In Vitro Digestibilities of Summer Forages Utilized by the Rivière George Caribou Herd

Ecological Applications

Tremblay

et al. 2017

Self Cite

Abstract. Global declines in caribou and reindeer (Rangifer) populations have drawn attention to the myriad of stressors that these Arctic and boreal forest herbivores currently face. Arctic warming has resulted in increased tundra shrub growth and therefore Rangifer forage quantity. However, its effects on forage quality have not yet been addressed although they may be critical to Rangifer body condition and fecundity. We investigated the impact of 8 yrs of summer warming on the quality of forage available to the Bathurst caribou herd using experimental greenhouses (n = 5) located in mesic birch hummock tundra in the central Canadian Low Arctic. Leaf forage quality and digestibility characteristics associated with nutrients (nitrogen and phosphorus), phenolics, and fiber were measured on the deciduous shrub Betula glandulosa (an important Rangifer diet component) at six time points through the growing season, and on five other very common vascular plant and lichen species in late summer. Experimental warming reduced B. glandulosa leaf nitrogen concentrations by~10% in both late June and mid-July, but not afterwards. It also reduced late summer forage quality of the graminoid Eriophorum vaginatum by increasing phenolic concentrations 38%. Warming had mixed effects on forage quality of the lichen Cetraria cucullata in that it increased nutrient concentrations and tended to decrease fiber contents, but it also increased phenolics. Altogether, these warming-induced changes in forage quality over the growing season, and response differences among species, highlight the importance of Rangifer adaptability in diet selection. Furthermore, the early season reduction in B. glandulosa nitrogen content is a particular concern given the importance of this time for calf growth. Overall, our demonstration of the potential for significant warming impacts on forage quality at critical times for these animals underscores the importance of effective Rangifer range conservation to ensure sufficient appropriate habitat to support adaptability in forage selection in a rapidly changing environment.

Section: Discussionmentioning

confidence: 99%

“…, Skarin et al. ) and digestibility (White and Trudell , Côté ). Preferred forage has relatively high digestibility and high protein content (White and Trudell , Côté ).…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Experimental warming alters migratory caribou forage quality

Zamin

Ecological Applications

Tremblay

et al. 2017

Self Cite

“…Factors other than, or in interaction with, dietary fiber may also be involved in DMD (Robbins et al 1987a, b) and thus in the selection we observed. Fiber may affect DMD in subtle ways, and only through in vitro or in vivo digestibility trials conducted with deer inoculum could these effects be teased out (Pearson et al 1980, Côté 1998.…”

Section: Discussionmentioning

confidence: 99%

Winter Forage Selection in White‐Tailed Deer at High Density: Balsam Fir is the Best of a Bad Choice

Sauvé

2007

J Wildl Manag

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We assessed winter forage selection by white-tailed deer (Odocoileus virginianus) on Anticosti Island, Quebec, Canada, using cafeteria-feeding trials. Winter habitat on Anticosti is degraded and free-ranging deer at high densities consume 70% balsam fir (Abies balsamea) and 20% white spruce (Picea glauca), even though spruce is much more available than fir. Deer ate 89.9% balsam fir and 10.1% white spruce when the availability of both trees was equal. Deer did not eat shredded twigs more than intact twigs. Fiber content and condensed tannins were greater in white spruce than in balsam fir. Deer preference for fir was not based on texture but, more likely, on plant constituents, so we concluded that deer will nearly eliminate fir before they use any significant amount of white spruce. Management actions, therefore, need to be undertaken to enhance balsam fir regeneration. (JOURNAL OF WILDLIFE MANAGEMENT 71(3): 911-914; 2007)

“…Rumen fill is determined by the quantity of vegetation ingested and foraging bout frequency, which in turn are limited by retention time, because short transit times allow more vegetation to be ingested (Renecker and Hudson 1986;Domingue et al 1991). Retention time is influenced by vegetation quality, since the digestion of cell walls increases with retention time (Côté 1998). Hence, an animal foraging on poor quality vegetation-for example, during winter-will tend to increase retention time (Gross et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Foraging decisions in a capital breeder: trade-offs between mass gain and lactation

Hamel

2009

Oecologia

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The high energetic costs of lactation can lead to fundamental trade-offs in life-history traits, particularly in young females that reproduce before completing body growth. We assessed whether lactating female mountain goats (Oreamnos americanus) used behavioural tactics at fine spatio-temporal scales to increase energy intake to compensate for the costs of lactation. Lactating females increased bite rate and chewing rate compared with non-lactating females, but selected similar foraging sites in terms of plant quality and abundance. At peak lactation, forage intake of lactating females was >40% greater than that of non-lactating females. For females that had reached asymptotic body mass (i.e. > or =6 years old), summer mass gain of lactating females was similar to that of non-lactating females. At 4 and 5 years of age, however, daily mass gain of lactating females was about 20% lower than that of non-lactating females. We conclude that increased foraging may allow fully-grown lactating females to compensate for the energetic costs of lactation, but that there is a major trade-off between mass gain and lactation for younger females.