RATES OF GROWTH AND MORPHOLOGICAL DIMENSIONS OF
BOTTLE-RAISED PRONGHORNS
STACIA K. MARTIN AND KATHERINE L. PARKER
Department of Zoology and Physiology, P.O. Box 3166,
University of Wyoming, Laramie, WY 82071-3166
Present address of KLP: Faculty of Natural Resources and Environmental Studies,
University of Northern British Columbia, 3333 University Way,
Prince George, British Columbia, V2N 429 Canada
Effective hand-raising protocols for neonatal ungulates should strive to produce animals
that ,are physiologically similar to maternally raised conspecifics. Young pronghorns (Antilocapra americana) were sucessfully bottle-raised on a formula of three parts evaporated
milk and one part water for participation in physiological and behavioral research. Neonatal
growth was assessed by monitoring changes in body weight, length of leg and, surface area
of body. Body weights increased linearly with age to 16 weeks; growth rates (g/d) were
not significantly different from those of maternally raised young. Lengths of leg, which
affect the efficiency of locomotion and maximal running speed, and surface area of body,
which affects heat exchange with the environment, increased with increasing body weight.
Key words:
leg
Antilocapra americana, pronghorn, rate of growth, surface area, length of
The development of effective hand-raising protocols for neonatal ungulates is important for wildlife managers raising orphans and of concern to researchers requiring tractable study animals. The primary
goal of any hand-raising protocol is to minimize mortality and poor health, but researchers must also strive to produce animals that are physiologically similar to maternally raised conspecifics.
Successful feeding protocols have been
developed for several wild species of ungulates (mule deer, Odocoileus hemionusCarl and Robbins, 1988; porcupine caribou,
Rangifer tarandus granti-Parker, 1989;
black-tailed deer, Odocoileus hemionus columbianus-Parker and Wong, 1987; whitetailed deer, Odocoileus virginianus-Robbins and Moen, 1975; elk, CenJus elaphus
nelson-Robbins et aI., 1981). These protocols were based on a scientific understanding of the behavior and physiology associated with species-specific lactation.
Formulas of milk approximated the composition of maternal milk; frequencies and
iOllr/w/ of Mamma/og.\', 78(1):23-30, 1997
volumes of feedings mimicked natural patterns. Consequently, neonates that are
raised according to the protocols typically
grow at natural rates and suffer few or no
gastrointestinal disturbances.
Until recently, feeding regimes for
pronghorns (Antilocapra americana) have
used a trial':and-error approach, partially
because of a lack of knowledge regarding
the characteristics of lactation by pronghorns. Inherent to such an approach have
been frequent occurrences of gastrointestinal problems and diet-related deaths Einarsen, 1948; Schwartz et aI., 1976). Gastrointestinal distress was remedied by limiting
the volumes of milk given to neonates
(Brinkley, 1987). Success of these feeding
regimes was evaluated strictly on the basis
of survival to weaning. Chronic gastrointestinal disturbances and underfeeding,
however, likely depress growth rates and
may result in small, weak adults.
The demand for a simple feeding protocol led Wild et a1. (1994) to raise young
pronghorns on undiluted evaporated milk
23
24
JOURNAL OF MAMMALOGY
(commercially processed cow's milk reduced by evaporation to 50% of original
volume), fed ad lib., at the Colorado Division of Wildlife, Foothills Wildlife Research Facility (referred to as the Foothills
Facility). The efficacy of this easily administered protocol was assessed by comparing
the mean growth rate of bottle-raised fawns
to that of a maternally raised fawn. Because
the difference was not significant, and because only two of the 19 young had single
bouts of diarrhea (both mild cases), Wild et
a1. (1994) concluded that the practical protocol was acceptable. Young pronghorns at
the Foothills Facility currently are raised
according to that protocol. The success of
feeding ad lib. is unusual. Overeating, the
major cause of diet-related diarrhea in bottle-raised ungulates, generally is attributed
to the inability of the neonate to regulate
intake of milk (Robbins, 1993).
The primary objective of this study was
to raise young pronghorns suitable for participation in physiological and behavioral
research as adults. In the absence of published records of composition and intake of
milk by pronghorns raised by their mothers,
we adopted the feeding protocol of Wild et
al. (1994). However, because rigorous testing of the protocol was not a main objective, we were willing to modify the feeding
regime in response to any diet-related problems rather than compromise the health of
research animals. During the study, the volumes of milk initially fed to some of the
less tractable young were restricted to promote habituation to presence of humans.
Growth rates of this diet-curtailed group
were compared to those of a group of tamer
fawns. Changes in body weight and measurements of body surface also were compared to those in reports of maternally
raised and bottle-raised pronghorn and other species of ungulates.
MATERIALS AND METHODS
Twelve young pronghorns (2 males. 10 females) were bottle-raised during summer t 993
at the Sybille Wildlife Research and Conserva-
Vol. 78. No.1
tion Education Center (referred to as Sybille), a
facility of the Wyoming Game and Fish Department, located 72 km northeast of Laramie, Wyoming. Eight females were captured at 1-2 days
of age using hand-held circular nets, on 8-14
June 1993 at Warren Air Force Base near Cheyenne, Wyoming, and transported by crate to Sybille. Between I and 18 June, four unrelated orphaned young (two males, two females; aged 18 days) also were brought to Sybille. Animals
were cared for in accordance with the principles
of the Guide to the Care and Use of Experimental Animals (Canadian Council on Animal Care,
1984).
Young pronghorns initially were housed inside an unheated building. Groups of two to
three occupied small (2 by 2 m) plywood pens
with soil-covered concrete floors. Between 1 and
6 weeks of age, depending on health and disposition, young were moved to a larger (4 by 6
m) pen inside a barn, and had daily access to an
outdoor grass and alfalfa pasture. Fawns were
given water, alfalfa hay, Calf Manna (Pro-Manna, Denver, CO), and a mixture of corn, oats,
and barley (3-Way; Wheatland Co-op Association, Wheatland, WY) ad lib. Fresh cuttings of
antelope bitterbrush (Purshia tridenrata) were
provided each week.
Warmed milk was fed from 240-ml plastic
baby bottles, with nipple openings slightly enlarged to increase flow of milk. Once a fawn
learned to nurse from a bottle (1-2 days), it was
no longer necessary for feeders to approach the
fawn or to restrain it for feeding. Instead, pronghorns were trained to initiate feedings. A feeder
encouraged a fawn to approach by using vocalizations and extending the bottle. If the animal
refused to approach within 15 min, the feeder
did not offer the bottle again until the next
scheduled feeding time. Only after several consecutive failed feeding attempts would the handler resort to restraining a fawn to feed it. Seven
young continued to require persistent persuasion
until they were several weeks old and are referred to as the diet-curtailed group; the other
five immediately accepted a bottle upon presentation and are referred to as the tame group in
our analyses.
The first young pronghorn to arrive at Sybille
was given unlimited quantities of undiluted
evaporated milk five times daily (using the protocol from the Foothills Facility) and developed
severe diet-induced diarrhea. At 3 days of age
February 1997
MARTIN AND PARKER-GROWTH OF BOTTLE-RAISED PRONGHORNS
(the 3rd day in captivity), its daily volume of
milk was 616 ml, an amount equivalent to that
consumed by pronghorns older than 4 weeks at
the Foothills Facility. To accommodate this apparent inability to appropriately regulate intake
of milk, we modified the feeding regime by using a more dilute formula (three parts evaporated milk to one part water); we also restricted
volumes of milk to those that approximated natural patterns of intake of milk by cervids (Parker
and Wong, 1987) because there were no published quantifications of intake of milk by maternally raised pronghorns at the time of this
study. Pronghorns were initially fed five times
daily between 0600 and 2130 h, and given 7084 mllfeeding. In the absence of gastrointestinal
disturbances, they were given larger volumes
per feeding the following day. Bouts of diarrhea
were rare, short-lived (1-2 days), and quickly
remedied with a few doses of Kaopectate (10
mllfeeding; The Upjohn Company, Kalamazoo,
MI) and a temporary reduction in volume of
milk. Volumes of milk were adjusted for the
diet-curtailed young in an attempt to reduce their
fear of humans. Beginning at 8-14 days of age,
daily volumes of milk were held constant to promote establishment of a human bond by increased appetite. Within a week, all diet-curtailed pronghorns tolerated presence of humans,
although they remained quite wild; accordingly,
daily increases in volumes of milk were resumed.
We defined a weaning schedule based on limited field observations that suggested that weaning in pronghorns begins in July (Autenrieth and
Fichter, 1975; Buechner, 1950). Milk is no longer nutritionally required by young by the end
of August (Einarsen, 1948), although nursing
may occur into September (Autenrieth and Fichter, 1975). Therefore, we gradually reduced
volumes of milk and frequency of feeding, based
on a completed weaning date of 25 August. The
weaning process began on 8 July, when fawns
were 29.5 ::!::: 1.3 days old. At this time, the frequency of feedings was reduced to four times
daily, although total daily volumes continued to
increase. Beginning 15 July (36.5 ::!::: 1.3 days
old), total daily volumes for the largest and oldest fawns gradually were reduced. We continued
to increase daily volumes given to the other
fawns, but volumes did not exceed those given
to the older and larger fawns. On 28 July (49.8
::!::: 1.4 days old), frequency of feeding was re-
25
duced to three feedings per day for all animals;
on 11 August (63.8 ::!::: 1.4 days old), frequency
of feeding was reduced to two feedings per day.
Employees at Sybille continued to occasionally
bottle-feed the fawns beyond 25 August to
maintain maximal tractability.
Young pronghorns usually were weighed
weekly, initially while being held on a small
portable scale, and subsequently while standing
with a researcher on a platfonn scale (Fairbanks
model 23-2520A, ::!::: 500 g, St. Johnsburg, VT)
located in a chute system within the bam. To
calculate surface area of body (Moen, 1973),22
measurements of height, width, and circumference were taken on each of five standing, tame
fawns that would allow the measurements (two
males and three females; 14 July, 28 July, 23
August, and 20 September). Three measures of
length of leg, brisket (total length of leg to
height of chest), length of tarsus, and length of
carpus, were determined to the nearest 1.0 cm
above the ground. The measurements also were
taken on two female fawns that would still tolerate the handling during winter (21 November
and 24 January; mean ages were 172 days and
235 days). We compared lengths of the brisket,
tarsus, and carpus to those of two adult pronghorns (aged 2 and 6 years; weighing 46.6 and
36.5 kg, representing the tallest and shortest individuals of a cohort of six captive adult females).
At ca. 1 month of age, two of the young
trapped at Warren Air Force Base showed signs
of a central-nervous-system deficiency and a
joint-leg disorder of unknown cause (Martin,
1995) so were not used in this study. Therefore,
only 10 animals (five tame, five diet-curtailed)
were considered in our data analyses. Peak intake of milk of the tame pronghorns was compared to that of the diet-curtailed young using
Student's I-test (Sakal and Rohlf, 1981). For the
tame animals, we used linear regressions to
quantify the relationships between lengths of leg
(brisket, tarsus, and carpus) and body weight
(Sakal and Rohlf, 1981). We used a nonlinear
curve-fitting package to describe the sigmoidal
relationship between surface area and body
weight (PROC NLIN-SAS Institute, Inc.,
1987). Growth rates of young were determined
to 16 weeks of age to compare with published
literature. Because some animals were no longer
at Sybille and others were not tame enough to
allow consistent weights by 16 weeks of age,
26
Vol. 78, No.1
JOURNAL OF MAMMALOGY
TABLE I.-Composition and energy content of the milk formula fed to young pronghorns in this
study, of commercial evaporated milk, and of milk of pronghorns.
Num-
b"
of Dry matter
sam(%)
x ± SE
pies
Source of milk
Milk fonnula
Evaporated milk
18.8
25.0
25.0
26.3
Pronghorn (no date)
Pronghorn (September)
Fat
Protein
(%)
(%)
x ± SE
x ± SE
Energy
(lJ/g)
x ± SE
4.6
6.1
6.9
5.6
7.5
13.0
9.6
Reference
This study
Wild et aI., 1994
Einarsen, 1948
4.23
5.65
4'
23.0 ::':: 0.2
8.8 ± 0.3
6.7 ± 0.3
5.68 ± 0.06
Browman and Sears,
1955
Martin, 1995
Pronghorn (32-53 days
4'
19.0 ± 0.4
5.3 ± 0.1
5.8 ± 0.1
4.28 ± 0.05
Martin, 1995
postpartum)
Pronghorn (60-74 days
postpartum)
3'
20.1 ± 0.9
6.9 ± 0.5
6.3 ± 0.2
4.93 ± 0.24
Martin, 1995
Pronghorn (4-25 days
postpartum)
• Samples of milk obtained from one animaL
growth rates were determined for only three animals (all females) in each group. We used linear
regressions to describe the growth rates between
groups; differences between groups were assessed by comparing 95% confidence intervals
around estimates of slope. We assumed a significance of P .:-=;: 0.05 for all analyses. All values
are presented as X ± 1 SE.
RESULTS
The formula of milk developed for neonatal pronghorns in this study in 1993 did
not deviate much from measurements of
quality of milk that we subsequently obtained for two maternally raised pronghorns
in 1994 (Martin, 1995). The formula was
similar in dry matter and energy content to
samples of milk collected from a captive
female 1 month after parturition; values for
fat and protein were slightly less (Table 1).
Intake of milk by pronghorns typically
increased during the 1st month from an initial introduction of 350-392 ml/day, and
then declined during the regulated weaning
phase of our feeding protocol. Slight variations in individual regimes occurred because of differences in body size and age
and because we controlled for differences
in disposition of young. Intake of milk for
all animals peaked at },087 ± 151 mllday
(n = 10) between 26 and 44 days of age.
The mean peak intake of milk by five dietcurtailed fawns (1,044 ± 50 ml/day) was
insignificantly lower than that of the tamest
five fawns (1,1900: 63 ml/day; P ~ 0.11).
Relative intake of milk (per unit body
weight) increased to a peak of 164.4 ± 5.9
ml/kg/day for the five tame animals, at 18.4
± 3.4 days of age (Fig. 1). The diet-curtailed young exhibited a similar pattern
200
••
175
~
S 125
Ew
"'"
;;
'"
•
150
100
f-
75
•
...
••
••
\
.
••
••• • ."
•
•
••
• ,.
•
~
"
50
'.
'\
25
." .,....
0
0
10
20
30
40
50
60
70
80
AGE (days)
FIG. I.-Intake of milk relative to body
weight by five tame pronghorn young at various
ages.
February 1997
MARTIN AND PARKER-GROWTH OF B01TLE-RAISED PRONGHORNS
27
25
(2
20
-
... • •
OJ
""
~
I-
15
>Cl
10
J:
Cl
[jJ
~
•
+ 3.82
• Y == 0.15X
0.96
•
•
• •.,
•
.
0
0
0
(IJ
5
o Y=0.11X+3.02
(2
=0.92
O+----.--~---,r---.---._--~
o
20
40
60
80
100
120
AGE (days)
FIG. 2.-Body weight in relation to age of tame (e) and diet-curtailed (0) pronghorn young.
with a much larger range of peak values
(\07-196 ml/kg/day at 8-27 days of age).
which occurred in response to restriction of
volumes of milk and because of their hyperreactive nature.
Body weights of 1-2-day-old pronghorns
averaged 3.36 ± 0.21 kg (n ~ 9). The dietcurtailed fawns grew significantly slower
(110 ± 5 g/day) than did the tame pronghorns (152 :t 5 g/day) to 16 weeks of age
(Fig. 2). Lengths of brisket, tarsus, and carpus of the tame pronghorns increased linearly as a function of body weight within
the narrow range of weights monitored
(Fig. 3a). At a mean age of 38 days, height
of brisket (39.3 ± 0.5 cm; n ~ 5) represented 80.2% of length of adult legs (49.0
::!:: 0.7 cm). By 7 months of age, the average
height of brisket (45.5 ± 0.4 cm; n = 2)
was 92.9% of brisket height of adults. Surface area increased sigmoidally with increasing body weight, ranging from 0.47 m 2
at 32 days of age to 1.03 m 2 at 240 days
(Fig. 3b).
DISCUSSION
Neonates raised according to feeding
protocols that promote natural rates of
growth by approximating natural patterns,
volumes, and composition of milk are more
likely to be physiologically similar to maternally raised conspecifics. Development
of feeding protocols for young pronghorns
according to this strategy has not been possible because of the absence of information
on lactational characteristics and natural
growth rates of neonates. Nevertheless, the
feeding protocol of Wild et aJ. (1994),
which did not restrict quantities of milk,
was successful; in that study, the average
growth rate of pronghorns to 16 weeks of
age (177 g/day; n = 19) was not significantly different from that of a male raised
by its mother in captivity during the same
28
JOURNAL OF MAMMALOGY
50
a
"-.~
~.
40
E
~
30
J:
t-
"'z
UJ
20
-'
• Y '" O.32X + 36.9; ,2:" 0.58
o y = O.33X + 26.0; ,2 = 0.81
10
• Y = O.20X + 22.5; ,2", 0.58
I
0
5
0
1.2
10
15
20
25
30
b
1.0
E
~O.8
UJ
.,
a:
'"
'"::>~
IJ.J
0.6
()
0.4
Y = 0.433 +
(f)
0.2
,2 _0.97
3 31
O.728X .
11709.9 + X3 .31
0.0 +---r--r-----,--,----r---,
10
o
5
15
20
25
30
BODY WEIGHT (kg)
FIG. 3.-Brisket (total length of leg, e),
heights of tarsus (0), and carpus (.) (a) and
surface area (b) relati ve to body weight of tame
pronghorn young :=;;7 months of age.
summer (194 glday). The average growth
rates of our tame and diet-curtailed young
to the same age (Fig. 2) were lower than
the values reported by Wild et al. (1994),
but were comparable to the growth rates of
captive twin pronghorns raised by their
mother in our subsequent study measuring
quality and production of milk by pronghorns (Martin, 1995). Specifically, the average growth rates of the tame pronghorns
in this study (152 ::!: 5 g/day) and one maternally raised twin (153 ± 4 glday) were
Vol. 78, No.1
not significantly different; the average
growth rates of the diet-curtailed fawns
(110 ± 5 g/day) and the other twin (124 ±
4 g/day) were not different.
Chronic, diet-related, health problems
likely depress growth rates of neonates, and
should be minimized in animals fed according to an acceptable feeding protocol. Feeding unlimited quantities of milk led to severe diarrhea in our first pronghorn. Limiting the volumes of milk given to our
fawns appeared to prevent severe gastrointestinal disturbance and also approximated
natural patterns of intake during weaning.
Intake of milk by the maternally raised
twins in our subsequent study in 1994, and
observations of mother-neonate interactions
indicate that, after the 1st 1-2 weeks, fawns
are not allowed to nurse until satiated (Martin, 1995). For example, at a mean age of
70 days, the relative intake of milk and energy of the maternally raised twins (24.6 ±
2.5 mllkg/day, 117.8 ± 12.0 kJlkg/day)
were similar to that of our bottle-raised
young (31.3 ± 1.4 mllkglday, 132.4 ± 5.9
kJlkg/day) and much less than the relative
intake of milk by pronghorns given unrestricted quantities of milk at the Foothills
Facility (70 mllkg/day, 395.5 kJlkg/dayWild et aI., 1994).
Growth rates of neonates are modified by
environmental conditions (Price and White,
1985). The different growth rates of captive
pronghorns (this study; Martin, 1995; Wild
et aI., 1994) are linked to factors that affect
intake and quality of milk. Maternally
raised pronghorns may not necessarily grow
at genetically defined maximal rates. That
is, it may be possible to bottle-raise young
that have higher rates of growth (Wild et
al.. 1994) than those of maternally raised
animals (Martin, 1995). In free-ranging
pronghorns, environmental stressors affecting maternal condition may be particularly
influential. Poor quality of forage has been
correlated with lower production of milk by
other ungulates and with significantly reduced rates of growth (Loudon et aI., 1983).
Further. the growth rate of one pronghorn
February 1997
MARTIN AND PARKER-GROWTH OF BOTTLE-RAISED PRONGHORNS
may be compromised if it has a twin (Carl
and Robbins, 1988). Measuring growth in
maternally raised neonatal pronghorns older
than a few weeks is practical only if captive
animals are used. Confidence in these estimates, as representative of natural growth
rates of neonates, would be promoted by
study protocols that control for the potential
effects of some environmental conditions.
For example, the dietary quality of captive
lactating females should be similar to that
of free-ranging lactating pronghorns.
Monitoring gain of weight over time provides a general index of growth. Measuring
changes in body dimensions defines development of fawns more specifically and permits inference of relative allocation and
constraints of energy. Changes in skeletal
dimensions have been used to evaluate the
energetic constraints of several species of
ungulates (mule deer and elk-Parker,
1987; porcupine caribou-Parker, 1989),
and to suggest strategies for survival in
winter. For example, although the efficiency
of locomotion increases with length of leg
(Parker et aI., 1984), the concurrent increase in surface area of body results in
greater losses of heat from poorly insulated
extremities. Because pronghorns rely on
speed to escape predators, highly efficient
locomotion is advantageous. The risk of a
young animal being captured would be expected to substantially decrease as its legs
approached lengths of adults; its running
velocity would increase and its ability to
keep up with fleeing adults would improve.
The potential for heat loss, though, is significant; winter habitat provides relatively
little thermal cover, and often has high wind
velocities and low temperatures. In early
winter (21 November), the mean length of
brisket of our pronghorns (43.5 cm) was
92.9% of length of briskets for adults (49.0
± 0.7 cm). In comparison, the predicted
length of brisket of a young mule deer with
an early winter weight of 30 kg (Parker,
1989; 50.2 em-Parker et al.. 1984) is only
86.6% of the length for an adult mule deer
(66.5 kg-Anderson et aI., 1974; 58.0 cm
29
length of brisket-Parker et aI., 1984). Relative to the energetic demands of thermoregulation, the surface area of young pronghorns also may place them at a slight thermoregulatory advantage over mule deer in
early cold-winter environments. In November, the surface area of our pronghorns was
1.03 m 2 (27 kg); young mule deer have a
predicted surface area that is 16.5% greater
than that of pronghorns (1.14 m 2 , 30 kgParker, 1987). Exact interspecific comparisons of the potential for heat loss are difficult, however, because of differences in
body weights in winter, thermal values of
pelage, and behavior.
Our formula of milk and feeding schedule for bottle-raising neonatal pronghorns
can be considered successful. The average
growth rates of our bottle-raised young to
16 weeks of age were within the range defined by the average growth rates of maternally raised pronghorns; average body
weights at 4 months also were not significantly different from animals raised by their
mothers (Martin, 1995). Given this similarity, we conclude that the changes in morphological dimensions exhibited by handraised fawns are representative of free-ranging neonatal pronghorns.
The ability of neonatal pronghorns in
captivity to grow faster than wild animals
and to adapt to different intake patterns of
milk (e.g., unlimited quantities-Wild et
aL, 1994, or the common cervid strategy of
an initial increase followed by a decrease;
Fig. 1) may imply that limitations to growth
are most affected by environmental constraints on maternal condition. Nonetheless,
the plasticity that allows young pronghorns
to quickly attain adult proportions appears
to be an important survival strategy for neonates of a species that depends on fleetness
for evasion of predators and is subject to
migrations in winter.
ACKNOWLEDGMENTS
We thank the Wyoming Game and Fish Department for the use of the Sybille Wildlife Research and Conservation Education Center, and
30
JOURNAL OF MAMMALOGY
employees H. Dawson, O. Perritt, L. Robinson,
and D. Zieler for assistance in capture and handling of young. We are grateful to M. P. Gillingham for technical assistance, and to T. Johnson
for animal care and data collection. Veterinary
care was provided by D. Kwiatkowski. Support
for this study came from the Wyoming Game
and Fish Department and a National Science
Foundation grant to the second author.
LITERATURE CITED
ANDERSON, A. E., D. E. MEDIN, AND D. C. BOWDEN.
1974. Growth and morphometry of the carcass, selected bones, organs, and glands of mule deer. Wildlife Monographs, 39: 122.
AUTENRtETH, R. E., AND E. flCHTER. 1975. On the be-
havior and socialization of pronghorn fawns. Wildlife Monographs, 42: I-Ill.
BRINKLEY, K. 1987. Pronghorn hand-rearing protocol
(Antilocapra americana americana). Animal Keepers' Forum, 14:234-237.
BROWMAN, L G., AND H. S. SEARS. 1955. Mule deer
milk. Journal of Mammalogy, 36:473-474.
BUECHNER, H. K. 1950. Life history, ecology, and
range use of the pronghorn antelope in Trans-Pecos
Texas. The American Midland Naturalist, 43:257354.
CANADiAN COUNCIL ON ANIMAL CARE. 1984. Guide to
the care and use of experimental animals. Canadian
Council on Animal Care, Ottawa, Ontario. 208 pp.
CARL, G. R, AND C. T. ROBBINS. 1988. The energetic
cost of predator avoidance in neonatal ungulates:
hiding versus following. Canadian Journal of Zoology, 66:239-246.
EINARSEN, A. S. 1948. The pronghorn antelope and its
management. Wildlife Management Institute, Washington, D.C., 238 pp.
LoUDON, A. S. I., A. S. McNEILLY, AND 1. A. MILNE.
1983. Nutrition and lactational control of fertility in
red deer. Nature. 302:145-147.
MARTIN, S. K. 1995. Characteristics of lactation and
neonatal growth in pronghorn antelope (Allfilocapra
americana). M.S. thesis, University of Wyoming,
Laramie, 106 pp.
MOEN, A. N. 1973. Wildlife ecology: an analytical
Vol. 78, No.1
approach. W. H. Freeman and Company, San Francisco, California, 458 pp.
PARKER, K. L. 1987. Body-surface measurements of
mule deer and elk. The Journal of Wildlife Management, 51:630-633.
- - - . 1989. Growth rates and morphological measurements of porcupine caribou calves. Rangifer, 9:
9-13.
PARKER, K. L, and B. WONG. 1987. Raising b1acktailed deer fawns at natural growth rates. Canadian
Journal of Zoology, 65:20-23.
PARKER, K. L., C. T. ROBBINS, and T. A. HANLEY. 1984.
Energy expenditures for locomotion by mule deer
and elk. The Journal of Wildlife Management, 48:
474-488.
PRICE, M. A., and R. G. WHITE. 1985. Growth and
development. Pp. 183-213, in Bioenergetics of wild
herbivores (R. J. Hudson and R G. White, eds.).
CRC Press, Inc., Boca Raton, Florida, 314 pp.
ROBBINS, C. T. 1993. Wildlife feeding and nutrition.
Academic Press, New York, 352 pp.
ROBBINS, C. T., and A. N. MOEN. 1975. Milk consumption and weight gain of white-tailed deer. The
Journal of Wildlife Management, 39:355-360.
ROBBINS, C. T., R. S. PODBlELANCIK-NoRMAL, D. L.
WILSON, and E. C. MOULD. 1981. Growth and nutrient consumption of elk calves compared to other
ungulate species. The Journal of Wildlife Management, 45:172-186.
SAS INSTITUTE, INC. 1987. SAS/STAT guide for personal computers, version 6 ed. SAS Institute, Inc.,
Cary, North Carolina, 1028 pp.
SCHWARTZ, C. c., J. G. NAGY, AND S. M. KERR. 1976.
Rearing and training pronghorns for ecological studies. The Journal of Wildlife Management, 25:66-70.
SaKAL, R R., AND E J. ROHLF. 1981. Biometry: the
principles and practice of statistics in biological research. Second ed. W. H. Freeman and Company,
San Francisco, California, 859 pp.
WILD, M. A" M. W. MILLER, D. L. BAKER, N. T.
HOBBS, R B. GILL, AND B. J. MAYNARD. 1994.
Comparing growth rates of dam- and hand-raised
bighorn sheep, pronghorn and elk neonates. The
Journal of Wildlife Management, 58:340-347.
Submilled 3 June 1995. Accepted 3 July 1996.
Associate Editor was Barbara H. Blake.