Intensive Hunting Research Articles

Breeding and rearing the Orinoco crocodile Crocodylus intermedius in Venezuela

Intensive hunting in the first part of this century placed the Orinoco crocodile Crocodylus intermedius in immediate danger of extinction. We studied the potential for enhancing populations through captive rearing. In an area of 35 000 m 2 seven enclosures were developed with six earthen and eight concrete ponds. In two years' operation a hatching rate of 72·4% and a hatchling survival rate of 42% were obtained. In the first year males attained an average total length of 745 mm and females 620 mm. In the second year average total length was 1362 mm and 1111 mm, respectively. Seasonal changes in growth and the influence of climatic conditions in mortality are discussed. Captive breeding and rearing appears to be an appropriate conservation strategy for this species.

Chronology of Autumn Migration by Greater Snow Geese

We wanted to know if migration chronology of greater snow geese (Chen caerulescens atlantica) is affected by the intensive hunting pressure and crowded conditions prevaling on their staging grounds in Canada. Consequently, we neckbanded 2,150 individuals to study the chronology and rate of autumn migration in the St. Lawrence estuary from 1985 through 1987

Relationships between allozymes, heterozygosity and morphological characters in red deer (Cervus elaphus), and the influence of selective hunting on allele frequency distributions

Morphological characters in red deer (Cervus elaphus), which serve as criteria for selective hunting, were examined in relation to electrophoretic variation in three populations from the Vosges in eastern France. From the polymorphic loci examined, certain alleles at Idh-2, Me-1 and Acp-1 showed significant associations with a special development of body and antler characters selected for by hunters. Idh-2(125) was associated with larger hind foot length in females and a higher number of antler points in males. Me-1(90) and Acp-1(100) were associated with small spikes. The populations studied differed from one another in the duration and intensity of selective hunting and the increase or decrease in the respective allele frequencies could be explained by selection for large body size, a high number of antler points and against small spikes in yearlings, rather than by genetic drift. Among other morphological characters examined, the length of the main beam was significantly associated with the allele Acp-2(100). In contrast, no associations could be detected between overall heterozygosity and the development or the degree of asymmetry (in paired structures) of any of the morphological traits in question. Although no obvious differences in the overall values of polymorphism or heterozygosity were found between the populations, selective hunting leads towards a change in allele frequencies and eventually to the loss of one or the other rare allele.

The changing otter population of Britain 1700-1989

Otters Lutra lutra were persecuted increasingly in Britain for fishery protection and for sport throughout the 18th and 19th centuries. There are indications of a population recovery occurring during the 1914-1918 war with the temporary cessation of hunting and keepering. Intensive otter hunting with packs of hounds throughout the 1920s and 1930s appears to have stressed the population by altering the age structure. A catastrophic decline occurring simultaneously over England, Wales and southern Scotland, but most severe in the south-east and starting in 1957-1958, appears to have been triggered in this stressed population by a single new factor, pollution of the rivers by organochlorine insecticides. The trough in the decline may have occurred around 1977-- 1979. The first signs of rivers being re-occupied by otters have been seen by the early 1980s and partial recovery seems possible with legal protection and improved water quality.

Demography of the George River Caribou Herd: Evidence of Population Regulation by Forage Exploitation and Range Expansion

The George River caribou herd in northern Quebec/Labrador increased from about 5000 animals in 1954 to 472,200 (or 1.1 caribou/km) prior to the 1984 calving season. The range used by the herd expanded from 160,000 to 442,000 sq km for the period 1971-84. The exponential rate of increase (r) was estimated at 0.11 in the 1970s. Calf:female ratio in autumn was relatively constant (x=0.52) from 1973 to 1983, but decreased to about 0.39 in 1984-86. The harvest rate was relatively low in the 1970s (about 3%/y), but seemingly increased in the mid-1980s to 5-7% as a result of more liberal regulations and a greater impetus to exploit caribou for subsistence. The cumulative impact of lower calf recruitment and more intensive hunting may have appreciably depressed the growth rate of the herd in 1984-86. A greater year-round competition for food resources and a greater energy expenditure associated with range expansion are presented as probable regulatory factors for the George River herd. It is argued that the nature of caribou-habitat interactions in continental regions generate long-term fluctuations in caribou numbers if human exploitation remains low. At present, wolf predation does not appear to be an important mortality factor capable of regulating the George River herd.Key words: caribou, population regulation, food limitation, northem Quebec, Labrador, wolf predation

FUR TRADE IN THE ECONOMY OF SIBERIA IN THE 17TH CENTURY

The author, a historian, analyzes the role of the sable fur trade in the economy of 17th-century Siberia on the basis of fur tribute and fur tithe returns from the region of most intensive hunting (principally Mangazeya, Yeniseysk, Ilimsk, and Yakutsk Counties) from the 1620s through the 1680s, when hunting by Russians was banned. He compares the dynamics of sable hunting in Mangazeya and Yakutsk Counties and in Yeniseysk and Ilimsk Counties. During the 70-year period Mangazeya and Yakutsk Counties each accounted for one-quarter of the total sable take, but the Yakutsk sables were more valuable. The state was responsible for slightly less than one-half of the total catch. The value of the fur catch was three to four times greater than that of the grain harvest, but fur trading was more rapacious and less long-lasting than farming. (The translation was prepared by James R. Gibson of York University, Toronto.)

A survey of the Southern River otter Lutra provocax in Lanin, Puelo and Los Alerces National Parks, Argentina, and evaluation of its conservation status

A survey of the huillin or southern river otter Lutra provocax distribution was made in Lanin, Puelo and Los Alerces National Parks. Signs of otters were found at only 4 of 175 sites visited and all of these were in the south of Lanin. According to local people the species occurred in all three National Parks until 25–40 years ago. The main reason for the loss of huillines seems to be intensive hunting in the past. The geography and structure of the hydrological basins may help explain the lack of recolonisation by huillines from remnant populations. Signs of mink Mustela vison were found in both Puelo and Los Alerces and, while mink could not have been responsible for the decline of the otter, they may hinder re-establishment of otter populations. Human disturbance and tourism are not thought to have a significant impact on huillin distribution although remote refuges should be maintained, and our results show the importance of good coastal vegetation cover for permanent populations of the species. It is clear that the only important and permanent population of huillines in Argentina, between 39°S and 43°S, occurs at Nahuel Huapi National Park, which was surveyed in 1982–1983. This population is now of critical importance for the conservation of the species, which should retain its ‘endangered’ status in Argentina. Measures to implement huillin conservation are proposed.

Habitat Use by Roosevelt Elk in Unmanaged Forests of the Hoh Valley, Washington

Primevally, Roosevelt elk (Cervus elaphus roosevelti) inhabited humid, coastal forests from northern California to Vancouver Island, British Columbia. During the 1890's and early 1900's populations declined or were eliminated under pressures of settlement and intensive market hunting (Rasmussen 1949). Today Roosevelt elk occupy much of their former range, but proliferation of agriculture, urbanization, and roads have altered many productive riverine habitats. Thus, Roosevelt elk are limited largely to forested uplands, which are managed predominantly for timber production. Additionally, Roosevelt elk are hunted throughout most of the range. A notable exception is Olympic National Park in northwest Washington, which is a major population center of unhunted Roosevelt elk and contains nearly 3,600 km2 of unharvested forest. Because so little was known of primeval distribution patterns of elk in northcoastal temperate forests, our objective was to describe habitat use by Roosevelt elk in an unmanaged riverine ecosystem with a significant old-growth forest component.

The Distribution of the Eastern Indigo Snake, Drymarchon corais couperi, in Georgia

A 2-year study was undertaken to survey the distribution of the eastern indigo snake (Drymarchon corais couperi) in Georgia and to characterize and delineate its habitat in the state. Data were gathered through questionnaires, follow-up interviews, intensive snake hunting, soil maps, vegetational analyses and satellite imagery. The majority of 511 sightings occurred in the Tifton Uplands of the Georgia Coastal Plain and were associated with deep, excessively drained, sandy soils along major streams. Winter sightings occurred almost exclusively on sandhills and in association with the burrows of the gopher tortoise (Gopherus polyphemus).

An analysis of the effect of hunting on Caiman crocodilus and Melanosuchus niger based on the sizes of confiscated skins

The size distributions of skins of Caiman crocodilus and Melanosuchus niger confiscated by the Instituto Brasileiro de Desenvolvimento Florestal in the regions of Manaus and the Rio Trombetas were compared with the size distributions of wild populations. The comparison indicates that hunting is selective, with 110 cm and 100 cm being the approximated lower limits for C. crocodilus and M. niger respectively. The size difference between animals entering the hunted population and those entering the breeding population combined with presumed growth rates of the two species indicate that there could be some recruitment to the breeding population of C. crocodilus one year after intensive hunting but that M. niger would require approximately three years.

In Search of Rare Forest Primates in Nigeria

When the author visited Nigeria in 1981 to look at forests on the lower Niger, there had been no reports for 15 years of the red-bellied guenon Cercopithecus erythrogaster, and only a single specimen of the olive colobus Procolobus verus was known from the country. He found surviving populations of both monkeys, but each is threatened by widespread, intensive hunting, and by habitat destruction. If effective measures are not taken to protect the guenon and its rainforest habitat, this species could become extinct, since it occurs only in southwestern Nigeria.

Positive regulatory elements involved in urea amidolyase and urea uptake induction in Saccharomyces cerevisiae

Urea amidolyase and the high affinity urea uptake system are induced by allophanate. durM (-) and durL (-) recessive mutations, which are easily obtained, totally prevent this induction. They are not linked to each other nor to the concerned structural genes. Despite an intensive hunt, no mutation of repressor or classical operator type has been selected. We conclude that urea amidolyase and urea uptake induction involves at least two positive elements coded for by the durM and durL genes.

Regenerating Adirondack Northern Hardwoods By Shelterwood Cutting and Control of Deer Density

Abstract Shelterwood cuttings to regenerate old-growth northern hardwoods in the Adirondack Mountains reduced the overstory to 50 square feet per acre of basal area. Precutting application of herbicides had killed understory vegetation composed predominantly of American beech (Fagus grandifolia Ehrh.). Intensive hunting had reduced deer density from 27 to 14 per square mile. Sugar maple (Acer saccharum Marsh.) dominated regeneration two years after seed cutting, but yellow birch (Betula alleghaniensis Britton) was tallest on more sample milacre plots six and ten years after seed cutting. At age 10, tallest saplings averaged 12 feet in height and 0.8 inch d.b.h., and 4,800 stems per acre had grown above 8 feet. Beech was present only in small numbers and tallest on no more than 20 percent of plots at all ages. Seed cutting, herbicide treatments, and deer density control successfully favored yellow birch and sugar maple over less desirable beech.

Evaluation on dynamic steps of path hunting in t‐s‐t types of switching networks

AbstractIn a high‐speed PCM switching system, it is possible to achieve low blocking probability and high switching efficiency due to the large number of available time‐division paths between a given inlet and outlet pair. However, in order to achieve high efficiency, the central control processor of the system must perform more intensive path hunting. In conventional switching network design, the efficiency of the network is a prime concern while the control procedure for path hunting is often overlooked. Depending on the type of switching network, the trade‐off between the efficiency of the network and the complexity of the control procedure should be considered. The main purpose of this paper is to evaluate the path hunting procedures for T‐S‐T type of time‐division switching networks. The path hunting procedure will be evaluated on the basis of theoretical analysis and simulation of typical switching networks. It will be shown that there is a trade‐off between the efficiency of the network and the complexity of the control procedure.

The extinction of the passenger pigeon ectopistes migratorius and its relevance to contemporary conservation

The passenger pigeon Ectopistes migratorius became extinct in 1914, largely as the result of intensive hunting by man. However, the final stages of its decline seem to have been too rapid to be accounted for entirely by human activity. It is suggested that social factors, namely colony size and reproductive success, were related in such a way that, though the species was apparently still quite common, its breeding rate was insufficient to offset mortality. A model relating colony size to breeding rate is put forward and its relevance to the conservation of living socially breeding species is discussed.

Phenology of sound-producing arctiid moths and the activity of insectivorous bats.

THE lepidopteran family Arctiidae contains a number of species that emit high frequency sounds when tactually stimulated or exposed to the intense hunting cries of insectivorous bats1–3. The sounds are produced as rapidly repeated clicks generated by the buckling action of the row of striae4 or microtymbals5 on the surface of the modified metepisternum (tymbal)6. The sounds seem to act as aposematic cues to discourage nocturnal, ultrasonically sensitive predators such as bats3. Flying bats will avoid otherwise palatable prey (mealworms) when accompanied by the recorded sounds of arctiid moths2. If bats play an important role in the evolution of sound production in arctiids then bat activity levels in an area should influence the phenology of acoustically active arctiids there. By examining the incidence of some silent and sound-producing Nearctic arctiids and its relationship to ambient levels of bat activity, some of those influences can be demonstrated.

Seasonal Vulnerability of Gray Squirrels to Hunting

Seasonal Vulnerability of Gray Squirrels to Hunting

History and present status of populations of harp and hooded seals

The biology of harp ( Pagophilus groenlandicus Erxleben) and hooded ( Cystophora cristata Erxleben) seals is described. These abundant species inhabit the seasonally-shifting pack ice of the North Atlantic. Intensive hunting over 150 years depleted but did not exterminate three harp seal populations, which initially may have totalled some 9 million animals and may now total some 3 millions. All are now hunted under quotas and other restrictions. One population is rising and the other two, while probably still declining slowly, are probably close to stability. Knowledge of hooded seals is less advanced; one of three major sub-populations has only recently been rediscovered after 150 years. These populations are more closely interconnected than populations of harp seals, and management of hooded seals seems likely to need a wider framework than exists at present.

A review of ivory exploitation and elephant population trends in Africa

SummaryA brief review of published data is presented, outlining the intensive exploitation of African elephants for ivory. Records suggest that this began in the early seventeenth century in western Africa, and that hunting pressure was sufficient to eliminate, or drive out, populations over wide areas. In eastern Africa intensive exploitation ensued between 1840 and 1890, leading to a sudden collapse of the ivory supply from over‐exploitation. Subsequent protection has apparently enabled surviving elephants to enter an exponential phase of population increase. Elephant population cycles, if they can be shown to have occurred, are probably reflections of over‐exploitation, followed by population recovery when hunting was no longer profitable. If cycles of scarcity and abundance were a natural feature of elephant populations, then they could have been masked by the intensity of hunting.

Ringkloster, en jysk indlandsboplads med Ertebøllekultur

Ringkloster, en jysk indlandsboplads med Ertebøllekultur