Aaron N. Moen

Energy Conservation by White‐Tailed Deer in the Winter

Behavior of white—tailed deer (Odocoileus virginianus) in Itasca Park, north—western Minnesota, USA was analyzed for energy—conservation adaptations during winter. Track records showed a decrease in activity with an increase in perdicted heat loss when activity and heat loss were compared on a sequential basis throughout the winter. Recognition of many seasonal but gradual changes in deer characteristics, such as antler growth, reproductive condition, and molting, suggest that seasonal physiological changes occur and also effect over behavior. Energy may be conserved by reducing the general level of activity, by seeking more level land and lesser snow depths, and by walking more slowly. Such energy—conservation measures may save up to 1,000 kcal/day (= 4,184 kJ/day) for a 60 kg deer, and 0.25—0.50 kg field—weight forage. Deer should remain as undisturbed as possible in the winter; harassment by dogs and snowmobile traffic is counter to their long term physiological and behavioral adaptations.

Milk Consumption and Weight Gain of White-Tailed Deer

Feeding trials were conducted with captive, white-tailed deer (Odocoileus virginianus) fawns to estimate the milk requirements of fawns and the requirements of lactating females for milk production. The growth rates of two groups of bottle-fed fawns consuming milk with a composition similar to whitetailed deer milk were compared to fawns raised by captive, white-tailed deer females. Maternal-nursed fawns gained 243.7 -+19.2 g/day. Similar rates of gain occurred in bottle-fed fawns. Bottle-fed fawns receiving lesser amounts of milk maintained a high rate of gain by increasing forage intake. Gastro-intestinal tract capacities were measured to determine relative changes as the fawns became functional ruminants. J. WILDL. MANAGE. 39(2):355-360 The estimation of productive requirements for lactating white-tailed deer females and of milk intake by fawns is dependent upon approximations or measurements of the chemical composition of the milk and the amount of milk produced. The composition of white-tailed deer milk throughout lactation has been measured by Ruff (1938), Murphy (1960), Silver (1961), and Youatt et al. (1965). It is, in general, higher in fat, protein, dry matter, and energy content than the milk of domestic ruminants. Milk protein and fat content change very little during early lactation, but milk fat increases approximately two-fold during very late lactation (Ruff 1938, Murphy 1960, Silver 1961). Milk production of mammals has been estimated by several methods, such as milking of the lactating female, weighing the suckling before and after nursing, or measuring the dilution of body water in the young animal by the known water content of ingested milk (McEwan and Whitehead 1971). Milk production has not been measured in white-tailed deer because of problems in conducting such experiments. Estimates of milk production will vary because of changes in production associated with nutrition, stage of lactation, number, size, and ex of the animals sucking, and age a size of the lactating female. Moen (1973) calculated milk production of whitetailed deer females on the basis of fawn requirements and the physiological and morph lo ical development of their gastrointestinal tract. Milk production of lactating white-tailed deer females was estimated during this study by comparing the growth r sponses of white-tailed deer fawns raised by captive, lactating females to fawns that were bottle-fed specific amounts of milk having the approximate composition of deer milk. Young fawns are able to adapt to variations in milk production by increasing forage or dry feed intake (Nordan et al. 1970, Moen 1973). The extent to which forage can substitute for milk in meeting energy and nitrogen requirements is dependent upon the development of the gastro-intesti al tract into that characteristic of a ruminant animal which is capable of fermenting large quantities of ingested forage. We gratefully acknowledge funding provided by the New York State Department of Environmental Conservation (PittmanRobertson Project W-124-R). The technical assistance of B. Robbins, T. Supplee, and W. Armstrong is appreciated. 1 Present address: Department of Zoology, Washington State University, Pullman 99163. J. Wildl. Manage. 39(2) :1975 355 This content downloaded from 207.46.13.158 on Wed, 16 Nov 2016 04:27:05 UTC All use subject to http://about.jstor.org/terms 356 WEIGHT GAIN OF DEER Robbins and Moen METHODS AND MATERIALS Twenty-two newborn fawns (14 males and 8 females) were acquired between 26 May and 21 June 1972 from the herd at the BioThermal Laboratory and the New York State Department of Environmental Conservation. The fawns were placed in small wire-covered pens until nursing well, approximately one week. The fawns were randomly divided into two test groups of high (Group I) and low (Group II) milk intake (Fig. 1). Female fawns of each test group received slightly more milk because of the higher fat and caloric content of the gain (Robbins 1973, Robbins et al. 1974). Milk was formulated from evaporated milk, casein, water, and a mineral-vitamin mixture to match as closely as possible the energy and protein composition of whitetailed deer milk (Silver 1961) (Table 1). The milk was warmed to 38 C and given in soft-drink bottles fitted with rubber sheep nipples. Since the casein did not go into solution well, each bottle was rinsed with water from a laboratory wash bottle and the rinse fed to the designated fawn. All fawns were initially fed six times daily at 3.5-h intervals beginning at 0600 until the peak of milk consumption had been reached. The fawns received a different amount of milk each day as determined by their weight in relation to the lactation curves (Fig. 1). The lactation curves were generated prior to the pen experiments from estimates of fawn requirements, efficiencies of nutrient utilization, feed composition, and capability of fawns for substituting dry feed for milk (Robbins 1973, Moen 1973). As the amount of milk fed declined, the number of feedings decreased until the fawns were weaned at 25 kg. Once the fawns were nursing well they were weighed, transferred to three large pens (12.2 x 12.2 m) constructed of slat1000.0

Surface Temperatures and Radiant Heat Loss from White-Tailed Deer

Measurements of surface temperatures and radiant heat loss from the trunks of two penned white-tailed deer (Odocoileus virginianus) fawns were made remotely with a portable radiometer during the winter. Surface temperatures were 6-8 degrees C higher than air temperatures. No difference was observed between the two deer in the surface temperature: air temperature relationships. The difference between air temperature and the surface temperature of the deer increased as air temperature decreased. Measurements of thermal radiation under clear skies at night showed a greater quantity of heat energy emanating from cedar cover than from upland hardwood cover or the clear sky in an open field. The radiant heat from the animal can be integrated with that from the different cover types if the radiation profile of the animal is known. The profile for white-tailed deer has not been determined, but may be estimated. Physiological evidence is cited which indicates the importance of radiant heat when the energy balance of an organism is being considered. The behavior of white-tailed deer with respect to observed weather conditions has been considered by several investigators. Observed responses of the animals have been assumed by some to be causally related to existing weather conditions, or perhaps to the microclimate surrounding the animal. An elucidation of these relationships is, indeed, a worthy goal for the animal ecologist. I suggest, however, that without a quantitative application of appropriate heat transfer parameters, it may be difficult to separate behavioral responses caused by weather conditions from those which may be related to social or psychological phenomena. The basic concept of energy, the means by which energy is transferred, and the energy environment of plants are discussed by Idso et al. (1966). Analyses of the energy exchange of sheep (Priestley 1957 and Blaxter et al. 1959), cattle (Kelly and Ittner 1948, Thompson et al. 1952, and Blaxter and Wainman 1964), swine (Bond et al. 1952) and chickens (Clayton and Boyd 1964) have been presented. The radiant 1 Study supported by the Graduate School, University of Minnesota. 2 Present address: Department of Conservation, Cornell University, Ithaca, New York. 338 energy exchange of the human with its environment has been studied by Hardy and DuBois (1938) and Suggs (1965). The energy relationships of wild species, including ruffed grouse (Brander 1965), whitetailed deer (Moen 1966), and Canada geese (LeFebvre and Raveling 1967) have been considered. Kelly et al. (1954) discuss the importance of thermal radiation in a consideration of animal-environment relationships. An important characteristic of the papers cited above is the explicit consideration of rates of heat transfer between the animal and its environment by different processes, as opposed to the simple comparison of animal behavior and weather data. This paper describes the radiant energy loss in relation to air temperature from the trunks of two well-fed white-tail fawns measured remotely in an outdoor pen during winter months. Measurements of radiation flux under clear skies at night in a nearby open field, upland hardwood stand, and cedar (Thuja occidentalis) habitats are also presented. The radiation data can be applied to the whole animal and integrated with other sources of heat loss (conduction, convection, and evaporation) if the radiaTEMPERATURES AND RADIANT HEAT LOSS FROM DEER * Moen 339 tion profile of the animal is known or assumed. Research was completed at the Cedar Creek Natural History Area (T34N, R23W), operated by the University of Minnesota, and about 35 miles north of the campus. The cooperation of Dr. W. H. Marshall, Director, Field Biology Program, is acknowledged. He also offered suggestions during preparation of the manuscript. The Minnesota Department of Conservation provided the test animals. Alvar Peterson, Resident Manager, and Bruce Kohn, Student Assistant, assisted in handling the deer.

Energy Exchange of White‐Tailed Deer, Western Minnesota

The energy exchange of white—tailed deer in an open field environment under clear winter skies at night is presented. Environmental radiation flux was measured with field instruments; radiation loss and surface temperature of deer were estimated with a simulator; heat loss by convection, evaporation, and warming ingested food was estimated from methods and data reported in the literature for other species. Metabolic heat production at three dietary levels, environmental radiation flux, and the heat loss at air temperatures from 0° to —40°C and wind velocities from ½ to 12 mph at deer height were integrated to provide a quantitative basis for determining the conditions under which thermal stress commences. Calculations are for fawns and does in a standing position in an open field under clear, nocturnal skies. The smaller deer reach a negative energy balance at air temperatures approaching 0°C and wind velocities of ½ to 1 mph if they are on a starvation diet. A maintenance to full diet enables them to wit...

The Critical Thermal Environment: A New Look at an Old Concept

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TURBULENCE AND THE VISUALIZATION OF WIND FLOW

Air flow in the natural environment affects the distribution of organisms, mechanical stresses, heat losses by convection, and moisture distribution. Air flow was visualized by bubble tracers in a wind tunnel, and the flow patterns over solid barriers 5 and 15 cm high and 0%, 25%, and 47% porosity barriers, each 10 cm high, were photographed. The leeward circulation pattern is very similar regardless of the barrier height. The leeward effect of the barrier extends a greater distance for the 47% porosity than for the 25% and 0% porosities. The three—dimensional characteristics of visualized turbulent flow clearly indicate the limitations of cup anemometers for measuring field velocities since these instruments do not respond to angles of attack from 70° to 90°. See full-text article at JSTOR

A modified model for projecting age-structured populations in random environments

A discrete-time age-structured population model with vital rates linked to a stochastic environmental process was developed as a generalization of an existing model by making the explicit link between variability in the vital rates and variability in the environment more flexible. This modified model uses biologically relevant probability distributions for the vital rates, and allows for temporal autocorrelation and an arbitrary covariance structure between vital rates. Through simulations, the properties of the projected population in the short-term were investigated and compared to analytical approximations. The distribution of the total population size did not quickly approach lognormality under all conditions. Furthermore, the sensitivity of the vital rates to the environmental process had a strong effect on the variance and distribution of the projected population size. These results suggest that short-term projections need to be carried out through simulation methods, as the analytical approximations technically apply only to the long-run asymptotic behavior. Techniques for parameter estimation were considered; recommendations depend on the form of the data available. The approach described allows the empirical calculation of the probability distribution for predicted population size, a quantity relevant to the use of formal decision analysis in natural resource management.

Rectal temperatures of 2 free-ranging white-tailed deer fawns

Rectal temperatures (N = 249) of 2 free-ranging white-tailed deer (Odocoileus virginianus) fawns were measured in all seasons in northeastern Minnesota while the animals were normally resting, standing, walking, feeding, and running. Rectal temperatures remained between 38.2 and 40.1 C despite ambient temperatures of -38 to 34 C. Deer were free to select habitats and activities and showed a narrower range of body temperatures (1.9 C) than has been reported for confined individuals (5.6 C). Seasonal and activity-related variations in rectal temperatures were slight but significant. J. WILDL. MANAGE. 51(1):59-62 Body temperatures of 37.2-42.8 C have been reported for captive or freshly captured whitetailed (Holter et al. 1975, Seal et al. 1978), mule (0. hemionus) (Thorne 1975, Parker and Robbins 1984), and Columbian black-tailed deer (0. h. columbianus) (Leopold et al. 1951, Cowan and Wood 1955). A narrower range would be expected for body temperatures of free-ranging deer if deer select habitats and activity levels that facilitate homeothermy (Verme 1965; Moen 1968b, 1985; Ozoga and Gysel 1972). Published data on body temperatures of free-ranging deer do not exist (Anderson 1981). In this study we measured rectal temperatures of free-ranging deer during various activities not prompted by man or other predators in open and forested habitats. We thank S. Demarais, L. Mason, W. W. Mautz, K. R. McCaffery, M. E. Nelson, and J. M. Sweeney for helpful suggestions on the manuscript.

Thermal Exchange, Physiology, and Behavior of White-Tailed Deer

“Life is a process that involves the expenditure of energy for the redistribution of matter” (Moen, 1973, p. 3). This process is self-sustaining in living organisms, driven by the metabolic machinery of the organism, and influenced by the energy flux and matter in the operational environment of each organism. The rates at which the various processes occur vary, depending on characteristics of both the organism and environment, and on the interaction between the two.

A tandem cosine algorithm for modeling rhythmic change

A tandem cosine algorithm which connects two or more successive half-waves is described, and may be used to represent many rhythmic ecological patterns, including air temperature patterns, vital signs such as body temperature rhythms, solar radiation patterns, and weight changes of mammals and birds over the annual cycle. Each of these is illustrated with an example in this paper. The tandem cosine algorithm is a pattern-generating procedure rather than a curve-fitting one, and may be used when few data are available. When modeling ecological relationships, it is better to represent rhythmic changes with a pattern than to ignore the rhythmic pattern and represent them with simple average values over time.