diversity was similar. Because herbaceous response to brush removal may depend on rainfall, other factors such n effects on browse availability and nutritional quality may need to be considered when planning brush management strategies to improve white-tailed deer habitat.

Long-term effects of root plowing on vegetation in the eastern south Texas plains

The long-term effects of root plowing in plant communities in south Texas are not clearly understood. Our objective was to compare plant species composition and diversity on root-plowed rangelands and untreated rangelands. Two rangeland sites that were root plowed during 1973-74 and 2 sites of native, untreated brush were selected on the Santa Gertrudis Division of the King Ranch, Kleberg and Jim Wells counties, Texas. Woody plant canopy cover was estimated with the line intercept method, and density was estimated with 20-X 1-m plots during 1990. Herbaceous canopy cover was estimated with 20 X 50-cm quadrats. Percent grass, lifter, and bare ground coverage were similar on root-plowed and untreated rangelands. Woody plant species and diversity averaged 19 +/- 2 species/ treatment (average +/- SE) and 2.56 +/- 0.15 on untreated areas compared to 7 +/- 1 species/treatment and 1.18 +/- 0.01 on root-plowed areas. Forb canopy coverage on root-plowed sites was about twice that of untreated sites. Huisache (Acacia smallii Ilsey) canopy cover and density were both more than 7-fold greater on root-plowed sites than on untreated sites. Browse species preferred by white-tailed deer (Odocoileus virginianus Raf.), such as colima [Zanthoxylum fagara (L.) Sarg.] and guajillo (Acacia berlandieri Benth.), were absent on root-plowed sites.

Effects of root plowing on white-tailed deer condition, population status, and diet

Determining the effects of plant community changes on animal populations is an important area of ecological research. We compared condition, population characteristics, and diet composition of white-tailed deer (Odocoileus virginianus) from 2 root-plowed (low brush diversity) and 2 untreated (high brush diversity) sites in the eastern Rio Grande Plains of Texas to test the hypothesis that root plowing, which decreases woody species diversity-, reduced deer habitat quality. We collected 8 adult female white-tailed deer from each site every 3 months for 6 sampling periods. We assessed condition from several physiological, reproductive, and digestive indices and determined food habits by microhistological analysis of rumen samples. We estimated population size from helicopter surveys

CEREBROSPINAL NEMATODIASIS CAUSED BY Parelaphostrongylus tenuis IN ANGORA GOATS IN TEXAS1

A natural infection of meningeal worm (Parelaphostrongylus tenuis) accounted for the death of 11 of 17 (65%) Angora goats in a study in South Texas during 1975. Clinical signs, gross pathology and histopathology in Angoras were similar to other abnormal hosts.

Effects of predator control on Angora goat survival in south Texas.

Highlight: Predator control was conducted in South Texas during January-July 1975 and 1976 to determine its effects on productivity and survival of Angora goats. The control effort, when compared to an area receiving no treatment, reduced activity of coyotes and bobcats by 80%. Predators, mainly coyotes, killed 33 and 16% of the known kid crop on untreated and treated pastures, respectively. Because predators apparently were responsible for most unknown losses, the true predation loss was as high as 95 and 59%, respectively, of the known kid crop. The net kid crop under intense predator control was 27 times greater than that under no control, but the crop under treatment was only 13.5% because predation losses were still high. Coyotes killed 49 of 204 nannies (91% of losses) in an untreated pasture. They killed none in a treated pasture, but 10% of 205 nannies succumbed to nonpredator mortality. The data indicate that, in regions of high coyote density, intense localized predator control with traps, snares, and M-44’s could curtail predation on adult goats, but would be insufficient to prevent heavy losses of kids.

White-tailed deer use of rangeland following browse rejuvenation

Mechanical top growth removal of certain shrub species stimulates sprouting and temporarily increases nutritional quality, availability, and yield of browse. We determined the effects of (1) roller chopping separate portions of rangeland, dominated by guajillo (Acacia berlandieri Benth.) and blackbrush acacia (A. rigidula Benth.), during consecutive years and (2) disking separate portions of rangeland, dominated by dense whitebrush (Aloysia lyciodes Cham.) thickets, during consecutive years on white-tailed deer (Odocoileus virginianus Raf.) use of the treated areas. Separate, adjacent portions of guajillo and blackbrush acacia-dominated rangeland were roller chopped in a pattern of alternating treated and untreated strips each year during summer for 4 consecutive years (1985-1988) on an area in Duval County, Tex., and for 2 years (1988-1989) on areas in Duval and McMullen counties, Texas. Whitebrush-dominated rangeland was disced in a similar pattern during 2 years (1988-1989). Twenty percent of each study site was treated each year. Estimated deer density in the roller-chopped area in Duval County was higher than estimated deer density in an untreated area during 1985-1987 and in 1989. Roller chopping in study areas in Duval and McMullen counties increased deer fecal pellet-group densities (groups ha-1 day-1) relative to untreated sites in winter, spring, and summer 1989 and when averaged over the 21-month study. Discing dense whitebrush-dominated sites increased pellet-group densities relative to untreated sites in spring and summer 1989 and when averaged across the 21-month study period. Increased deer use of treated areas was probably a function of several factors, including increased forb availability and increased nighttime visibility for predator detection.

Turkey Productivity in Two Vegetative Communities in South Texas

Differences in productivity of the Rio Grande turkey (Meleagris gallopavo intermedis) between mesquite (Prosopsis juliflora) and live oak (Quercus virginiana) vegetative communities on the King Ranch in South Texas were investigated from June 6, 1968, to January 3, 1969. The average brood size in August for the mesquite area, as determined from 1,720 poult observations, was 6.9, while 721 poult observations on the live oak area revealed an average brood size of 4.6 The overall poult: hen ratios at this same ffme were 4.7 and 2.6 while the hens seen without poults xrere 31 and 40 percent respectively. The August productivity, or percent of increase in the population due to reproduction, was 336 percent for the mesquite area and 159 for the live oak. The November, or pre-hunting season productivities were 315 and 129 percent. Poult mortality for the 13-week period, between 2 and 15 weeks of age, was calculated to be 22.9 percent for the mesquite area and 12.1 for the live oak. A helicopter census yielded a calculated density of 56 turkeys per 1,000 acres on the mesquite area and 51 on the live oak. Road counts revealed overestimations of these densities ranging from 95-193 percent. Turkey productivity on the King Ranch in South Texas has fluctuated tremendously from year to year. In years of normal precepitation, production has been good, whereas in dry years there has been almost no production of young turkeys ( W. H. Kiel, Jr., personal communication). There are several possible ecological explanations for this situation, all of which may be related to the limited vegetation during dry years. An assessment was made of the turkey productivity in two vegetative communities, mesquite and live oak. This assessment, in two different environments, explored some of the ecological causes of poor turkey productivity. Field work was carried out from June 8, 1968, to January 3, 1969. Turkey densities on the King Ranch have been reported as being considerably greater in live oak than mesquite (Lehmann 1957 ) . In order that the live oak areas maintain higher turkey densities, there must be, through time, either higher productivity, survival, immigration, or some combination of these factors. 1 Research was supported by King Ranch, Inc., University of Wisconsin, and the Ceasar Kleberg Wildlife Foundation. 166 I gratefully acknowledge W. H. Kiel) Jr.7 biologistv King Range, Inc., and R. A. McCabe of the University of Wisconsin for advice, assistance, and editorial help throughout this project. O. J. Rongstad of the University of Wisconsin, provided suggestions in preparing the manuscript.

Hookworms in South Texas Coyotes and Bobcats

Hookworm (Ancylostoma caninum) ova were found in 89.3 percent of the fecal samples of 75 coyotes (Canis latrans) and 97.7 percent of 44 bobcats (Lynx rufus) in the present South Texas study. Examination of field-collected scats of these two species showed 90.4 percent hookworm infestation in coyotes and 91.9 percent in bobcats. The degree of hookworm parasitism in these South Texas coyotes and bobcats, and the severity of hookworm infestations in many young host animals, suggest that hookworms could account for some of the natural mortality in wild populations of coyotes and bobcats. J. WILDL. MANAGE. 38(3):455-458 Hookworms occur in almost all suitable regions of their tropical and subtropical distribution (Miller 1971). These parasites are commonly found in dogs, cats, and other closely related carnivores. Hookworm infection is more severe in pups than adults, with the more visible characteristic symptoms being progressive anemia, emaciation, hemorrhagic diarrhea, and general weakness, sometimes resulting in death. The parasites action is on the wall of the small intestine where it periodically attaches to suck blood and then releases to move to another site. A loss of blood ranging from 0.07 ml to 0.12 ml per worm per day occurs both from the hookworms feeding and the abandoned oozing wound (Clark et al. 1961). Wells (1931), however, reported blood losses as high as 0.8 cc per worm per 24-hour period. Infection may occur by ingestion or cutaneous penetration (Morgan and Hawkins 1960:227), in utero by placental migration (Clapham 1962), or via the colostrum (Stone 1966). Hookworm infestations have been reported in populations of wild animals in several parts of North America. Olsen (1958) reported that hookworms (Uncinaria lucasi) were responsible for a rather high mortality of young fur seals (Callorhinus ursinus) on the Pribilof Islands. Hookworms have been reported in 33 percent of 66 coyotes sampled in Michigan (Dunatchik 1967), 25 percent of 1,850 Kansas coyotes (Gier and Ameel 1959), and 3.2 percent of 61 coyotes examined in Minnesota (Erickson 1944). Of 15 bobcats examined by Miller and Harkema (1968) in the Carolinas, 33 percent were infected with Ancylostoma caninum and 20 percent with A. braziliense. Little et al. (1971) found A. caninum in all seven bobcats checked from South Texas but in none of two West Texas bobcats. In general, the reported infestation rates per animal are relatively low but this is of little consequence since pregnant females acquiring light infestations can produce heavily infected young. The purpose of the present study was to establish the degree of hookworm infestation in wild populations of coyotes and bobcats in a portion of South Texas. This research was supported financially by the Caesar Kleberg Research Program in Wildlife Ecology through the Texas Agricultural Experiment Station, College Station, and the King Ranch, Inc. Thanks are extended to R. G. Sims, Field Assistant, U. S. Fish and Wildlife Service, for providing many of the animals used in the present study. B. A. Fall, Department of Wildlife and Fisheries J. Wildl. Manage. 38 (3):1974 455 This content downloaded from 207.46.13.168 on Sat, 09 Apr 2016 06:36:17 UTC All use subject to http://about.jstor.org/terms 456 HOOKWORMS IN COYOTES AND BOBCATS * Mitchell and Beasom Sciences, Texas AM R. B. Davis, Biology Department, Texas AM and J. P. Smith, Department of Veterinary Parasitology, Texas A&M University, are gratefully acknowledged for critically reading the manuscript.

Fecal pH of Pronghorn and Sheep as Related to Diet

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