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Spatial organization, group living and ecological correlates in
badgers
Journal
Journal of Animal
Ecology, Volume 71,Number 3, May 2002, pp. 497-512 -
Blackwell Publishing
Authors
Revilla E.; Palomares F.
Abstract
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Territoriality and group living are described in a low-density population
of Eurasian badgers, Meles meles L., by studying the patterns of spatial
grouping and territory marking, as well as the differences between individuals
in some of their characteristics (body condition and dispersal) and in their
space use (seasonally, periods of activity and interaction between pairs of
individuals) under strong seasonal fluctuations in the availability of the key
resource (young rabbits, Oryctolagus cuniculus L.). Finally, the role of
the spatial distribution of the main prey (young rabbits) in the development of
sociality was also studied in order to test some of the assumptions and
predictions of the resource dispersion hypothesis (RDH).
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Badgers were territorial, showing a flexible system of territory marking,
which includes the marking of the most used areas (sett-latrines at the centres
of activity) and additionally, at the smaller territories, a system of
border-latrines in the areas of contact between territories. The maximum use of
border-latrines was associated with the reproductive season, and that of
sett-latrines with the season of food scarcity.
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In the study area where badgers had rabbits as main prey, territories were
occupied by small groups of animals, formed by one adult female who reproduced,
one adult male who also showed signs of reproductive activity, the cubs of the
year (if there was reproduction) and some animals born during previous years,
which remained in their natal territory until their dispersal (normally during
the mating season of their third or fourth year of life). This system was not
strictly fixed as males, given the opportunity, expanded their territories to
encompass additional females. Territories in another study site were occupied by
one adult female (marked), plus the cubs of the year and another adult
individual (unmarked).
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In winter and spring dominant females and subordinates used only a small
fraction of their territories, moved short distances, at a low speed and
covering small areas per night. These seasons corresponded with the reproduction
of rabbits (highest food availability). Dominant females were the only
individuals using all the territory available in the summer (lowest food
availability), when badgers had the worst body condition. Food availability
increased again in autumn, as did body condition, while range sizes were again
reduced. Dominant males used the same proportion of their territories over all
seasons. However, in winter (reproductive season) they moved faster, over longer
distances, and covered larger areas per period of activity. These results
indicate that use of space by dominant males was affected by different factors
from that of dominant females and subordinates.
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RDH does not seem to explain group living in our populations because: (a)
territoriality in each pair of primary animals was driven by different factors
(trophic resources for females and females for males); (b) dominant males acted
as expansionists; and (c) territory size was related to its richness and not to
patch dispersion.
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We propose an integrative hypothesis to explain not only group formation
but also interpopulation variability in the social organization of badgers
within ecological, demographic and behavioural constraints and in the light of
current theory on delayed dispersal.
Keywords
group living; integrative hypothesis; Meles meles;
resource dispersion hypothesis; social organization; sociality; space
use; territoriality
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