Adults: The importance of sagebrush in the diet of adult sage-grouse is
impossible to overestimate. Numerous studies have documented its year-round use
by sage-grouse [9,23,24,72,92,108,110,122,123]. A
Montana study, based on 299 crop samples, showed that 62% of total food volume
of the year was sagebrush. Between December and February it was the only food
item found in all crops. Only between June and September did sagebrush
constitute less than 60% of the greater sage-grouse diet .
Sage-grouse select sagebrush species differentially. Greater sage-grouse in
Antelope Valley, California, browsed black sagebrush more frequently than
the more common big sagebrush . Young and Palmquist  state
the browse of black sagebrush is highly preferred by greater sage-grouse in
Nevada. In southeastern Idaho, black sagebrush was preferred as forage .
Among the big sagebrush subspecies, basin big sagebrush is less nutritious
and higher in terpenes than either mountain or Wyoming big sagebrush.
Sage-grouse prefer the other two subspecies to basin big
sagebrush . In a common garden study done
in Utah, Welch, Wagstaff and Robertson  found sage-grouse
preferred mountain big sagebrush over Wyoming and basin big sagebrush. However,
when leaves and buds of the preferred species became limited, the birds shifted
to the lesser-liked plants. The authors concluded the birds, while expressing
preference, are capable of shifting their eating habits.
Sage-grouse lack a muscular gizzard and cannot grind and digest seeds;
they must consume soft-tissue foods . Apart from sagebrush, the
adult sage-grouse diet consists largely of herbaceous leaves, which are
utilized primarily in late spring and summer . Additionally,
sage-grouse use perennial bunchgrasses for food .
Sage-grouse are highly selective grazers, choosing only a few plant genera.
Dandelion (Taraxacum spp.), legumes (Fabaceae), yarrow (Achillea
spp.) and wild lettuce (Lactuca spp.) account for most of their forb
intake [6,110]. Martin  found that from July to September, dandelion
comprised 45% of greater sage-grouse intake; sagebrush comprised 34%.
Collectively, dandelion, sagebrush, and two legume genera (Trifolium
and Astragalus) contributed more than 90% of the sage-grouse diet.
Insects are a minor diet item for adult sage-grouse. Martin and others 
reported insects comprised 2% of the adult greater sage-grouse diet in
spring and fall and 9% in summer. Sagebrush made up 71% of the year-round
Herbaceous dicots are used heavily by females before egg laying and may be
essential for sage-grouse nutrition because of their high protein and nutrient
Favored foods of prelaying and brood-rearing greater sage-grouse hens in
Oregon are :
common dandelion (Taraxacum officinale)
goatsbeard (Tragopogon dubuis)
western yarrow (Achillea millifolium)
prickly lettuce (Lactuca serriola)
sego lily (Calcochortus macrocarpus)
In southeastern Oregon, Barnett and Crawford  studied
prelaying nutrition of greater sage-grouse hens,
March to April, 1990 and 1991.
of occurrence among crops
|relative dry weight|
|big sagebrush 1990 (N = 7) %||low sagebrush 1990 (N = 13) %||low sagebrush 1990 (N = 22) %||big sagebrush 1990 (N = 7) %||low sagebrush 1990 (N = 13) %||low sagebrush 1990 (N = 22) %|
|desert-parsley (Lomatium spp.)||86||92||68||7||16||8|
|hawksbeard (Crepis spp.)||57||62||37||11||14||3|
|long-leaf phlox (Phlox longifolia)||86||92||55||12||4||2|
|mountain dandelion (Agoseris spp.)||28||69||11||2||4||1|
|clover (Trifolium spp.)||0||31||18||0||4||1|
|everlasting (Antennaria spp.)||43||69||41||8||3||2|
|woollypod milk-vetch (Astragalus purshii)||57||31||9||2||<1||<1|
|buckwheat (Eriogonum spp.)||14||8||0||2||<1||0|
|arcane milk-vetch (A. obscurus)||0||31||5||0||2||<1|
|buttercup (Ranunuculus spp.)||0||8||0||0||<1||0|
|other phlox (Phlox spp.)||14||15||18||<1||<1||<1|
|blue-eyed Mary (Collinsia spp.)||0||38||9||0||<1||<1|
|bluebells (Mertensia spp.)||0||0||5||0||0||<1|
|larkspur (Delphinium spp.)||0||0||5||0||0||<1|
|rockcress (Arabis spp.)||14||0||0||<1||0||0|
Juveniles: In their 1st week of life, sage-grouse
chicks consume primarily insects, especially ants and beetles . Their diet
then switches to forbs, with sagebrush gradually assuming
primary importance. In a Utah study, forbs composed 54 to 60% of the summer
diet of juvenile sage-grouse, while the diet of adult birds was 39 to 47%
In a Wyoming study, Johnson and Boyce  evaluated
effects of eliminating insects from the diet of newly-hatched greater
sage-grouse chicks. All chicks hatched in captivity and not provided insects
died between the ages of 4 and 10 days, whereas all chicks fed insects
survived the 1st 10 days. Captive greater sage-grouse chicks required insects
for survival until they were at least 3 weeks old. Greater sage-grouse chicks
> 3 weeks old survived without insects, but their growth rates were lowered
significantly, indicating insects were still required for normal growth after
3 weeks of age. As quantity of insects in the diet increased, survival and
growth rates also increased up to 45 days, the length of the experiment.
In a study conducted in Idaho, Klebenow and Gray  measured food items
for juvenile greater sage-grouse for each age class, classes being defined
by weeks since birth. In the 1st week insects were very important - 52% of the
total diet. Beetles, primarily family Scarabaeidae, were the main food item.
Beetles were taken by all other age classes of chicks, but in smaller amounts.
All ages fed upon ants and while the volume was generally low, ants were
found in most of the crops. After week 3, insect volume dropped and stayed
at a lower level throughout all the age classes, fluctuating but always under
Forbs were the major plant food of the chicks. Harkness gilia
(Linanthus harknessii) was the main forb species in the 1st week and
then steadily decreased. It was not found in the diet after 6 weeks.
Loco (Arabis convallarius) and common dandelion were important food
items for most of the collection period and occurred with generally high
frequencies. Common dandelion was the most abundant food item and the
mainstay of the sage-grouse chicks. At 6 weeks of age, goatsbeard reached
its peak in the diet and sego lily was found in greatest volume a week later.
These 5 species were the most important forbs.
The only shrub of importance was big sagebrush. It appeared in the diet at
4 weeks of age and as the ages progressed, the volume
increased steadily. These 6 plants comprised 83% of the total sample and
are listed in order of decreasing percent total volume :
|food item||part||% of total|
|common dandelion||buds, seeds||80|
|Sego lily||buds, capsules||100|
With plants like common dandelion and goatsbeard, all aboveground parts of
the plant were sometimes eaten. The stems, however, were not of main
importance. The reproductive parts, mainly buds, flowers, and capsules,
were the only parts taken from some of the other species.
Conversely, leaves were the only parts of sagebrush found in the crops.
Leaves and flowers of the species listed above and other dicots
contained higher amounts of crude protein, calcium, and phosphorus
than sagebrush and may be important in greater sage-grouse diets for these
In a central Montana study, Peterson  analyzed crop contents of
juvenile greater sage-grouse. Data indicate increasing use of sage species and
decreasing use of insects. Percent frequency and
percent volume of food items commonly utilized by 1- to 12-week-old
greater sage-grouse collected during 1966 and 1968 were:
|1-4 n = 26||5-8 n = 47||9-12 n = 54|
|food item||%Freq/(%Vol)||%Freq /(%Vol)||%Freq /(%Vol)||Total1 % Freq/ (%Vol)|
|curlycup gumweed (Grindelia squarrosa)||9/trace||28/3||39/4||25/2|
|alfalfa (Medicago sativa)||--||21/2||22/2||14/1|
|littlepod false flax (Camelina microcarpa)||9/1||2/trace||--||4/trace|
|skunkbush sumac (Rhus trilobata)||--||3/3||--||1/1|
|Ttotal volumes of|
|TOTAL PERCENT PLANT VOLUME||70||76||83||76|
|TOTAL VOLUMES OF TRACE MATERIAL||8||--||--||3|
|TOTAL PERCENT ANIMAL VOLUME||30||24||17||24|
1 Totals are derived by aggregating the
percentages from every week-class, thereby eliminating any bias introduced by
the individual sample size and crop holding capacity of each age-class.
Five most preferred1 plant species in each
2-week age division of juvenile sage-grouse, 1966 and 1968 are listed below.
Note only 1 sagebrush species is listed and that it is not preferred
until weeks 7-8 :
|food item||1-2, n=8||3-4, n=8||5-6, n=17||7-8, n=16||9-10 n=11||11-12 n=9||13-14 n=6|
|common pepperweed (Lepidium densiflorum)||4||2||-||-||-||-||-|
|littlepod false flax||-||4||-||-||-||-||-|
|American vetch (Vicia americana)||1||-||-||-||-||-||-|
|Breitung blue lettuce (Lactuca pulchella)||-||-||1||-||-||-||-|
|sedges (Carex spp.)||-||-||-||-||-||-||1|
1Number assigned to each species, in descending order
of importance, indicates its status as a preferred plant food item.
Water: Sage-grouse apparently do not require open water
for day-to-day survival if succulent vegetation is available. They utilize free
water if it is available, however. Sage-grouse distribution is apparently
seasonally limited by water in some areas. In summer, sage-grouse in desert
regions occur only near streams, springs, and water holes. In winter in Eden
Valley, Wyoming, sage-grouse have been observed regularly visiting partially
frozen streams to drink from holes in the ice .