dc.identifier.citation |
Revathe, T. 2022, Calf development, calf conspecific interactions, and the effect of calves on female social structure in the kabini Asian elephant population, southern India, Ph.D thesis, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru |
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dc.description.abstract |
Group-living is widespread among vertebrates and is expected to provide benefits such as
decreased predation, enhanced feeding success, and higher survival of young ones (for
example, Holekamp et al. 1997, Clutton-Brock et al. 1999, Packer et al. 1990). In large
mammals, in which adults have few natural predators and grouping is likely to increase
feeding competition, higher survival of young ones may be an important benefit of group
living. Better survival of young ones through decreased predation or infanticide may result
from increased group size, active guarding of young, or increased vigilance (Lee 1987, Packer
et al. 2001, Santema and Clutton-Brock 2013). Better survival and improved well-being of
young ones may also result from better care because of the participation of individuals apart
from the mother in rearing offspring (Moehlman 1979, Clutton-Brock et al. 2001, Meehan et
al. 2016). The arrival, therefore, of young ones may have considerable effects on social
structure and behaviour of social mammals, especially those that show fission-fusion
dynamics, in which groups or subgroups can split or rejoin flexibly to change group size and
composition in response to fluctuating ecological and social environments (Aureli et al.
2008). Such species may show regrouping, increasing group sizes and/or forming new
associations in the presence of young ones, and increased sociality and cooperation, possibly
because of the need for cooperative offspring care (see Lee 1987, Wells et al. 1987, Gero et
al. 2013, Holmes et al. 2016, Marealle et al. 2020). Thus, studying the effect of young ones
on adult grouping patterns and sociality would help us understand the extent to which social
structure is shaped by their presence and associations with them. In this thesis, I attempted to understand the importance of young ones in female Asian
elephant (Elephas maximus) society, collecting field data from Nagarahole and Bandipur
National Parks and Tiger Reserves (Kabini elephant population) in southern India. Asian
elephants are long-lived (Sukumar 2003), organised into matrilineal clans of mostly related
females (Vidya and Sukumar 2005, Shetty 2016, Nandini et al. 2018), have a long period of
dependency of young ones (Lahdenperä et al. 2016), and likely have a relatively low lifetime
reproductive success. Thus, young ones are very valuable, and it has been suggested that
cooperative care may be the raison d’être for female sociality in the Asian elephant (Gadgil
and Nair 1984, Gadgil et al. 1985). I examined how the presence of calves (<1 year of age) affected female group sizes and associations, studied the development of various behaviours
in calves and how calves interacted with various conspecific females, and then examined
allomothering (care by non-mother females) and some reasons for such care. The thesis is
organised as a set of manuscripts. |
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