Wyniki wyszukiwania

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Moulting patterns in Clethrionomys gapperi

100%

Sare D. T. J., Millar J. S., Longstaffe F. J.

Acta Theriologica

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2005

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tom 50

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nr 4

561-569

Small northern mammals undergo regular developmental and seasonal moults. However, the moulting patterns of many small mammals are not well known. Development and subsequent moulting of the pelage was documented in adult red-backed volesClethrionomys gapperi Vigors, 1830 and their offspring in relation to age, weight, and sex. Red-backed voles exhibited 4 developmental pelages (nestling, juveniles, subadult, and adult) through diffuse, rapid hair growth. Rapid growth was associated with early moulting at the nestling, juveniles and adult stages. However, a trade-off between moulting and growth existed at the subadult stage such that delayed moulting was associated with rapid growth. Adult voles completed a unique moult progression with highly variable timing. Male and femaleC. gapperi showed no differences in pattern or locations of moulting. Variation in the number and timing of moults in small mammals may reflect differences in life-history strategies and highlights the need for a consistent mammalian pelages and moults nomenclature.

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Diet selection by red-backed voles Clethrionomys gapperi

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Kasparian K., Millar J. S.

Acta Theriologica

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2004

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tom 49

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nr 3

Food supplementation studies often assume that animals will select artificial diets in their natural environment, and that high-protein, high-energy foods are the most appropriate supplement. These assumptions were tested in red-backed voles Clethrionomys gapperi Vigors, 1830 using food-choice experiments with sunflower seeds, oats, and commercial diets in the laboratory and field. Preferred level of dietary protein was also examined using isocaloric diets that varied only in protein content (14%, 20% and 30%). Preferences exhibited in the above trials were subsequently examined relative to natural forage. Voles demonstrated a strong preference for sunflower seeds over oats, dried alfalfa, and rabbit, guinea pig, rat and cat food. Voles preferred the 14% protein diet over the 20% and 30% protein diets. Although sunflower seeds contain more than 20% protein, voles consistently preferred this food over natural forage, perhaps because of their high fat and energy content. This indicates that tradeoffs in protein content may be made to maximize energy. We suggest that red-backed voles will select sunflower seeds in their natural environment, and that their preference for low protein likely reflects their herbivorous diet. This study highlights the importance of an a priori understanding of species-specific preferences and requirements when designing food supplementation studies.

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Maximizing survivorship in cold: thermogenic profiles of non-hibernating mammals

84%

Merritt J. F., Zegers D. A.

Acta Theriologica. Supplement

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2002

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tom 47

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nr 1

Winter-active small mammals residing in seasonal environments employ many different behavioral, anatomical and physiological mechanisms to cope with cold. Herein we review research on survival mechanisms in cold employed by small mammals with emphasis on the families Soricidae, Muridae and Sciuridae. The focus of this review is on research delineating the role of seasonal changes in resting metabolic rate (RMR), nonshivering thermogenesis (NST), body mass, and communal nesting in enhancing winter survivorship of six species of small mammals (masked shrew Sorex cinereus, short-tailed shrew Blarina brevicauda, southern red-backed vole Clethrionomys gapperi, white-footed mouse Peromyscus leucopus, deer mouse P. maniculatus, and southern flying squirrel Glaucomys volans) residing in the Appalachian Mountains of Pennsylvania, USA. Each species shows good over-winter survivorship but exhibits a different suite of mechanisms to maximize survival in cold. B. brevicauda, S. cinereus, and G. volans show slight increases in RMR during winter, whereas Peromyscus and C. gapperi exhibit decreased RMR overwinter. All six species experience elevated NST in winter. The comparatively low RMR and NST of G. volans during winter was attributable to a decreased energy expenditure due to a larger body mass, coupled with communal nesting in cavities of trees that provided insulation from low ambient temperatures. Squirrels nesting singly experienced a longer period of elevated NST in winter and higher mean NST year-round than did squirrels nesting communally. Energy conservation in the form of growth retardation in winter was exhibited by C. gapperi and S. cinereus but not the other species.

Ograniczanie wyników

2 Acta Theriologica

1 Acta Theriologica. Supplement

2 Millar J. S.

1 Kasparian K.

1 Longstaffe F. J.

1 Merritt J. F.

1 Sare D. T. J.

1 Zegers D. A.

1 2005

1 2004

1 2002

Moulting patterns in Clethrionomys gapperi

Diet selection by red-backed voles Clethrionomys gapperi

Maximizing survivorship in cold: thermogenic profiles of non-hibernating mammals