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A REVIEW OF MOOSE FOOD HABITS

STUDIES IN NORTH AMERICA

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be ascertained in order to fully under­stand the interspecific, intraspecificand environmental relationships of thespecies. A variety of moose food ha­bit studies have become available sincePeterson (1955) compiled the availa-

Cet article passe en revue 41 etudes portant sur les habitudes alimentaires deI'orignal, qont 13 ont ete effectuees dans la cordilliere interieure. 6 en Alaska et 22au Canada, au Minnesota, a I'Isle Royale et dans Ie Maine. Seulement neuf de cesetudes traitent des habitudes alimentair~estivales. alors que seulement quatre de cel­les-d traitent de la pMnologie annuelle des habitudes alimentaires de I'orignal et seule­ment deux etudes s'etendentsur plus d'un an. Les variations locales des habitudes ali­mentaires sont tres importantes et des gimeralisations concernant les especes pre­ferees, sans que soit corroboree I'information pour une region donnee, apparaissentrisquees. Une combinaison des methodes utilisees semble pertinente, car chaque methodea ses restrictions propres. Bien qu'une vue d'ensemble pour I'Amerique du Nord puisseetre tracee a partir de I'information disponible, I'auteur conclut neanmoins que lesdonnees manquent pour comparer, entre differentes regions. les patrons d'utilisationannuels, saisonniers de meme qu'en fonction des differents types d'habitats. L'auteurestime qu'it est essentiel d'evaluer les habitudes alimentaires avant d'apprecier lesconditions du milieu et leurs changements, ou, avant d'entreprendre des recherchesportant sur la valeur nutritive et la digestibilite des dilferentes especes vegetalesconcernees.

Department of Entomology, Fisheries and Wildlife,University of Minnesota, St. Paul, Minnesota, United States

J. M. PEEK2

AbstractThis review covers 41 studies of moose food habits. including 13 from the

intermountain west, 6 from Alaska, and 22 from Canada, Minnesota. Isle Royale, andMaine, Only nine of these studies include information on summer food habits. onlyfour on year-long food habits and only two studies were longer than one year, Local va­riations in forage preferences were very important, and generalizations about prefer­red food items without confirming data for any given area appeared risky. A cQmbi­nation of methods for obtaining food habits data appears the most useful. since anygiven method in use has limitations, It was concluded that. although a generalized pic­ture of moose forage preferences for the North American ranges can be obtainedfrom the data on hand, there was not enough information to compare the annual,seasonal, or habitat-type forage use patterns between areas, Evaluation of foragepreferences is a prereq·uisite to evaluating habitat conditions and trends, and inves­tigations of nutritive values and forage digestibility.

Resume

A REVIE'vV OF MOOSE FOOD HABITS STUDIES IN NORTH AMERICA I

1 Paper No, SHO, Scientific Journal Series. Minnesota Agricultural Experiment Station. St. Paul,Minnesota 55101, .

:Present address: College of Forestry, Wildlife and Range Sciences. University of Idaho, Moscow,Idaho 83843.

Introduction

Food habits express a fundamentalrelationship between animals and· theirenvironment. The feeding habits andplants used by moose for food should

. [va/WilliS/I! can., 101: 195.215 (197;]

Winter forages varied according toconditions of winter range. When snO'Ndepths were less than 30 cm sedgeswere used. After snow depths increa­sed beyond Blat figure, birch sterns

aspen and cottonwood supplied 95 per.cent of the winter forage in their studies.Conifers were apparently not importantin the diet of Alaskan moose, primarilybecause the two major species present.white spruce (Picea glauca) and blackspruce (Picea mariana), were not pala-table (Murie, 1944). .

Spencer and Hakala (1964) recordedSalix depressa. S. scouleriana, S.arbusculoides, and S. barclayi asparticularly important willow specieson the Kenai peninsula. These speciesattain small tree size in that area. Bogbirch (Betula glandulosa) , dwarf birch(B. nana), serviceberry (Amelanchieralnifolia), mountain ash (Sorbus seo­pUlina), and high-bush cranberry wereconsidered of minor importance. Hosley(1949) reported work done by L. J. Pal-

. mer on the Kenai in the 1930's whichindicates that tree and ground birches,willows, mountain ash, red and blackcurrant (Ribes spp.) and serviceberrywere highly palatabl.e. The winter dietaccording to Palmer was mainly willows,ground birches, cottonwood and thegreen bases of bunch and marsh gras­ses.

LeResche and Davis (1973) provideinformation on moose food habitsfrom Kenai peninsula. Summer foodsof three semi-tame moose were twothirds birch leaves, one fourth forbs,including cloudberry, (Rubus chamae­morus), sundew (Drosera rotundifolia).

. fireweeds (Epilobium angustifolium andE. latifolium) and rupine (Lupinusnootkatensis). Mushrooms were eaten·whenever encountered and grasses, sed·ges ,:lnd aquatics constituted about tenpercent of the observed diet.

LE NATURALISTE CANADIEN, VOL. 10 '. 1974

,I Scientific plant names follow Fernald('1950) for· eastern North America. Davis (1952)for the mountain states and Hulten (1968) forAlaska.

Alaska food habits studies

Spencer and Chatelain (1953) providedata on moose food habits in south­central Alaska based on spring browsesurveys (Aldous, 1944). Willows andKenai birch (Betula kenaica) headthe winter preference list, and quakingaspen was· considered important be­cause of the quantity of forage it pro­duced. Cottonwoods (Populus balsa­mifera), high bush cranberry (Vibur­num edule), red elder (Sambucus ra­cemosa), rose (Rosa spp.) and rasp­berry (Rubus idaeus) were less impor­tant browses in the diet. Willow, birch.

ble data in the 1950's for North Ameri­ca. The purpose of this review is tobring all known studies together forthe continent and summarize the ma-jor findings.

It has been well established ,thatmoose are primarily a browsing spe­cies, especially during winter. Mooseoccupying western ranges seem to usewillows (Salix spp.) 3 as a prima­ry food source (Hosley, 1949), whiletrees such as paper birch (Betula pa­pyrifera) , quaking aspen (Populustremuloides) and balsam fir (Abiesbalsamea) assume importance on theeastern ranges (Pimlott, 1961). Forbsand aquatic plants may be importantduring the growing season, while grassand grass-like plants assume re­latively little importance, with someexceptions. Food habits studies havebeen summarized according to generalregion as follows: (1) Alaska; (2) themountain states of Idaho, Montana,Utah. Washington and Wyoming; (3)western Canada (British Columbia­Manitoba); (4) eastern Canada, IsleRoyale, Maine and Minnesota.

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PEEK: MOOSE FOOU HABITS

comprised 72 percent of the· use fromFebruary to' May, low-bush cranberry(Vaccinium vitis-Idaea) 26 percent. wil­lows and alder (Alnus spp.) 6% each, andoccasionally ~ fruticose lichen (Peltigerasp.) was taken on range considered to berepresentative of the wintering area.

On depleted ranges, browse con­sumption declined to 23 percent of thediet between February and May, withbirch predominant, while lichen con­sumption increased to 24 percent. Inlate April and May, when snow depthsdeclined, lichens and low bush cran­berry comprised most of the diet. Thenorthern Kenai Peninsula winteringarea exhibits moderate snow condi­tions, which provide access to low­growing shrubs and forbs and lichens.The more persistent snows of interiorAlaska require that taller browse spe­cies be available for moose in winter.The Kenai work also reflects changesin food habits relative to availability,where lower-growing forms were usedmore on heavily used range. Murie(1944) considered willows the majorsummer and winter food of moose inMt. McKinley Park. Dwarf birch wasregularly browsed. Quaking aspen(Populus tremuloides) and cotton­wood were used, but were less impor­tant because of their limited occur­rence. Murie (1944) started that gras­ses, sedges, various herbs and sub­merged vegetation was eaten in sum­mer.

The following willows, listed in or­der of decreasing preference, were im­pertant forage species in interior Alas­ka near Fairbanks (Milke, 1969): Sa­lix interior, S. alaxensis, S. arbusculoi­des, and S. pulchra.- The relativeabundancG of a species did not seemto affect the utilization, perhaps dueto inherent palatability differences de­tectable to the moose. However, lesspalatable species were more heavily

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197

utilized when in proximity to speciesof higher palatability. Milke's analysisshowed that the tallest plants (over151 cm) were preferred. A positive

. correlation between plant density andintensity of browsing was also noted,suggesting that the stands were notacting as barriers to moose. A combi­nation of high moisture, protein, andcaloric contents were possibly relatedto the high preference for Salix ala­xensis, and the low values of S. ni­phoclada could explain its low pala­tability, although such conclusionswere considered tentative.

Montana, Utah, Washington andWyoming food habit studies

Since Peterson (1955) mentioned. thelack of detailed moose food habit stu­dies' on western ranges, several studieshave become available. These studiesgenerally support the contention thatmoose primarily depend upon willowsfor forage on western ranges. The fee­ding site examination method (Cole,1956) and rumen analysis (Martin'et al.,1946) have been the main means of ob­taining data in the following studies.

Comprehensive food habits studieshave been done in Jackson Hole, Wyo­ming and southwestern Montana areas.These areas represent two generallydifferent types of moose winter rangein the intermountain west. The Jack­son Hole winter range (Harry, 1957;Houston, 1968) was mostly an exten­sive valley wherein floodplain vegeta­tion was the major area used by moo­se. Some use of adjacent forest com­munities was also recorded (Houston,1968). Knowlton (1960) reported thatwillow bottoms, the most extensivelyused winter range, were limited tomoist areas along streams and springsin the Ruby River area of Montana.

Bitterbrush and chokecherry (Pru­nus virginiana) were the only two spe­cies which Chadwick (1960) observedeaten by moose on the Juniper Buttes,Idaho winter range.

Knowlton (1960) reported moosewinter food habits in the Ruby Riverarea of Montana. Early winter foodsof importance were willow, subalpinefir and currant (Ribes spp.). Later.willows, silverberry (Eleagnus commu­tata) and thinleaf alder (Alnus tenui­folia) were important. Willow constitued67 and 59 percent of the early and latewinter diets, respectively. This range wasbeing heavily browsed at that time, withwillow and silverberry plants deteriorat­ing in condition (Peek, 1963).

ten browsed heavily, the average per­cent of browsed trees was light duringHouston's studies, which may indicatedifferences in palatability among indi­vidual fir trees. In this area, willowconditions have varied over the 1950­1966 period, suggesting differentialbrowsing pressu reo In 1966, 3 to 5 yearold blueberry willow stems were pro­ducing most of the forage and receivingmost of the use for this species, olderJive stems being severely hedged and·younger stems being unbrowsed.

Browse constituted 99.8 percent ofthe observed diet in winter on the RedRock Lake Refuge, Montana, with Sa­lix myrtillifolia, S. planifo/ia, S. beb­biana, and S. geyeriana each consti­tuting over 10 percent of the use (Dorn,1970). Red osier dogwood was not im­portant because of its scarcity. Use oflow-growing species like S. wolfii and

. bog birch was limited to early winterwhen they were available to moose brow­sing close to the snow level. Use of S.wolfii in summer by cattle was alsoheavy, probably because the low growthform renders it available. In the Dou­glas fir- type, subalpine fir received mo-

LE NATURALISTE CANADIEN. VOL. 101. 1974198

This s"cudy area of 148 km 2 contained58.3 hectares of willow bottom communi­ties along 33.5 km of streams (Peek,1961). While willow communities gener­ally typify moose winter range in themountain west, some areas are muchmore extensive than others. This cau­ses considerable variation in lengthof time used, and degree of concen­tration of moose on the- willow. Densi­ties on the extensive willow commu­nity in Jackson Hole, ranged up to19.3 moose per km 2 in winter (Houston,1968). Harry (1957) and Houston (1968)reported winter moose food habit studiesin Jackson Hole. Harry (1957) ratedserviceberry (Arne/anchier a/nifo/ia),red osier dogwood (Comus stolonifera),mountain ash (Sorbus scopulina), bogbirch (Betula glandululosa), snow­brush (Ceanothus velutinus) and bit­terbrush '(Purshia tridentata) as "ve­ry highly palatable" to moose in winter.Since willows (Salix spp.) made upover three quarters of the winter dietand were ext~nsively distributed onwinter ranges, he considered these themost important forage species. Hous­ton (1968) regarded blueberry willow(Salix pseudocordata) as the "key"forage plant. Forage preferences wererelated to vegetative type and blue­berry willow, interior willow (S. interior)subalpine fir (Abies lasiocarpa) andbitterbrush were species receiving 50percent or more of the use observed onthe specific types in which they occur­red. While Harry felt that red-osierdogwood, service-berry, mountain ash,and bog birch were in danger of beingeliminated from the winter range in1954. an indication of the degree of

. use these species received, Houstonreported that condition of red osierdogwood and interior willow plants im­proved· from 1964 to 1966 suggestingthat. the winter. range was less inten­sively browsed during his study. Whileindividual subalpine fiJ trees were of-

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re use than Douglas fir (Pseudotsugamenziessi) , but use was restricted tocertain trees which seemed to be con­sistently browsed.

Smith (.1962) and Stone (1971) report­ed moose food habits in the Rock Creekarea of western Montana. Willows com­prised the major share of the winter

. diet; Salix discolor and S. lemmoniwere preferred to S. commutata.Plants less than 15 years old receivedthe heaviest use. Red osier dogwoodwas important in March. On this range,red osier dogwood was either veryheavily llsed or, else, was in poor con­dition affording only limited forage.

Stevens (1970) reported food habitsstudies on a mountain winter rangein the Gallatin region of Montana. Tim­ber types received 82 percent of theobserved use during the study period.Willow constituted 25 percent of the diet,sub-alpine fir 16 percent, mountain maple(Acer spicatum) 16 percent and redosier dogwood 11 percent. This winterrange was being heavily used.

Wilson (1971) reported that Salixdrummondiana made up 92 percentand S. geyeriana made up 4.7 per­cent of the total observed winter brow­se use in the Uinta Mountains of Utah.River birch (Betula occidenta/is) com­prised 2 percent of the use and 7 otherspecies were observed to be browsed.

Poelker (1972) foundb-rowsing on fal­se box (Pachistima myrsinities) inearly fall in the Kalispell. Basin of north­eastern Washington. As snow coveredthis species, snowbrush, Douglas maple(Acer glabrum) and. willows were ta­ken. In mid-winter, instances of brows­ing on lodgepole pine (Pinus contorta)and alders were noted.

Table I provides a resume of impor­tant moose winter forage species as

199

derived from six studies reported forfive areas of the intermountain west.While willows were the primary forageplant in three of the four areas, allof the studies indicated that red-osierdogwood was ·a more palatable foragespecies, although it was less abundantand therefore less important thanwillows. Subalp·ine fir was an im­portant forage species in the spruce­fir communities. Douglas fir receivedonly limited use in the Jackson Holeand Gallatin studies, but Smith con­sidered it to be a palatable species.Lodgepole pine (Pinus contorta) re­ceived sparing utilization.

Bog birch, silverberry, snowbrush,serviceberry, chokecherry, currant, moun­tain ash, mountain maple, and bitter­brush are palatable browses to mooseand may be important locally. Salixdiscolor, S. lemmoni, S. myrtillifolia,S. pseudocordata, S. drummondiana,S. geyeriana, and S. interior, all taI­ler growing, seem to be preferred wil­low species.

Forbs, grasses and grasslike plantsreceive only sparing use by moose inwinter. Harry (1957) did not record useof these forage classes. but Houston(1968) recorded use on bluegrass andbromegrass on agricultural (hayfield)situations in Jackson Hole. Green algaereceived use in aquatic situations. Theseforage classes received less than onepercent of the total winter forage inHouston's studies.

Elk thistle (Cirsium foliosum) andniggerhead (Rudbeckia occidentalis)received less than one percent of thewinter use in Knowlton's stUdy. Stevens(1967) however, reported that grassand grass-like plants constituted 26 per­cento~ the contents of 10 moose ru­mens taken in December and Januaryon a winter range associated with hayfields in the Big Hole valley of Monta­na. Since snow depths were high enough

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TABLE I

Winter food habits of shiras moose on western ranges

Reference Location Years Most important species Remarks

Houston. 1968 Jackson Hole, Wyo. 1967 Salix pseudocordata I, S. wolfi, S. interior. Feeding site examinationS. lucida, Abies /asiocarpa.

Knowlton. 1959 Gravelly Range. 1959 Salix ~pp., Ribes spp., Abies /asiocarpa, Early winter; 95% ofMontana Populus tremu/oides, E/eagnus commutata, forage late winter;

A/nus fenuifolia. 96% forage feeding siteexamination

Smith. 1962 Rock Creek Montana 1959 Salix spp:, Comus st%nitera, Populus Rumen analysistremu/oides, Shepherdia canadensis, Feeding sites;Physocarpus ma/vaceus, Rosa spp., Pinus Salix 90% (S. disc%r.eontorta. S./emmonsi)

Harry, 1957 Jackson Hole. Wyo. 1954·54 Salix spp., Abies /asiocarpa. See text for additionaldetails

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Stevens, 1970 Gallatin. Montana 1966 Prunus virginiana. Comus sl%nitera, Dec.·M,arch feeding siteSalix scou/eriana, S. myrtillifolia, examinationS. drummondiana, Ribes spp., Ame/anchiera/nifolia,

OOr;), 1970 ' R('d Rock Refuge. 1968·69 Salix myrtillifolia, S. geyeriana, S. Feeding site examination1\10ntana p/anifolia. S. bebbiana, Betu/a g/andulosa Dec. 20, 1968 - March 17

1969,

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cent, and grasses and grass-Ii ke plants0.6 percent of the summer diet in theGravelly Range area. Willows com­prised 19.3 percent and sticky gera­nium (Geranium viscosissimum) 64.2percent of the diet. This area is oneexample of a western moose rangewherein aquatic vegetation is extre­mely limited because of the high gra­dient nature of streams.

Knowlton (1960), comparing the va­rious summer food habit studies ofmoose available, felt tliat variationswere attributable to differences in ve­getation on the study areas. Subse­quently, Peek (1961) reported that onthe Gravelly-Snowcrest study area,browse increased in importance du­ring summers which were drier thanthe 1958 summer from which Knowltonobtained data. ·Consequently, it ap­pears that annual variations in foodhabits of moose may occur within thesame area.

Houston (1968) reported that browseconstituted the greatest share of thesummer moose diet in the JacksonHole area, with willow again receiv­ing extensive utilization. Quaking as­pen (PopUlus tremuloides) menziesia,(Menziesia ferruginea), thimbleberry(Rubus parviflorus) , Utah honeysuck­le (Lonicera utahensis), and fireweed(Epilobium spp.) were other impor­tant items. Water crowfoot (Ranucu­Ius aquatilis) and leafy pondweed (Po­tomageton foliosus) were used exten­sively in aquatic situations.

to make this forage class generally un­available, haystacks were consideredthe main source· of grass forage inthe area. Smith (1962) reported thatgrasses. grass-like plants, and forbsreceived less than one percent of theo:Jserved winter diet on his study area,while Stone (1971) reported some useof bull thistle (Cirsium vulgare) andlupines.

Browse species apparently cons­titute increasingly greater percenta­ges of the Shiras moose diet from earlyto late fall. Knowlton (1960), Houston(1968) and Smith (1962) reported thatbrowse plants constituted from 70 to90 percent of the fall diets. Willow,subalpine fir, currant, aspen, huckle­berry (Vaccinium scoparium) moun­tain ash, serviceberry, Ceanothus, bit­terbrush, buckthorn (Rhamnus sp.), ho­neysuckle (Lonicera canadensis), pa­per birch (Betula papyrifera) and redosier dogwood were important fall for­age plants. Forbs and grasses compris­ed relatively larger percentages of thefall diets than winter diets. There was Darn (1970) found' that Salix myr­more variation in the fall diets bet- til/ifolia, Salix geyeriana, and Salixween areas than in the winter diets, planifolia and bog birch leaves cons­perhaps because the use of a greater· tituted 86% of the summer moose dietnumber of vegetative types occurred at Red Rock Lakes Refuge. Montana.in the fall, and there was greater chan- Most leaf-stripping occurred on plantsce of variation in communities bet- over one m tall. Use of aquatics wasween areas. considered minimal.

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Summer food habits studies revealeven greater variation between areas.In Yellowstone National Park, McMil­lan (1953) recorded willow as 88.5 per­cent, aquatics as 9.3 percent, and gras­ses and forbs as 2.2 percent of thediet, based on amount of time spentfeeding on each forage class. Salixgeyeriana was used three times morefrequently than S. wolfii. BluegrassE;lsand wheat grasses (Agropyron spp.)were the grass species utilized.

Knowlton (1960) reported that browseconstituted 28.6 percent, forbs 70.6 per-

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J ~,~ .t·j. ~ 202 LE NATURALISTE CANADIEN. VOL. 101,1974

Moose food habits have been in~esti­gated primarily in winter in easternNorth America. Newfoundland studiesinclude those of Dodds (1960). Pimlott(1953), and Bergerud and Manuel(1968).

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Western Can'adian food Analysis of 23 moose rumen contenthabit studies collected in February 1970 in Cypres

In British Columbia, Hatter (fide Hills Provincial Park in southeasterrHosley, 1949) considereq red-osier dog- Albe~ta was reported by Barrett (1972)wood, paper birch, willows, service- Serviceberry comprised 56 percent 0

berry, quaking aspen, mountain ash the identified material on a dry weigh(Sorbus scopulina) and bog birch to basis, quaking aspen 21 percent ancbe palatable winter moose forage plants. Prunus spp. 12 percent. Red osielCowan, Hoar, and Hatter (1950) added dogwood, willows, honeysuckle, Cle­hazel (Corylus californica) , high- matis spp. Rosa spp. and lodgepolebush cranberry (Viburnum pauciflo- pine contributed less than 10 percenlrum), and alpine fir (Abies lasiocar- of the identifiable material. Cypresspa). Scouler and Bebb willows (S. Hills form a low plateau surroundedscouleriana, S. bebbiana), were the by treeless grass plains, an island ofimportant willow species. Douglas Fir moose habitat. The moose population(Pseudotsuga menziesii) was seldom increased from a transplant of foureaten on their study areas. These data animals in 1956 to 130-180 animals insuggest that moose food habits in Bri- 1970, and severe browsing was com­tish Columbia more closely approach mon at the time of collections. This stu­those of moose on more eastern ran- dy represents the highest proportion ofg~s, as will be reported. serviceberry reported in the diet of

moose, and Barrett considered thisRitcey (1965) recorded instances of species to be preferred over willow.

use of forage by moose on the WellsGray P"ark, British Columbia, winter Howard (pers. comm.) reported thatrange. Willow and false box (Pach is- browse surveys along the Saskatchewantima sp.) comprised over 75 percent River delta in northern Manitoba takenof the observed use, with paper birch, by J. E. Bryant in 1955, showed that redhazel and red osier dogwood also recei- osier dogwood and willows were theving use. Extensive overlap in the diets main species eaten. Balsam fir, quaking(but not the areas of use) of moose aspen, Viburnum spp. box elder (Acerand mule deer (Odocoileus hemionus) negundo) balsam fir, balsam-poplarwas found. An experimental clear-cut- (PopUlUS balsamifera) and raspberryting increased browse production and (Rubus idaeus) were also commonly ta­utilization by moose for at least four ken. In more southerly portions of

__~earsJoJlowil"'lg_the_cutting.-----------_mo_ose__range-in-ManitGsa,--mol:lfltain-,. maple, quaking aspen and hazel appea-

AquatiC specIes used by moose in red to be important.summer at Bowron Lake Park, B. C.,included swamp horsetail (£quisetumfluviatile), burreed (Sparganiumspp.), and pondweeds (Potorriageton Eastern Canadian, Isle Royale, Mainarichardson;;, P. robinsii, P. 9ramineus, and Minnesota food habit studiesP. natans. and P. amplifolius, inorder of importance) according to Rit­cey and Verbeek (1969). Aquatic plantsappeared to form the bulk of the sum­mer diet. Burreeds were consideredto be the chief aquatic food in WellsGray Park by these investigators.

203

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ing eastern Minnesota where this spe­cies occurs infrequently on the majormoose range as well as on areas wheremoose and deer are scarce.

Ev.aluation of the ability of 12 year­old balsam fir to withstand varyingamounts of browsing was determinedby Bergerud and Manuel (1968). Overhalf of the trees from which 75% ofgrowth was removed died two yearsafter clipping, while only one of ninetyclipped at1 0-50% levels died. It wasnot stated whether current or totalgrowth was removed. Balsam fir treesfour-foot tall were found to withstandup to 12 years of heavy browsing wi­thout dying. A preference for balsamfir with dark green needles over chlo­rotic, light green colored fir was noted.Crude protein content was lower inchlorotic fir, indicating that moose wereselecting the most nutritious plants.Clipping experiments resulted in somedarkening of the foliage of chloroticfir. Light browsing may improve pro­tein content by stimulating adventi­tious nutrient-rich shoots.

It is significant that these investi­gators doubted that an equilibrium bet­ween moderate moose densities anda quantity of highly palatable diver­sified winter moose foods could bemaintained in Newfoundland, becauseof inaccessibility of many moose tohunters, because foods such as yewand quaking aspen could not withstandmoderate use, and also because moosetended to congregate on 'sites whereinsought-after species were intensivelyutilised. However, the diet of balsamfir and white birch was considered ade­quate to maintain a healthy moose po­pUlatio~.

Summer moose food habit data fromeastern ranges are scarce. Dodds(1960) stated that in Newfoundlandmoose fed on herbaceous materialsduring summer. Grasses and sedges.

PEEK: MOOSE FOOD HABITS

Dodds (1960) recorded 35 species ofwoody plants browsed by moose basedon examination of browsing intensitieson woody plants within sampling plots.In an area of high moose density domi­nated by balsam fir, winter browseuse was chiefly on balsam fir (47 per­cent), white birch (20 percent), andraspberry (13 percent). In a lightermoose density area dominated by un­cu't white spruce (Picea glauca) andbalsam fir, balsam fir constituted 44percent, willows 22 percent and alder11 percent of the winter browse use.On a cutover area of high moose den­sity, fire cherry (Prunus pennsylvani­ca) was 29 percent, white birch 25percent, ·oalsam fir 1"5 - percent andquaking aspen 10 percent of the diet.

Pimlott (1953) considered balsam firand white birch the two species ofuniversal importance to moose in New­foundland. White birch was the mostimportant browse species in habitatswhich had been burned or logged, con­taining low or moderate moose densi­ties (Pimlott, 1963). Balsam fir exceed­ed white birch in the diet where highdensity populations existed. Yew' (Ta­xLis canadensis) was most seriouslyaffected by moose browsing, beinghighly palatable and relatively into­lerant to browsing (Pimlott, 1963).Pimlott thought it possible to classifybrowse conditions on the basis of useof these three species. If yew was high­ly or moderately used. the range wasbelow carrying capacity and many pa­latable browse species would be avai­lable. If white birch was available,balsam would provide a small percen­tage of the winter food. If fir was heavi­ly browsed, yew would be killed outand the palatable decid uous specieswould be severely overbrowsed and aportion eliminated from the habitat.It should be noted that the absenceOr scarcity of yew may not be attri­butable to moose in some areas, includ-

LE NATURALISTE CANADIEN. VOL. 101. 1974

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percent. Apparently these studies weremade at a time when heavy browsingby moose was occurring in the area.

DesMeuJes (1965) determined wintermoose food habits from browse sur­veys in Laurentide Park, Quebec. Infour yards examined. balsam fir com­prised most of the winter diet. whilein four other yards, deciduous speciesdominated the diet and balsam fir wasmoderately .used. Mountain maple,white birch and willows were the mostcommonly browsed deciduous species.Red-osier dogwood, willows. and moun­tain ash the highest palatability ra­tings where available. Balsam fir be­came more heavily utilised as snowdepths increased to highs in late winter.Fire cherry bark was used more com­mo~ly than quaking aspen, mountainash or red maple bark, but all werefed upon where palatable twigs wereavailable and hence were consideredpreferred foods. No 'evidence ofbrowsing on arboreal lichens was no­ted although they were abundant insome areas studied.

DesMeules (1965) postulated thatheavy utilization of balsam fir in latewinter may save energy, since fir twigsweigh eight to 13 times more than deci­duous twigs of similar length and there­fore require less time and efforts toconsume equivalent amounts. In onelate winter yard, balsam fir comprised 86and white birch 14% of the diet. Thisyard was about ten acres in size andwas believed capable of supporting onemoose for 200 days of winter (DesMeu­les, 1962).

.Stomach analyses of 24 Ontario moose.one Manitoba and one Quebec moose,'taken from October 19 to May 5 (Pe­terson, 1953) indicated that balsam firoccurred in 21 of 23 stomachs wherethe tree occurs, and white cedar (Thu­ja occidentalis) occurred in smallamounts in 4 stomachs, willow 'in 16.

204

Dyer (1948) reported browse surveysin Baxter State Park, Maine. Balsamfir, mountain maple. mountain ash,white birch and fire cherry were thefive most important browse speciesfor moose. Two types of moose yardswere described in this region. .Onhigh altitude yards, near summitsof mountain tops, snow depths of 2.5to 3.2 m limited browsing to repro­duction .above that height. Balsam firwas stripped of lateral branches upto 1.25 cm in diameter. Low altitudeyards were the most common type ofyarding situation in the region. Sevenspecies made up 99 percent of the foodeaten: balsam fir, mountain maple,mountain ash, white birch, stripedmaple (Acer pensylvanicum). firecherry and quaking aspen in that orderof importance. Fir constituted 54 per­cent of the diet,. mountain maple 23

leaves of shrubs were commonly taken.There were few aquatic areas in New­found land: however, small ponds, Jakesand rivers were frequented. On anaquatic area used heavily within Dodd'sstudy area, grazing was light until lateJune. heavy during July and decreasedin August.

Telfer (1967) reported winter rangesurveys in Nova Scotia. Speckled alder(Alnus rugosa), Canada honeysuckle(Lonicera canadensis), alleghenyblackberry (Rubus allegheniensis)sugar maple (Acer saccharum) andyellow birch (Betula a/leghaniensis)were the five most highly preferredbrowse species of nine species whichwere used in a moose yard. Beakedhazel (Corylus cornuta) was rankedover balsam fir, mountain maple, Alle­gheny blackberry and meadow-sweet(Spiraea latifolia). For the entirewinter range, yellow birch, red maple(Acer rubrum). sugar maple and moun­tain maple (A. spicatum) were im­portant forage species.

205

Manweiler (1941) stated that themain winter foods of moose in Minne­sota were maples, ash, dogw,ood, hem­lock (Tsuga sp.) quaking aspen, bal­sam poplar, birches, willows. june­berry (Amelanchier sp.), fire cherry,chokecherry and basswood (Tilia sp.).The' basis for this was not reported,and hemlock and basswood are rareon Minnesota moose ranges. The Red

black spruce on Isle Royale. Yew wasconsidered a highly preferred moosefood, and was once widely distributedacross Isle Royale (Murie, 1934). By1950, it was" not considered to be asource of food on the island. Mountainmaple ranked higher on the palata­biiity lists than beaked hazel, but lightutilization for both species was encoun­tered.

Krefting (1951) reported that stomachsof moose collected in the fall of 1949 con­tained mountain maple. balsam fir andquaking aspen. Murie (1934) reportedstomach contents analysis of six moosetaken between May 20 and August 10of the summers of 1929, 1930 and 1931.Mostly browse species were found, in­cluding quaking aspen, alder, fire cherry,yew, bush honeysuckle (Lonicera sp),mountain maple. raspberries. beakedhazel. and willow. Small amounts ofsedge. grass, mushrooms, horsetail(Equisetum spp.) pondweeds andlarge-leaved aster (Aster macrophyl­Ius) were also found. Murie (1934)reported that. wood fern (Dryopterissp.), and swamp horsetail (Equise­tum sp.) sedges, marsh marigold (Gal­tha palustris) , jewelweed (Impatienssp.) and large-leaved aster were exten­sively grazed. Large yellow pond lily(Nymphaea advena). sweetscentedwhite pond lily (Castalia odorata) andPotamageton sp. were reported as ex­tensively fed upon when available butwere rare due to heavy u·se by mooseon Isle Royale (Murie, 1934).

PEEK: MOOSE FOOD HABITS

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Browsing investigations in Ontarioon ·St." Ignace Island (Peterson, 1953)suggested that balsam, fir constituted27 percent of the available diet, whitebirch 12 percent, 'mountain maple andred osier nine percent each andhighbush cranberry five percent. Consi­derable seasonal vari~tion was found infoods eaten. Conifers were practicallyuntouched from early spring to late fall.Quaking aspen was commonly barked onSt. Ignace. Mountain maple was mostconsistently barked, though mature treeswere very scarce.

The'lsle Royale browse studies (Al­dous and Krefting, 1946; Krefting. 1951)illustrate annual variations in winterutilization patterns of moose on thesame range (Table II). The diet includ­ed 33 woody species but seven species(quaking aspen, white birch, balsamfir, mouri-tain ash, willows, red osierdogwood, yew) contributed 80 percentof the total diet and three (quakingaspen, white birch, balsam fir) contri­buted 48 percent, based on three yearsof spring browse survey data. Chan­ges in importance of individual specieswere primarily _related to the heavybrowsing which occured during the pe­riod (Krefting, 1951). Quaking aspenbecame less important in the diet af­ter 1945 because the amount eaten upto then was in excess of production.Quaking aspen accounted for 54 per­cent of all trees and shrubs' destroyedby moose in very heavy browsingsituation. Conversely, ,whit birch, be­cause of its higher ability to withstandbrowsing, increased in importance.Krefting (1951) concluded that balsamfir could not withstand continued heavybrowsing and was being replaced by

white birch in 11, beaked hazel in 10,quaking aspen in nine, fire cherry infour, bog birch and red-osier dogwood

"in two and serviceberry and maplein one each..

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LE NATURALlSiE CANADIEN, VOL. 101. 1974206

Lake area of northwestern Minnesotaconsists of willow, quaking aspen andbog birch communities interspersedwith small stands of spruce and jackpine (Pinus banksiana) (Ledin andKarns, 1963).- A browse survey in thatarea in 1949 indicated that willow form­ed 58 percent of the winter food, whilebalsam fir, white cedar, bog birch, bal­sam poplar, red osier dogwood, rasp­berry. mountain ash, aspen and tama­rack (Larix laricina) comprised 39percent. while black spruce, black ash(Fraxinus nigra), beaked hazel, whitebirch, highbush cranberry and aldercomprised two percent of the diet. Therange was considered to be in goodcondition. Although there was no .men­tion of moose-deer competition for anydominant species, one suspects thatwhite cedar was probably used moreby deer than by moose.

Peek (1971) investigated forage pre­ferences in northeastern Minnesotaon a year long basis (Fig. 1), usingthe feeding site examination. Willowswere the most important browse, year­long, but received greatest use inSeptember through December. Bebband pussy willows (Salix bebbiana,S. discolor) were the most preferredwillows. Quaking aspen was the mostimportant browse in June, declined invalue through late summer, fall, andearly winter, then received increaseduse in mid-winter. White birch rankedthird in importance year-long, and re­mained relatively constant throughoutthe year. Beaked hazel, fou rth in over­all importance, was most intensivelyused in mid-winter. Fire cherry wasimportant primarily in summer and.early fall. Red osier dogwood was usedprimarily in fall and though remainingimportant. decreased in value as thewinter progressed. Virtually no use oc­curred until twigs reddened. Juneberry and mountain ash remained inthe diet at low but constant levels year-

long. Balsam fir, almost entirely a wirter forage. received progressively moruse through the winter and was aimportant late winter forage suppl~

Mountain maple was used most commonly in late summer and again during the winter, but was never a rnajor item in the diet.

Winter severity, especially snow depttand its rapidity of accumulation (VanBallenberghe and Peek, 1971), appear~

to have some influence on food habitsBalsam fir and beaked hazel becameimportant items in the diet at relati·vely later dates during two milder win·ters than during the severest winterof the study. Red osier dogwood remain­ed important in the diet for a longerperiod during the mildest winter thanduring the others. Since movement todense cover occurred most rapidly du­ring the severest winter, use of fora­ge species characteristic of com­munities dominated by balsam fir andthe spruces also occurred earlier. Snowdepths appeared to be critical in useof red osier dogwood. since many plantsdisappeared under one m of snow.

Except in summer, browse constitut­ed all of the observed diet. The relati­ve importance of forbs in summer waslow, but aquatics were probably themajor forage source during early sum­mer. Yellow pond lily (Nuphar va­riegatum). wild rice (Zizania aqua­fica), pondweeds, burreed (Sparganiumspp.) and wild calla (Calla palustris),were commonly used.

Table II lists the five most importantbrowse species for ten separate surveysin six areas of eastern North America.White birch, mountain ash, mountainmaple and balsam fir occurred in fourof the five areas. The Nova Scotia stu­dy area (Telfer. 1967) was lightlybrowsed, and balsam was used onlysparingly. No mount3in ash or quakingaspen was reported in that study area

---~PEEK: MOOSE FOOD HABITS 207

WHITE BIRCH

BEAKED HAZEL

MTN. ASH

BALSAM FIR •

WILLOWS

not severely browsed by moose (Peek,1971).

Mountain maple, balsam fir, andwillows were important in four areas.Quaking aspen may be important onlylocally in Newfoundland. With the ex-

JUNEBERRY

FIRE CHERRY

MTN. MAPLE

RED OSIER DOGWOOD

QUAKING ASPEN

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Figur~ J. Percentage use often important browse species by moose in Northeastern Minnesotaas determined by feeding site examination, after Peek (1971).-- ,--

and Rowe (1957) does not mentionmountain ash as being a commonspecies in his description of Nova Sco­tia area. Balsam. fir served mainly asa late winter forage in northeasternMinnesota. where forage supplies were

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TABLE II

Important browse species to moose in eastern North America

ReferenceFive most important browse species

RemarksArea in order or importance .Peek. 1971 NE Minnesota Willows, quaking aspen, white birch, beaked hazel, Moderately high moose'population

fire cherry Feeding site examination technique

Aldous & Isle Royale Quaking aspen, white birch, balsam fir, mountain High moose population (1945)Krefting, 1946 Michigan ash, willows Browse survey technique

Krefting, 1951 Isle Royale Balsam fir, white birch, mountain ash, quaking 1948 higher moose population than 1945Michigan aspen, willows

Krefting, 1951 Isle Royale White birch, quaking aspen, red'osier dogwood, 1950 lower moose population than 1945.Michigan willows, mountain ash

Peterson. 1953 SI. Ignace Balsam fir, white birch, mountain ash, red·osier 1947·48. Most important species rather thanIsland, Ontario dogwood, mountain maple most palatable

Dyer. 1948 Maine Balsam fir, mountain maple, mountain ash, white 1940's. browse survey techniquebirch, fire cherry

Telfer. 1967 Nova Scotia Mountain maple, yellow birch, sugar maple, red maple, 1968 light browsing pressure,Canada honeysuckle slem counts in spring (his Fig. 3)

Pimlotl, 1953 Newfoundland White birch, balsam fir, mountain maple, mountain Stem count method, heavy browsingash, fire cherry pressure

Dodds. 1960 Newfoundland Balsam tir, white birch, raspberry, elderberry, High moose density, cutover areajune berries 1953, '56, '57. Area different from below.

Dodds, 1960 Newtoundland Balsam lir. willows. alders, mountain maple, Low moose density, stem count method.rhododendron Area different from above.

.. I'I'i,

209

This survey has covered 41 differentreports, 13 from the intermountain west,six from Alaska, and 22 from Canada,Minnesota and Maine. Since Peterson's(1955) review, at least 29 food habitstudies have become available. Onlynine of these studies include informa­tion on summer food habits; only fourstudies contain information on year­long food habits; only two were longerthan one year's duration.

Although the general conclusions arethat willows are important to Shirasand Alaskan moose, and that balsamfir, quaking aspen, and paper birchare important to Canadian moose, localvariations in forage preferences areimportant. This is especially relevantbecause habitat management shouldfavor the locally preferred species.However, species such as red osierdogwood may be highly preferred itemsin the diet across the entire Canadianmoose range, but may vary in abun­dance enough between areas to affectmanagement considerations. Some spe­cies such as juneberry, mountain mapleand beaked hazel appear to be prefer­red in some areas and unimportantin others. Although woody species aregenerally preferred, several studiessuggest that forbs and aquatics maybe of high local significance to moosewhen available and palatable.

It therefore does not appear to bevery illuminating from the mana-

and Peterson (1955) in Ontario and Peek(1971) in northeastern Minnesota,moose appeared to begin and end useof aquatics earlier further south.

Table III shows major aquatics usedin ten different areas of North Ame­rica. While considerable variation oc­curs and is to be expected, yellow pondlily, pondweeds, and horsetail appearto be preferred wherever they occur.

Discussion and conclusions

PEEK: MOOSE FOOD HABITS

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ception of areas in which balsam firand white birch occur only sparinglyor are absent, these two species appearto be major forages of moose on east­ern North American ranges. Aldous(1952) concluded that white birch pro­duces well under moderate to heavyuse and should be used at leastmoderately if plant growth is to bekept within reach of deer. Bergerudand Manuel (1968) indicate that bal­sam fir has a strong survival tenacity.

The role of aquatics in thediet of moose

Moose are so frequently observedor photographed in water that it iseasily assumed that the aquatic envi­ronment is a necessity for the species.However, major popUlations exist inareas across the continent, such asthe Matanuska Valley of Alaska, theGallatin Mountains of Montana, andthe Cobequid Hills of Nova Scotia, wherethe aquatic habitats are of little sig­nificance. By contrasts, aquatics onIsle Royale have been reduced, follow­ing heavy use by moose (Murie, 1934;Krefting, 1951).

Use of aquatic areas has been attri­buted to escape from insect attack(Flook, 1959; Ritcey and Verbeek, 1969)and to the presence of palatable plants(Peterson, 1955; Murie, 1934; deVos,1956). Use of aquatic vegetation hasbeen correlated with the pheno.logicalstate of the important forage species,yellow pond lily and .wild rice, innortheastern Minnesota (Peek, 1971).Pond lily was used primarily beforeseed-set, and wild rice was used mostbefore plants floated on the water sur­face. Use of aquatics was variable be­tween years in that area, apparentlydependent upon water levels which maycontrol phenological development, butoecurred primarily in early summer.Based on observations by DeVos (1956)

-"

TABLE III

Summarization of aquatic plants preferred by moose in ten areas of North America

_.'- --

Aitcey & Verbeek. 1969

Reference

Aitcey & Verbeek, 1969

Macon, 1956), which in turn will affectthe density of associated species, someof which may be more palatable thanaspen. Response of various moose foragespecies to various cutting treatmentsand to prescribed burning should befurther investigated.

Many of these studies do not give ameasure of the intensity of utilizationof the various species, which causesproblems in comparing food habits be­tween areas. Heavy browsing, to thepoint where forage preference andavailability has been affected, may pre­clude determination of true forage pre­ferences for an area. Food habits stu-

Swamp horsetail. burreed.pondweeds

Major plants used

Burreed

LE NATURAlISTE CANADIEN, VOL. 101, 1974

Location

Walls Gray Park.B.C.

Bowron Lake. B.C.

210

gement standpoint to generalize aboutmoose forage requirements, exceptthat many preferred species appearcharacteristic of successional stages.Even this may be misleading becausewillows characteristic of riparian com­munities, or, of alpine tundra may beextremely long-lived, and mature bal­sam fir plants may be important win­ter forage sources..

The various forage species may res­pond to management practices in dif­ferent ways. For instance, quaking as­pen may sprout more readily and indenser stands from winter cutting thanfrom summer cutting (Stoeckler and

r,.

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f~ ­f;i.. '

Little MissinaibiLake. Ontario

Horsetail. eelgrass, pondweed.yellow pond lily. bullrush

deVos, 1958

SI. Ignace. Onto Pondweeds Peterson. 1955

Isle Royale Swamp horsetail. pondweeds.sedges. yellow pond lily.sweet-scented pond lily

Murie. 1934

Algonquin ParkOntario

Yellow pond lily. watershield.sweet-scented pond lily

Peterson. 1955

YellowstoneNational Park

Alaska

Jackson Hole,

Wyoming

NE Minnesota

Mud plaintain. water milfoil.bladderwort. pondweeds

Horsetail. rUSh. pondwced.burreed

Water crowfoot. leafy

pond weed. hornwort. greenalgae

Yellow pond lily, wildrice, burrecd

McMillan, 1953

Palmer (in Hosley, 1949)

Houston, 1968

Peek. 1971

PEEK: MOOSE FOOD HABITS 211 .

During the 1940's the use of balsamfir on Isle Royale was considered tobe causing deterioration and eli­mination of the species, while the New­foundland studies suggested that bal­sam fir could withstand veri heavyuse for as long as 12 years and su rvive.On Isle Royale, heavy browsing hadcaused quaking aspen to become lessavailable and apparently white birchwas replacing it as the most used itembecause of this.

Besides being influenced by speciescomposition and intensity of grazing,forage preferences may be influencedby weather conditions, and general ac­tivity and whims of the animal (Stod­dart and Smith, 1955). For instance,Peek (1971) found that increased useof alder during the rutting period inlowland types in northeastern Minne­sota could be related to intensive rut­ting activity, wherein this highly abun­dant species may serve as· displace­ment feeding source during momentsof high interaction between individuals.Many of these food habit studies weremade by examinations of browse inspring. The major disadvantage of thistype of survey is that changes in foragepreference which may occur duringthe winter cannot readily be deter­mined, as these studies depict woodystem use for the whole period whenwoody stems are eaten. Moose maybrowse woody stems during the grow­ing season, as well as during dor­mancy. When relating moose food ha-

larger population which was intensive­ly browsing the available forage inNewfoundland (Dodds, 1960). The highuse of balsam fir in both situationsappeared to be primarily related toavailability, and may not be a goodmeasure of the actual palatability of thisspecies. Balsam fir appears to be lessimportant when a variety of other spe-cies are present. .

JI

A related problem that involves con­siderations beyond moose mana­gement is demonstrated by the New­f'Jundland studies. Apparently a pro­ductive and relatively dense moose po­pulation can be maintained on a winterdiet of paper birch and balsam fir,while other preferred, but less brow­sing-tolerant species are being eli­minated. Since balsam fir was repro­ducing itself satisfactori Iy from thetimber management standpoint, andthe moose population was being main­tained, by traditional criteria of wild­life management and forestry, the si­tuation appeared to be satisfactory.However, when elimination or an im­portant reduction occurs of other non­merchantable species, the situation maybe considered to be unduly altered fromthe standpoint of species diversity. Ifmoose habitat management is to befully integrated into other land uses,perhaps forage. deterioration whichdoes not affect moose densities or tim­ber resources should not be consideredthe proper management goal. Of course,the problems of achieving adequatemoose harvest to actually regulate den­sities, distributions and forage re­sources are among the practical limi­tations which must probably be givenmore immediate priority. Nevertheless,the wildlife biologist should be awa­re that resources other than mooseor merchantable timber may be adver­sely affected under such conditions.

There is also a need to distinguishb~tween . the effects of natural suc­cession and of previous over-utilizationon forage preferences. For instance,balsam fir was important in the dietIn an area of virgin timber supporting

_a l.~~ density moose population, as wellas In a logged area supporting a much

dies should include information on uti­lization and availability of forage spe­cies.

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riod, the method does not readily determine forage preferences for eaclhabitat type. Forage availability an(feeding habits of the animals undevarious conditions are not consideredOrdinarily, only a small number 0

rumens can be obtained, and one atwo samples which may reflect atypical circumstances may misre·present the usual diet. Analysis is timeconsuming and often only a small por­tion of the' ru men is identifiable.

The use of "feeding minutes" as byMcMillan (1953) in Yellowstone Parkis applicable only to areas where theanimals and forage species can be rea­dily observed at close range, and wh8nplant composition is simple enough thatitems in the diet can be readily iden­tified. Also, whether semi-domesticatedanimals reflect forage preferences ofwild conspecifics or not remains to beevaluated. In view of the problems as­sociated with each method of obtainingfood habits data, several approacllesshould be LJsr.d wllenevcr possible.

Feeding site examinations requireextensive field effort, but yield in­formation which can be specific to agiven habitat type. Problems usingthis technique include 1) determiningwhat constitutes "fresh use" or useby the individual which one is follow­ing, 2) the fact that use on certainspecies such as willows and balsamfjr may be more- readily observablethan on species in the herbaceousstratum, such as mushrooms, 3) thesubjective determination of what cons­titutes a "bite" for each plant species,and 4) the problem of securing feed­ing sites an areas where tracks andsign are more readily observable butwhere the animal may only be curso­rily browsing on its way to a morepreferred feeding area which is lessreadily observable.

lE NATURAllSTE CANADIEN, VOl. 101, 1974212

bits to range condition-trend, it is im­portant to know when a species is mostintensively browsed: th'e physiologicalresponse of a shrub to browsing maybe expected to differ according to itsphenological state. Young and Payne(1948) fOl,Jnd that summer use of fourbrowse species by domestic sheep innorthern Idaho had a more detri­mental influ~nce upon the plant thanfall use.

Dodds (1960) listed several other pro­blems with relying on this method toobtain food habits data: 1) rebrowsingof already browsed stems, 2) overlapin food habits between two or morespecies present on the same area, 3)early fall frosts may kill terminalshoots of same plants, including ~Iders,

which may resemble browsing. Also,this approach does not usually con­sider use of leaves. Yet, the majoradvantage of the browse examination,is that one does not have to locate in­dividual animals, a tedious procedurein some habitat types; moreover, ade­quate sample sizes may be relativelyeasy to obtain and only one exa­mination of an area during the yearis necessary to obtain information.

Rumen analysis is also fraught withcertain problems. Several biases ofthis technique include: larger plantfragments, being most easily identifia­ble, may not be representative of theentire rumen contents because of dif­ferential digestion between plants (Ber­gerud and Russell, 1964). Although thismay be a minor bias when only woodystems are eaten, certain shrubs suchas elder and the honeysuckles maybe more quickly digested than balsamfir and willows and the smaller, moredelicate stems may also be digestedmore quickly than the coarser stems,making identification more difficult.For animals Wflich may frequent diffe­rent habitat types during a feeding pe-

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PEEK: MOOSE FOOD HABITS•

It must also realized that a short­term study may not provide adequateinformation on the forage preferencesof moose for any given area. Pref­erences have been found to vary be­tween years in southwestern Montanaand on Isle Royale. And on areas asclose together as Yellowstone Lake,the Ruby River of southwestern Mon­tana, and Jackson Hole, Wyoming,summer food preferences appear tobe quite' different.

Assessment of winter forage sourcesalone may not provide enough in­formation to determine whether fo­rage supplies are a limiting factor ornot; spring, summer and fall diets mayhave an important influence on pro­duction and survival, as indicated for

.deer (Klein, 1970). Most certainly aknowledge of year-long forage require­ments will be important in effectingproper management invo,lving habitatmanipulation. Peek' (1971) recommen­ded logging practices that would favourcreation of areas which could providespring and fall habitats for moose asan important management procedure innortheastern Minnesota.

Food habits data are probably bestinterpreted when supporting infor­mation on habitat condition and trend,and population performance are alsoavailable.. Until .a measure of actualforage preferences of a population ina given area can be obtained throughexperimental procedures, habitat andPOpulation performance are meaning­ful ways of determining the adequacyof a diet based on field observation.

It is concluded that these studies' donot depict food habits well enough toadequately compare annual, seasonal~nd habitat-type forage use patternsIn all but a few instances. Trends infood habits according to successionalS~q\Jence are inadequately reported.

213

The influence of weather, predpitation',plant phenology and succession, as wellas social behaviour, on forage use shouldbe further investigated. A knowledgeof forage requirements and preferencesis prerequisite to investigations of nu­tritive values and d igestibil ity of foragesources.

Acknowledgements

I am indebted to J. L. Howard of the ManitobaDepartment of Mines and Resources for providingunpublished information.

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•PEEK: MOOSE FOOD HABITS 215

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