Frederick A. Servello

Energy Intake Relationships for White-Tailed Deer on Winter Browse Diets

Food intake by white-tailed deer (Odocoileus virginianus) is affected by digestibility, but this relationship has not been well quantified for natural winter diets. We studied relationships between digestible energy (DE) content of winter diets and intake of food and DE by white-tailed deer in Maine. We fed 8 winter browse diets varying in DE content and 1 pelleted commercial diet to 9 captive fawns in 4 sets of digestion trials. Digestible energy content of browse diets ranged from 1.95 to 2.39 kcal/g. Dry matter intake (g/kg 0.75 /day) and DE intake (kcal/kg 0.75 /day) were positively and linearly related to dietary DE (r 2 = 0.75-0.82, P ≤ 0.01). Daily DE intake (DEI) of browse diets by deer provided 30-88% of maintenance requirements. When dietary DE was 2.2 kcal/g, the reported minimum DE value at which deer can regulate intake at maintenance requirements (Ammann et al. 1973), DEI of fawns in the present study was only 63% of maintenance. The 2.2 kcal/g threshold, commonly considered a minimum requirement for dietary DE, appears inadequate for maintenance on winter browse diets. We estimated that fawns on diets composed of >70% hardwood browses would lose ≥30% body mass. Therefore, more digestible foods such as northern white cedar (Thuja occidentalis), lichen (Usnea spp.), and possibly litterfall (deciduous leaves and conifer shoots) may be important winter forages

Litterfall : an overlooked food source for wintering white-tailed deer

Litterfall in mature forest stands may be a significant food resource for white-tailed deer (Odocoileus virginianus) wintering in northern regions, but has received little study. To determine forage production, we measured biomass of litterfall in unharvested stands of 3 wintering areas, and biomass of browse from deciduous trees and shrubs in unharvested stands and harvested patches of the same wintering areas during January-March 1994. Mean biomass of northern white-cedar (Thuja occidentalis), eastern hemlock (Tsuga canadensis), arboreal lichens (Usnea spp. and Evernia spp.), and hardwood leaves in unharvested stands was 18.4 kg/ha (SE = 4.80). At mean digestible energy (DE) levels of 1.5 and 1.7 kcal/g dry matter (DM), biomass of hardwood browse and litter biomass did not differ (P > 0.15) between harvested patches and unharvested stands. At greater mean levels of digestible energy (1.9 and 2.1 kcal/g DM), biomass was greater (P < 0.05) in unharvested stands than harvested patches because of the relatively high DE content of litterfall. We concluded that litterfall in unharvested stands was high relative to the availability of more commonly measured browses (e.g., understory trees and shrubs), and may be more palatable and of greater nutritional value. However, availability of hardwood browse during winter may be more predictable than litterfall.

Investigating the mechanism for maintaining eucalcemia despite immobility and anuria in the hibernating American black bear (Ursus americanus)

Ursine hibernation uniquely combines prolonged skeletal unloading, anuria, pregnancy, lactation, protein recycling, and lipolysis. This study presents a radiographic and biochemical picture of bone metabolism in free-ranging, female American black bears (Ursus americanus) that were active (spring bears and autumn bears) or hibernating (hibernating bears). Hibernating bears included lactating and non-lactating individuals. We measured serum calcium, albumin, inorganic phosphate, creatinine, bone specific alkaline phosphatase (BSALP), CTX, parathyroid hormone, insulin-like growth factor-I (IGF-l), leptin, 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)(2)D] and sclerostin from 35 to 50 tranquilized hibernating bears and 14 to 35 tranquilized spring bears. We compared metacarpal cortical indices (MCI), measured by digital X-ray radiogrammetry, from 60 hunter-killed autumn bears and 79 tranquilized, hibernating bears. MCI was greater in autumn than winter in younger bears, but showed no seasonal difference in older bears. During hibernation eucalcemia was maintained, BSALP was suppressed, and CTX was in the range expected for anuria. During hibernation 1,25(OH)(2)D was produced despite anuria. 1,25(OH)(2)D and IGF-I were less in hibernating than spring bears. In a quarter of hibernating bears, sclerostin was elevated. Leptin was greater in hibernating than spring bears. In hibernating bears, leptin correlated positively with BSALP in non-lactating bears and with CTX in lactating bears. Taken together the biochemical and radiographic findings indicate that during hibernation, bone turnover was persistent, balanced, and suppressed; bone resorption was lower than expected for an unloaded skeleton; and there was no unloading-induced bone loss. The skeleton appears to perceive that it was loaded when it was actually unloaded during hibernation. However, at the level of sclerostin, the skeleton recognized that it was unloaded. During hibernation leptin appeared anabolic in non-lactating bears and catabolic in lactating bears. We hypothesize that ursine hibernation may represent a natural model in which suppression of the sympathetic nervous system prevents unloading-induced bone loss by influencing leptins skeletal effects and preventing transmission of loading information.

Winter Foraging Ecology of Moose on Glyphosate-Treated Clearcuts in Maine

The herbicide glyphosate is widely used in northern coniferous forests of the United States and Canada to promote conifer dominance on clearcut sites by suppressing regeneration of deciduous species. We determined effects of glyphosate treatment of regenerating clearcuts on (1) browse availability (total biomass, by species, and proportion with high digestible energy [DE] content), (2) browse use, and (3) diet quality of moose (Alces alces) in winter in Maine during 2 periods: 1-2 and 7-11 years posttreatment. We measured browse availability and use and collected browse samples for nutritional analyses on 12 clearcuts in January-March 1991 before aerial treatment with glyphosate of 6 of these clearcuts in August 1991. We conducted posttreatment sampling of treated and untreated clearcuts during January-March 1992 and 1993. We also sampled 14 clearcuts that had been treated with glyphosate 7-11 years earlier and 5 untreated clearcuts of similar age in January-March 1992 or 1993. Available biomass (kg/ha) of deciduous browse decreased (P = 0.001) 70% on treated clearcuts relative to untreated clearcuts from pretreatment to year 2, but was not affected (P = 0.29) at 7-11 years posttreatment. Available browse from red maple (Acer rubrum) and paper birch (Betula papyrifera) appeared to decrease less than pin cherry (Prunus pensylvanica) in years 1-2 suggesting that species composition on sites may influence the magnitude of effects on total browse availability. The proportion of deciduous browse biomass with a relatively high DE content (1.8 kcal/g) was not affected (P = 0.37) by treatment at 1-2 years, but was greater (P = 0.047) on treated than untreated clearcuts at 7-11 years posttreatment. Biomass and percent of available deciduous browse eaten by moose were not affected (P > 0.1) by glyphosate in years 1-2, but were 4-5 times greater (P 0.1) by treatment in either time period. Initial reductions in browse availability may decrease the suitability of clearcuts for foraging by moose, but this effect would decrease over the next 5-9 years because browse availability decreases naturally on untreated sites. We concluded that glyphosate did not have important effects on diet quality. Heavy browsing in older treated clearcuts suggests that moose may be attracted to these sites, but this behavior was not directly related to browse availability or nutrition. We discuss management options for minimizing effects of glyphosate treatment on moose habitat.

Winter use of glyphosate-treated clearcuts by moose in Maine

Aerial treatment of naturally regenerating clearcuts with the herbicide glyphosate initially reduces the availability of deciduous browse, but may subsequently improve bedding cover for moose (Alces alces). However, the potential effects of these vegetative changes on use of clearcuts by moose has received little study. We studied effects of glyphosate treatment of clearcuts in Maine on (1) use of clearcuts by moose and (2) conifer cover during 2 periods, 1-2 and 7-11 years posttreatment. We made counts of moose tracks, beds, and pellet groups on transects in treated and untreated clearcuts in January-March 1992 and 1993 and measured conifer densities in January-March 1991-93. At 1 and 2 years posttreatment, tracks of foraging moose were 57 and 75% less abundant on treated than untreated clearcuts (P = 0.013). Counts of moose beds, total tracks, and pellet groups exhibited similar patterns as tracks of foraging moose but did not differ (P > 0.1) between treatments. At 7-11 years posttreatment, tracks of foraging moose (P = 0.05) and moose beds (P = 0.06) were greater on treated than untreated clearcuts. Conifer densities at 1-2 years posttreatment were not affected (P > 0.1) by treatment, but conifers 2.0-2.9 m tall were 2 times more abundant (P < 0.1) on treated than untreated clearcuts at 7-11 years posttreatment. Less foraging activity at 1-2 years posttreatment appeared to be the result of reduced browse availability because conifer cover for bedding was similar on treated and untreated clearcuts. We hypothesized that greater counts of tracks of foraging moose on older treated clearcuts was due to increased foraging activity on sites with more abundant conifer cover.

Predicting metabolizable energy in the diet of ruffed grouse

The percent metabolizable energy (ME) in 13 of 14 diets fed to captive ruffed grouse (Bonasa umbellus) in metabolism trials was highly related (P = 0.0001, R2 = 0.88) to the percent neutral detergent solubles (NDS) minus total phenol content of the diets. A regression equation based on these data provided good prediction of the ME of 8 diets fed to grouse in a 2nd set of metabolism trials. The ME of diets containing acorn meat was underestimated by the prediction equation; therefore, a multiple regression equation based on NDS minus phenols and percent acorn meat was developed to predict the ME of diets containing acorn meat. The effects of storage and drying treatments of forages on measured NDS, total phenols, and predicted ME levels were determined. Oven-drying fresh, leafy forages and oven-drying after frozen storage consistently resulted in lower levels of NDS and total phenols than freeze-drying fresh forages. Effects on predicted ME were small because changes in NDS and total phenol levels are offsetting to a large extent in the prediction equation. J. WILDL. MANAGE. 51(3):560-567 Ruffed grouse food habits are well documented (Brown 1946, Bump et al. 1947, Korschgen 1966, Phillips 1967, Woehr and Chambers 1975, Stafford and Dimmick 1979, Seehorn et al. 1981), but relationships between food habits and diet quality are largely unknown. Little information is available on the ME of grouse forages or diets. This is due in part to a lack of accurate and efficient methods for measuring the ME in the natural diet of ruffed grouse. Studying all forages individually in conventional metabolism trials is impractical because of the varied diet of grouse. In addition, 1-time measurements of ME from metabolism trials does not account for variation among seasons, years, or locations. Predicting the ME of forages of ruffed grouse from forage chemical composition is a promising alternative method because large numbers of forages could be studied much more efficiently and crop contents could be chemically analyzed, thereby eliminating the bias between hand-picked forages and forages selected by wild birds. The Van Soest method of forage chemical analysis (Goering and Van Soest 1970) has proven to be reliable for predicting forage digestion in both ruminant and monogastric mammals (Van Soest 1967, Mould and Robbins 1982, Servello et al. 1983, MacPherson et al. 1985) and may be useful for avian species also. However, high levels of phenolic compounds in forages may complicate prediction of forage digestion when using the Van Soest analysis. Phenols are extracted as part of the theoretically highly digestible neutral detergent soluble fraction; i.e., primarily soluble carbohydrate, protein, and fat. However, they have little or no nutritional value and also may interfere with digestion and absorption (McLeod 1974; Mould and Robbins 1981a,b, 1982). Also, storage and drying treatments can influence measured chemical constituents of forages, especially highly reactive phenols (Mould and Robbins 1981a). The objectives of the present study were: (1) to determine the relationship between forage chemical composition (as measured by the Van Soest method) and forage ME for ruffed grouse, (2) to develop a predictive equation for estimating ME based upon this relationship, (3) to determine the influence of phenolic compounds on prediction of forage ME, and (4) to determine the effects of a number of commonly used storage and drying treatments on NDS and phenol levels and therefore on prediction of forage ME. We thank W. B. Morehead, S. L. MacPherson, and K. B. Preli for assistance with metabolism trials and laboratory analyses. This research was supported in part by the Natl. Rifle Assoc. and the Dep. Fish. and Wildl. Sci., Virginia Polytechnic Inst. and State Univ. The senior author was supported by a John Lee Pratt Anim. Nutr. Fellowship.

Nest survival of wild turkeys Meleagris gallopavo silvestris in a mixed-use landscape: influences at nest-site and patch scales

Nest survival is a critical factor affecting avian demographics, and can be influenced by nesting chronology, fine scale nest-site selection and broad-scale landscape characteristics. We modeled the relative influences of nest age, temporal variation in nest success and habitat-related covariates at two spatial scales (nest-site and patch scale) on daily nest survival during incubation for eastern wild turkeys Meleagris gallopavo silvestris in a mixed-use landscape. Daily survival rate of turkey nests during incubation increased as percent understory cover (vegetation < 1 m tall) increased and decreased with increasing density of woody shrubs and saplings and herbaceous stems < 1 m tall (understory vegetation density) around the nest. We suggest that nest survival may be dependent on a balance of sufficient understory cover around nests to provide concealment for hens and nests, but with understory vegetation density below levels that reduce the hens ability to detect a predator or to escape after detecting a potential threat. The balance between sufficient understory cover and limited density of understory vegetation occurred where understory (< 1 m tall) cover exceeded 50% and understory vegetation density was < 25 stems/m2. Models that included variables related to the patch scale (e.g. fragmentation, edge and dominant land-cover class in a patch) did not receive strong support, demonstrating the relative importance of finer scale nest-site variables over patch-scale variables in determining survival of wild turkey nests in our highly variable mixed-use landscape.

Evaluation of urinary indices of nutritional status for white-tailed deer : Tests with winter browse diets

Urea nitrogen:creatinine (U:C) and potassium:creatinine (K:C) ratios in nrine are used to assess nutritional status of white-tailed deer (Odocoileus virginianus) and other ungulates in winter. We evalnated the ratio of glucuronic acid:creatinine (G:C) in urine as a new index of diet quality and composition, and determined the effects of natural diets and food intake on G:C. U:C, and K:C ratios in winter. Glucitronic acid excretion reflects intake of plant secondary compounds and use of low-quality browse because conjugation with glucaronic acid is a major pathway of excretion of secondary compounnds. We fed a 100% deciduous browse diet and 3 diets each composed of 45% of the decidnons diet and 55% of 1 of 3 conifer browses (northern white tedar [Thuja occideutalis], castern hemlock [Tsuga canadensis], balsam fir [Abies balsamea]) to 6-7 fawus per diet in feeding trials in 1996 and collected nrine for analyses. We also analyzed urine samples from a similar set of trials in which 8 diets composed of varying proportions of decidnous browse, northern white cedar, and a small amount of lichen (Usitea spp.) were fed to deer in 1991. For the 1996 and 1991 trials, there were positive relationships (r 2 = 0.37-0.56) between G:C ratio and food intake for the pooled browse diets, Except for the 100% deciduous diet, there was a strong positive relationship (r 2 = 0.79) between G:C ratio and intake for each mixed diet in the 1996 trials. In the 1996 trials, deer fed the 55% balsam fir diet had a 2.9 times greater G:C ratio than all other diet groups, and the deciduous diet resulted in the lowest mean value. In the 1991 trials, deer fed diets with ≥55% northern white cedar had 1.7-3.2 times greater G:C ratio than those on thets with 5% or 30% northern white cedar. Urinary G:C ratio has potential as an indey of the proportion of deciduons and conifer browse in winter diets and as an index of the use of balsam fir Only deer with a high intake of balsam fir had G:C values >6. We found no evidence that U:C ratio was influenced by short-term ration in diet composition or food intake. We found high variability in the relationship of K:C ratio to food intake with winter browse diets, and we suggest cantion in using this index in field studies.

Fat indices for ruffed grouse

Percent wing fat (WF), gizzard fat weight (GFW), and body weight (BW) were tested as indices of percent carcass fat (CF) and a lipid index (LI) in ruffed grouse (Bonasa umbellus). Gizzard fat weight was related (P < 0.0001) to the natural log of both CF and LI. Prediction equations were developed for estimating CF and LI from GFW. These relationships were not affected by sex or season of collection. Fat content of the distal half of the wing was correlated (P < 0.05) with CF and LI, but relationships differed (P < 0.05) by sex in the spring. Correlation coefficients for the fall season were low (r = 0.55-0.58). Relationships between BW and CF were not consistent for sexes or seasons. Percent carcass fat and LI of 118 ruffed grouse collected in North Carolina during the fall and winter were predicted from GFW. Percent carcass fat and LI were greater (P = 0.036) in females than males and tended to be greatest for both sexes in December. J. WILDL. MANAGE. 51(1):173-177 Norman and Kirkpatrick (1981) reported that wing fat was correlated with CF in ruffed grouse collected in Virginia. However, correlations were weaker in the spring and summer than in the fall and winter, indicating potential problems with the technique. An advantage of using WF as an index of condition is that wings can be easily collected from hunters for analysis. Weight of the fat attached to the gizzard of ruffed grouse also may be a useful index of CF. Abdominal or visceral fat deposits were strongly correlated with body fat (BF) in waterfowl (Woodall 1978, Bailey 1979, Chappell and Titman 1983, Thomas et al. 1983). Dowell and Warren (1982) used GFW as a nutritional index for ring-necked pheasants (Phasianus colchicus). Gizzards and attached fat of ruffed grouse also could be obtained from hunters. The objectives of the present study were to: (1) determine the reliability of WF, GF, and BW as indices of CF in ruffed grouse and (2) estimate the CF levels of ruffed grouse collected in North Carolina during fall and winter. This research was supported by the John Lee Pratt Anim. Nutr. Fellowship Prog. at Virginia Polytechnic Inst. and State Univ. (VPI&SU), the Dep. Fish. and Wildl. Sci. at VPI&SU, and the Natl. Rifle Assoc. Grants-In-Aid Prog. D. Beck coordinated collections of ruffed grouse gizzards in N.C. S. L. MacPherson and W. Morehead assisted in the laboratory. P. F. Scanlon, J. D. Fraser, M. R. Vaughan, and K. E. Webb, Jr. reviewed drafts of the manuscript. METHODS Sixty-two ruffed grouse were collected in southwestern Virginia during March and April 1982-84. Twenty additional grouse were collected between 1 November and 1 January from 1981 to 1984 in Virginia (N = 8) and New York (N = 12). Whole body weights were measured after removing crop contents. Grouse were completely plucked, and lower legs were removed at the tibio-tarsus-tarsometatarsus junction. Reproductive and digestive tracts were removed, but mesentery fat was stripped from the organs and replaced in the body cavity. Gizzard Fat Weight and Index Fat adhering to the gizzard was weighed after lightly blotting surface moisture, and the fat was returned to the body cavity. The empty gizzard was weighed, and a gizzard fat index (GFI) was calculated by dividing the weight of the fat attached to the gizzard by the gizzard weight.

Patterns in winter nutritional status of white-tailed deer Odocoileus virginianus populations in Maine, USA

We used urinary indices to determine temporal and regional patterns in nutritional status of white-tailed deer Odocoileus virginianus in nine wintering areas in northern and central Maine, USA. Winter severity was greater in the northern region, and we expected deer in that region to exhibit greater evidence for nutritional restriction. We collected an average of 26 urine samples from snow on a biweekly basis during 1 January- 31 March 1993 in each wintering area and analyzed them for ratios of urea nitrogen (N):creatinine (C), an index of nutritional status, and potassium (K):creatinine (C), an index of forage intake. Mean urea N:C ratios increased to 3.0 and 3.3 during March in northern and central Maine, respectively, suggesting that nutritional status of deer in these populations was poor. There were no differences in ratios of urea N:C between regions within time periods, except for late March when urea N:C ratios were greater in the central region. The proportions of deer exhibiting severe nutritional restriction (urea N:C ≥3.5) were greatest in March in both regions (0.16–0.31); however, proportions were highly variable among populations (range: 0–0.44). K:C ratios decreased during winter, but did not differ among regions. Our results indicate that urinary indices of free-ranging deer populations in wintering areas vary greatly, and we contend that high variability among populations is an important consideration for designing future deer research.