Effects of Summer‐autumn Nutrition and Parturition Date on Reproduction and Survival of Elk

Cook, John G.; Johnson, Bruce K.; Cook, Rachel C.; Riggs, Robert A.; DelCurto, Timothy; Bryant, Larry D.; Irwin, Larry L.

doi:10.2193/0084-0173(2004)155[1:eosnap]2.0.co;2

Cited by 334 publications

(92 citation statements)

References 76 publications

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“…This combination of changes will ultimately result in reduced forage quantity (i.e. shorter growing seasons result in less biomass) and duration of high-quality forage for herbivores, both of which could reduce the body condition and population performance of large herbivores (Cook et al 2004, Middleton et al 2013. Although migratory species have movement strategies that optimize responses to rapidly changing conditions, for example, by moving to higher-quality habitats, partially migratory or resident species may face nutritional constraints due to a shortened green-up period (Hebblewhite et al 2008).…”

Section: Discussionmentioning

confidence: 99%

“…Since maternal body stores of capital breeders (e.g. elk, Cervus canadensis) are accumulated late in the previous growing season and are used to compensate the high energetic demands of early reproduction (Gustine et al 2017), phenological changes to forage as it matures can affect the nutritional resources available for reproduction (Cook et al 2004, Monteith et al 2013. Plant senescence can also trigger behavioral cues for migratory ungulates to leave their summer range and begin fall migration (Rivrud et al 2016).…”

Section: Introductionmentioning

confidence: 99%

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Climate change effects on understory plant phenology: implications for large herbivore forage availability

Brown

Coe

Clark

et al. 2022

Environ. Res.: Ecology

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Consistent with a warming climate, the timing of key phenological phases (i.e., phenophases) for many plant species is shifting, but the direction and extent of these shifts remain unclear. For large herbivores such as ungulates, altered plant phenology can have important nutritional and demographic consequences. We used two multi-year datasets collected during 1992-1996 and 2015-2019 of understory plant phenology in semi-arid forested rangelands in northeastern Oregon, United States, to test whether the duration of phenophases for forage species has changed over time for three plant functional groups (forbs, graminoids, and shrubs). Duration of spring green-up was approximately two weeks shorter in the later years for forbs (19 ± 3.8 d) and graminoids (13.2 ± 2.8 d), and senescence was three weeks longer for graminoids (25.1 ± 5.1) and shrubs (22.0 ± 4.6). Average peak flowering date was 3.1 ± 0.2 d earlier per decade for understory forage species with approximately 1/3 of the species (35%) exhibiting earlier peak flowering dates over time. Variation in late-winter precipitation had the greatest effect on the duration of understory green-up, whereas variation in summer precipitation had a greater effect on duration of the senescent period. Collectively, these results indicate climate-related progression towards shorter periods of peak plant productivity, and earlier and longer periods of plant senescence, the combination of which substantially reduces the temporal window of forage available in growing forms most usable to herbivores. This work adds a needed component to the climate change literature, by describing links between shifting climate variables, multiple phases of understory plant phenology, and possible nutritional consequences for herbivores under a warming climate.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Climate change effects on understory plant phenology: implications for large herbivore forage availability

Brown

Coe

Clark

et al. 2022

Environ. Res.: Ecology

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“…Our results suggested authors need to provide greater detail regarding the methods used for lab assays than has been customary in the past. We recommend that when reporting methods of analyzing fiber content of forages, authors include additional details on the amount of sample used, the number of replicates analyzed (e.g., single, duplicates, With increasing evidence that nutritional deficiencies, including those in summer, have important limiting effects on ungulate populations and that seemingly small differences in forage quality, particularly DMD, has disproportionately large effects on ruminant performance (White 1983, Cook et al 2004, Cebrian et al 2008, biologists and managers increasingly require reliable and accurate estimates of forage quality on large ungulate ranges. Forage quality surveys can provide insights for wildlife and land managers about whether landscape management that features improvement of forage resources should be considered.…”

Section: Discussionmentioning

confidence: 99%

“…With increasing evidence that nutritional deficiencies, including those in summer, have important limiting effects on ungulate populations and that seemingly small differences in forage quality, particularly DMD, has disproportionately large effects on ruminant performance (White 1983, Cook et al 2004, Cebrian et al 2008), biologists and managers increasingly require reliable and accurate estimates of forage quality on large ungulate ranges. Forage quality surveys can provide insights for wildlife and land managers about whether landscape management that features improvement of forage resources should be considered.…”

Section: Discussionmentioning

confidence: 99%

“…For example, digestibility ranged from 30 to 80% in ruminant diets during summer in the northwestern US (Cook 2002;Cook et al 2014Cook et al , 2016Berry et al 2019;Ulappa et al 2020). Cell-wall fiber also increases rumination time and reduces passage rate of ingesta, thus decreasing the total amount of food ruminants can eat each day (Weston and Poppi 1987, Robbins 1993, Grey and Servello 1995, Hobbs 2003, Cook et al 2004). Accordingly, low-quality (high fiber) forage, no matter the quantity, cannot substitute for high-quality forage (Cook et al 2004, Hanley et al 2012, and even small changes in digestibility of forages can have significant effects on the performance of ruminants (White 1983, Cook et al 2004, Cebrian et al 2008.…”

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confidence: 99%

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Sequential detergent fiber assay results used for nutritional ecology research: Evidence of bias since 2012

Cook

Shipley

Cook

et al. 2022

Wildlife Society Bulletin

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Forage quality surveys can provide a variety of insights into the nutritional well-being of herbivores. Even small differences in how much of the food eaten can be digested and used for life requisites (dry matter digestibility %; DMD) can affect performance of ruminants, and thus methods for determining forage digestibility must be accurate, repeatable, and robust among laboratories and over time. In 2013, we observed levels of DMD as determined from sequential detergent fiber assays with the filter bag method and the ANKOM fiber analyzer 200/200® that were greater than expected given the plant species, season, and environmental setting. Using stockpiled and previously analyzed forage samples from Oregon, Washington, and Idaho, we evaluated whether fiber results had shifted since 2012, potential causes of the shifts, and whether results since 2012 aligned with data on ungulate performance.Beginning in 2012, our results indicated that sequential detergent fiber analysis began significantly overestimating DMD compared to the same samples analyzed using identical methodology prior to 2012. Magnitude of the difference increased as soluble fiber increased and overestimated DMD

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Linking landscape‐scale differences in forage to ungulate nutritional ecology

Proffitt

Hebblewhite

Peters

et al. 2016

Ecological Applications

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Understanding how habitat and nutritional condition affect ungulate populations is necessary for informing management, particularly in areas experiencing carnivore recovery and declining ungulate population trends. Variations in forage species availability, plant phenological stage, and the abundance of forage make it challenging to understand landscape-level effects of nutrition on ungulates. We developed an integrated spatial modeling approach to estimate landscape-level elk (Cervus elaphus) nutritional resources in two adjacent study areas that differed in coarse measures of habitat quality and related the consequences of differences in nutritional resources to elk body condition and pregnancy rates. We found no support for differences in dry matter digestibility between plant samples or in phenological stage based on ground sampling plots in the two study areas. Our index of nutritional resources, measured as digestible forage biomass, varied among land cover types and between study areas. We found that altered plant composition following fires was the biggest driver of differences in nutritional resources, suggesting that maintaining a mosaic of fire history and distribution will likely benefit ungulate populations. Study area, lactation status, and year affected fall body fat of adult female elk. Elk in the study area exposed to lower summer range nutritional resources had lower nutritional condition entering winter. These differences in nutritional condition resulted in differences in pregnancy rate, with average pregnancy rates of 89% for elk exposed to higher nutritional resources and 72% for elk exposed to lower nutritional resources. Summer range nutritional resources have the potential to limit elk pregnancy rate and calf production, and these nutritional limitations may predispose elk to be more sensitive to the effects of harvest or predation. Wildlife managers should identify ungulate populations that are nutritionally limited and recognize that these populations may be more impacted by recovering carnivores or harvest than populations inhabiting more productive summer habitats.

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Effects of Summer‐autumn Nutrition and Parturition Date on Reproduction and Survival of Elk

Cited by 334 publications

References 76 publications

Climate change effects on understory plant phenology: implications for large herbivore forage availability

Climate change effects on understory plant phenology: implications for large herbivore forage availability

Sequential detergent fiber assay results used for nutritional ecology research: Evidence of bias since 2012

Linking landscape‐scale differences in forage to ungulate nutritional ecology

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