United States Department of Agriculfc Bureau of Biological Survey Wildlife Research and Management Leaflet Washington, D. - C. * FALL AND WINTER FOOD HABITS OF DESK IK NORTHEASTERN MINNESOTA By Shaler E. Aldous, Section of Wildlife Surveys, and Clarence F. Smith, Section of Food Habits, Division of Wildlife Research Contents Page Winter food supply 1 Stomach analyses 2 Field observations 4 Surrey of the Jonvick Yard Conclusions Page 7 7 WINTER FOOD SUPPLY The northern white- tailed deer ( Odocoileus virginianus borealis ) is depleting its winter food supply in the Lake States region to such an extent as to create a situation that, if not corrected, will have disas- trous effects on the animals themselves. The available winter food supply is a limiting factor on the deer populations in areas where the animals are greatly restricted in movements "oy extreme cold wea,ther and heavy snows. Under such conditions the doer often eat the choice foods early in winter and then are compelled to subsist upon less nutritious plants when their physical condition is poorest. In parts of northeastern Minnesota, fires and logging activities in the past have improved general conditions for deer, but they have also greatly reduced winter cover, especially white cedar and other conifers, and have forced the deer to retreat into the remaining clumps of ever- greens for winter protection. Because of the small size of many of these yarding islands and the heavy concentrations of deer using them, the food supply is often insufficient. The area here reported on lies between Lake Superior and United States Highway No. 53 from Duluth to International Falls, Minn. I rtala the eholoa food plants and the species eate rf ng critical period, two se.-ieu of d-er stomachs were collected a. contents . ed. 1/ -ore stomachs were tl ron de> Lied ring the ] .. n the 1 condition and had access to a wide vari \ food^. Late 1 Of 1. - ,51 stomachs were collected fro« ic I ad been killed by predatoro or automobiles, or had died from p— lincml a or ex. . Sight of the 21 fall stomachs were taken fro I Xabetogoma Stat it, near Hay, Minn. , and the remaining 13 fro Suporior Nation b, near Ily, Mi: .... Die winter stomachs w. fpon areas as follows: 12 from the Cloquet Valley State Fore, son, lUnn., and 39 from the Superior National Forest. Of the latter, all were taken from the ens - of the forest: 5 f ce deeryard, 2 from the 0u.nf3.int district, and 18 froi ryard. vere taken near Ely, Minn., ir. the sane general area as fall stomachs from the Superior National Forest. • percentages by volume of the more important foods i: two series of stomachs arc s ... figure 1. It will be noted fall, plants of the .-illow family (Salioaceao) were eaten in I -st forming 2? percent of the total, but late in winter they droj. to 3.8 percent. are of this group in the fall food were quaking aspen (Pojgulus tremuloidos ) and balsam poplar (P. balsam if era ' , 17.4 percent, and willow r. ( Salix cpp.), 11.4 Late in winter only willow was found. Balsam fir ( Abies balsamea ) , which formed 13.4 percent of total* ranked second in the quantity of food eater, in fall. Feeding esq :.ts conducted in Y.cv York 2/ end Michigan 3/ indicate that balsam as the solo food, or in too large proportion oven who: . others, does not •tain deer in a stror. ical c . That balsam is a starvation diet is illustrated in the present study by the quant it stom- achs of deer that died late in irlnter, when the plant ranked first and for - :2.7 percent of the food. Balsam f orffled 80 percent or more of the con- tents of 17, or a third, of the stomachs, 5 of which held nothing else. TThen there ic a choice, deer may feed on balsam frequ* but only 1 ly in comparison with the q y taken when choice foods are not available. Zven though the volume consumed in fall was less than one-1 rl of that eaten late in winter, the percentage of the total number of deer feeding upon bal- sam was higher — 86 compared with 80 (fig. 2). 1_/ Stomach I r.ations were made by the junior author in the Food Habits Laboratory at I rgton. 2/ rd, L. A.; Bump, Gardiner: Darrow, Pobert; and Woodward, '• Z. . Food Pre- [uirei unts of tho White-tailed I Joint contribution of tho New Toxk 51 Lepar- md the New York State College of Agri ! e. 35 pp. 1'. . .port, L. A.. B Marked Food Preferences. Midi. Conser . 4- .11. I9ff . - a - Pine is usually assumed to have at>out the same nutritive value as "balsam. During the fall it was eaten "by 73 percent of the animals and formed 7 percent of the total food. Late in winter the number of deer eating pine dropped to 33 percent, but the quantity consumed doubled (14 percent). Jack pine ( Pinus bank si ana ) was found in 54 percent of the fall stomachs, white pine (P. strobus ) in 18, and red pin© (P. re si no sa ) in 14. Jack pino occurred in 10 percent of the late-winter stomachs, white pine in 22, and red pine in 16. White cedar (Thuja occidentalism ) , generally considered one of the best deer foods, was found in 23 percent of the fall stomachs and formed 9 percent of the total food. The quantity consumed increased to 13 percent during the winter, when it was found in 39 percent of the stomachs. This figure represents the maximum utilization of this food and indicates strenuous effort on the part of tho deer to obtain it, for much of it was available to the animals only after heavy snows raised their browsing reach. Some of the cedar oaten from one "yard" was that lopped off to feed tho animals during a critical period. Spruce (in this region chiefly black spruce [ Picea mariana ]) is not an important deer food and is not eaten in large quantities until conditions are severe. It formed only 0.7 percent of the food in fall and 2 percent in winter. Even though not taken in quantity, it was eaten frequently and was found in 32 percent of the fall and 33 percent of the winter stomachs. The birch family was represented in the diet by paper birch ( Be tula pap.yrif era ) . alder ( Alnus sp. ), beaked hazelnut ( Corylus ro strata ), and hophornbeam ( Ostrya virginiana ). Paper birch was by far the most important of these species and was noted most frequently and in greatest quantity. Alder was found in only one wintor and four fall stomachs, while hazelnut and hophornbeam were each noted once in the fall stomachs. Although the birch family occurred in 59 percont of the fall stomachs and formed 10 percent of the volume, it was present in only 25 percent of the winter stomachs and comprised 4 percent of the total food. Members of the heath family (Ericaceae) eaten by deer were winter- green ( Gaul the ria procumbens ), Labrador- tea ( Ledum groenlandicum ) , and leatherleaf ( Chamaedaphne calyculata ) . These plants were selected by 23 percent of the deer in fall and by 12 percent in winter and formed 5 and 3 percent, respectively, of the total volume. Being unavailable after deep snows, these low plants wore oaten less frequently in winter. The honeysuckle family ( Capri foliaceao) was represented in the fall diet of the deer by the twinflowcr ( Linnaoa borealis ) , which occured in 14 percent of tho stomachs but formed only a trace (i.e. less than 1 percent) of the total food, and in tho winter diet by viburnum, which was found in 10 percent of the stomachs and composed 5 percent of the total food. Bunchberry ( Cornus canadensis ) occurred in 27 percent of the fall stomachs and formed 2.2 percent of their contents by volume. In the winter series, dogwood ( Cornus sp. ) was found in only one stomach and - 3 - formed less than 1 percent of the total food of the deer. Field observa- n3 would indicate that tni s dogwood was probably red-osier (C. st .1. ifera ) . as it is the most common species in this area that would be avail- able above deep snows. Its low use by deer sight be interpreted I an that it is uncommon or unpalatable, but neither is the case. I . .ecies is moderatoly common in the areas wh .e winter stomachs were collected and had been browsed hoavily by deer. Although it i6 one of I vored deer foods, the available supply was small and was removed early in the p, before the stomachs representing this study were collected. Species of the rose family (Rosaceae) rere found la 27 perc< of the fall and 4 percent of the winter stomachs and formed 3 pe: by volume of the former and less than 1 percent of the latter. The family was represented by raspberry, cherry, strawberry, rose, and spiraea. Club mosses, lichens, and fungi combined were found in 35 percent of the fall stomachs and represented 2.2 percent of the volume eaten. In the winter series one occurrence of lichen represents this gre . Grasses (G-ramineae) appeared in 27 percent of the fall and 23 perce I of the wir.tor stomachs and formed 2 percent of the volume in each seri<. . Sedges (Cypcraceae) were found in only ono fall stomach. All the foods found in the examined stomachs (including eaten la too small a quantity to form 1 percent by volume) are listed in table 1. Some of the stomach contents were too finely masticated for positive identification, and these were divided into two groups: Items that could be identified only as seed plants (angiosporms) , which formed 10.7 percent of the fall and 3.5 percent of the winter food, and other unidentified items, which formed 3 percent of the winter food. FIELD QBSEWAIIOHS 1/ . feeding experiments in Michigan showed that white codar is the only native browse that fed alone will support deer in winter. To supply I required nutrients, all other browse species had to be fed in larger quanti- ties and in combination with cedar or with a variety of other plants. The results of the experiments emphasize the difficulties faced by deer la winter. only is food in general more scarce at that season, but with most of the white cedar gone, other foods must be found in greater quantit; . Reduction in the variety of food available in winter is indicated, as shown in table 1, by the contents of the deer stomachs on vrhich thll study is based. Necessarily, therefore, the deer had to eat larger quanti- ties c species available at that time, and if the nutritional value of Be foods was less, the quantity needed to sustain life might be greatly 4/ See footnote 3, page 2. - 4 - increased. The problem of supplying adequate winter "browse for large deer herds is no easy one. For example, if conditions for white cedar, one of the "best deer foods, are to he improved, depleted stands could he fenced off for its protection, hut the cost might he prohibitive. If white cedar cannot he reproduced or grown in the wintering areas, the number of deer would have to he reduced. The results of a survey made by the United States Forest Service , of the available brcrasein 19 deeryards in the Superior National Forest—' are an aid in interpreting the findings in the present study. Data obtain- ed in that survey as to availability of the most common browse species, ex- pressed in percentage of total pounds of browse available, is the basis of figure 3. To show the great difference? in browse conditions between various sections of the forest, two individual deeryards also arc compared. Olson's figures, as well as the senior author's observations, show that balsam fir is abundant and available in most of the deeryards in the Superior Forest. In the Jonvick yard it is very abundant and of a size small enough to be available, while in the Temperance yard the trees are larger and not so much browse is within reach of the deer. Spruce is an important cover species over most of the Superior Forest and is largely available for browsing, but in the Jonvick and Temperance yards the trees are of value chiefly for cover, as they are so tall and clean-boled as to supply little food. Field studies reveal that pine forms only a fraction of 1 percent of the available food and that it occurs mainly outside of the yarding areas. Pine formed no part of the food of the deer taken from the two yards individual- ly represented in the graph, but it did occur in stomachs of deer taken in areas where the animals yarded little or not at all. Some cedar is still available in most of the yards, but very little is within reach of the deer in the Jonvick and Temperance yards, although much of the yarding cover in both areas is composed of mature trees of this species. White cedar is reproducing but, being cropped by a herd of heavily concentrated animals, never gets above the snow line. Alder is abundant in most of the yards of the Superior Forest but is rarely found in the Jonvick area. This species is seldom eaten in fall and is broweed in winter only after other deer foods are exhausted. Most of the birch within the yards is of tree size, thus little is available to deer. On the uplands and old burns this species is often abundant, but in winter such areas are not frequented by the deer. Dwarf, yellow, and paper birches occur, but only the last is common enough in this area to be an important food. 5/ Olson, Herman F. , An Analysis and Interpretation of Deer Study Data on Superior National Forest, 1934-37, inclusive. Typed report dated October 15, 1937, filed in the office of the United States Forest Service, Duluth, Minn. - 5 - Aspen and willow seem to occupy areas that are better drai: ;e usually used by deer for yardt. : theast sota, •.rpon appears to be nore dominant in wet places than willow. Red-osier is tty * coomon dogwood species that i .ter browse. This shrub is abundant in small patches but rarely covers any exU I found '.There tho deer concontrato it is browsed heavily during the early wintor months. It suckers abundantly .as boon browBod so hoavily in the Jonvick yard that the annual gj is doclining t.\ Jicld observations have chow, that maple brash is among the more i:.-.purtant o: leer browse species in the Superior National J^res Alor*.- the northern shore of Lake Superior, the mountain maple A a; icatum ) is the most abundant form, while over the western two— 1 . rds of the forest the red maple (A. rubjum) is dominant. Both these species, ever, occur over the entire area. They areamong the first to browsed and are usually depleted earlier in the year. She mountain maple is commonly associated with white cedar, but the red maple grows on higher and better-drained soils. Figaro 3 shows the availability of maple as a browse species throughout the forest. It suckers profusely and even under • rcme browsing usually makes a good annual growth. The mountr.; lo i3 one of the principle trov/se species in the Jonvick yard, yet it was not :.d in any of the 15 winter stomachs from that area. Die ex. . -on is, as mentioned above, that all that was available was eaten earlier in tho yoar. The beaked hazelnut is well distributed throughout the Superior ".rest but usually occurs on upland areas and therefore; is not so common where the deer concentrate in winter. Cne exception, however, is the abundance of this species in the Temperance yard, ■ ferer.t from all others in the forest in that it comprises a hilly area or. both sides of the Temperance River and has a mature but thin stand of ::.ixed -iwoods, cedar, balsam fir, and spracc, and a luxuriant growth of brush. Because the annual output of twigs on the hazelnut La mall the plant grows largoly outside the yards, it is not of gr importance to deer in winter. fountain- ash ( So rbu s americana ) is a splendid deer food but, as indicated in figure 3, is not readily available. Two distinct groups of La plant are in the area: ( l) Those above the reach of deer; and (2) those that never get above tho snow line because of browsing. On sc of the so th< had oaten twigs up to three- eighths of on La diameter. Sed elderberry ( Sambucus racemosa ) is a choice deer food but is not available in sufficient quantity to be of much value in wi .:• :-. In the 19 deeryards studied on the Superior National Forest, the • lowing plants were available in quantities too small to be considered ^rtant as potential winter doer foods: Tamarack , b imblc- ■ black ash, jack pine, pin ch<. and jur.cberry. _ ,- _ SURVEY OF THE JONVIGK YARD To learn which of the available species were "being eaten, a browse- utilization survey was made in the Jonvick yard early in May 1936. This was done after the yarding' season, so it represents the Drowse eaten through- out the winter period. One hundred and twenty plots, each 0.01 acre in size, were surveyed for the species present and for degree of browsing. These were located on lines at 5-chain intervals so that no element of human choice affected their selection. Availability in each case wa3 considered to "be any succulent twigs of hardwoods or leafy parts of conifers that were within 7 feet of the ground. Grasses, sedges, and ground forms were not recorded, "because they were usually too far beneath the snow during the yarding season to "be important to deer. The results of this survey, shown in table 2, indicate clearly the species that are important as food in this yard. Mountain maple, "because of its abundance and heavy utilization by deer, was the most important browse species present. Thimbleberry and honeysuckle showed a high frequency of browsing but these species are more available after the snow begins to recede in spring. Because only the terminal buds of the thimbleberry and a small part of the annual growth of the honeysuckle were eaten, the actual quantity of food obtained from these species was rather small, but it was available in time of need. Paper birch, red-osier dogwood, mountain-ash, and black ash were heavily browsed, but their availability was so low that they are of little importance to deer in this yard. Balsam fir was found in a large percentage of the plots, and many of the trees had been browsed lightly. The aggregate feeding in so many places, however, makes balsam one of the dominant foods. Although white cedar was found on 32 percent of the plots, in each it was represented by only a few limbs that deer could reach from cmstcd snow or by recumbent branches that were available only after the snov? had receded. The browsing was therefore very light and actually provided very little food. CONCLUSIONS 1. Stomach analyses and available-browse surveys indicate that the winter carrying capacity for deer in northeastern Minnesota is declining. 2. The browse species that form the greater part of the winter food are those now most available but not those of greatest nutritive value. 3. Many of the choice browse species are either uncommon or are becoming unavailable because of heavy browsing in previous years. - 7 - 4. Balsam be good deer browse when eaten in i. ooabinatioi • • _ _ foods it is ing the doer in eood health. les y 'dc locally lant b. not gi • Loa in avail f ccr* _pecies i: I deer concentration grounds indicates u-s 'or li- areas. -^ 1« — lint of food i tir.s f o..rd in 72 r t !'-'■. r collected in northr-astc-m ccta in fall and late in winter Food items Tall st-rachs — 1 Gcc pccur- rences ! Parts eaten 'rences Parts eaten Alder ( All , ) .pulus trearaloider. / . 3asswood ( Tilia a^oricana) . Birchj undet. ( Be- tula sp.). oer W 11 2 1 Birch family (3otulaccae x . . Birch, paper ( Be tula paoyri - f era ) . "■'•' i Corais cana- densis . Cedar, white ( Lhuja occi - ::talis ) . ", pin ( Prunus penn-yl - . Cherry, wild ( Prar.-s sp.) . . Clover ( Tri folium sp.). . . . posito family (Compoeitae) 3d ( Cornus cp. ) . American '" ican.- ' . jam ( Ab x lsamca ) . gvie (shelf • rod ( Solidaro sp . ) . . . : Vitis sp.) . .' . . . . Grapefern C Botryc ... . ' . . -neae; ~ro:.>. dium c_ - tn Q o o u. cr UJ UJ 5 si 82 © (A tn 43 0) t-i iH PRINCIPAL DEER FOODS FALL FOODS LATE WINTER FOODS C 10 20 30 40 50 60 7 8 ( BA ) 10 20 30 40 50 60 70 8 BALSAM FIR LSAM FIR p« pj jgyv/fy Pll SP ^^^^^^^^^^^^^^ PU JE ^E^^^^^^^l \s M F"J RUCE "© $yyy//A SP ruce! ^■.J "© H -® WHITE CEDAR WH^ECEDAR . 1 m Vz/ftw BIF CH F/> MILY BIRCH^MILY ■ H FAMILY 1^ -© Wl _LOW WILU3WFAMILY fr 7 J ^^^^^^%^^l J — ■0 GR ASS FAMILY GRASS FAMILY 14© | Va -® HEATH FAMILY HE^>^MILY F -© I -® HONE n JCKLE 1 TRACE FAMI _Y HC )NE E :ys I JCKLE "© FAMI LY DOGWOOD DOGWOOD ■1 "© -® Ltz TRACE < ) 10 20 30 40 5 60 70 8 D 10 20 30 40 50 60 70 E 1 Percentage of stomachs i n which found 7// / Percentage (by volume) of total food FIGTO2 2. — Principal foods eaten by white- tailed deer in northeastern Minnesota, 1936-37. AVAILABLE DEER BROWSE BALSAM MAPLE HAZELNUT MOUNTAIN ASH ® 7TT ELDERBERRY © Average of 19 deer yards. Jonvick deer yard. Temperance deer yard. 12 14 16 20 FIGURE Z. — Quantity of certain kinds of browse (expressed in percentage of total weight poands) available to deer in the Superior National Forest, 1934-37.