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Barboza PS, Shively RD, Thompson DP. Robust Responses of Female Caribou to Changes in Food Supply. ECOLOGICAL AND EVOLUTIONARY PHYSIOLOGY 2024; 97:29-52. [PMID: 38717369 DOI: 10.1086/729668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2024]
Abstract
AbstractUngulates can respond to changes in food supply by altering foraging behavior, digestive function, and metabolism. A multifaceted response to an environmental change is considered robust. Short seasons of plant growth make herbivores sensitive to changes in food supply because maintenance and production must be accomplished in less time with fewer options in a more fragile response. Caribou live at high latitudes where short summers constrain their response to changes in food supply. We measured the ability of female caribou to resist and tolerate changes in the quality and quantity of their food supply during winter and summer. Caribou resisted changes in food abundance and quality by changing food intake and physical activity with changes in daily temperature within each season. Peak food intake rose by 134% from winter pregnancy to summer lactation (98 vs. 229 g kg-0.75 d-1), as digestible requirements to maintain the body increased by 85% for energy (1,164 vs. 2,155 kJ kg-0.75 d-1) and by 266% for N (0.79 vs. 2.89 g N kg-0.75 d-1). Caribou required a diet with a digestible content of 12 kJ g-1 and 0.8% N in pregnancy, 18 kJ g-1 and 1.9% N in early lactation, and 11 kJ g-1 and 1.2% N in late lactation, which corresponds with the phenology of the wild diet. Female caribou tolerated restriction of ad lib. food intake to 58% of their energy requirement (680 vs. 1,164 kJ kg-0.75 d-1) during winter pregnancy and to 84% of their energy requirement (1,814 vs. 2,155 kJ kg-0.75 d-1) during summer lactation without a change in stress level, as indicated by fecal corticosterone concentration. Conversely, caribou can respond to increased availability of food with a spare capacity to process digestible energy and N at 123% (2,642 vs. 2,155 kJ kg-0.75 d-1) and 145% (4.20 vs. 2.89 g N kg-0.75 d-1) of those respective requirements during lactation. Robust responses to changes in food supply allow caribou to sustain reproduction, which would buffer demographic response. However, herds may decline when thresholds of behavioral resistance and physiological tolerance are frequently exceeded. Therefore, the challenge for managing declining populations of caribou and other robust species is to identify declines in robustness before their response becomes fragile.
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Dickinson ER, Orsel K, Cuyler C, Kutz SJ. Life history matters: Differential effects of abomasal parasites on caribou fitness. Int J Parasitol 2023; 53:221-231. [PMID: 36801266 DOI: 10.1016/j.ijpara.2023.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 01/16/2023] [Accepted: 01/19/2023] [Indexed: 02/18/2023]
Abstract
Parasites can impact wildlife populations through their effects on host fitness and survival. The life history strategies of a parasite species can dictate the mechanisms and timing through which it influences the host. However, unravelling this species-specific effect is difficult as parasites generally occur as part of a broader community of co-infecting parasites. Here, we use a unique study system to explore how life histories of different abomasal nematode species may influence host fitness. We examined abomasal nematodes in two adjacent, but isolated, West Greenland caribou (Rangifer tarandus groenlandicus) populations. One herd of caribou were naturally infected with Ostertagia gruehneri, a common and dominant summer nematode of Rangifer sspp., and the other with Marshallagia marshalli (abundant; winter) and Teladorsagia boreoarcticus (less abundant; summer), allowing us to determine if these nematode species have differing effects on host fitness. Using a Partial Least Squares Path Modelling approach, we found that in the caribou infected with O. gruehneri, higher infection intensity was associated with lower body condition, and that animals with lower body condition were less likely to be pregnant. In caribou infected with M. marshalli and T. boreoarcticus, we found that only M. marshalli infection intensity was negatively related to body condition and pregnancy, but that caribou with a calf at heel were more likely to have higher infection intensities of both nematode species. The differing effects of abomasal nematode species on caribou health outcomes in these herds may be due to parasite species-specific seasonal patterns which influence both transmission dynamics and when the parasites have the greatest impact on host condition. These results highlight the importance of considering parasite life history when testing associations between parasitic infection and host fitness.
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Affiliation(s)
- Eleanor R Dickinson
- Faculty of Veterinary Medicine, University of Calgary, 3280 University Drive, NW, Calgary, AB T2N 1N4, Canada.
| | - Karin Orsel
- Faculty of Veterinary Medicine, University of Calgary, 3280 University Drive, NW, Calgary, AB T2N 1N4, Canada
| | - Christine Cuyler
- Greenland Institute of Natural Resources, P.O. Box 570, 3900 Nuuk, Greenland
| | - Susan J Kutz
- Faculty of Veterinary Medicine, University of Calgary, 3280 University Drive, NW, Calgary, AB T2N 1N4, Canada
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Johnson HE, Lenart EA, Gustine DD, Adams LG, Barboza PS. Survival and reproduction in Arctic caribou are associated with summer forage and insect harassment. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.899585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Investigators have speculated that the climate-driven “greening of the Arctic” may benefit barren-ground caribou populations, but paradoxically many populations have declined in recent years. This pattern has raised concerns about the influence of summer habitat conditions on caribou demographic rates, and how populations may be impacted in the future. The short Arctic summer provides caribou with important forage resources but is also the time they are exposed to intense harassment by insects, factors which are both being altered by longer, warmer growing seasons. To better understand the effects of summer forage and insect activity on Arctic caribou demographic rates, we investigated the influence of estimated forage biomass, digestible energy (DE), digestible nitrogen (DN), and mosquito activity on the reproductive success and survival of adult females in the Central Arctic Herd on the North Slope of Alaska. We tested the hypotheses that greater early summer DN would increase subsequent reproduction (parturition and late June calving success) while greater biomass and DE would increase adult survival (September–May), and that elevated mosquito activity would reduce both demographic rates. Because the period when abundant forage DN is limited and overlaps with the period of mosquito harassment, we also expected years with low DN and high harassment to synergistically reduce caribou reproductive success. Examining these relationships at the individual-level, using GPS-collared females, and at the population-level, using long-term monitoring data, we generally found support for our expectations. Greater early summer DN was associated with increased subsequent calving success, while greater summer biomass was associated with increased adult survival. Mosquito activity was associated with reductions in adult female parturition, late June calving success, and survival, and in years with low DN, had compounding effects on subsequent late June calving success. Our findings indicate that summer nutrition and mosquito activity collectively influence the demographic rates of Arctic caribou, and may impact the dynamics of populations in the future under changing environmental conditions.
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Spilinek S, Reitz R, Weckerly F. Rumen–reticulum organ mass and rumen mucosa surface area of white-tailed deer (Odocoileus virginianus) consuming two energy diets. CAN J ZOOL 2020. [DOI: 10.1139/cjz-2020-0043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Flexibility in gut morphology has fitness consequences in herbivores. To accommodate dietary variation in energy concentration, rumen–reticulum absorptive capacity and organ mass might also covary. We hypothesized that low energy diets result in greater food intake but lower volatile fatty acid concentrations. The consequence would be heavy rumen–reticulum organs and low absorptive capacity. We measured rumen–reticulum organ mass and absorptive capacity in captive white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) from central Texas, USA. Deer consumed a pelleted ration, ad libitum, of 1.77 kcal/g (low) or 2.67 kcal/g (standard) digestible energy from the time animals were weaned. In December, 4.5- and 5.5-year-old deer were euthanized, the rumen–reticulum was extracted, thoroughly rinsed, wrung out, and weighed. Four 1 cm × 3 cm samples were extracted from four regions of the rumen and mucosal surface area was measured. Our surrogate of food intake and mastication intensity was first molar height. Molar height was lower in animals consuming the low energy diet. Analyses indicated sex-specific responses. Males eating the low energy diet had heavier rumen–reticulum organs, but females did not. Females consuming the low energy diet had a lower surface enlargement factor, but males did not. The processes driving variation in rumen–reticulum morphology from dietary variation require further examination.
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Affiliation(s)
- S.G. Spilinek
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - R. Reitz
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - F.W. Weckerly
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
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Thompson DP, Crouse JA, McDonough TJ, Barboza PS, Jaques S. Acute Thermal and Stress Response in Moose to Chemical Immobilization. J Wildl Manage 2020. [DOI: 10.1002/jwmg.21871] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Daniel P. Thompson
- Alaska Department of Fish and GameKenai Moose Research Center 43961 Kalifornsky Beach Road Suite B Soldotna AK 99669 USA
| | - John A. Crouse
- Alaska Department of Fish and GameKenai Moose Research Center 43961 Kalifornsky Beach Road Suite B Soldotna AK 99669 USA
| | | | - Perry S. Barboza
- Department of Wildlife and Fisheries SciencesTexas A&M University Room 274, Wildlife, Fisheries and Ecological Sciences Building, TAMU 2258 Building 1537, 534 John Kimbrough Boulevard College Station TX 77843 USA
| | - Scott Jaques
- Texas A&M Veterinary Medical Diagnostic LaboratoryTexas A&M University 483 Agronomy Road College Station TX 77840 USA
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Thompson DP, Barboza PS. Seasonal energy and protein requirements for Siberian reindeer (Rangifer tarandus). J Mammal 2017. [DOI: 10.1093/jmammal/gyx132] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Pilfold NW, Hedman D, Stirling I, Derocher AE, Lunn NJ, Richardson E. Mass Loss Rates of Fasting Polar Bears. Physiol Biochem Zool 2016; 89:377-88. [DOI: 10.1086/687988] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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VanSomeren L, Barboza P, Thompson D, Gustine D. Monitoring digestibility of forages for herbivores: a new application for an old approach. CAN J ZOOL 2015. [DOI: 10.1139/cjz-2014-0207] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ruminant populations are often limited by how well individuals are able to acquire nutrients for growth, maintenance, and reproduction. Nutrient supply to the animal is dictated by the concentration of nutrients in feeds and the efficiency of digesting those nutrients (i.e., digestibility). Many different methods have been used to measure digestibility of forages for wild herbivores, all of which rely on collecting rumen fluid from animals or incubation within animals. Animal-based methods can provide useful estimates, but the approach is limited by the expense of fistulated animals, wide variation in digestibility among animals, and contamination from endogenous and microbial sources that impairs the estimation of nutrient digestibility. We tested an in vitro method using a two-stage procedure using purified enzymes. The first stage, a 6 h acid–pepsin treatment, was followed by a combined 72 h amylase–cellulase or amylase–Viscozyme treatment. We then validated our estimates using in sacco and in vivo methods to digest samples of the same forages. In vitro estimates of dry matter (DM) digestibility were correlated with estimates of in sacco and in vivo DM digestibility (both P < 0.01). The in vitro procedure using Viscozyme (r2 = 0.77) was more precise than the in vitro procedure using cellulase (r2 = 0.59). Both procedures can be used to predict in sacco digestibility after correcting for the biases of each method. We used the in vitro method to measure digestibility of nitrogen (N; 0.07–0.95 g/g), which declined to zero as total N content declined below 0.03–0.06 g/g of DM. The in vitro method is well suited to monitoring forage quality over multiple years because it is reproducible, can be used with minimal investment by other laboratories without animal facilities, and can measure digestibility of individual nutrients such as N.
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Affiliation(s)
- L.L. VanSomeren
- Department of Biology and Wildlife, University of Alaska Fairbanks, P.O. Box 756100, Fairbanks, AK 99775-7000, USA
| | - P.S. Barboza
- Institute of Arctic Biology, Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK 99775-7000, USA
| | - D.P. Thompson
- Alaska Department of Fish and Game, Division of Wildlife Conservation, Kenai Moose Research Center, 43961 Kalifornsky Beach Road, Suite B, Soldotna, AK 99669, USA
| | - D.D. Gustine
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508-4626, USA
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Thompson ID, Wiebe PA, Mallon E, Rodgers AR, Fryxell JM, Baker JA, Reid D. Factors influencing the seasonal diet selection by woodland caribou (Rangifer tarandus tarandus) in boreal forests in Ontario. CAN J ZOOL 2015. [DOI: 10.1139/cjz-2014-0140] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We used remote video cameras to assess seasonal diet composition of woodland caribou (Rangifer tarandus tarandus (L., 1758)) at three areas across the boreal forest of Ontario. Caribou consume lichens in winter, but we expected they would significantly reduce lichen consumption in favour of higher protein levels in green plants in summer. We sampled videos from 23 caribou, from 2 years, to derive seasonal diet composition. Diet differed among seasons and study areas, except in winter when lichens dominated. Diet breadth doubled from winter to summer, but overlap between seasons was still >60%. Green plants were less commonly eaten than we expected, only three genera were preferred, and few species constituted more than 2% of the diet. Preferred foods varied by land-cover types. Diet differed between managed and unmanaged landscapes but did not result from use of plant species found in successional habitats. Caribou selected a nonoptimal diet in the snow-free seasons, especially with respect to protein, suggesting factors other than nutrition influenced diet choice, and indicating the possibility of bottom-up limitation on production.
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Affiliation(s)
- Ian D. Thompson
- Great Lakes Forestry Centre, Canadian Forest Service, 1219 Queen Street East, Sault Ste. Marie, ON P6A 2E5, Canada
| | - Philip A. Wiebe
- Great Lakes Forestry Centre, Canadian Forest Service, 1219 Queen Street East, Sault Ste. Marie, ON P6A 2E5, Canada
| | - Erin Mallon
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Arthur R. Rodgers
- Ontario Ministry of Natural Resources, Centre for Northern Forest Ecosystems Research, 955 Oliver Road, Thunder Bay, ON P7B 5E5, Canada
| | - John M. Fryxell
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - James A. Baker
- Ontario Forest Research Institute, Ontario Ministry of Natural Resources, 1235 Queen Street East, Sault Ste. Marie, ON P6A 2E5, Canada
| | - Douglas Reid
- Ontario Ministry of Natural Resources, Centre for Northern Forest Ecosystems Research, 955 Oliver Road, Thunder Bay, ON P7B 5E5, Canada
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Thompson D, Barboza P. Nutritional implications of increased shrub cover for caribou (Rangifer tarandus) in the Arctic. CAN J ZOOL 2014. [DOI: 10.1139/cjz-2013-0265] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Shrubs are increasing in the annual range of arctic caribou (Rangifer tarandus (L., 1758)), but it is unknown how much summer browse caribou could consume. We measured instantaneous intakes of resin birch (Betula glandulosa Michx.) and feltleaf willow (Salix alaxensis (Andersson) Coville) by caribou during summer. Daily intake of a formulated diet without toxins was measured during the same period to monitor appetite. Caribou appetite increased from 64.1 to 86.7 g DM·kg–0.75·day−1 as animals gained body mass from 96.8 to 113.5 kg. We estimated that caribou required 645 kJ·kg–0.75·day−1 of digestible energy to maintain body mass and 1113 kJ·kg–0.75·day−1 to gain body mass for autumn reproduction. Caribou had the same bite mass (9.7 mg·bite−1·kg–0.75) and instantaneous intake rate (0.17 g DM·min−1·kg–0.75) on both forages; however, birch contained more phenols (3.3% vs. 1.5%) and less available protein (6.2% vs. 10.2%) than willow. A 100 kg female caribou would need to consume 2.4–8.7 kg of fresh browse, requiring 3.1–8.5 h·day−1 of eating time to meet daily energy requirements. Birch is unlikely to provide enough nitrogen for maintenance of body protein. Therefore, caribou may depend on abundance and diversity of plants to offset toxin loads and low protein intake from shrubs during summer.
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Affiliation(s)
- D.P. Thompson
- Department of Biology and Wildlife, University of Alaska, Fairbanks, P.O. Box 756100, Fairbanks, AK 99775, USA
| | - P.S. Barboza
- Institute of Arctic Biology, Department of Biology and Wildlife, University of Alaska, Fairbanks, P.O. Box 757000, Fairbanks, AK 99775, USA
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Bårdsen BJ, Næss MW, Tveraa T, Langeland K, Fauchald P. Risk-sensitive reproductive allocation: fitness consequences of body mass losses in two contrasting environments. Ecol Evol 2014; 4:1030-8. [PMID: 24772280 PMCID: PMC3997319 DOI: 10.1002/ece3.1010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 01/10/2014] [Accepted: 01/28/2014] [Indexed: 11/26/2022] Open
Abstract
For long-lived organisms, the fitness value of survival is greater than that of current reproduction. Asymmetric fitness rewards suggest that organisms inhabiting unpredictable environments should adopt a risk-sensitive life history, predicting that it is adaptive to allocate resources to increase their own body reserves at the expense of reproduction. We tested this using data from reindeer populations inhabiting contrasting environments and using winter body mass development as a proxy for the combined effect of winter severity and density dependence. Individuals in good and harsh environments responded similarly: Females who lost large amounts of winter body mass gained more body mass the coming summer compared with females losing less mass during winter. Additionally, females experienced a cost of reproduction: On average, barren females gained more body mass than lactating females. Winter body mass development positively affected both the females' reproductive success and offspring body mass. Finally, we discuss the relevance of our findings with respect to scenarios for future climate change.
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Affiliation(s)
- Bård-Jørgen Bårdsen
- Norwegian Institute for Nature Research (NINA), Arctic Ecology Department, Fram Centre Tromsø, NO-9296, Norway
| | - Marius Warg Næss
- CICERO - Center for International Climate and Environmental Research, Fram Centre Tromsø, NO-9296, Norway
| | - Torkild Tveraa
- Norwegian Institute for Nature Research (NINA), Arctic Ecology Department, Fram Centre Tromsø, NO-9296, Norway
| | - Knut Langeland
- Norwegian Institute for Nature Research (NINA), Arctic Ecology Department, Fram Centre Tromsø, NO-9296, Norway
| | - Per Fauchald
- Norwegian Institute for Nature Research (NINA), Arctic Ecology Department, Fram Centre Tromsø, NO-9296, Norway
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