Showing papers on "Habitat destruction published in 1986"

Synthesis and Evaluation

Abstract: What has been depicted in the preceding chapters is a portrait of the Hudson River under somewhat haphazard management. Three distinct types of threats to the Hudson ecosystem were at issue, representing direct reductions of animal populations (power plant operation), removal of toxic substances (PCB pollution), and habitat destruction (Westway construction). Each situation that we have chosen to study has had the same characteristics: 1) scientific investigations have been used to help gather information, to clarify phenomena, or to explain effects; 2) none of the findings have gone unchallenged; so that 3) aspects of all of these impacts have gone to trial; and 4) action, if any, has proceeded by court edict more often than not.

The ecology and management of the gopher tortoise in the southeastern united states

Abstract: Recent research on the gopher tortoise (Gopherus polyphemus) has indicated its ecological importance, revealed reasons for its decline, and suggested management strategies. It is generally associated with the sandhill community but occurs in a variety of other natural and ruderal habitats. Limiting factors include well-drained sandy soil, adequate herbaceous food, and sunlit nesting sites. Tortoise densities and movements are related to herbaceous biomass. As the principal sandhill grazer, the gopher tortoise serves as a seed dispersal agent for native groundstory plants. The burrowing habits of the gopher tortoise return leached nutrients to the surface and the burrows provide refuges for many other species. Female gopher tortoises reach sexual maturity at 10-20 yr of age and produce a single annual clutch of about six eggs. Recruitment is reduced by heavy egg and hatchling predation. The major reasons for the decline of the gopher tortoise are habitat destruction, habitat degradation, and human predation. Recommended conservation mea- sures include prescribed burning of sandhill habitat, establishment of preserves, protection from over-harvest, restocking, and public education.

Responses of long-tailed macaques to drought and fire in eastern Borneo: a preliminary report

Abstract: During a 20-month study that spanned a severe drought and forest fire in a Bornean rain forest, a group of long-tailed macaques adapted successfully in the short term to extreme habitat damage by shifting to less preferred food items and exploiting an insect outbreak while fruits and flowers were scarce. Charred and desiccated fruits were major food sources just before the insect outbreak. The group dispersed widely to forage and increased its terrestrial travel. Riverine refuging became more erratic late in the drought and after the fire. The continued presence of sizable populations of this and other diurnal primate species, relative to those of some other frugivores with fixed home ranges and more restricted diets, suggests that dietary breadth is an important factor mediating frugivore responses to habitat degradation. FROM JUNE 1982 THROUGH MAY 1983, the El Ninio Southern Oscillation caused drought and forest fires in East Kalimantan, Indonesia (eastern Borneo), severely damaging approximately 3 million ha of evergreen forest, including large tracts of swamp forest, peat forest, and both selectively logged and undisturbed lowland rain forest (Anonymous 1984, Leighton & Wirawan, in press). My field study of the behavioral ecology of long-tailed macaque monkeys (Macacafascicularis) in the Kutai National Park, conducted from January 1982 through September 1983, spanned the entire drought, fire, and a 5month post-fire period, enabling me to record the responses of one group of macaques to drastic ecological change. In this paper I describe some of the monkeys' feeding and ranging responses. Leighton and Wirawan (in press) provide a general account of the effects of drought and fire on Kutai flora and fauna.

The orang-utan in Sabah

Abstract: A survey of orangutans in Sabah, Borneo, which was carried out by the author and John Payne, resulted in an encouraging picture. In the primary forest of eastern Sabah alone, there are at least 4000 orangutans, but habitat destruction is fragmenting the population. Hunting is also common, especially in the central and western areas where orangutans are already scarce. Some orangutans are protected in conservation areas, but the future of the species outside these places depends on logging being carried out in a more conservation-oriented way. Among other things, we need to discover the size of primary-forest patches that need to be left in logged forest to support a viable population of orang-utans, which will be able to recolonize the logged forest as it regenerates.

Small mammals in modified pinyon-juniper woodlands, New Mexico.

Abstract: The effects of pinyon (Pinus edu#s)-juniper (Juni@rus spp.) treatments on rodent abundance, 13 to 18 years after treatment, were studied in southwestern New Mexico from 1981 to 1983. Treatments included bulldozing, bulldozing/piliig/burning, tbinning, and untreated woodland. The area bad not been grazed by livestock since time of treatment but was subjected to light and irregular use by wild ungulates. Total rodent numbers were significantly greater (PZO.05) on all treated areas compared to untreated woodlands but individual species and groups responded differently. Woodrats (Neotoma spp.) and brush mice (Peromyscus boy/ii) increased in abundance as slash accumulations increased, regardless of condition of overstory. Pinyon mice (P. truei) and rock mice (P. difficilus) numbers were also greater where slash was present, but only if the pinyon-juniper overstory was relatively intact. Grassland rodents, as a group, were more abundant on areas where the pinyonjuniper overstory and slash bad been removed (bulldozed and bulldozed/piled/burned), but reduced numbers on bulldozed plots where slash was left suggested slash accumulations may have detrimental effects on numbers of these species. Treatments did not influence number of different rodent species. Data indicate that numbers of individuals and proportions of rodent species can be affected by manipulation of pinyonjuniper overstory and method of slash disposal. Pinyon-juniper (Pinus edulis-Juniperus spp.) woodlands occupy 20.5’30 and 18.0% of the land surface in Arizona and New Mexico, respectively (Short 1979). Mechanical methods such as chaining and bulldozing have been used to control large tracts of these woodlands (Springfield 1976) and generally have resulted in increased herbage production, but effects on wildlife habitats have been variable (Severson and Medina 1983). Studies on effects of pinyon-juniper treatments on small mammals include the following: cottontails (Sylvilagus audubonii) (Kundaeli and Reynolds 1972) and white-throated woodrats (Neotoma albigulu) (Turkowski and Watkins 1976) in New Mexico, and several species of small mammals in Utah (Baker and Frischknecht 1973, Smith and Urness 1984); Colorado (O’Meara et al. 1981); and Arizona (Turkowski and Reynolds 1970, Kruse et al. 1979). Most were conducted on areas grazed by livestock, and time intervals between treatment and study dates varied from 1 (Turkowski and Watkins 1976) to 25 years (Kruse et al. 1979). The objective of this study was to test the hypotheses that there were no differences in number of rodent species, total individuals, and number of individuals of selected species and species groups on untreated pinyon-juniper woodland compared to woodlands subjected to mechanical control practices 13 to 18 years after treatment. Study Area and Methods The study was conducted on the Fort Bayard Allotment, Gila National Forest, 16 km east of Silver City, New Mexico. Important trees and shrubs include pinyon, one-seed juniper (Juniperus monosperma), alligator juniper (J. deppeana), gray oak (f&ercus Author is research wildlife biologist, USDA Forest Service, Rocky Mountain Forest and Range Experiment Station. Research was conducted at the Station’s Research Work Unit in Tempe, Ariz., in cooperation with Arizona State University. Station headauarters is in Fort Collins. Cola. Author woidd like to thank personnel of the Gila National Forest and the New Mexico Game and Fish Department for their assistance throughout the study and Dr. Bruce Hayward, Western New Mexico University, for identifying and weighing specimens. Special thanks are extended to Mary Gilbert and Gary Helbing for their assistance with collections. Manuscript accepted 30 April 1985. JOURNAL OF RANGE MANAGEMENT 39(l), January 1988 g&a), and hairy mountainmahogany (Cercocarpus breviflorus). More than 30 grass species occur on the allotment but two-thirds of the perennial grass production is from blue grama (Boutelouu gracilis) and sideoats grama (II. curtipendulu). Over 50 species of forbs have been identified, but no single species is dominant. Common forb genera include globemallow (Sphaerulcea spp.), goosefoot (Chenopodium spp.), and buckwheat (Eriogonum spp.) (Kundaeli and Reynolds 1972). Upland soils are primarily Lithic and Lithic Vertic Haplustolls while Aquic Haplustolls are common in lowland areas (Unpulished data, A.L. Medina, Rocky Mountain Forest and Range Experimental Station, Tempe, Ariz.). Elevation ranges from 1,806 to 2,070 m. Annual precipitation averages 393 mm, 55% of which falls as rain from July through September. Annual precipitation for 198 1,1982, and 1983 was 427, 332, and 454 mm, respectively. Mean annual temperature is 12.8 OC, with mean monthly extremes of 3.5 “C (January) and 22.6 “C (July). Weather records are from Fort Bayard State Hospital on the southern edge of the study area. The Allotment is part of the Fort Bayard military reservation which was established in 1869. Yearlong, excessive use by livestock resulted in deteriorated range conditions in 1937 when all livestock, except for a few pack and saddle animals, were removed (Reynolds 1964). The pinyon-juniper control treatments described in the following paragraph were established as part of a mule deer (Odocoileus hemionus) and elk (Cervus elaphus) habitat study. The areas used in the rodent study described herein have not been grazed by livestock since the treatments were applied. The military reservation, however, is within the range of 90 to 120elk, about 100 mule deer, and about 75 white-tailed deer (Odocoileus virginianus). The area used for this study was approximately 10% of the entire reservation and use by wild ungulates was probably proportional. Pinyon-juniper treatments were randomly established in each of 2 blocks. The lower block, at an elevation of 1,880 to 1,935 m, was treated in 1965 and the upper block, 1,935 to 2,040 m, in 1970. Treatments included (1) thinning (pinyon and junipers were cut to a minimum spacing of 6.1 m and left in place); (2) bulldozing (all pinyon and junipers were pushed over with a bulldozer and left in place); (3) bulldozing/piling/ burning (trees were pushed and piled with a bulldozer, then burned); and (4) undisturbed woodland. All treated plots were approximately 120 ha. During September 198 1, each plot was divided into 6 sampling areas and a set of 2 transects was randomly placed in each. Each transect consisted of 17 trapping locations spaced 10 m apart. Each location consisted of 2 traps, a standard rat trap, and a museum special. Trapping was conducted during the second and third weeks of September each year. Traps were baited with a mixture of peanut butter, oatmeal, and an ant repellent, dimethylpthalate (Anderson and Ohmart 1977). Traps were run in one transect within each plot segment in 1981, the other in 1982, and the first transect again in 1983. Because of the time required to check and bait traps only 3 transects were run within each treatment for 4 consecutive days; then the traps were moved to 3 other transects and run for the next 4 consecutive days. Traps were left open for 24-hour trap sessions and were checked daily. Each of the 8 treatment areas received 8 16 trap-days effort per year. Captured individuals were tagged, placed in plastic bags, and frozen; then identified and weighed as time permitted. Rodent data were analyzed with 3-factor analyses of variance (blocks, years, and treatments) with 6 observations per cell. Each

Herpetofaunal use of a desert riparian island and its adjacent scrub habitat

Abstract: The restriction of water flow in 1959 in Queen Creek in Whitlow Ranch Dam, Pinal County, Arizona, has caused the development of a 15-ha riparian island upstream behind the dam. The herpetofaunas of the riparian interior, riparian edge, desert wash, and upland habitats were sampled to assess the value of this type of development for mitigating continued losses of riparian habitat. Total species richness was 4 in the riparian interior, 7 in the riparian edge, 14 in the desert wash, and 15 in the desert upland. Many of the locally expected riparian species were absent. The lack of invasion by typical riparian species probably results more from biogeographic considerations and flooding patterns than from structural and physical conditions of this newly formed riparian habitat. Regression models for species abundance emphasize the importance of using floristic information rather than summary variables in developing animal-habitat relationships. J. WILDL. MANAGE. 50(4):752-761 Riparian vegetation supports some of the richest terrestrial vertebrate faunas in the arid Southwest (Carothers et al. 1974, Brown et al. 1977). The dependence of many bird species on riparian plant assemblages has been well documented (Szaro 1980, Ohmart and Anderson 1982). Other riparian fauna-flora relationships are less well known, but there doubtless are mammalian, reptilian, and amphibian species that also depend on riparian zones (Hubbard 1977). Reptiles and amphibians have received relatively little attention with respect to the importance of riparian habitats to their distribution, density, and diversity. Jones (1981a) and Vitt et al. (1981) reported on faunal richness and abundance for riparian communities of reptiles and amphibians, but compiling species lists remains primarily guesswork in most areas. Data resulting from government-sponsored inventories frequently go unpublished or are available only in unreviewed report form (Scott and Campbell 1982). Although some literature is available on habitat requirements of single species or small species groups in riparian habitats (Vitt and Ohmart 1974, van Loben Sels 1976, Vitt et al. 1981, Tinkle 1982) more sitespecific distribution and species-specific habitat use data in riparian situations are needed. Unfortunately, human activities of the southThis content downloaded from 157.55.39.181 on Thu, 29 Sep 2016 05:36:27 UTC All use subject to http://about.jstor.org/terms J. Wildl. Manage. 50(4):1986 DESERT RIPARIAN HERPETOFAUNA * Szaro and Belfit 753 western United States have resulted in degradation of critical wildlife habitat particularly in riparian zones (Patton 1977). Recent studies emphasize the importance of watershed vegetation management and flood control dams for subsequent development of riparian vegetation and their impact on riparian bird populations (Szaro 1981; Szaro and Jakle 1982, 1985). The development of riparian vegetation above and below dams and the creation of artificial oases along canals or other water developments are options available to habitat managers for mitigation of the continued loss of riparian habitat. Primary purposes of this study were to: (1) develop habitat models for reptile and amphibian species abundance, (2) determine the utility of summary variables such as diversity indices and single measures of plant community components such as low or high shrub cover in predicting species abundance, (3) determine the response of a Sonoran Desert herpetofauna to vegetative changes resulting from a flood control dam, (4) determine if there was a subsequent invasion of riparian-dependent species, and (5) determine the mitigation potential of a flood control structure for the habitat degradation of those areas with rich riparian herpetofaunas. Data also were gathered on community composition and species habitat preference in comparison with other riparian areas. We thank R. B. Bury, J. Collins, K. B. Jones, and R. King for their thought-provoking reviews of this manuscript. Special thanks to J. D. Gomez for her help in preparing this manu-

Returns and Winter-Site Fidelity of North American Migrants Banded in Belize, Central America

Abstract: The rapid destruction of Central and South American forests is causing concern over the potential impact of deforestation on North American migrant birds that winter in these areas (see Rappole and Morton 1985,and Terborgh 1980, for discussion and references). A t least 49 of these migrant species, which spend a majority of the year in the tropics,demonstrate winter-site fidelity (McNeil 1982, see Loftin 1977 for summary of species), and thus may be particularly sensitive to habitat destruction. Studies of winter-site fidelity in the Neotropics to date have been widely dispersed geographically and most have not compared results between sites which have been subjected to differing degrees of human disturbance. We report returns from wintering North American migrants banded at three study sites in Belize, Central America, each of which has been subjected to different degrees of human disturbance

Arabian ungulates—their status and future protection

Abstract: Ungulate populations are at a low ebb in Saudi Arabia. Indiscriminate hunting and habitat degradation are the main factors causing population declines in three of the five endemic species. The author collected information on the status of these animals while working as a wildlife ecologist for the Food and Agriculture Organization of the United Nations in the northern province of Al-Jouf.

Conservation Planning in a Checkerboard World: The Problem of Size of Natural Areas

Abstract: In addition to outright habitat destruction, selective removal of certain species (e.g. whaling), introduction of exotic species and wholesale application of toxic substances and other chemicals to the environment, one of the major ways in which people are affecting the biology of the planet is through fragmentation of natural landscapes (Da Costa Lobo, Chapter 3; Burgess and Sharpe, 1981). This has a pervasive effect throughout the terrestrial portion of the globe and probably occurs, but to a much more limited extent, in the benthic portions of freshwater and marine habitats.

An ecological model of the effects of exotic factors on limiting Hawaiian honeycreeper populations

Abstract: The object of this study was to construct a quantitative model to compare the effect of several exotic factors on limiting natural populations. The effect of habitat loss, range loss due to avian disease, feral ungulate activity, and interspecific competition for food resources from exotic birds on 33 populations of 16 Hawaiian honeycreeper species was examined. The impact of the four limiting factors was characterized in terms of the percent reduction in range or population density. Habitat loss resulted in a 74% average reduction in the original range; probable range loss due to disease averaged 46% of the available habitat; and feral ungulates and exotic birds lowered honeycreeper population densities by an average of 22% and 9%, respectively. The combined effect of the four limiting factors, which was modelled as their multiplicative product, represented an average loss of 89% in potential population size due to their operation, and accounted for 75% of the variation in present population sizes. OHIO J. SCI. 86 (3): 095-100, 1986 INTRODUCTION The relative importance of factors that limit the size of animal populations is a special concern in wildlife management (Leopold 1933). Attempts to quantify the relative roles of various factors have generally focused on detailed life history studies of individual species through techniques such as key factor analysis (Williamson 1971). In this paper I will develop a quantitative model to compare the relative effects of limiting factors of exotic origin on populations of the Hawaiian honeycreepers (Drepanidinae). The Hawaiian honeycreepers have a spectacular range of morphological and behavioral adaptations to feed on foliage insects, timber-boring insects, nectar, fruits, seeds, molluscs, and seabird eggs (Amadon 1950, Berger 1981). Unfortunately, excessive perturbation from exotic elements to native Hawaiian ecosystems has created the highest concentration of endangered birds in the world (King 1978). Extant honeycreepers (Table 1) represent only 30% of the species present at Polynesian contact ca. 400 A.D. (Olson and James 1982); 14 of the 20 extant species are protected under the Endangered Species Act of the United States. Due to limited funding, identifying the relative roles that various exotic factors play in limiting honeycreeper populations is a crucial step in efficiently managing the recovery of endangered species. Numerous exotic factors have been suggested as contributing to the decline of honeycreeper populations, including habitat loss due to human activity (Olson and James 1982, Berger 1981), gradual habitat degradation due to feral ungulate activity (Scott et al. 1986), avian disease (Warner 1968, van Riper et al. 1982), food competition from exotic birds (Mountainspring and Scott 1985), predation from rodents and carnivores (Perkins 1903, Atkinson 1977), invertebrate predators on the food base (Banko and Banko 1976), exotic plant invaders (Smith 1985, Scott et al. 1986), and wildfire in dry habitats (Tomich 1971). In this paper the effect on natu^anuscript received 11 October 1985 and in revised form 24 February 1986 (#85-48). ral populations of habitat loss, avian disease, feral pig (Sus scrofa) activity, and food competition from the Japanese White-eye (Zosterops japonicus) will be modelled quantitatively for the honeycreepers inhabiting the islands of Hawaii, Maui, Molokai, Lanai, Oahu, and Kauai. Inclusion of the last two factors in the model is well justified. In the wetter forests that most honeycreepers inhabit, the chief habitat modifier at present is the feral pig, whose rooting and wallowing activities drastically modify understory and eventually canopy composition (Tisdell 1982). The analysis of interspecific competition for food resources focuses on the Japanese White-eye because this abundant and omnivorous species appears to have the greatest impact of exotic birds on honeycreeper populations (Mountainspring and Scott 1985). THE QUANTITATIVE MODEL Shelford (1913) was the first to articulate the Law of Tolerance, stating that given a series of factors that operate independently to reduce a population from its potential, the combined effect of these factors can be characterized as their multiplicative product. A similar multidimensional conceptualization is found in the niche theory of Hutchinson (1958) and Whittaker et al. (1973). This concept provides the basis for the mathematical development below. Let Fx be the effect of factor 1 on reducing the population of a species. A value of 0.1 would signify that the population is reduced 10% due to the operation of factor 1. Let F2..N represent the effect of factors 2 through N, with each Fk constructed so as to account for the operation of Fu . . . ,Fk-i (i.e., the factors are orthogonal). The fraction of the population remaining after accounting for the operation of Fk is thus 1 — Fk. The fraction of the potential population remaining after the combined effect of all factors is considered will be termed the Remaining Potential Population (RPP). This value is computed as the percent of the original population predicted to remain to permit comparison between species with different carrying capacities and is given by: 96 S. MOUNTAINSPRING Vol. 86

Threats to Unique Wildlife Through Indian Habitat Destruction

Abstract: Over the years, the problems facing conservation have changed. The 20th century has been characterized by two pertinent traits—concern for wildlife and the explosive growth of human population—both destined to loom larger and larger as the century progressed. As an example, the soaring demands for food, timber, and housing, have led to the destruction of the natural abode—the forests of Gujarat—of much of the beautiful Indian wildlife.

Of tbb causes of fluctuation in fishery stock sizes time series regrbssion methods for the evaluation

Abstract: The resent aper constitutes a preliminary report on tfe formufation and development of statistical approaches to partition the effects of fishing mortality, natural mortality and pollutlon mortality caused by habitat degradation on fishery stocks in estuarine waters. The selected approaches bass in the Potomac river. are illustrated using a data set involving striped