Robert G. White

Foraging patterns and their multiplier effects on productivity of northern ungulates

In most of their arctic and subarctic ranges reindeer, caribou and muskoxen adopt generalist foraging strategies; they consume a wide variety of plants even though they feed selectively. This paper analyses some aspects of selective feeding behavior and its possible influence on animal production. Selective feeding that makes only small changes in quality or amount of food intake may cause a greatly enhanced, or multiplier, effect on animal production. In an example for reindeer grazing in arctic coastal tundra during summer, selective grazing increased digestibility by 14% and dry matter intake by 27%, which combined to give a 268% increase in projected daily weight gain. Weight gain may then influence populations through control over conception rate and survival during winter. An increase by 14% in bodyweight of young female reindeer during summer results in a 35% increase in the probability of conception in autumn. Winter range conditions can affect birth weight, milk production and calf growth rates, all of which affect future reproduction and survival and provide additional avenues for multiplier effects.

Energy expenditures by caribou while cratering in snow

The rate of energy expenditure by caribou (Rangifer tarandus granti) digging in snow for lichens was determined by heart rate telemetry and an analysis of cratering mechanics. Based on a significant linear relationship between energy expenditure and heart rate, the mean cost per digging stroke in light, uncrusted snow was 118 J, whereas in denser (0.36 g/cm3) snow with a thin, hard crust the mean cost was 219 J/stroke. The cost of cratering through snow compacted by a snowmobile was 481 J/stroke. A comparison of metabolic and mechanical energy required for cratering suggested that caribou have evolved an energetically-efficient mechanism for obtaining food from beneath the snow layer. J. WILDL. MANAGE. 49(4):987-993 The ability of caribou to obtain lichens and other forages from beneath the snow by digging is well known. The amount of time caribou and reindeer (R. t. tarandus) reportedly spend digging for food in winter varies from only a few minutes per day in areas of shallow or patchy snow (Boertje 1981, Duquette 1984) to approximately 2 hours/day where snow is deep and continuous (Segal 1962, Thing 1977). During the winter months, caribou often obtain energy by catabolizing body fat and protein (McEwan and Whitehead 1970, Dauphine 1976), and thus it is important to the body condition and survival of the animal that the energy cost of obtaining food be low or be compensated for by the energy derived from the forage. Previous estimates of the energy expenditure associated with digging in snow by caribou and reindeer (Makarova and Segal 1958, Thing 1977) did not include the energy costs of digging in different snow types and at different rates. The most frequently used field method for measuring energy expenditure, using a gastight muzzle mask to measure oxygen consumption (White and Yousef 1978), cannot easily be used to measure digging costs because the mask restricts the animals ability to smell and/or eat the forage. In addition, the valves in the mask may freeze or become clogged with snow, thereby affecting energy cost determinations. Heart rate telemetry has been used successfully with several domestic and wild ungulate species to predict energy expenditure (e.g., Webster 1967, Yamamoto et al. 1979, Renecker and Hudson 1983, Nilssen et al. 1984, Richards and Lawrence 1984) and appeared to be suitable for measuring cratering costs under various conditions. This study was supported by State of Alaska funds for organized research through the Inst. of Arct. Biol. and by a Graduate Fellowship in Resource Problems from the Univ. of Alaska to the senior author. The heart rate transmitters were implanted by R. A. Dieterich. We thank B. C. Anderson, S. L. Zeylmaker, N. J. Ferron, and D. R. Ashby for assisting with data collection and training and handling of captive caribou. R. D. Cameron and D. R. Klein provided helpful comments on the manuscript. We also thank E. A. Sturm and D. A. Borchert for pre-

The digestive physiology of wild ruminants

Ruminant animals have proved remarkably adaptable and successful herbivores. The suborder Ruminantia comprises 176 species ranging in weight from about 1 kg in the lesser mousedeer (Tragulus javanicus) to 1000 kg in a large bull giraffe (Giraffa camelopardis). The suborder Tylopoda, on the other hand, is a relict group of only six species of camelids and will be referred to only occasionally for comparison with the Ruminantia55.

Estimating fat content of caribou from body condition scores

Body condition scores provide a subjective measure of body fatness. We scored the condition of 64 barren-ground caribou (Rangifer tarandus granti) and 10 reindeer (R. t. tarandus) that were later killed and analyzed for chemical composition. A body reserve index (product of body condition score and body mass) was superior to either body mass or body condition score as a predictor of fatness for older calves and adults. The probability of pregnancy for adult female caribou was significantly related to both body condition score (n = 107, P = 0.017) and body reserve index (n = 103, P < 0.001).

Lichen Intake Estimates for Reindeer and Caribou during Winter

Lichen intakes by reindeer and caribou (Rangifer tarandus) during winter were estimated using penned reindeer, esophageal fistulated reindeer, and by the application of the fallout radiocesium method to free-grazing caribou. Estimated mean values for lichen intake as determined by the 3 methods were 16.4, 31.6, and 61.3 g/day of dry lichen per kg body weight or approximately 1.3, 2.5, and 4.9 kg/day dry lichen for an 80-kg reindeer or caribou. The 4-fold range in lichen intake estimates may be attributed to differences in environmental exposures inherent in the methods. Penned reindeer were necessarily sedentary without the stresses and activities normally associated with free-grazing animals. Esophageal fistulated reindeer were required to obtain forage for themselves. However, they were tethered or protected and therefore not subjected to influences such as migration or harassment by predators. The fallout radiocesium method is unique in that it does not affect the normal activity of the animal and thus has the potential for determining the most realistic estimate of lichen intake for an animal in the natural system. The forage intake rates in terms of metabolizable energy available to reindeer and caribou are compared to the probable energy requirements of the animals. J. WILDL. MANAGE. 43(1):192-201 The food habits of free-ranging reindeer and caribou are similar throughout the northern arctic (Kelsall 1968). In late spring as the snow begins to melt, reindeer and caribou actively seek out fresh green vegetation as the new forages appear. During the summer months forage is abundant and the diet consists of a wide variety of plants including shrubs, sedges, heaths, grasses, and lichens. As the deciduous forages mature and become fibrous, reindeer and caribou select increasing amounts of lichen. This transition continues through late fall when lichens become the predominate forage. Throughout winter and early spring when forage is often in short supply, lichens are consumed extensively. Winterkilled nonlichen vegetation is consumed, but to a lesser extent. Extreme cold temperatures during winter suggest greater energy demands for thermoregulation, a situation that is exacerbated whenever reindeer or caribou are required to excavate lichens and other forages from deep or ice-encrusted snow. Therefore, survival of reindeer or caribou is highly dependent upon an adequate forage intake during this critical p riod. Although there is considerable information concerning forage selection by reindeer and caribou (Skoog 1956, Courtwright 1959, Kelsall 1968), little quantitative data on forage intake exist. Forage intakes as calculated from metabolic and nutrient requirements (Brody 1945:470, Kelsall 1968:81) seem inadequate for reindeer or caribou subsisting in their winter environment. This paper reports estimates of lichen intakes based on feeding trials with pe ned and esophageal fistulated reindeer as well as lichen intake estimates derived from application of a fallout radiocesium method. The radiocesium method was first proposed by Holleman et al. (1971), and some preliminary lichen intake estimates for caribou were made. Hanson et al. (1975) applied the radiocesium method to data collected in northern Alaska during 1963-70 and esimated lichen intake by free-grazing car192 J. Wildl. Manage. 43(1):1979 This content downloaded from 157.55.39.217 on Tue, 06 Sep 2016 05:42:33 UTC All use subject to http://about.jstor.org/terms LICHEN INTAKE BY REINDEER AND CARIBOU. Holleman et al. 193 Table 1. Meterological summary for each study period. Temperature C Mean snow depth Study Dates Mean Max. Min. (cm) Pen feeding trial 1 Nov-Dec 1969 -16.7 -11.7 -22.0 15.9 Pen feeding trial 2 Mar-Apr 1974 -6.0 0.3 -12.8 33.0 Pen feeding trial 3 Nov-Dec 1975 -17.4 -13.9 -20.9 23.5 Esophageal fistula trial Mar, Apr 1973 -6.6 -2.1 -11.1 49.9 Radiocesium trial Jan, Feb, Mar 1976 -17.9 -13.5 -22.2 19.2 ibou. Alldredge et al. (1974) used the fallout radiocesium method to determine forage intake rates of mule deer (Odocoileus hemionus). We now report lichen intake estimates for reindeer and caribou from November through March in interior and northern Alaska. This study was part of a continuing study of the nutrition and metabolism of reindeer and caribou in Alaska (Luick 1967-74, Luick 1977). Lichen intake estimates in winter were obtained at the Institute of Arctic Biology, Fairbanks, Alaska; the Reindeer Research Station, Cantwell, Alaska; and Old John Lake in northern Alaska. Only studies involving penned reindeer were conducted at the Institute of Arctic Biology, whereas both penned reindeer and esophageal fistulated reindeer studies were conducted at the Reindeer Research Station. Estimates of lichen intake using the radiocesium method were made on caribou collected at Old John Lake. The study was supported by U.S. A.E.C. contract AT (45-1)2229 and U.S. E.R.D.A. contract EY-76-

Flow of digesta in the intestine and caecum of the rock ptarmigan

The role of the cecum in digestion of foodstuffs and production of vitamins is not well known for ptarmigan and grouse species. Presumably the function of the avian cecum is to digest and ferment complex carbohydrate molecules, proteins and other nutrients that escape intestinal absorption. The extent of fermentation in the cecum is a product of forage quality, cecum size and mean residence time of dry matter (DM), therefore mechanisms controlling filling and emptying of the cecum determine the kinetics and

Detection of early pregnancy in Caribou : Evidence for embryonic mortality

To investigate relations between body condition and fecundity, we determined pregnancy status of arctic caribou (Rangifer tarandus granti) from presence or absence of pregnancy-specific protein B (PSPB) and progesterone concentration in blood sera or plasma. We drew peripheral blood samples from female caribou 3-5 (n = 142) and 20-23 (n = 44) weeks after the breeding season. We then weighed and estimated the fat content of each caribou, and we radiocollared 115 of 184 individuals. We verified parturition status for 96 of these radiocollared females in June. In addition, we determined presence of PSPB for captive caribou in autumn and early winter. Progesterone concentration was superior to PSPB as a predictor of pregnancy during early gestation, and a threshold value of 1.5 ng/mL was used to separate pregnant from nonpregnant females in autumn and winter. Pregnancy status was strongly related to body condition in both autumn and winter, and fatter or heavier caribou were more likely to be pregnant. Use of both PSPB and progesterone concentration allowed detection of early embryonic mortality among lactating caribou that were in poor condition.

Modeling sustainability of Arctic communities: an interdisciplinary collaboration of researchers and local knowledge holders.

How will climate change affect the sustainability of Arctic villages over the next 40 years? This question motivated a collaboration of 23 researchers and four Arctic communities (Old Crow, Yukon Territory, Canada; Aklavik, Northwest Territories, Canada; Fort McPherson, Northwest Territories, Canada; and Arctic Village, Alaska, USA) in or near the range of the Porcupine Caribou Herd. We drew on existing research and local knowledge to examine potential effects of climate change, petroleum development, tourism, and government spending cutbacks on the sustainability of four Arctic villages. We used data across eight disciplines to develop an Arctic Community Synthesis Model and a Web-based, interactive Possible Futures Model. Results suggested that climate warming will increase vegetation biomass within the herd’s summer range. However, despite forage increasing, the herd was projected as likely to decline with a warming climate because of increased insect harassment in the summer and potentially greater winter snow depths. There was a strong negative correlation between hypothetical, development-induced displacement of cows and calves from utilized calving grounds and calf survival during June. The results suggested that climate warming coupled with petroleum development would cause a decline in caribou harvest by local communities. Because the Synthesis Model inherits uncertainties associated with each component model, sensitivity analysis is required. Scientists and stakeholders agreed that (1) although simulation models are incomplete abstractions of the real world, they helped bring scientific and community knowledge together, and (2) relationships established across disciplines and between scientists and communities were a valuable outcome of the study. Additional project materials, including the Web-based Possible Futures Model, are available at http://www.taiga.net/sustain.

Digestion of Dry Matter and Absorption of Water in the Intestine and Cecum of Rock Ptarmigan

Despite the many investigations of functional aspects of the hindgut in avian species (Sturkie 1965, Hill 1971, Hudson et al. 1971, Jayne-Williams and Fuller 1971, Ziswiler and Farner 1972), information about digestive function is still incomplete. The primary functions of the hindgut appear to be microbial digestion of carbohydrate and protein, absorption of end products of fermentation, water, some minerals, and microbial synthesis of vitamins. The cecum of all vertebrate

Responses of caribou to overflights by low-altitude jet aircraft.

Military training exercises have increased in Alaska in recent years, and the possible effects of low-altitude overflights on wildlife such as barren-ground caribou (Rangifer tarandus) have caused concern among northern residents and resource agencies. We evaluated the effects of overflights by low-altitude, subsonic jet aircraft by U.S. Air Force (USAF) A-10, F-15, and F-16 jets on daily activity and movements of free-ranging female caribou. This study was conducted on caribou of the Delta Caribou Herd in interior Alaska during each of 3 seasons in 1991: late winter, postcalving, and insect harassment. Noise levels experienced by caribou were measured with Animal Noise Monitors (ANMs) attached to radiocollars. Caribou subjected to overflights in late winter interrupted resting bouts and consequently engaged in a greater number of resting bouts than caribou not subjected to overflights (P = 0.05). Caribou subjected to overflights during postcalving were more active (P = 0.03) and moved farther (P = 0.01) than did caribou not subjected to overflights. Caribou subjected to overflights during the insect season responded by becoming more active (P = 0.01). Responses of caribou to aircraft were mild in late winter, intermediate in the insect season, and strongest during postcalving. We conclude that females with young exhibit the most sensitive response to aircraft disturbance. Accordingly, military training exercises should be curtailed in areas where caribou are concentrated during calving and postcalving.