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Foraging Patterns and Their Multiplier Effects on Productivity of Northern Ungulates

Robert G. White
Oikos
Vol. 40, No. 3, Herbivore-Plant Interactions at Northern Latitudes. Proceedings of a Symposium Held 14-18 September, 1981, at Kevo, Finland (May, 1983), pp. 377-384
Published by: Wiley on behalf of Nordic Society Oikos
DOI: 10.2307/3544310
Stable URL: http://www.jstor.org/stable/3544310
Page Count: 8
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Foraging Patterns and Their Multiplier Effects on Productivity of Northern Ungulates
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Abstract

In most of their arctic and subarctic ranges reindeer, caribou and muskoxen adopt generalist foraging strategies; they consume a wide variety of plants even though they feed selectively. This paper analyses some aspects of selective feeding behavior and its possible influence on animal production. Selective feeding that makes only small changes in quality or amount of food intake may cause a greatly enhanced, or multiplier, effect on animal production. In an example for reindeer grazing in arctic coastal tundra during summer, selective grazing increased digestibility by 14% and dry matter intake by 27%, which combined to give a 268% increase in projected daily weight gain. Weight gain may then influence populations through control over conception rate and survival during winter. An increase by 14% in bodyweight of young female reindeer during summer results in a 35% increase in the probability of conception in autumn. Winter range conditions can affect birth weight, milk production and calf growth rates, all of which affect future reproduction and survival and provide additional avenues for multiplier effects. /// На бопьшей части ареала в Арктике и Субарктике олени, карибу и овцебыки обнаруживают стратегию неизбирательной фуражировки при селективном корм-лении. В данной статье анализируются некоторые аспекты пищевого поведе-ния и его возможное влияние на продуюцию жнвотных. Селектнвное пнтание, выявляющее лишь мелкие различия качества или характера потребления пищи, могут вызвать сильный эффект прироста или кратного увеличения продуюции животного. На примере выпаса оленей в арктивческой прибрежной тундре се-лектнвный выпас повышает переваримость на 14%, и усвоение суточного вещест-ва на 27%, что сочетается с увеличением предполагаемого суточного при-роста на 26%. Весовой прирост может затем влиять на популяцню в целом путем регуляции скорости оплодотворения. Так, у молодых самок оленей вес тела повыщается на 14% во время спаривания, что приводит к увеличению вероятности оплодотворения на 35%. Изменения усл\r=??\ыий зимнего ареала име-ют значение для регуляции веса новорожденных, продукции молока и скорости роста телят. Обсуждается возможные влияния перехода от зимы к леты.

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