Winter Diet Basics
This broad plant group (including grasses, sedges, and rushes) dominated elk winter diets in the review.
What are graminoids?
Across 17 studies with habitat data, elk almost always had this relationship to graminoids: they ate them more than you’d expect from availability.
What is “they preferred them”?
n the paper, winter ranges are divided into two broad types based on openness and tree cover: “open” and this.
What are “closed” ranges?
In this paper, “predation risk” on winter ranges is mainly measured by the presence or absence of this human activity.
What is hunting by humans?
Name one of the three main methods used in the original studies to estimate elk diets.
What is rumen analysis, fecal microhistology, or plant-use/feeding-site observation? (Any one.)
On average, this plant group made up only about 5–10% of elk winter diets and was usually “incidental” to grazing.
What are forbs?
For this plant group, there was no evidence of strong preference; use didn’t track availability very well, and they were often under-used compared to what was out there.
What are forbs?
On open winter ranges in normal winters, about what percentage of elk diets was herbage (graminoids + forbs): ~10%, ~40%, or ~85%?
What is about 85%?
In open ranges during normal winters, hunted elk herds had slightly less herbage in their diets than unhunted herds. Did they respond to hunting by increasing or decreasing browse use?
What is increasing browse use?
Fecal analysis differs from rumen analysis mainly in the time scale: fecal samples reflect foraging decisions over this time frame rather than just the last meal.
What is over several days?
Christianson & Creel grouped plants into three main categories: graminoids, forbs, and this woody category.
What is browse?
Browse was generally eaten in proportion to this, meaning its use was mostly driven by where elk chose to be on the landscape.
What is availability (or habitat composition)?
Deep, hard snow reduces elk access to graminoids by doing this to low-growing grasses.
What is burying them (making them hard to reach/expensive to dig out)?
Hunting can push elk into this type of habitat, which offers more cover but also tends to have more browse and less grass.
What are forested/closed or timbered habitats?
True or False: The authors found huge, consistent differences between rumen-based and fecal-based diet estimates that invalidated comparisons across studies.
What is False? (They were very similar overall.)
When graminoids, forbs, and browse in the diet add up to 100%, these two together are called “herbage” in the paper.
What are graminoids and forbs?
Compared to other sympatric ruminants like deer and moose, elk consistently selected this plant type more strongly in winter, except when compared to bison.
What are graminoids (grass and grass-like plants)?
In hard winters on open ranges, herbage in the diet drops from around 85% to roughly this much (answer within 10% is fine).
What is about 40% (around 39.6%)?
Some hunted elk herds had diets where browse made up the majority of the diet, but this was never true for which group: hunted or unhunted herds?
What are unhunted herds?
For their ANOVAs, the authors “weighted” diet estimates by the number of independent samples, but capped the weight at this maximum number to avoid letting a few huge studies dominate.
What is 10?
In the 72 studies, elk diets were usually graminoid-dominated, but this woody category could reach over 90% of the diet in some populations under certain conditions.
What is browse?
The paper concludes that elk are not environmentally forced into their graminoid-biased diets. Name the type of evidence they used to support that claim.
What are comparisons of elk diets to sympatric ruminants and use vs. availability analyses (showing preference even when other diets were possible)?
Explain the two-scale interpretation the authors give: how do elk combine fine-scale diet selection with broad-scale habitat selection to produce the observed patterns?
What is that elk pick habitats based on conditions (snow, cover, predators, etc.) at a broad scale, and then within those habitats selectively graze graminoid patches at a fine scale, so the final diet reflects both habitat choice and strong within-patch preference for grasses?
The paper also mentions wolves as predators. Elk under wolf predation risk tend to change their behavior in two main ways. Name two such changes mentioned in relation to predation risk (wolves or hunters).
What are things like reducing time spent foraging, increasing vigilance, shifting more into timber/cover, changing habitat selection, or altering group size? (Any two of these.)
From a management perspective, the authors warn that even “inconspicuous” behavioral changes in response to environmental stimuli can have important consequences. What kind of consequences, and why might managers care?
What are nutritional and population-level consequences—because changes in habitat use and diet (e.g., more browse, less grass) can affect body condition, survival, and reproduction, which influences population dynamics and issues like crop depredation, supplemental feeding, and predator–prey interactions?