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A Relative Measure of Predation on Web-Spiders in Temperate and Tropical Forests

Ann L. Rypstra
Oikos
Vol. 43, No. 2 (Jul., 1984), pp. 129-132
Published by: Wiley on behalf of Nordic Society Oikos
DOI: 10.2307/3544758
Stable URL: http://www.jstor.org/stable/3544758
Page Count: 4
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A Relative Measure of Predation on Web-Spiders in Temperate and Tropical Forests
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Abstract

A relative measure of predation on web-spiders was determined for temperate (Pennsylvania, USA), subtropical (Peru), and tropical (Gabon) forests. Predation was quantified by comparing the losses of matched individuals in four treatment groups. Spiders in groups 1 and 2 were released on natural vegetation in the forest. Group 2 was paint-marked and group 1 was not. Groups 3 and 4 were paint-marked and released in cages constructed in the study areas. Group 3 spiders were released in cages with no tops. Group 4 spiders were released in complete cages. Both cages were open enough to allow the free movement of spiders and their insect prey. The number of spiders lost from groups 1,2, and 3 during the daytime on the two tropical sites was significantly higher than losses in group 4 or during any other time period. These results might indicate that predation, at least by vertebrates, is more intense during daytime periods on those tropical sites. /// Относительный пресс хищничества на пауках-тенетниках, определяли в умеренных (Пеннсильвания, США), субтропических (Перу) и тропических (Габон) лесах. Пресс хищничества определяли по потере равноценных особей в 4-х исследованных группах пауков. Пауков І. и ІІ. группы выпускали на естественную растительность лесов. ІІ. группа метилась краской, а І. - не метилась. ІІІ. и ІV. группы метились и выпускались в контейнерах, установленных в исследуемых участках. ІІІ. группу пауков выпускали в контейнеры без крышек, ІV. группу выпускали в закрытые контейнеры. Однако, оба контейнера были достаточно открытыми для свободных передвижений пауков и их жертв (насекомые). Количество исчезнувших пауков из групп І., ІІ.и ІІІ. в течение дневного времени в двух тропических местообитаниях эначительно выше, чем потери в ІV. группе, либо в другие часы суток. Эти результаты могут означать, что хищничество, по крайней мере позвоночных, более интенсивно в дневные часы в соответствующих тропических местообитаниях.

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