La Tierra estuvo enferma v.1-2 (Spanish Edition)

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Diciembre Harvard Sem. Note lo siguiente:. Hechos 7: Ella habla de una batalla, muestra personas vestidas como Cananeos, y habla de Egipto destruyendo semilla de Israel. Charemon citado ibid. Pero si A. Desde esta fecha circa , A. El abandono de Avaris durante el reinado de Amenhotep II. Wright T. July 20, Algunos factores son relevantes. Reino Nuevo de Egipto ca. El reto es identificar al hijo mayor de Amenhotep II.

Algunos candidatos son posibles. En algunos casos, los culpables cuidadosa y completamente cortaron la silueta de su imagen de los relieves, dejando a menudo una distinta laguna, en forma de Hatshepsut en medio de la escena, a menudo como un paso preliminar para reemplazarla con una imagen diferente o una imagen real, tal como la de Thutmose I o II.

Ahora es posible responder a las preguntas planteadas antes. Los enemigos de la tierra han despojado? Grabbe, p. Hay un registro en el papiro Ipuwer que parece hablar de egipcios que se conviertieron en extranjeros:. IV:1 Ciertamente, toda persona muerta es como un hombre bien nacido. Aquellos que eran egipcios [se han convertido] en extranjeros y son arrojados a un lado. Las admoniciones de Ipuwer. Los esclavos que eran seguidores se convirtieron en seguidos por algunos de los egipcios.

Consecuentemente los extranjeros son expulsados. Assmann J. Additionally, cougar predation made up a smaller proportion of mortality rates in areas with a larger assemblage of carnivores Griffin et al. Davidson et al. Reducing the Davidson et al. Cougar density was lower in SW than in NE and this is likely a biological phenomenon rather than ineffective sampling. Harvest of cougars in NE varied annually and we contend this caused cougar densities to vary among years. Broadly, these patterns follow timing of predation observed in other studies Smith and Anderson ; Singer et al.

Studies conducted in YNP and Wyoming included predation by grizzly bears, which was not always differentiated from predation by black bears, confounding comparisons of proportions of neonates killed by black bears. Proportion of mortality attributable to black bears may be related to bear density and the suite of carnivores present Griffin et al. Bear predation on neonate elk was restricted to the first few weeks of life because after this time, juveniles were sufficiently mobile to avoid capture. We documented black bears scavenging or usurping 43 of juvenile elk killed by cougars in NE from birth to 1 November before we investigated the mortality we used this cutoff date because bears were typically in dens and not active on the landscape.

This high degree of kleptoparasitism may cause cougars to abandon the carcass and kill another animal, increasing the effect of cougars on elk calf survival. Although Clark et al. Further, cougar kill rates appear best explained by the proportion of juveniles Knopff et al.

Wolf reintroduction may have reduced coyote densities and their subsequent effect on juvenile elk survival Merkle et al. Although wolf packs were not established in our study areas, cougar densities in NE were some of the highest reported in western North America Davidson et al. Cougars kill coyotes Knopff et al. If predation by cougars on coyotes was sufficiently high, cougars may have depressed coyote densities such that their densities were lower than in YNP. We have no estimates of coyote densities to support this hypothesis.

Throughout the range of cougars in North America, including Oregon, deer are their primary prey Iriarte et al. Consequently, cougar density in our study areas was likely determined by deer rather than elk density.

Selection of a secondary prey species by a generalist predator can cause population declines or allow predators to maintain secondary prey species at low densities Messier , Sinclair et al. The wide variation in success White et al. It also supports the conclusion of Linnell et al.

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We could not manipulate predator numbers to directly address whether predation in our study areas was additive or compensatory with other sources of mortality. Consequently, we used a set of hypotheses Appendix A to assess the degree to which predation was additive or compensatory. The high rates of predation by cougars and strong relationship between cougar density and juvenile survival Fig. In areas where summer nutrition is marginal or inadequate Cook et al.

This increases the proportion of lactating females with relatively low nutritional condition Gerhart et al. The magnitude of any one of these responses may be small, but in combination they may compensate for reductions in predation to a biologically significant degree. Thus, one limiting factor nutrition may partially replace another predation if predation is reduced.

The potential for compensation between nutrition and predation is likely dependent on a number of environmental influences. Further, stochastic effects of precipitation and temperature at various times of the year may influence compensatory relationships from year to year. The positive effect of summer precipitation on IFBF autumn indicates an indirect link between summer precipitation and pregnancy Johnson et al. Finally, juvenile survival over winter was positively related to summer precipitation and negatively related to current winter precipitation totals.

The higher pregnancy rates probably reflect greater levels of precipitation in our study areas compared to most of the ecoregion Heyerdahl et al. Thus, it is likely that most elk in the region have lower quality nutritional resources and are limited to a greater extent by inadequate summer nutrition than in our NE study areas. This discrepancy between IFBF autumn and pregnancy rates may be due to complex interactions among late summer precipitation, nutrition, and physiology on ovulation. In the Blue Mountains physiographic province, late summer and early autumn precipitation, operating through nutritional pathways, was likely responsible for much of the annual variation in pregnancy rates of lactating females Appendix C; Johnson et al.

Survival and subsequent recruitment of juveniles was largely limited by predation from cougars; however, our results also indicate nutritional limitations operated to reduce productivity of elk mainly by reducing pregnancy rates of lactating females, delaying conception and thus parturition, and increasing susceptibility of juveniles and adults to predation and winter starvation.

Although not evaluated as part of this study, nutritional limitations undoubtedly retarded growth and development of juveniles and subadults Cook et al. Our data also suggest partial compensatory interactions between nutrition and predation, the relative effects of which would vary in response to stochastic variation in weather across the annual cycle. Thus, the effects of predation and nutrition were not independent.

Although we strove to separate the influences of nutrition and predation, many questions remain unanswered about how the 2 factors interact, particularly in the context of prescribing management action to increase productivity of the elk. Our insights would have benefited from a larger sample of lactating females for understanding compensatory responses in pregnancy and body mass and nutritional condition data of juveniles in late autumn for insight into vulnerability to predation in winter. Our results certainly suggest management aimed at reducing cougar densities could potentially increase productivity White et al.

Our results, however, also indicated cougar predation was not completely additive; thus, predator reductions may fail to satisfy objectives for ungulate populations Hurley et al. Throughout their range, elk occupy vastly different habitats where seasonal and regional differences in quality and quantity of nutritional resources vary as evident by autumn body fat of lactating females Cook et al. Additionally, assemblages and densities of carnivores vary throughout the range of elk, leading to variation in juvenile and adult survival Griffin et al.

These studies highlight the importance of understanding factors affecting population dynamics of elk at local and regional scales before embarking on management actions to improve productivity.

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Of the factors we evaluated that affected elk population dynamics, the 2 most limiting were nutrition in summer and early autumn and predation of juveniles by cougars. Wildfire suppression efforts since the early s in the Inland Northwest and northern Rock Mountains has greatly reduced annual rates of burning Keane et al.

Forest management strategies that reduce tree density e. In contrast, in the xeric forest types and rangelands of the interior Northwest, hot summers and limited and variable summer precipitation support variable nutritional resources typically of low quality in summer Cook et al. In these dry habitats, there may be little managers can do to bolster nutritional resources during most of summer other than maintain diverse and productive communities of native perennial plants to the extent possible.

Concomitantly, road management needs to be integrated with habitat treatments to minimize unintended effects of human disturbance Rowland et al. The positive influences of disturbance such as wildfire or logging on developing diverse and productive plant communities may be countered by chronic herbivory because these community types are often highly attractive foraging areas Wisdom et al.

A classical perception is that reducing densities of herbivores may help bolster per capita nutrition, nutritional condition, and productivity Fowler , McCullough Reducing elk numbers could lead to a predator pit scenario i. Given the strong effect of cougar predation on juvenile survival observed in our NE study area, reducing cougar populations may increase survival of juvenile elk.

Sport hunting with pursuit dogs can be successful in manipulating cougar populations Anderson and Lindzey , Lambert et al. Cougars are classified as a hunted game mammal across much of their current range Anderson et al. Anderson and Lindzey and Wolfe et al.

The ability of cougar populations to rapidly increase in size following reductions by high levels of human harvest may provide managers the opportunity to reduce cougar populations over 1 or 2 years to respond to pulse events e. As carnivore populations continue to recover in North America, their effects on ungulate productivity will likely increase Griffin et al. When managers need to address declining elk recruitment but lack empirical data to support management actions, we suggest several metrics that could be measured to identify potential limiting factors: Use the most accurate indices available to identify nutritional limitations e.

Consult Cook et al. Assess juvenile to adult female ratios in autumn Sep—Oct and at end of winter to determine timing of juvenile mortality. Low juvenile to female ratios in late summer indicate that substantial mortality occurred assuming high pregnancy rates and resources should be targeted toward understanding low rates of summer survival. Using all of the above data, develop elk population models Clark , Eacker et al. Identifying which of these metric are correlated will allow managers to more efficiently invest resources to identify proximate causes of low recruitment.

These results can then be used to frame management hypotheses that can be tested via an adaptive framework. In sum, the fundamental difficulty for managers faced with declining recruitment involves making decisions with less than complete information. Managers may either implement detailed field studies to evaluate causes of declines to provide the information, or implement actions based on incomplete evidence that may or may not achieve desired outcomes.

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Such efforts should be developed and stringently monitored in an adaptive management framework to address specific hypotheses to discriminate between the compensatory and additive components of predation. To influence elk populations, managers can manipulate harvest of adult females, densities of carnivores to increase juvenile survival, and vegetative conditions to improve both quality and quantity of nutritional resources available.

In light of this, when managers implement actions to improve population performance, we encourage actions be developed in ways that outcomes can be evaluated through testable hypotheses. We dedicate this Monograph in honor and memory of Dr. Robert Anthony, our mentor, collaborator, and friend. Bob reviewed the MARK analyses but did not have the opportunity to review final drafts of this manuscript and rather than put words in his mouth, we thought this was our best way to recognize his effort in our work.

His critical thinking, insightful commentary, commitment to wildlife, and humor are missed. Hagerman superbly piloted helicopters and R. Spencer darted and net gunned the vast majority of elk captured by air. In addition, B. Brim, J. Pope, Sr.

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Pope, Jr, R. Swisher, and D. Uttecht piloted helicopters, P. Matthews net gunned neonates and L. Bender darted female elk. Culp, K. West, and J. Field assistance to capture neonates, investigate mortalities, and capture cougars were provided by ODFW employees M. Boulay, D. Bronson, J. Cadwell, L. Erickson, M. Hansen, H. Hayden, D. Immell, D. Jones, J. Kercher, A. Larkin, R. Madigan, P. Matthews, J. Orr, J. Paustian, B.

Ratliff, J. Smith, R. Torland, and Z. Turnbull, student interns L. Bristol, B. Carroll, J. Prikart, and D. Speth and many volunteers including S. Daugherty and D. Doctors C. Gillin, T. McCoy, and M. Omann provided veterinary support. We sincerely thank T. Craddock, W. Craddock, R. Culver, D. Gilbert, K. Forney, R. Croweater, and D. Likens for their skill in raising and handling dogs to pursue and tree cougars for research purposes. We thank L. Juarez for translation of the Spanish abstract. Figgins, E. Hafer, H. Johnson, S. Johnson, R. Johnson, J. Schmekel, and L.

Riggs was instrumental in facilitating access to Boise Cascade Corporation lands. We are grateful for thoughtful comments by Editor M. Publication costs were provided by Oregon Department of Fish and Wildlife.

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Hypotheses of compensatory, additive, and partially additive mortality to assess effects of cougar and black bear predation on juvenile elk. Hypothetical relationships in the first scenario A represent expectations of additive, partially additive, and compensatory mortality in relation to a threshold, represented by the vertical line at point C, where all mortality becomes additive. Hypothetical relationships in the second scenario B show predicted expectations for additive, partially additive, and compensatory mortality that occurs below the threshold where all mortality becomes additive.

We calculated juvenile and adult female elk ratios from surveys conducted annually by Oregon Department of Fish and Wildlife personnel. During late autumn hunts, elk hunters collected uteri for assessing pregnancy status, lower jaw for aging from cementum annuli of the central incisor, and mammary tissue for assessing lactation status Johnson et al. A priori hypotheses and models for testing the effects of various factors on survival rates S of juvenile elk for 30 days, 16 weeks, and 12 months.

Hypothesis description Model S are different among study areas S area S are different among years S year S are different between males and females S sex S among areas, sexes, and years are constant S. No unmarked cougars were killed in Steamboat and Toketee study areas in southwestern Oregon.

All cougars were killed by hunters except for 3 cougars removed by administrative action in — Study area Sex Sled Springs Female n 2 1 1 1 Age 5. Models M are time t , heterogeneity h , intercept. Physical attributes by lactation status of female elk 2—14 years old captured in late autumn in Sled Springs and Wenaha study areas in northeastern Oregon, USA, —, and Steamboat and Toketee study areas in southwest Oregon, — We directed fall capture efforts at known lactating females when flying conditions or budgetary constraints limited time and accessibility of animals.

Physical attributes by pregnancy status of female elk 2—14 years old captured in spring in Sled Springs and Wenaha study areas in northeastern Oregon, USA, —, and Steamboat and Toketee study areas in southwest Oregon, — We reduced mass of pregnant elk by the estimated mass of the fetus and associated reproductive tissues.

Model selection results for annual survival of adult female elk in Sled Springs and Wenaha study areas northeastern Oregon, USA, — All abiotic covariates are from the current year. Wildlife Monographs Volume , Issue 1. Wildlife Monograph Open Access. Bruce K. Dewaine H. Rachel C. Darren A. Clark Corresponding Author E-mail address: darren. Priscilla K. John G. Spencer N. Scott L. James H. Tools Request permission Export citation Add to favorites Track citation. Share Give access Share full text access. Share full text access.

Please review our Terms and Conditions of Use and check box below to share full-text version of article. Figure 1 Open in figure viewer PowerPoint. Figure 2 Open in figure viewer PowerPoint. Mean monthly Dec—Feb 3. Figure 3 Open in figure viewer PowerPoint. We estimated ratios during helicopter classification flights.

Adult female elk We captured adult female elk beginning in late November in Sled Springs and late March in Wenaha to determine age, pregnancy, and lactation status and to estimate nutritional condition. Neonates We used 3 primary methods to capture neonates: 1 monitored females with VITs to locate and capture neonates VIT neonate ; 2 observed behavior of solitary females from the ground or helicopter to locate and capture neonates by hand hand neonate ; and 3 searched by helicopter for females accompanied by neonates captured via net gun shot from the helicopter netted neonate.

Neonate birth weight and birth date We identified relationships between capture mass and age at capture by sex for all VIT and hand neonates from NE using normal linear regression models. Survival Analysis Neonate survival We developed a set of a priori candidate models for analysis, which were based on biological hypotheses, to test for potential effects of a multitude of variables on juvenile survival rates Appendix D through the first 30 days, 16 weeks, and 12 months of life.

Nutritional Condition and Performance of Elk We captured 4 yearling and adult female elk times across 4 study areas with and capture events in spring and autumn, respectively. Figure 4 Open in figure viewer PowerPoint. We estimated age panels A, B from counts of cementum annuli of vestigial canine teeth, mass panels C, D from girth measurements with mass adjusted for pregnancy status in spring, and IFBF panels E, F from ultrasonography and body condition scoring.

Sled Springs Densities of independent female and adult cougars were 0. No unmarked cougars were reported killed within Toketee and Steamboat study areas during or in the 4 years following data collection. He remained in the study area and included in the population estimate. Although cougar harvest was less in SW than NE, this low level of mortality from hunting combined with increased natural mortality rates in this region Clark et al. We identified 32 individual bears 11 females, 21 males in Sled Springs and 49 individual bears 19 females, 30 males in Wenaha from DNA analysis of hair.

Within study areas, estimates of bear populations in Sled Springs or Wenaha were similar for models that included heterogeneity or time, but models that accounted for behavior produced estimates that were larger with broad confidence intervals; consequently, we dropped behavioral models from our population estimates. These estimates indicated black bear densities were relatively similar among study areas and years. We captured 4 yearling and adult female elk times across 4 study areas with and capture events in spring and autumn, respectively.

In Sled Springs, we captured 68 females times in spring and times in autumn. In Wenaha, we captured 53 females times in spring and 67 times in autumn. In Steamboat, we captured 31 females 54 times in spring and 25 times in autumn. In Toketee, we captured 44 females 61 times in spring and 24 times in autumn. Ages of females that received VITs generally increased over time within a study area because our study design relied on repeated measurements of nutritional condition of females Figs. During and when we caught VIT neonates in all 4 study areas, ages of pregnant females did not differ among study areas or between years Table 4.

In autumn, measures of nutritional condition of BM autumn and IFBF autumn of females 2—14 years old varied significantly by pregnancy and lactation status. For lactating elk, neither age nor BM autumn differed among study areas. Among study areas, however, IFBF autumn of lactating elk differed and was 2.

Mass of females did not differ among the other 3 study areas Appendix H; Fig. Mean age of females in NE observed with delayed breeding These results suggest that mean nutritional condition entering winter had a much stronger effect on mean IFBF spring than any of our measures of winter weather in NE. There was no evidence to indicate cougar density influenced female survival because this model ranked lower than the constant survival model. Overall, annual survival including all sources of mortality was 0.

We identified an additional 56 birth sites in NE where we did not capture the neonate. Mean ages at capture were 1. Given that timing of conception was influenced by nutritional condition Cook et al. From —, we captured neonates in NE: from elk with VITs, from behavioral observations of solitary unmarked elk, and using a net gun fired from a helicopter.

Median birth date for hand and VIT neonates was day We captured 2 neonates 1 from a female with a VIT that were abandoned and in poor condition when we found them and subsequently died of starvation. One VIT neonate with a deformed hoof was killed by a black bear 3 days after its capture. Even though skin wounds had healed when carcasses were recovered, we are unsure the role, if any, the injuries played in their deaths. We collected 21 femurs from juveniles killed by cougar or unknown predation from 1 December through the end of May. We captured neonates in — 46 from VITs, 42 from behavioral observations of solitary unmarked female elk, and 68 using a net gun fired from a helicopter.

The VIT neonate captured on 28 April weighed 6. We judged it to be born prematurely and censored it from survival analyses. Unknown predation included 8 probable cougar and 2 probable bear predations. We did not collect femurs from mortalities in SW. We assumed lactation status predicted juvenile survival through late November. Female mass and IFBF spring were highly correlated, explaining why both appeared as competing models and were never included in the same model.

When we included time trend effects i. Three models were within 2 AIC c points of the top model. Competing models included covariates for female age and cougar density Appendix L. Time trend model LnT was 3. Model selection results for the analysis of VIT neonates to 12 months followed similar patterns for survival to 16 weeks. Two models were competing; in one model, female age entered the model and in the other model region replaced cougar density Appendix M. In models where region replaced cougar density, survival was higher in SW where cougar densities were lower.

There was no support for the other covariates. Survival rates differed by study area, but a pattern of increased survival was consistent over time during the first 30 days, 16 weeks, and 12 months of life. The negative relationships of juvenile survival with female mass or IFBF were contrary to our initial hypotheses. In a post hoc analysis attempting to explain the negative relationship of IFBF and mass with juvenile survival, we found evidence that maternal success varied among females.

Because lactating females were thinner in both autumn and spring across all study areas, this could explain the negative relationship between juvenile survival and maternal condition we observed. Survival was higher when cougar density was lower Fig. Signs of coefficients were positive for capture age and sex male but negative for birth date and cougar density Fig. Competing models included effects of cougar density and birth date Appendix P.

Signs of coefficients were positive for capture age and negative for cougar density and birth date Fig. Consequently, we were unable to identify any abiotic or biological factors that substantially influenced juvenile survival from 7—12 months of age and this indicates variation in environmental factors was only weakly associated with juvenile survival during this period in NE.

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In contrast to NE, the best performing models for survival of juvenile elk in SW included abiotic factors and cougar density was rather unimportant in explaining survival of juveniles. April—May total precipitation entered into the models with a negative coefficient Fig. Birth date entered into the top model with a positive coefficient Fig. December—February precipitation t — 1 entered into 1 competing model with a positive coefficient Appendix R. Across our 4 study areas, survival of juveniles was strongly related to cougar density.

We found that variation in cougar density explained the majority of variation in juvenile survival through the end of summer and recruitment of juvenile elk into the adult populations. We observed minimal effects of climatic variation on vital rates of elk, but some factors e. Although these results were consistent with other studies that demonstrated the strong effect of predation on juvenile elk survival Myers et al.

Population growth rates of elk tend to be most sensitive to adult female survival followed by juvenile survival, and finally pregnancy rates Raithel et al. Harvest of adult female elk has the greatest effect on elk population dynamics Clark , Eacker et al. As wildlife managers reduced antlerless elk hunting to maintain elk populations Brodie et al.

Using empirical data observed from field studies conducted in northeastern Oregon e. Pregnancy rates of female elk were influenced annually by lactation status, elk density, August precipitation, and previous year winter severity see results from Johnson et al. At each step of the simulation, values of covariates known to influence pregnancy e. Using these randomly generated covariate values, estimates of pregnancy and survival were calculated based on observed relationships to populate the Leslie matrix at each time step of the simulation.

Other parameters in the Leslie matrix e. At the conclusion of simulations, Clark regressed effects of covariates against estimated population growth rates to determine the relative effect, measured by the slope and fit of the regression, for each covariate and vital rate on elk population growth rates. Similar to Eacker et al. However, in cases with lower cougar densities, elk populations would still increase under mean environmental conditions.


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The results of Raithel et al. We were unable, however, to detect negative effects of increased winter precipitation or severity on spring body fat. Summer drought can decrease forage quantity and quality Vavra and Phillips , Weisberg et al. These effects suggest that for NE, summer precipitation indirectly influenced elk population performance.

The relatively mild winters in our study areas suggest that effects of winter weather on juvenile survival may be less severe compared to other elk populations in the northern Rocky Mountains. For survival analysis of all neonates captured in NE, climatic covariates were uninformative predictors. In contrast, in SW several climatic covariates explained variation in juvenile survival through either 30 days or 16 weeks but not to 12 months. We hypothesize that this may be due to wetter conditions in early spring that resulted in increased vulnerability associated with hypothermia.

Remotely sensed metrics, such as NDVI, may indirectly represent available forage with higher levels of greenness and forage quality Pettorelli et al. The negative influence of December—February precipitation totals suggests harder winters most precipitation during this time is likely snow will decrease overwinter survival of juvenile elk, which was expected.

During periodic severe winters, or if winters become increasingly severe in the face of climate change, overwinter survival of juvenile elk would likely decline Proffitt et al. We measured and tracked adult female nutritional condition and reproductive performance in early spring and late autumn and linked adult condition to reproductive status, neonate birth mass, and survival.

In general, IFBF autumn of lactating females is a reflection of the balance between energy expenditure and the nutritional value of summer and early autumn forage Cook et al. Using these criteria, we documented 3 lines of evidence of nutritional limitations in our study areas. In SW, females had lower body fat than many populations in the northern Cascades but higher than observed in coastal environments Cook et al. The IFBF autumn levels were a third to a half of what elk are able to achieve if provided excellent nutrition throughout summer and early autumn see Table 9 in Cook et al.

Cook et al. This spatial pattern was evident in nutritional condition of wild elk in the Cascades with elk in northern environments having higher body fat Cook et al. This suggests variation in regional nutritional resources is associated with broad regional climatic factors, ecological context, disturbance, and succession that have substantial influences on nutritional condition and reproductive performance of elk Cook et al. By not capturing females and assessing pregnancy until early December, our approach to document delayed breeding could only identify those elk breeding at least 1.

Perhaps more telling, we found an inverse relation between IFBF autumn and birth date the following spring. Even when pregnancy rates are high, if nutrition is limiting, ovulation may be delayed; the higher the nutritional limitation, the later the breeding date Trainer , Albon et al. This effect of inadequate summer and autumn nutrition is significant because timing and synchrony of birth date may be important for survival by allowing juveniles to increase body mass and be able to better withstand extreme winter events Keech et al. In drier ecosystems such as NE where forage quality declines rapidly across the summer season Vavra and Phillips , being born later also has important implications relative to juvenile growth Cook et al.

When we analyzed survival of all neonates separately by region, birth date influenced survival estimates in both SW and NE, but the coefficients had opposite signs. We found that nutritional condition of females declined across winter, as expected, and that elk that entered winter in better condition exited winter in better condition Cook et al. In other populations sampled by Cook et al.

Reduced body fat during winter could increase risk of starvation mortality and potentially predation risk Bender et al. This indicated that death by starvation was imminent regardless of the proximate cause of mortality Ratcliffe , Depperschmidt et al. In adults, these low femur fat levels were consistent with the low IFBF spring levels that we documented i. Thus, our data strongly suggest important nutritional implications for elk successful in raising a juvenile.

Under the relatively low summer nutritional regimes available to elk in our 4 study areas, success in raising a juvenile imposed reduced nutritional condition and the potential for increased mortality risk during winter; better nutrition in summer would play an important role in ameliorating this potential risk for lactating females.

Longer and harsher winters than the relatively mild winters we encountered during this study may be required to fully evaluate this hypothesis. However, drier summers are also predicted Mote and Salathe , Dalton et al. In our systems, given the low levels of winter mortality, regardless of the proximate cause observed in our study, elk can, through compensatory mechanisms Cook et al.

When birth mass was estimated with similar methods, we observed mean birth mass of neonates to be similar to that reported in Wyoming Even with these differences, we were unable to identify any relationship between birth mass and survival of neonates, similar to findings by Smith et al. We were unable to detect a relationship between IFBF spring of the dam and birth mass of her offspring. It has long been recognized that deficient nutrition during winter is well compensated by good nutrition during the third trimester for livestock Holland and Odde and elk Cook , Cook et al.

Therefore, if maternal experience was an important factor influencing juvenile survival, we would expect spring body condition of females to enter a juvenile survival model with a negative coefficient. Furthermore, effects of predation can dampen or eliminate effects of density dependence Wang et al. When one or more prey and predator species coexisted, population responses of prey varied in response to changes in predator assemblages Kunkel and Pletscher , Wittmer et al. The composite picture from these studies suggests that effects of predation can operate in multiple ways, depending on the suite and abundance of prey and predator species.

In our study areas, multiple species of ungulates, primarily elk and deer, and predators cougar, black bear, coyotes, and bobcat were resident. Proportions of neonates killed by cougars and black bears did not differ among VIT, hand, or netted neonates so we combined these methods in a general discussion of predation. Our results broadly follow the reproductive vulnerability hypothesis Lima and Dill that suggests juvenile ungulates are most vulnerable to predation at young ages and risk declines as they grow larger such that survival of juveniles increased on daily, weekly, and monthly time steps.

Most predation in our study was attributable to cougars and throughout their range, cougars disproportionately prey on i. In Oregon, cougar prey selection switches seasonally, with juvenile elk strongly selected during summer parturition—31 Oct and deer selected during late fall and winter Clark et al. This pattern of prey switching is likely an optimal foraging strategy by cougars that balanced the risk of injury or ease of prey capture with energetic reward as juvenile ungulates obtain mass over time Carbone et al. In summer, juvenile elk compared to deer provide a higher energetic reward e.

Additionally, because of low summer survival rates this study , fewer juvenile elk were present in winter, which likely decreased encounter rates between cougars and juveniles, causing cougars to switch to more abundant alternative prey. Finally, the lack of prey selection for juvenile elk during winter observed in Oregon Clark et al.

This change in habitat use may make them less vulnerable to cougar predation because of the lack of stalking cover. In our post hoc analysis of juvenile survival from months 7—12, cougar density did not enter into any competing models, which may be explained by the shift in prey selection by cougar from juvenile elk to deer during this time of year Clark et al. Juvenile elk are selected by cougar as prey in Oregon, but adult elk are infrequently killed by them Clark et al. As a result of this selective predation, cougar density explained most of the variation in juvenile survival observed across seasons, years, and study areas.

Cougar predation, however, was not an important predictor of adult survival. In studies where cougar densities were low, few predation events were attributed to them Murphy , Ruth , Smith et al. Additionally, cougar predation made up a smaller proportion of mortality rates in areas with a larger assemblage of carnivores Griffin et al. Davidson et al. Reducing the Davidson et al. Cougar density was lower in SW than in NE and this is likely a biological phenomenon rather than ineffective sampling.

Harvest of cougars in NE varied annually and we contend this caused cougar densities to vary among years. Broadly, these patterns follow timing of predation observed in other studies Smith and Anderson ; Singer et al. Studies conducted in YNP and Wyoming included predation by grizzly bears, which was not always differentiated from predation by black bears, confounding comparisons of proportions of neonates killed by black bears.

Proportion of mortality attributable to black bears may be related to bear density and the suite of carnivores present Griffin et al. Bear predation on neonate elk was restricted to the first few weeks of life because after this time, juveniles were sufficiently mobile to avoid capture.

We documented black bears scavenging or usurping 43 of juvenile elk killed by cougars in NE from birth to 1 November before we investigated the mortality we used this cutoff date because bears were typically in dens and not active on the landscape. This high degree of kleptoparasitism may cause cougars to abandon the carcass and kill another animal, increasing the effect of cougars on elk calf survival. Although Clark et al. Further, cougar kill rates appear best explained by the proportion of juveniles Knopff et al.

Wolf reintroduction may have reduced coyote densities and their subsequent effect on juvenile elk survival Merkle et al. Although wolf packs were not established in our study areas, cougar densities in NE were some of the highest reported in western North America Davidson et al. Cougars kill coyotes Knopff et al. If predation by cougars on coyotes was sufficiently high, cougars may have depressed coyote densities such that their densities were lower than in YNP. We have no estimates of coyote densities to support this hypothesis. Throughout the range of cougars in North America, including Oregon, deer are their primary prey Iriarte et al.

Consequently, cougar density in our study areas was likely determined by deer rather than elk density. Selection of a secondary prey species by a generalist predator can cause population declines or allow predators to maintain secondary prey species at low densities Messier , Sinclair et al. The wide variation in success White et al. It also supports the conclusion of Linnell et al.

We could not manipulate predator numbers to directly address whether predation in our study areas was additive or compensatory with other sources of mortality. Consequently, we used a set of hypotheses Appendix A to assess the degree to which predation was additive or compensatory. The high rates of predation by cougars and strong relationship between cougar density and juvenile survival Fig. In areas where summer nutrition is marginal or inadequate Cook et al.

This increases the proportion of lactating females with relatively low nutritional condition Gerhart et al. The magnitude of any one of these responses may be small, but in combination they may compensate for reductions in predation to a biologically significant degree. Thus, one limiting factor nutrition may partially replace another predation if predation is reduced.

The potential for compensation between nutrition and predation is likely dependent on a number of environmental influences. Further, stochastic effects of precipitation and temperature at various times of the year may influence compensatory relationships from year to year. The positive effect of summer precipitation on IFBF autumn indicates an indirect link between summer precipitation and pregnancy Johnson et al. Finally, juvenile survival over winter was positively related to summer precipitation and negatively related to current winter precipitation totals.

The higher pregnancy rates probably reflect greater levels of precipitation in our study areas compared to most of the ecoregion Heyerdahl et al. Thus, it is likely that most elk in the region have lower quality nutritional resources and are limited to a greater extent by inadequate summer nutrition than in our NE study areas. This discrepancy between IFBF autumn and pregnancy rates may be due to complex interactions among late summer precipitation, nutrition, and physiology on ovulation.


  1. Hispania. Volume 77, Number 3, September 1994.
  2. The Social Drinker: How To Keep It That Way.
  3. Its Always A Game.
  4. Adventures of a Girl In Space - Comic Book 005.
  5. Bible Search?
  6. Roles of maternal condition and predation in survival of juvenile Elk in Oregon.
  7. About The Author.
  8. In the Blue Mountains physiographic province, late summer and early autumn precipitation, operating through nutritional pathways, was likely responsible for much of the annual variation in pregnancy rates of lactating females Appendix C; Johnson et al. Survival and subsequent recruitment of juveniles was largely limited by predation from cougars; however, our results also indicate nutritional limitations operated to reduce productivity of elk mainly by reducing pregnancy rates of lactating females, delaying conception and thus parturition, and increasing susceptibility of juveniles and adults to predation and winter starvation.

    Although not evaluated as part of this study, nutritional limitations undoubtedly retarded growth and development of juveniles and subadults Cook et al. Our data also suggest partial compensatory interactions between nutrition and predation, the relative effects of which would vary in response to stochastic variation in weather across the annual cycle. Thus, the effects of predation and nutrition were not independent.

    Although we strove to separate the influences of nutrition and predation, many questions remain unanswered about how the 2 factors interact, particularly in the context of prescribing management action to increase productivity of the elk. Our insights would have benefited from a larger sample of lactating females for understanding compensatory responses in pregnancy and body mass and nutritional condition data of juveniles in late autumn for insight into vulnerability to predation in winter.

    Our results certainly suggest management aimed at reducing cougar densities could potentially increase productivity White et al. Our results, however, also indicated cougar predation was not completely additive; thus, predator reductions may fail to satisfy objectives for ungulate populations Hurley et al.

    Throughout their range, elk occupy vastly different habitats where seasonal and regional differences in quality and quantity of nutritional resources vary as evident by autumn body fat of lactating females Cook et al. Additionally, assemblages and densities of carnivores vary throughout the range of elk, leading to variation in juvenile and adult survival Griffin et al.

    These studies highlight the importance of understanding factors affecting population dynamics of elk at local and regional scales before embarking on management actions to improve productivity. Of the factors we evaluated that affected elk population dynamics, the 2 most limiting were nutrition in summer and early autumn and predation of juveniles by cougars. Wildfire suppression efforts since the early s in the Inland Northwest and northern Rock Mountains has greatly reduced annual rates of burning Keane et al.

    Forest management strategies that reduce tree density e. In contrast, in the xeric forest types and rangelands of the interior Northwest, hot summers and limited and variable summer precipitation support variable nutritional resources typically of low quality in summer Cook et al.