Alces (A Journal Devoted to the Biology and Management of Moose)
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DISPERSAL AND MIGRATION IN NORTHERN FOREST DEER - ARE THERE UNIFYING CONCEPTS?
No full textI summarize studies of natal dispersal and seasonal migrations in 5 species of forest deer: moose (Alces alces), roe deer (Capreolus capreolus), white-tailed deer (Odocoileus virginianus), mule deer (O. hemionus), and black-tailed deer (O. h. columbianus). Six main features of behavior characterize dispersal in these species: season of dispersal; biased or equal dispersal by the sexes; dispersal in relation to animal density; dispersal in the presence of adult aggression; pre-dispersal excursions; and dispersal distance. These traits are highly variable among and within species and also vary in their proximate causation: mate and resource competition; avoidance of inbreeding, and founder effect. Seasonal migrations are common to all 5 species. These movements are the result of many generations of summer dispersal, and a return to a traditional winter range. Although dispersal appears flexible in relation to different environmental conditions, seasonal migration is a more rigid system of behavior across species. Snow is a key triggering factor and determines occurrence and extent of migration. Snow depth and weather, not plant phenology, appear to determine onset of migration in spring and autumn. Also, the strong tradition in use of seasonal ranges are shared by the species. Summer range located at higher elevation than the winter range is typical of northern cervids in alpine landscapes. Nevertheless, more research is needed to understand relationships among altitude, range quality, and migration patterns of northern deer
REPRODUCTIVE PATTERNS OF FEMALE MUSKOXEN IN NORTHEASTERN ALASKA
No full textReproductive success is an important variable in the dynamics of a re-established population of muskoxen (Ovibos moschatus) is the Arctic National Wildlife Refuge, Alaska, USA. From observation of marked female muskoxen between 1982 and 1999, I generated reproductive histories based on the presence or absence of young in late June. I determined age at first reproduction and maximum age at which females successfully reproduced and calculated rates of reproduction by age class and changes in mean reproductive intervals (years between successful reproductive events) over time. Age at first reproduction ranged from 2 to 5 years. Nine of 15 females first reproduced successfully at age 3 years. Thirteen of 17 females >10 years old reproduced successfully at 11-18 years of age; 4 of these had young at age 15-18 years. Two females ceased reproducing at age 6-8 years. Age-related differences in rates of reproduction were not apparent. Reproductive intervals varied within and among individuals. By 1991-1993, most female muskoxen in this population successfully reproduced at intervals of 2-3 years
MODELING MOOSE SIGHTABILITY IN SOUTH-CENTRAL BRITISH COLUMBIA
No full textWe developed a model to correct sightability bias in aerial surveys of moose in the southern interior of British Columbia. Sightability trials were conducted by searching sample blocks where radio-collared moose were recorded and used as independent variables for a logistic regression model of sightability. Univariate analysis revealed that percent vegetative cover, percent snow cover, and daily temperature all significantly influenced the probability of detecting a moose. However, multivariate analysis retained only vegetative cover as teh significant variable to predict sightability probability. This mirrors the results of analysis of similar trials done in western Wyoming that used the same independent variables as well as 6 additional ones. Two logistic regression models were developed for moose sightability; one based on 5 classes of vegetative cover and a second, less accurate, based on 3 classes of vegetative cover
REDUCED COST OF REPRODUCTION IN MOOSE ALCES ALCES THROUGH HUMAN HARVEST
No full textIn life history theory there is a cost related with all resource allocation. For female moose (Alces alces), the cost of reproduction in terms of survival may be reduced for females if calves, or cows without calves, are selectively hunted during the fall. Cows with calves might experience higher hunting survival and therefore face a reduced trade-off between survival and reproduction. This hypothesis was tested during a 7-year study in northern Sweden. Females age and whether she had given birth or not best explained female moose survival during the hunting period, not the number of calves born or alive at the hunt. Still, the analysis suggests that the cost of reproduction was reduced for middle-aged females. Females not giving birth experienced a 3.2-fold greater risk of being harvested comparted to those giving birth. This suggests that the application of life-history theory is crucial to fully understand the evolutionary consequences of management decisions on heavily harvested populations of ungulates
CHANGES IN THE RELATIONSHIP BETWEEN PALMATE AND CERVINE ANTLERS IN MOOSE (ALCES ALCES) IN SOUTHEASTERN NORWAY
No full textMoose (Alces alces) have evolved 2 antler morphs; palmate and cervine. Using data from 1,186 antlers collected from moose harvested in southeastern Norway during 1950-1997, I rested the widely held hypothesis that the cervine morph has become the predominant antler type in Norway. The antlers were categorized according to palmate, intermediate, and cervine form. I also used quantitative measurement of tines (average length and number) to study trends in morphology. An adaptive landscape method was used to study a combination of the relative number of tines and relative tine length. Since 1950, the palmate morph decreased significantly by 0.52% per year (P = 0.002), while the cervine morph increased significantly by 0.39% per year (P = 0.008). Number of tines decreased in the palmate morph, but there was no trend in tine length. Th intermediate morph increased in the number of tines and decreased in tine length, while the cervine morph showed no trends in morphology. Combined for all morphs in the adaptive landscape, the relative number of tines decreased and relative tine length increased throughout the time series, indicating a change toward more cervine antlers in southeastern Norway. The causes for this change are discussed in relation to frequency-dependent selection and density/social stress hypotheses
DENSITY DEPENDENCE OF UNGULATES AND FUNCTIONAL RESPONSES OF WOLVES: EFFECTS ON PREDATOR-PREY RATIOS
No full textPredator-prey ratios have been used widely to interpret effects of wolf (Canis lupis) predation on their ungulate prey. Use of those simple indices may be misleading unless they are interpreted with regard to species composition of available prey, rate of growth of the prey population, proximity of the prey to carrying capacity (K), and the functional response in the rate of predation by wolves to changing density of prey. We incorporate theoretical models for predator-prey dynamics with data from field studies on ungulated and wolves to test for differences between species of ungulates in their ability to support wolves per unit of biomass. We conduct sensitivity analyses of those models, which integrate density-dependent growth of ungulate populations and functional responses of wolves, to evaluate the relative importance of those factors to the relation between ungulate and wolf densities. Finally, we develop a stochastic model that predicts ungulate-wolf populations at equilibrium, which indicates why interpreting those ratios in wild, may be problematic. Our models and analysis indicate that some ungulates, such as white-tailed deer (Odocoileus virginianus), likely will support a higher density of wolves than will other species with lower intrinsic rates of increase. Thus, we question the use of comparisons of total ungulate biomass and wolf density unless species composition of prey is considered. We hypothesize that growth rates of prey populations, their response to density dependence, and their proximity to K have important influences on the relation between ungulate and wolf density, whereas the functional response exhibited by wolves is relatively unimportant, especially at high density of prey
VIGILANCE BEHAVIOUR IN WILD AND SEMI-DOMESTIC REINDEER IN NORWAY
No full textWe recorded a vigilance behavior of wild reindeer (Rangifer tarandus tarandus) population in Rondane North and a population of semi-domesticated origin in Norefjell-Reinsjøfjell during 3 periods (April-May, June-July, and August) in 1997 in southern Norway. The 2 areas studied have different histories of hunting, domestication, predation, and human activity. A vigilance bout was defined as the act of interrupting feeding by lifting the head above the shoulders and briefly observing the surrounding area for < 10 seconds before returning to feeding. The Rondane North population of reindeer displayed a higher rate of vigilance during all periods compared with the Norefjell-Reinsjøfjell population (P<0.0001). The Norefjell-Reinsjøfjell reindeer devoted more time to predator-vulnerable activities such as lying head down and lying head flat, than the population inhabiting Rondane North. Higher rates of vigilance behavior displayed by the Rondane reindeer most likely are related to differential elimination of animals during the evolutionary history of domestication, and by hunting in the 2 areas. Habituation of humans and the presence or absence of large mammalian predators may also contribute to the observed differences in vigilance behavior
TREE RUBBING BY WHITE RHINOS: POTENTIAL FUNCTIONS OF AN UNDESCRIBED BEHAVIOR
No full textI observed white rhinos (Ceratotherium simum) in Matobo National Park, Zimbabwe, perform a behavior previously undescribed for this species; males vigorously removed the bark from commiphora trees (Commiphora marlothii) with their horns, and then rubbed their head and rostrum on the debarked areas. To explore this behavior further, I sampled commiphora trees in the Whovi Game Park, a fenced reserve within Matobo National Park, which contained a population of 43 white rhinos. Almost 30% of commiphora trees available to rhinos had been debarked. Only 2 marks were observed on 107 trees outside the fenced reserve, in an area without a resident population of rhinos. Tree rubbing in white rhinos is similar to "sign-posting" in cervids and some bovids, and may function as a scent-marking behavior. Alternatively, perhaps rhinos ingested bark or resin during tree rubbing. Therefore, other potential functions of this behavior may include nutritional or medicinal use of commiphora
EFFECTS OF HORN-CURL REGULATIONS ON DEMOGRAPHY OF DALL'S SHEEP: A CRITICAL REVIEW
No full textResearchers studying Dall's sheep (Ovis dalli dalli) associated with a large mineral lick on Dry Creek in the central Alaska Range south of Fairbanks, Alaska, USA, claimed that removal of nearly all mature males by intensive harvest of three-quarter curl or larger males by hunters during the 1970s resulted in accelerated mortality of young males and low productivity in female sheep. Changing to a more conservative harvest of seven-eighths and then full-curl males purportedly reversed these trends and resulted in higher overall sustained harvest of males. Review of Dry Creek study reports and of original data records revealed questionable assumptions and errors in data analysis and study design. Conclusions about accelerated mortality of young males were based primarily on resighting data from marked males at the mineral lick, but data from aerial surveys of the larger study area around the lick indicated much higher abundance of males than was apparent at the lick. Reanalysis of data showed that males had low fidelity to the lick, and in many years the lick was not observed frequently enough to detect all sheep that may have used it. Harvest only reduced abundance of mature males by about one-half and had no discernable effect on survival of younger males. Low ovarian activity and high rates of parturition in 2-year-old females (thought to be associated with alternate year reproduction in later life, and therefore undesirable) were attributed to low abundance of mature males from 1972 to 1979, but most data were actually collected wither before or after those dates, when male abundance supposedly was high. Harvest of mature males increased through the 1980s, but an apparent correlation with more restrictive horn-curl regulations disappeared through the 1990s. Harvests of mature males under full-curl management in recent years have been far lower than ever occurred under three-quarter curl regulations, but by long-term weather patterns that affected sheep productivity, survival, and abundance.
SEXUAL SEGREGATION IN MOOSE: EFFECTS OF HABITAT MANIPULATION
No full textWe studied effects of mechanical crushing on abundance of forage and quality of feltleaf willow (Salix alaxensis) in winter, 3 years following habitat manipulation in interior Alaska, USA. We also examined differences in snow depth and track counts for Alaskan moose (Alces alces gigas) between the crushed site and an adjacent area containing old-growth stands of willow. Likewise we tested for differences in foraging by moose between areas, and noted differences in use of the 2 sites by adult males, and females and their young. Mechanical crushing resulted in a 5-fold increase in the number of leaders of current annual growth and a 3-fold increase in dry mass for willows subjected to crushing compared with the uncrushed site. The size of individual leaders resprouting from the crushed area was similar to stump sprouts available to moose on the uncrushed area. Moose took larger bites, however, on the crushed compared with the uncrushed. No significant differences occurred in the chemical composition of willows, including concentration of tannins, between crushed and uncrushed areas. Similarly, there were no differences in in vitro dry matter digestibility of willow between sites. Moose sexually segregated in winter. Males occurred predominantly on the more open crushed area, whereas females and young used the uncrushed area where the dense vegetation offered substantial concealment cover. We hypothesized that mechanical manipulation of willow benefited primarily male moose 3 years following crushing, and that females and young faced a tradeoff between feeding on the greater abundance of forage on the crushed area and a reduced risk of predation on the uncrushed site. We see merits in considering the sexes of moose as if they were separate species for purposes of management, and recommend that future management of habitat to benefit moose consider differences in requirements of the sexes, especially factors related to risk of predation