habitat suitability index models: eastern wild turkey - USGS National ...

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(Christisen and Korschgen 1955). Mast failures in Georgia and Alabama did not affect turkey survival due to the general availability of alternate food sources (Markley 1967). Turkeys in Louisiana had high population densities in some habitats where oaks were scarce (Dickson et al. 1978). Turkeys in this area obtained green forage from winter crops or from areas that were burned in the winter, as well as mast from species other than oaks. Grass leaves and seeds are important foods and are consumed most frequently duri ng wi nter and spri ng (Korschgen 1967). Turkeys in Mi ssouri used a wide variety of foods; optimum management practices provide for establishing and maintaining diversified habitats within their annual range (Korschgen 1973). Food produced in forest openi ngs and open woodl ands was used extensively by turkeys. Flowering dogwood (Cornus florida), black gum (Nyssa syl vati ca), wil d cherry (Prunus serotina), hackberry (Celtis oCCTdentalis), and similar trees add diversity to the food supply and improve turkey habitat. Food was not believed to be a limiting factor for turkeys in West Virginia (Bailey and Rinnell 1968) or in the Georgia and Alabama portion of their range (Mark"ley 1967). However, Davis (1976) noted that food can be a limiting factor in areas with 1arge pure stands of pi ne (Pi nus spp.). I n an Alabama study area dominated by young pine plantations, food was provided primarily by other forest types (Kennamer et al. 1980). Food also may be lacking during winters in the upper Mississippi Valley portion of the wild turkey's range (Porter et al. 1980). Home range size and habitat use are influenced by the available food resources, with winter food needs exerting the greatest impact (Lewis and Kurzejeski 1984). The food habits of eastern wild turkeys vary throughout the year (Bailey and Rinnell 1968). Fruits of virtually all plant species are taken in season. Spring foods in Missouri were. obtained from the following plant types (percentages are volume measurements): trees (mostly oaks), 53.6%; farm crops, 16.6%; forbs, 13.4%; native grasses, 3.9%; shrubs, 3.7%; sedges (Carex spp.), 3.1%; and vines, 0.8% (Korschgen 1973). Animal foods and plant galls provi ded the remainder of the spri ng foods. Green herbaceous growth from wheat (Triticum aestivum), rye (Secale cereale), and alfalfa (Medicago sativa) was an important spring food source in another Missouri study (Ellis and Lewis 1967). In West Virginia, grass is important all year, but especially in early spring when turkeys apparently subsist on it (Bailey and Rinnell 1968). Wheat, rye, and other similar green vegetation provides important turkey forage in late winter and early spring (Hurst, unpubl.). Insects are important summer foods for young turkey poults (Bailey and Rinnell 1968; Hurst and Stringer 1975). In Mississippi, poults 3 to 7 days old consumed 79% animal food and 21% plant food (Hurst and Stringer 1975). The percentage of animal foods consumed declined steadily as poults got older, and animal foods accounted for only 13% of the diet at 22 to 38 days of age. Insects made up over 80% of the animal foods consumed. Summer foods of juvenile turkeys in Alabama included 61.5% grasses (mostly seeds) and 15.5% grasshoppers (Orthoptera), by volume (Hamri ck and Davi s 1972). Animal foods were more abundant in forest openings and other areas with abundant herbaceous growth, than in forested habi tats (Bl ackburn et a 1. 1975; Hurst and Stri nger 1975; Martin and McGinnes 1975). Forest clearings in Virginia contained 25 2
times more insects than were present under the forest canopy, and turkey poults needed less time in clearings than in forests to obtain the same quantity of insects (Martin and McGinnes 1975). Alfalfa fields provided important feeding habitat in Minnesota during the spring and summer (Porter 1978). Important fall foods of the wild turkey include crabgrass (Digitaria sanguinalis), acorns, grass and sedge leaves, tick-trefoil (Desmodium spp.), and beechnuts (Fagus grandifolia) (Korschgen 1967). Turkeys in Alabama fed in more open fi e1ds and pastures in the fall, and shi fted to forested habi tats that supplied acorns and other mast as food became less plentiful towards winter (Barwick and Speake 1973). Fall range in the mountains of the Southeast consisted of mast producing hardwood forests (Healy 1981). The value of the range increased as both the proportion of hardwood forest and the percent in mast production increased. Trees that may provide fall and winter foods for the eastern wild turkey include oaks, dogwoods, beech, gums, ash (Fraxinus spp.), pecans and hickories (Carya spp.), pines, cherries, sumacs (Rhus spp.), and hawthorn (Crataegus spp.) (Korschgen 1967). ---- Early winter foods in Virginia included grapes (Vitis spp.), acorns, corn (Zea mays), dogwood fruits, grass blades, and ash seeds (Martin et al. 1939). Frui t i ng shrubs provi ded over 10% of the wi nter di et of the eastern wi 1d turkey (Korschgen 1967). Waste grain was an important winter food in Missouri (Ellis and Lewis 1967). Turkeys in the Upper Missouri Valley made extensive use of corn fields located adjacent to hardwood stands (Porter et al. 1980). Areas 1acki ng corn experi enced a 60% loss of turkeys duri ng severe wi nters, whereas those with available corn had losses of less than 15%. Corn, oats (Avena sativa), and wheat are the primary cultivated grains consumed by turkeys (Korschgen 1967). Corn is highly digestible, whereas oats are less digestible by wild turkeys (Glover and Bailey 1949). Soybeans (Glycine max) are a highly preferred food in Missouri (J. B. Lewis, Missouri Departmentof Conservation, Columbia; letter dated November 8, 1984). Croplands played a major role in maintaining turkey populations in northern Missouri (Lewis and Kurzejeski 1984). Cropfields without adjacent stands of mature timber were seldom used. Furthermore, regardless of the amount of adjacent mature timber, croplands were used much less when acorns were abundant. Thi s suggests that crops may be a secondary food source. Wi nteri ng turkeys in Mi nnesota fed on ei ther acorns in hardwood forests or corn dependi ng on the abundance of these two major food resources (Porter 1978). Hardwood habitats were important, but agricultural areas provided the reliable and abundant food supplies needed to maintain turkey populations. Turkeys also eat tubers, bulbs, rhizomes, earthworms, millipedes, spiders, snails, and salamanders hidden within and below the layer of leaves and organic matter on the ground (Bailey and Rinnell 1968). These food items are available year round, except during periods of deep snow or frozen ground. Water Water is an essential factor in good turkey range. Turkeys in the eastern United States can easily obtain water year-round from streams, ponds, seeps, 3
Page 1 and 2: BIOLOGICAL REPORT 82(10.106) AUGUST
Page 3 and 4: MODEL EVALUATION FORM Habitat model
Page 5 and 6: Biological Report 82(10.106) August
Page 7: PREFACE This document is part of th
Page 10 and 11: ACKNOWLEDGMENTS William M. Healy, G
Page 14 and 15: or depressions in the ground (Korsc
Page 16 and 17: Striped skunks (Mephitis mephitis),
Page 18 and 19: Iowa has reintroduced turkeys into
Page 20 and 21: Cover types. This model was develop
Page 22 and 23: ..--l Fig. 1a 1.0 1.0 ::::- ::::- .
Page 24 and 25: The amount of acorn mast produced i
Page 26 and 27: Fig. 3a Fig. 3b 1.0 1.0 \D r-, :::-
Page 28 and 29: in the fall, but plowed in the spri
Page 30 and 31: Figure 5. The relationships between
Page 32 and 33: 0.2 a Fig. 6a 1. a -+---...........
Page 34 and 35: Habitat variable Li fe regu isite C
Page 36 and 37: Variable (definition) Percent canop
Page 38 and 39: SOURCES OF OTHER MODELS Williamson
Page 40 and 41: Hamrick, W. J., and J. R. Davis. 19
Page 42 and 43: Pack. J. C., R. P. Burkert. W. K. I
Page 44 and 45: 502n·101 REPORT DOCUMENTATION 11.
Page 46: DEPARTMENT OF THE INTERIOR u.s. FIS

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