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Vigilance and group size in impala ( Aepyceros melampus Lichtenstein): a study in Nairobi National Park, Kenya
Author(s) -
Shorrocks Bryan,
Cokayne Aimee
Publication year - 2005
Publication title -
african journal of ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.499
H-Index - 54
eISSN - 1365-2028
pISSN - 0141-6707
DOI - 10.1111/j.1365-2028.2005.00541.x
Subject(s) - vigilance (psychology) , national park , foraging , herd , demography , geography , significant difference , ecology , psychology , biology , medicine , sociology , neuroscience
One of the advantages of living in groups is that individuals may need to be less vigilant, allowing them more time for other important activities, such as foraging. This relationship between group size and per cent time spent being vigilant was investigated by observing impala in Nairobi National Park, Kenya. Three types of individual were observed: females, territorial males and bachelor males. Only females showed the predicted negative relationship between per cent vigilance and herd size. Both types of male showed no significant change of vigilance with increasing group size. There was no difference in levels of vigilance in open or closed habitats and no difference in vigilance between herds ‘alone’ and herds with other species that might have provided ‘extra eyes’.