Food is recognized as an important limiting factor in the abundance and ecological distribution of most species of birds. Because of this, food studies of game birds such as Blue Grouse (genus.Dendragapus) should be of considerable interest to the ecolo- gist and ornithologist and of primary importance to the game administrator. The present study is based on the analyses of the crop and stomach contents of 267 adult and 21 juvenal Blue Grouse. The food habits of the two closely related species Of Blue Grouse, Dendragapus obscurus and Dendragapus fuliginosus, are dis- cussed separately, chiefly because of the great difference in the vegetation found within their respective ranges, which reflects itself in the food of these birds. Dendragapus obscurus, sometimes called the Dusky Grouse, occurs in the Rocky Mountain region from Yukon south to New Mexico and Arizona and in a few of the higher motretains in the Great Basin. Dendrctgapus ]uliginosus, known as the Sooty Grouse, is found on the coastal ranges and on the Cascades and Sierra Nevada, from Alaska south to Cali- fornia. In both species, no essential difference in food was noted between birds found at extreme northern and southern portions of the range. Seasonal and geographic distribution of specimens of Dendragapus obscurus Adults Early Late Spring - summer summer Fall Winter Total Apr. May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. year Arizona 2 3 5 British Columbia 4 12 1 2 3 1 23 Colorado 6 4 6 2 18 __ ........ !_d3h 9 ..... 1 3 5 12 26 3 4 2 4 60 Mackenzie 1 1 Montana 1 2 3 2 5 5 1 1 20 New Mexico 2 2 3 1 2 10 Nevada I 3 2 6 Oregon 2 2 2 1 7 Utah 1 1 2 Washington 2 2 Wyoming 1 1 8 ? 17 4 34 101 11 21 171 Juveniles Alaska 1 1 Colorado 1 4 5 Idaho 8 8 Nevada 2 2 Utah 1 1 Wyoming 2 2 1 18 19 The food data concerning Dendragapus obscurus.were derived from the examina- tions of the crops and stomachs of 171 adult and 19 juvenal birds, whereas the data concerning Dendragapus ]uliginosus were derived from the examinations of the crops and stomachs of 96 adults and 2 juvenal birds. Grateful acknowledgment is made to A. C. Martin of the Fish and Wildlife Service, who assisted with most of the more difficult identifications of food items. Seasonal and geographic distribution of specimens of Dendragapus Juliginosus Adults Sprinit Early Late summer summer Fall Winter Total Apr. May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. year British Columbia 8 1 1 6 8 24 Alaska 2 1 2 I 6 California 11 13 1 1 2 1 29 Oregon 4 1 1 1 15 1 2 16 Washington 3 11 6 I 21 39 6 20 7 '24 96 ß Juveniles California 2 2 SEASONAL ASPECT The foodsof Blue Grouse may be presented more or less naturally by means of five seasonal groupings: winter (November, December, January, February, and March); spring (April and May); early summer (June and July); late summer (August and September); and fall (October). The number of specimens examined.for certain seasons for both species is meagre and under these circumstances the information may not be especially significant except to indicate in a general way the feeding tendencies. Gravel, which was generally found to occur in appreciable amounts in the stomach and occa- sionally in small amounts in the crops, is not included in the following summations of food habits. WINTER DIET D. obscurus D. ]uliginosus Type of food (21 birds) (24 birds) Volume per cent Volume per cent Coniferous needles 90.2 87.7 Buds and twigs 4.5 1.7 Green leaves (other than coniferous needles) 1.8 4.5 Coniferous cones ................ Flowers ........ Fruits and seeds 3.5 6.0 Undetermined plant material ................ Animal matter ......... 1 The needles of Douglas fir (Pseudotsuga taxiJolla) represent the outstanding food (78.2 per cent) of Dendragapus obscurus during the winter. Other coniferous needles which were consumed in much smaller amounts include spruce (Picea) and pine (Pinus). The buds and twigs were of two kinds: cherry (Prunus) and willow (Salix), while the green leaves were Anemone and alum-root (Heuchera). The fruit of rose (Rosa) was found in fair quantity in one crop, and the fruits of manzanita (Arctostapttylos) and juniper (Juniperus) were found in very small quantities in others. Although coniferous needles are the most important type of winter food for Den2 dragapus ]uliginosus as well as for D. obscurus, the proportions of the various species used are considerably different. The needles of fir (A hies) are Laken in largest quantity (64.8 per cent) by Dendragapus ]uliginosus, and other coniferous needles taken in fair quantity include hemlock (Tsuga), Douglas fir (Pseudotsuga taxiJolla), pine (Pinus) an{[ spruce (Picea). Green leaves taken in small quantity include small cranberry (Vac- cinium oxycoccas), foamflower (Tia. rella), spreading wood fern (Dryopteris dilalata) and moss. The twigs of dwarf mistletoe (Arceutttobium) were found in considerable quantity in one stomach and the buds of aspen (Populus) were found in another. The only fruits and seeds eaten were those of salal (Gualttteria shallon) and Douglas fir. Fig. 17. Typical winter habitat of Blue Grouse in Douelas firs. Photo taken in Idaho by W. H. Marshall, March 15, 1o40. SPRING DIET Type of food D. obscuru D. Juliginoss (4 birds) (39 birds) Volume per cent  olume per cent Coniferous needles ß 26.2 76.5 Buds and twigs ........ 9.2 Green leaves (other than coniferous needles) 34.8 3.6 Coniferous cones 21.2 10.7 Flowers 11.2 Fruits and seeds 4.9 Undetermined plant material 1.7 Animal matter The crops and stomachs of the four specimens of Dendragapus obscurus collected in the spring were found to contain an ample amount of coniferous needles mixed with many other types of food. The needles of Douglas fir were taken in considerable quan- tity and a small amount of pine needles was also represented. A considerable variety of green leaves was taken, although the only kinds taken in appreciable quantity were those of pussytoes (Antennaria), Eriogonum, and hawkweed (Hieracium). Flowers which were taken in rather small quantities included snowbrush (Ceanothus), larkspur (Delphinium), cherry (Prunus) and pussytoes. The only fruits and seeds taken in con- spicuous quantities were those of pink microsteris (Microsteris gracilis). The spring diet of Dendragapus ]uliginosus continues to be made up predominantly of coniferous needles. In the central part of its range, the needles of fir (Abies) and Douglas fir (Pseudotsuga taxiJolla) are the principal types taken. In the southern part of its range the needles of pine (Pinus) are substituted to some extent whereas toward the north the needles of other types such as spruce, especially Sitka spruce (Picea sit- chensis) are increasingly important. The staminate cones of conifers, especially those of fir and Douglas fir, were found to be fairly important as food during this period. Green leaves were taken in small quantity. especially the leaves of ferns (Polypodiaceae) and white clover (TriJolium repens). The buds and twigs of aspen (Populus) were taken in fair quantity by several birds. EARLY SUMMER DIET IP. obscurus D. ]uliglnosus Type of food (34 bids) (6 bkds) yolume'per cent Volume per cent Coniferous needles 12.9 1.2 Buds and twigs ................ Green leaves (other than coniferous needles) 22.0 24.1 Coniferous cones 5.1 Flowers 13.2 57.4 Fruits and seeds 33.3 17.3 Undetermined plant material 1.8 ........ Animal matter 11.7 ........ One of the outstanding features of the early summer diet is the great variety of foods that is taken. Nineteen kinds of fruits and seeds were taken by Dendragapus obscurus, the most important of which are listed as follows in the approximate order of their importance: manzanita (Arctostaphylos), strawberry (Fragaria), currant (Ribes), sedge (Carex), shepherds purse (Capsella. bursa-pastoris), smartweed (Poly- gonurn), buffalo berry (Shepherdia canadensis), and honeysuckle (Lonicera). A great variety of green leaves was also consumed and the more important of these are listed as follows in the order of their importance: Eriogonum, vetch (Vicia), willow (Salix), buffalo berry ( Shepherdia canadensis ) , dandelion ( Taraxacum ) , currant (Ribes), shootingstar (Dodecatheon) and aspen (Populus). Various kinds of flowers frequently are taken, especially those of the family Compositae. Those flowers taken in greatest quantity include cherry ( Prunus) , Eriogonum, Microseris, dandelion ( Taraxacum ) and Agoseris. Coniferous needles and cones are still taken in fair amount, especially those of pine (Pinus). An appreciable portion of the dia is now made up of animal food in the form of insects. Those which were taken in greatest quantity are scarabaeid beetles (Scarabaeidae), leafhoppers (Cicadellidae) and saw-fly larvae (Tenthredini- dae). Ants (Formicidae) Were taken frequently but never in large quantity. Flowers are apparently of major importance in the early summer diet of Dendraga- pus fuliginosus. The flower of cats-ear (Hypochaeris) were found to comprise 35.7 per cent of the total. Other flowers of less importance were salal (Gaultheria shallon) and sheep sorrel (Rrnex acetosella). Green leaves were taken in fairly large quantities, especially those of blueberry (Vaccinium). Other leaves taken in smaller quantities include black medic (Medicago lupulina) and bracken (Pteridium. aquilinum). The fruits and seeds which were taken in largest quantity were blueberry (Vaccinium), red elderberry ( Sambucus callicarpa ) , bramble ( Rubus ) and tarweed (Maria). One crop examined contained a small amount of hemlock needles. LATE SUMMER DIET D. obscurus D. luliginosus Type of food ' (101 birds) (20 bkds) Volume per cent Volume per cent Coniferous needles 8.8 4.3 Buds and twigs Green leaves (other than coniferous needles) 35.3 31.0 Coniferous cones ........ Flowers 2.9 15.4 Fruits and seeds 44.6 47.1 Undetermined plant material ' 1.1 ........ . Animal matter 7.3 2.2 The late summer is characterized by a bountiful production of food of all types and this is reflected in the varied diet of the Blue Gouse. Fruits and seeds are found in great abundance ad a great variety of these is taken as food. Those eaten in greatest quan- tity by Dendragapus obscurus are listed as follows in the approximate order of their importance: blueberry (Vaccinium), manzanita (Arctostaphylos), pine (Pinus), rose (Rosa), cherry ( Prunus ) , serviceberry ( A melanchier ), snowberry ( Sym pkoricar poS ), mountain ash (Sorbus) and currant (Ribes). Green leaves are also taken in great vari- ety and quantity and the more important of these are listed as follows in the approxi- mate order of their importance: Eriogonum, willow (Salix), aspen (Populus), blueberry ( V accinium ) , currant (Ribes), cherry ( Prunus ) , vetch (Vicia), pussytoes ( A ntennaria ) and clover (TriJolium). Coniferous needles were taken in small quantities, especially those of Douglas fir. The needles of spruce (Picea), tamarack (Larix) and pine were also found in a few crops and stomachs. Flowers were occasionally taken, especially those belongin, g to the Cichoriaceae. The most important forms of animal food taken were short-horned grasshoppers (Acrididae) and ants (Formicidae). The late summer diet of Dendragapus ]uliginosus is in most respects closely similar to that of Dendragapus obscurus. Fruits and seeds are represented by a considerable number of .species, the more important of which are listed as follows in the order of their importance: blueberry (Vaccinium), manzanita (Arctostapkylos), bramble (Rubus), and mountain ash (Sorbus). The most important green leaves taken are blue- berry (Vaccinium), clover (TriJolium), ferns (Polypodiaceae), Eriogonum, and hawk- weed (Hieracium) all of which are listed in order of their importance. Floweri are' consumed in considerable quantities during this period, especially those of the cats-ear (Hypoctaeris). Animal matter, which is consumed in small quantities, is made up principally of three groups: short-horned grasshoppers (Acrididae), leaf beetles (Chrysomelidae) and ants (Formicidae). FALL DIET D. obscurus D. iulitlnosus Type of food (11 birds) (7 birds) volume per cent Volume per cent Coniferous needles $1.O ........ Buds and twigs ................ Green leaves (other than coniferous needles) 26.$ 41.1 Coniferous cones ........ Flowers ........ 12.7 Fruits and seeds 22.3 45 Undetermined plant material ......... 6 Animal matter .2 .3 The fall diet of'Dendragapus obscurus in many ways represents a transition between the summer and winter diet. Coniferous needles are again consumed in large amounts, especially those of Douglas fir, although pine needles were taken in fair quantity too. Green leaves continue to be taken in ample amounts, those of Erysimum, blueberry, (Vaccinium) and alum-root (Heuchera) being taken in greatest quantity. Fruits and seeds continue to hold an important place in the diet, those taken in greatest quantity being mountain ash (Sorbus), blueberry (Vaccinium) and elderberry (Sambucus). One bird.was found to have fed almost exclusively on the grain of oats (Avena sativa). Animal matter in the fall diet is apparently of negligible importance. Fruits and seeds and green leaves make up the greater part of the fall diet of Den- dragapus ]uliginosus. The fruits and seeds which were taken in greatest abundance are DoUg!as fir, sedge (Carex), manzanita (Arctostapllos) and blueberry (Vaccinium). The more important green leaves taken were alum-root (Heuclera), willow (Salix), Fig. 18. Fall feeding area of Blue Grou. Boise National Forest, December 8, 1939. Photo by W. H. Marshall. ferns and clover. One bird was found to have consumed a considerable quantity of the flowers of the cats-ear (Hypochaeris). DIET OF JUVENILES All the young birds collected in July and August had grown beyond the "downy" stage and are considered as juveniles. No specimens representing the downy stage were available for study. D. obscurus D. kruliginosus Type of food (19 birds) (2 brds) Volume per cent Volume per cent Coniferous needles 2.6 ........ Buds and twigs ................ Green leaves (other than coniferous needles) 30.6 ........ Coniferous cones Flowers 5.4 47.0 Fruits and seeds 26.9 40.5 Undetermined plant material .3 8.0 Animal matter 34.2 4.5 The diet of juveniles of Dcndragapus obscurus is about equally divided between green leaves, fruits and seeds, and insects. The leaves of Eriogonun were taken in large quantities and those of blueberry, dandelion and cherry were taken in fair amounts as well. Other species of leaves were represented by very small quantities. The more im- portant fruits and seeds are listed as follows: cherry, blueberry, manzanita, serviceberry (.4melanchier), smartweed (Polygonurn) and currant. A great variety of insects was taken, although only the short-horned grasshoppers (Acrididae) and ants (Formicidae) were taken frequently, and in large quantity. Flowers were taken occasionally, especially those of the Cichoriaceae. Needles of the Douglas fir were taken a few times in small quantity. The two specimens of Dendragapus Juliginosus examined were found to contain a large quantity of the flowers of the cats-ear (Hypochaeris) and a considerable quantity of the fruit of blueberry and sheep sorrel (Rurnex acetosella). A relatively small amount of animal matter was found, chiefly in the form of short-horned grasshoppers (Acridi- dae) and ground beetles (Carabidae). MAJOR TYPES' OF FOOD Coni]erous needles.---Coniferous needles probably represent the most important type' of food of Blue Grouse-since they comprise a predominant portion of the food during the critical winter months; they are fed on in large quantities during the spring and fall and even in small quantities during the summer, when many other types of food are available. The needles of Douglas fir are the outstanding food of this type for Dendragapus obscurus whereas Dendragapus ]uliginosus feeds to a large extent on fir (Abies) needles, althodgh needles of Douglas fir are consumed in appreciable quantities too. Both species of Blue Grouse also feed to a considerable extent on the needles'of pines and to a somewhat smalljr extent on those of spruce. The needles of other conifers which were taken in very small amounts are hemlock (Tsuga), tamarack (Larix) and yew (Taxus breviJolia). Leaf buds enclosing newly formed coniferous needles were frequently taken, indicating some preference for the younger, more tender needles. Beer (Jour. Wildlife Manag., 6, 1943:32-44) mentions that on Silver Star Moun- tain, and on East Moscow Mountain, Idaho, Blue Grouse in the winter sought Abies almost exclusively although many Pseudotsuga were present. He states that the needles of larch were a favorite food during July, August and September. Near Wheatland, Wyoming (Nellson, Condor,' 28, 1926:99-100), birds were found feeding largely on needles of pines, in the spring and fall. In central California, Belding (Zoe, 3, 1892: 232-233) found that conifers used were firs (Abies concolor and A. magnifica and hemlock spruce (Tsuga pattoniana [=mertensiana], the latter apparently being pre- ferred. On Kupreanof and Kuiu Islands, Alaska (Swarth, Univ. Calif. Publ. Zool., 7, 1911:56-58), the males remain in the hemlock trees during April, feeding on the foliage and sometimes not leaving a tree for days at a time. Simpson (Amer. Game' Conf. Trans., 21, 1935:218-219) found that Blue Grouse in captivity eat many fir and pine needles and some hemlock needles in winter; but they pass up spruce needles if any of the others are available. Staminate cones.--The staminate cones of conifers are consumed in fairly large quantities in spring and in small quantities in early summer. Those' which were posi- tively identified to genus or species are pine (Pinus), fir (Abies), Dougla fir (Pseudot- suga taxiJolla), and spruce (Picea). The small pistillate cones of some conifers, such as hemlock and certain spruce were also taken in very small amounts. In central California, Belding (loc. cit.) found that in one year, when late summer frosts had destroyed the berry and seed crop, the grouse were feeding almost exclusively on the fallen dried staminate cones of the yellow pine (Pinus ponderosa) during the fall. Buds and twigs.--Buds and twigs are eaten in small amounts in winter and spring. The prevailing types are aspen, cherry and willow. Green leaves.---Leaves, other than needles of conifers were fed on in fairly large quantities in all seasons except winter, when they represent a very small portion of the diet. A surprisingly great variety of leaves is used as food but those which were eaten most frequently and in greatest quantity are listed as follows in the approximate order of their relative importance: blueberry, Eriogonum, ferns, clover, willow, alum-root ( H eucher a ) , pussytoes ( A nt enneria ) , hawkweed ( H ier acium ) , dwarf mistletoe ( A r ceu- thobium), vetch (Vicia), aspen, and currant or gooseberry. With a few minor varia- tions, such as the greater consumption of Eriogonum by Dendragapus obscurus and the greater consumption of ferns by Dendragapus Juliginosus, the types of leaves used as food by the two species of Blue Grouse are similar. Flowers.--Flowers are consumed in appreciable quantities throughout the warmer months of the year. Flowering heads of species of plants belonging to the Cichoreaceae ?epresent the principal type used as food and are apparently taken in greater quantities by Dendragapus ]uliginosus than by Dendragapus obscurus. The cats-ear ( Hypochaeris ) is by far the most important flower of this type consumed by Dendragapus ]uligino- sus and it is frequently taken in such ample amounts that it must be one of the pre- ferrel foods of that species. Composite flowers which are occasionally taken in fairly large quantities by Dendragapus obscurus include: Agoseris, Microseris, Dandelion, hawkweed (Hieraciurn), and sowthistle (Sonchus). Other types of flowers which were infrequently taken include: cherry, Eriogonurn, salal, snowbrush, and manzanita. Fruits and seeds.--Fruits and seeds were taken in small quantities during winter and spring, but during summer and fall a great variety was taken in large quantities. The fruits of blueberry and manzanita were generally taken in larger quantities and more frequently than any of the others. Other fruits which were occasionally taken in considerable amounts are: strawberry (Fragaria), serviceberry (Arnelanchier), snow- berry (Syrnphoricarpos), currant or gooseberry, mountain ash (Sorbus), cherry, bram- ble, elderberry and rose. The small quantities of fruit consumed in winter and spring were largely made up of the more persistent types such as rose and salal. The seeds of smartweed (Polygonurn) and .sedge (Carex) were taken quite frequently during the warmer months but never in large quantities. The seeds of conifers, especially those of pine and Douglas fir, were taken a few times in fairly large quantity. The seeds of Pinus ponderosa (Beer, loc. cit.) composed 7.17 per cent of the food in eastern Washington and northern Idaho in August, whereas Munro (Auk, 36, 1919: 65-67) mentions that Blue Grouse feed chiefly on the seeds of this species between Sep- tember f and the middle of October in the Okanagan Valley, British Columbia. In cen- tral California, Belding (loc. cit.) found that the thimbleberry (Rubus nutkanus) appears to be the favorite article of diet and next to this the serviceberry (Arnelanchier alni/olia). He states further that several kinds of currants and gooseberries (including Ribes sanguineurn and Ribes menziesii) and red elderberries ( Sarnbucus racernosa) are hardly less acceptable. Beer loc. cit.) states that preference is given to fruits of Rubus over nearly any other food and that they formed 17.5 per cent of the yearly diet in western Washington. He also mentions that where hawthorns (Crataegus) are abundant they probably form a major part of the diet during the period when they are available. Beer found that salal berries were eaten in large quantities in the coastal areas of Wash- ington, British Columbia and. Oregon. In June and July he found that the seeds of Balsamorhiza were taken in large quantities. Insects.--Animal food, which is made up almost entirely of insects, was found to comprise a sizable portion of the diet during the summer but was either totally absent or of negligible importance at other seasons. A great variety of adult and larval forms of insects is taken. In the early summer, scarabaeid beetles (Scarabaeidae), leafhoppers (Cicadellidae) and saw-fly larvae (Tenthredinidae) head the list of those taken, where- as in late summer short-horned grasshoppers (Acrididae), ants (Formicidae) and leaf beetles (Chrysomelidae) are the most important. Short-horned grasshoppers, when taken, are generally consumed in larger quantity than the others, while the ants (For- micidae) generally have the highest frequency of occurrence. The food of juveniles of the species Dendragapus obscurus was found to be quite similar to the late summer diet of the adults except that the animal food comprises a much larger proportion while the proportion of fruits and seeds is noticeably reduced. Short-horned grasshoppers (Acrididae)' were found to comprise nearly two-thirds of the animal food of juveniles. In the case of juvenal Dendragapus ]uliginosus, the number of specimens examined was too small to make any generalizations concerning food habits. In the Powell District of the Lolo Forest in northern Idaho (Cooney, U.S. Forest Service, Northern Rocky Mountain Region, Field Notes on Wildlife, 1, 1938:4-5) the crops of 30 Blue Grouse were collected and examined in September and the most im- portant single item of food appeared to be grasshoppers. SUMMARY The food habits of Blue Grouse vary from a simple winter diet that is made up predominantly of coniferous needles to a complex diet during the summer months, char- acterized by great variety of foods including green leaves, fruits and seeds, flowers,' animal matter and coniferous needles. The spring and fall, which represent the transi- tion periods between these two, are characterized by feeding habits that are generally intermediate. The diets of the two species of Blue Grouse, Dendragapus obscurus and Denclragapus fuliginosus, are quite similar as far as major types of food are concerned, but they differ considerably in the species that are taken. Such differences reflect dif- ferences in the vegetation within the ecologic and geographic ranges occupied by the two specie. United States Fish and Wildlife Service, Chicago, Illinois, March 28, 1944.