Protein Status Of Muskoxen And Caribou In Late Winter

Thesis (Ph.D.) University of Alaska Fairbanks, 2010The conservation and management of northern ungulates depends upon our understanding of the influence of habitat associations on the nutritional condition of individuals and population productivity. Adverse foraging conditions in late winter may reduce the availability of body proteins for reproduction. Therefore, assessing nitrogen (N) or protein status in late winter could be a valuable tool to monitor populations of northern ungulates. I collected >1,800 excreta samples to evaluate isotopic metrics of protein status [proportion of serum amino acid N derived from body N (p-AN), proportion of urea N derived from body N (p-UN), and the difference between the isotopic ratios of N (delta15N) in body tissues and urinary urea (DeltaBody-urea)] in captive and wild populations of muskoxen (Ovibos moschatus) and caribou (Rangifer tarandus) in late winter. I evaluated the dynamics of body protein and delta15N in a captive population of female muskoxen (2007). Diets and protein status were assessed in populations of wild muskoxen in northern Alaska (2005--2008); a semi-captive (penned) population of wild, pregnant caribou (2006); and wild populations of migratory and sedentary ecotypes of caribou (2006--2008). Captive female muskoxen lost body protein (~6%) in late gestation and these losses corresponded with the protein deposited in reproductive tissues. The concentration of plasma urea, the p-AN, and p-UN tended to increase throughout winter. During late gestation, most penned pregnant caribou on an ad libitum feeding schedule lost core body mass (55%) and were in negative protein status (54%). For groups of wild muskoxen (n = 30), abundance of preferred forages improved protein status (p-UN; R2 = 0.45). At the foraging sites of wild caribou (n = 32), the amount of shrubs in a lichen-rich diet had a positive effect on protein status (DeltaBody-urea, r2 = 0.26). Foraging constraints in late winter will decrease the amount of body proteins available for reproduction. However, considerable challenges remain to applying the p-UN as a monitoring tool at broad scales for caribou, but with appropriate consideration, isotopic proxies may be used to evaluate environmental constraints for northern ungulates at small scales

Evaluating Potential Effects of an Industrial Road on Winter Habitat of Caribou in North-Central Alaska

Worldwide, some caribou (Rangifer tarandus) populations are experiencing declines due partially to the expansion of industrial development. Caribou can exhibit behavioral avoidance of development, leading to indirect habitat loss, even if the actual footprint is small. Thus, it is important to understand before construction begins how much habitat might be affected by proposed development. In northern Alaska, an industrial road that has been proposed to facilitate mining transects a portion of the Western Arctic caribou herd’s winter range. To understand how winter habitat use might be affected by the road, we estimated resource selection patterns during winter for caribou in a study area surrounding the proposed road. We assessed the reductions of habitat value associated with three proposed routes at three distance thresholds for disturbance. High-value winter habitat tended to occur in locally rugged areas that have not burned recently and have a high density of lichen and early dates of spring snowmelt. We found that 1.5% to 8.5% (146–848 km2) of existing high-value winter habitat in our study area might be reduced in quality. The three alternative routes were only marginally different. Our results suggest that the road would have minimal direct effects on high-value winter habitat; however, additional cumulative impacts to caribou (e.g., increased access by recreationists and hunters) should be considered before the full effects of the road can be estimated.À l’échelle mondiale, certaines populations de caribous (Rangifer tarandus) connaissent des déclins partiel­lement attribuables à l’expansion industrielle. Pour des raisons de comportement, le caribou peut éviter le développement, ce qui entraîne une perte d’habitat indirecte, et ce, même si la place réellement occupée est petite. Par conséquent, il est important de comprendre, avant même que des travaux de construction ne soient amorcés, dans quelle mesure l’habitat sera touché par les travaux proposés. Dans le nord de l’Alaska, une route industrielle dont la construction a été proposée pour faciliter l’exploitation minière coupe transversalement une partie de l’aire d’hivernage du troupeau de caribous de l’ouest de l’Arctique. Afin de comprendre comment l’utilisation de l’habitat d’hivernage pourrait être touchée par la route, nous avons estimé des modèles de sélection des ressources pendant l’hiver pour le caribou se trouvant dans une aire d’étude entourant la route proposée. Nous avons évalué la diminution de la valeur de l’habitat liée à trois routes proposées à trois seuils de distance afin d’en déterminer la perturbation. Un habitat d’hivernage de grande valeur avait tendance à se manifester dans les régions locales accidentées qui n’avaient pas fait l’objet de brûlages récents, régions caractérisées par une forte densité de lichen et une fonte des neiges hâtive au printemps. Dans le cadre de notre étude, nous avons constaté que la qualité de 1,5 % à 8,5 % (146–848 km2) de l’habitat d’hivernage actuel de grande valeur pourrait être réduite. Les trois routes différaient à peine. Nos résultats suggèrent que la route aurait des effets directs minimes sur l’habitat d’hivernage de grande valeur. Cependant, il y a lieu de considérer les incidences cumulatives supplémentaires (comme l’accès accru par les amateurs de plein air et les chasseurs) afin de pouvoir estimer les effets complets de la route

Using ultrasound measurements of rump fat to assess nutritional condition of woodland caribou in northern British Columbia, Canada

Body reserves (fat and protein) of cervids are important to the reproductive success of individuals, and therefore may limit productivity of populations. We used a portable ultrasound machine to measure thickness of rump fat for 39 woodland caribou (Rangifer tarandus caribou) captured in the winters (January–February) of 2003 and 2004. We compared thickness of rump fat between pregnant and non-pregnant individuals in the Besa-Prophet drainage of northern British Columbia, Canada. Thirty-eight of the 39 females captured in British Columbia were adults and 34 of the adult caribou were pregnant (89.5 ± 5.1%, x– ± binomial SE). Pregnant individuals had more rump fat (0.60 ± 0.067 cm) than nonpregnant animals (0.20 ± 0.029 cm). Recognizing that deposition and mobilization of fat vary with age and possibly across the winter season, ultrasonography can be used as a non-invasive technique in the field to assist in estimating body fat of caribou

Strong Ramsey Games in Unbounded Time

For two graphs $B$ and $H$ the strong Ramsey game $\mathcal{R}(B,H)$ on the board $B$ and with target $H$ is played as follows. Two players alternately claim edges of $B$. The first player to build a copy of $H$ wins. If none of the players win, the game is declared a draw. A notorious open question of Beck asks whether the first player has a winning strategy in $\mathcal{R}(K_n,K_k)$ in bounded time as $n\rightarrow\infty$. Surprisingly, in a recent paper Hefetz et al. constructed a $5$-uniform hypergraph $\mathcal{H}$ for which they proved that the first player does not have a winning strategy in $\mathcal{R}(K_n^{(5)},\mathcal{H})$ in bounded time. They naturally ask whether the same result holds for graphs. In this paper we make further progress in decreasing the rank. In our first result, we construct a graph $G$ (in fact $G=K_6\setminus K_4$) and prove that the first player does not have a winning strategy in $\mathcal{R}(K_n \sqcup K_n,G)$ in bounded time. As an application of this result we deduce our second result in which we construct a $4$-uniform hypergraph $G'$ and prove that the first player does not have a winning strategy in $\mathcal{R}(K_n^{(4)},G')$ in bounded time. This improves the result in the paper above. An equivalent formulation of our first result is that the game $\mathcal{R}(K_\omega\sqcup K_\omega,G)$ is a draw. Another reason for interest on the board $K_\omega\sqcup K_\omega$ is a folklore result that the disjoint union of two finite positional games both of which are first player wins is also a first player win. An amusing corollary of our first result is that at least one of the following two natural statements is false: (1) for every graph $H$, $\mathcal{R}(K_\omega,H)$ is a first player win; (2) for every graph $H$ if $\mathcal{R}(K_\omega,H)$ is a first player win, then $\mathcal{R}(K_\omega\sqcup K_\omega,H)$ is also a first player win.Comment: 18 pages, 46 figures; changes: fully reworked presentatio

Influence of Infanticide Risk on Brown Bear Den-Site Selection

The risk of infanticide in brown bears (Ursus arctos) may influence den-site selection and chronology for female brown bears with dependent young. Strategies to reduce risk of infanticide include females avoiding larger, more dominant adult males through spatialor temporal segregation. We assessed whether variation in den location, den habitat, and den entrance and emergence dates of male and female bears supported sexual segregation in Lake Clark National Park and Preserve, Alaska. Den-sites (n = 56) were located using GPS telemetry data from bears in 2014 (n = 21) and 2015 (n = 35). We used mixed model analysis of variance to compare slope, elevation, and aspect of den sites for adult male and adult female bears with and without dependent young. We also used these variables to model probable denning habitat using maximum entropy modeling. We examined timing of female den entry and emergence in relation to males using generalized linear mixed models. Our preliminary results using 2014 data suggest that females with dependent may den at higher elevations (944 ± 140 m, x ? ± SD) than solitary females (866 ± 189 m) but at lower elevations (984 ± 118 m) than males. They also may use less steep slopes (25 ± 11.8°) than solitary females (29 ± 9.9°) or males (34 ± 4.9°). Additionally, females with dependent young (Julian day: 289 ± 8 days) denned 2 days later than solitary females (287 ± 6 days) and 20 days earlier than males (309 ± 21 days). Females with dependent young (122 ± 17 days) also emerged from dens 6 days earlier than solitary females (128 ± 9 days) and 10 days earlier than males (132 ± 10 days). Differences in den entrance and emergence dates suggest support our hypothesis that females with dependent young temporally segregate from male bears

Variation in δ\u3csup\u3e15\u3c/sup\u3eN and δ\u3csup\u3e13\u3c/sup\u3eC values of forages for Arctic caribou: effects of location, phenology and simulated digestion

RATIONALE: The use of stable isotopes for dietary estimates of wildlife assumes that there are consistent differences in isotopic ratios among diet items, and that the differences in these ratios between the diet item and the animal tissues (i.e., fractionation) are predictable. However, variation in isotopic ratios and fractionation of δ13C and δ15N values among locations, seasons, and forages are poorly described for arctic herbivores especially migratory species such as caribou (Rangifer tarandus). METHODS: We measured the δ13Cand δ15N values of seven species of forage growing along a 200-km transect through the range of the Central Arctic caribou herd on the North Slope of Alaska over 2 years. We compared forages available at the beginning (May; n = 175) and the end (n = 157) of the growing season (September). Purified enzymes were used to measure N digestibility and to assess isotopic fractionation in response to nutrient digestibility during simulated digestion. RESULTS: Values for δ13C declined by 1.38‰ with increasing latitude across the transect, and increased by 0.44‰ from the beginning to the end of the season. The range of values for δ15N was greater than that for δ13C (13.29 vs 5.60 ‰). Differences in values for δ13C between graminoids (Eriophorum and Carex spp.) and shrubs (Betula and Salix spp.) were small but δ15N values distinguished graminoids (1.87 ± 1.02‰) from shrubs (-2.87 ± 2.93‰) consistently across season and latitude. However, undigested residues of forages were enriched in 15Nwhen the digestibility of N was less than 0.67. CONCLUSIONS: Although δ15N values can distinguish plant groups in the diet of arctic herbivores, variation in the digestibility of dietary items may need to be considered in applying fractionation values for 15N to caribou and other herbivores that select highly digestible items (e.g. forbs) as well as heavily defended plants (e.g. woody browse)

071089_Innmat_12.indd

Absttact: Body reserves (fat and protein) of cervids are important to the reproductive success of individuals, and therefore may limit productivity of populations. We used a portable ultrasound machine to measure thickness of rump fat for 39 woodland caribou (Rangifer tarandus caribou) captured in the winters (January-February) of 2003 and 2004. We compared thickness of rump fat between pregnant and non-pregnant individuals in the Besa-Prophet drainage of northern British Columbia, Canada. Thirty-eight of the 39 females captured in British Columbia were adults and 34 of the adult caribou were pregnant (89.5 ± 5.1%, x -± binomial SE). Pregnant individuals had more rump fat (0.60 ± 0.067 cm) than nonpregnant animals (0.20 ± 0.029 cm). Recognizing that deposition and mobilization of fat vary with age and possibly across the winter season, ultrasonography can be used as a non-invasive technique in the field to assist in estimating body fat of caribou

Environmental and physiological influences to isotopic ratios of N and protein status in a Montane ungulate in winter.

Winter severity can influence large herbivore populations through a reduction in maternal proteins available for reproduction. Nitrogen (N) isotopes in blood fractions can be used to track the use of body proteins in northern and montane ungulates. We studied 113 adult female caribou for 13 years throughout a series of severe winters that reduced population size and offspring mass. After these severe winters, offspring mass increased but the size of the population remained low. We devised a conceptual model for routing of isotopic N in blood in the context of the severe environmental conditions experienced by this population. We measured δ15N in three blood fractions and predicted the relative mobilization of dietary and body proteins. The δ 15N of the body protein pool varied by 4‰ and 46% of the variance was associated with year. Annual variation in δ15N of body protein likely reflected the fall/early winter diet and winter locations, yet 15% of the isotopic variation in amino acid N was due to body proteins. Consistent isotopic differences among blood N pools indicated that animals tolerated fluxes in diet and body stores. Conservation of body protein in caribou is the result of active exchange among diet and body N pools. Adult females were robust to historically severe winter conditions and prioritized body condition and survival over early investment in offspring. For a vagile ungulate residing at low densities in a predator-rich environment, protein restrictions in winter may not be the primary limiting factor for reproduction

Correction: Range Expansion of Moose in Arctic Alaska Linked to Warming and Increased Shrub Habitat.

[This corrects the article DOI: 10.1371/journal.pone.0152636.]

Range Expansion of Moose in Arctic Alaska Linked to Warming and Increased Shrub Habitat.

Twentieth century warming has increased vegetation productivity and shrub cover across northern tundra and treeline regions, but effects on terrestrial wildlife have not been demonstrated on a comparable scale. During this period, Alaskan moose (Alces alces gigas) extended their range from the boreal forest into tundra riparian shrub habitat; similar extensions have been observed in Canada (A. a. andersoni) and Eurasia (A. a. alces). Northern moose distribution is thought to be limited by forage availability above the snow in late winter, so the observed increase in shrub habitat could be causing the northward moose establishment, but a previous hypothesis suggested that hunting cessation triggered moose establishment. Here, we use recent changes in shrub cover and empirical relationships between shrub height and growing season temperature to estimate available moose habitat in Arctic Alaska c. 1860. We estimate that riparian shrubs were approximately 1.1 m tall c. 1860, greatly reducing the available forage above the snowpack, compared to 2 m tall in 2009. We believe that increases in riparian shrub habitat after 1860 allowed moose to colonize tundra regions of Alaska hundreds of kilometers north and west of previous distribution limits. The northern shift in the distribution of moose, like that of snowshoe hares, has been in response to the spread of their shrub habitat in the Arctic, but at the same time, herbivores have likely had pronounced impacts on the structure and function of these shrub communities. These northward range shifts are a bellwether for other boreal species and their associated predators