Ž
0.75
. Hinds gained weight, except during spring y2.9 0.8 grkg
. Gains peaked in
0.75
Ž .
early summer at 12.5 1.4 grkg p - 0.001 , whereas hinds maintained weight
Ž
0.75
. Ž
0.75
. Ž .
stasis in late summer 0.3 0.8 grkg and autumn 0.6 1.2 grkg
p 0.05 .
4. Discussion
Attempts to maintain marked difference in phytomass between H and L were successful. Unfortunately, between-session time constraints and concern about maintain-
ing animal condition resulted in H forage availability being well above that which would Ž
Ž normally be regarded as limiting for wapiti e.g., 900 kg DMrha Gates and Hudson,
.. 1983 . This may explain the general lack of contrast between pastures. For example,
Ž .
when Heydon et al. 1993
compared lactating red deer hinds on high and low Ž
phytomass pastures, they found a considerable difference in BR high: 62 bitesrmin; .
low: 82 bitesrmin . The higher phytomass pasture contained 1659 kg DMrha, while forage availability would likely be considered a limiting factor in the ‘low’ pasture, with
only 466 kg DMrha. Further research similar to this study should be undertaken, incorporating pastures with a more limited forage supply, in order to better examine
possible inter-pasture effects of seasonal availability during gestation and lactation.
Wild cervids are well known for their crepuscular habit, however, animals on game Ž
farms or research stations often show feeding cycles throughout the day Gates and .
Hudson, 1983; Jiang and Hudson, 1996 . The biphasic pattern displayed by Jiang and Ž
. Hudson’s 1996 non-reproductive hinds in early summer, emphasizes the difference in
lactating hinds that have higher energy demands and nurse their calves throughout the Ž
. day. Gates and Hudson 1983 also observed biphasic patterns in spring and summer,
Ž however, only three of nine animals were lactating i.e., there were also two stags and
. four calves , which may account for the disparity.
Daily foraging time in the present study was comparable to those found in other Ž
investigations Craighead et al., 1973; Collins et al., 1978; Hanley, 1982; Jiang, 1993; .
Florkiewicz, 1994 . Some studies did not distinguish grazing from total active time, therefore, foraging was estimated by correcting with seasonal values of percent active
Ž .
time foraging found in this study Table 2 . Grazing time of reproductive hinds in the Ž
. present study was similar to Jiang’s 1993 non-reproductive hinds at the same research
station. This implies that greater nutrient requirements of gestating and lactating wapiti were not satisfied by increasing grazing time.
Ž .
Gates and Hudson 1983 suggest that fatigue and demand of alternate activities place an upper limit on daily foraging time, and this is commonly cited to be around 12 h.
Ž .
Ž .
This presumption is supported by Clutton-Brock et al. 1982 and Heydon et al. 1992 , whereby, increases in daily grazing time between non-reproductive and reproductive red
deer hinds were 9.8 to 11.8 h and 10.8 to 12.2 h, respectively. Perhaps, if lactating hinds had access to pastures with higher forage availability, they could better manipulate their
BR and BS to maintain intake within these grazing time constraints.
When not foraging, wapiti usually bedded; however, maternal care disrupted this Ž
. alternating cycle. In autumn post-weaning , increased nocturnal bedding corresponded
with an almost equal decrease in nocturnal foraging. These associations did not occur
while hinds were lactating. For example, the reduction in nocturnal bedding during peak lactation was accompanied by a decrease in nighttime grazing. Clutton-Brock et al.
Ž .
1982 found the same proportion of diurnal to nocturnal foraging in lactating red deer hinds.
The slight increase in daylight foraging and reduced bedding in early summer may result from insect harassment. Higher prevalence of nocturnal foraging in spring and
Ž .
summer has been reported in other work on wapiti Gates and Hudson, 1983 and Dall’s Ž
. Ž .
sheep OÕis dalli Hoefs and McTaggart Cowan, 1979 .
The increased length and decreased frequency of foraging bouts in summer agree Ž
. with other works on wapiti Hanley, 1982; Florkiewicz, 1994; Jiang and Hudson, 1996 .
Ž .
Ž Spring similarities to Jiang and Hudson’s
1996 non-reproductive hinds
also at . Ž
Ministik Jiang and Hudson: 70 minrbout, 9.2 boutsrday; this study: 64 minrbout, 9.7
. Ž
boutsrday and early summer differences
Jiang and Hudson: 149 minrbout, 4.8 .
boutsrday; this study: 67 minrbout, 10.2 boutsrday , underscore the effects of lactation. In late gestation, reduced rumen capacity caused by the rapidly developing
fetus, may force shorter feeding bouts, while increasing bout frequency. During lacta- tion, although diel grazing times are comparable, lactating hind foraging is regularly
interrupted for nursing and other cow–calf interactions.
Adaptation of BR, BS, and grazing time help ruminants regulate and maintain intake Ž
over a wide range of forage availability Allden and Whittaker, 1970; Arnold and .
Dudzinski, 1978; Trudell and White, 1981 . For example, at Ministik on spring pasture Ž
. Ž
. of similar phytomass 1880 kg DMrha , Jiang’s 1993 wapiti hinds had lower mean
Ž .
Ž .
BR 34 bitesrmin and nearly double the BS 229 mg of those in this study. To satisfy the increased energy demands of fetal growth, BR and grazing time were augmented;
however, hinds were apparently unable to meet their nutritional requirements, as reflected in spring weight loss. As this is a natural element in their annual cycle of
weight fluctuation, it is likely ineffectual to supplement hind nutrition during pre-parturi- tion. Moreover, calving problems can arise with overweight hinds.
In this study, peak BR occurred in late summer when forage availability was highest. This is unexpected, as other studies have demonstrated, that higher forage availability
Ž was accompanied by lower BR
e.g., Jamieson and Hodgson, 1979; Hudson and .
Nietfeld, 1985; Heydon et al., 1993; Semiadi et al., 1993 . BR may be limited at both Ž
. Ž
very low through difficulty prehending short, stemmy vegetation and at very high due .
to time involved masticating large bites phytomass levels. In this study, perhaps the range of higher phytomass values encountered occurred at levels where foraging rate
Ž .
declines with phytomass. Alternatively or additionally , a combination of greater intake requirements and foraging interruptions associated with lactation may demand aug-
Ž mented BR from hinds in late summer, regardless of forage availability Trudell and
. White, 1981; Forbes and Coleman, 1987 .
A positive correlation between BS and forage availability has commonly been Ž
reported for wapiti Wickstrom et al., 1984; Hudson and Nietfeld, 1985; Hudson and .
Watkins, 1986 . They also found a reciprocal response of BR with BS, and hence, phytomass. This may reflect differences in wapiti ingestion efficiencies. When grazing a
well-cropped pasture, wapiti feed very close to the ground where inedible elements may Ž
. be encountered e.g., fecal matter, stones, twigs, etc. . Excessive variation in BS may
occur, due to objects displacing prehended vegetation andror loss of plant material during manipulation and ejection of inedible portion. These problems are less likely to
occur in the lightly grazed pasture, as long grass stems are not easily lost, and wapiti forage in a higher horizon. The possibility of greater ingestion efficiencies on superior
pasture may incline managers to graze lactating hinds on the best available summer pasture.
Comparison of whole pasture and feeding patch phytomass indicates that wapiti tend to select foraging locations of higher forage availability. Criteria for selection of
foraging location may be based more on vegetation density than plant species.
5. Conclusion
