Summary
This paper investigates, through experiments using surrogate predators, differences in intraspecific alarm calls between
familiar and unfamiliar Bronze Mannikin Spermestes cucculatus groups. Four groups of mannikins were captured with mist
nets from four areas in Durban (i.e. original groups) and randomly mixed (i.e. assorted groups). These groups were exposed
to latex terrestrial snakes and mounted aerial raptors, and their alarm calls and predator response behaviours recorded.
The Bronze Mannikins were able to discriminate between predators of different sizes, and increased their calling rate and
decreased the end frequency of the alarm call in response to larger predators. This perhaps signalled increased threat,
while simultaneously decreasing the conspicuousness of the flock. When the alarm call structure of the original and assorted
groups in response to both raptors and snakes was compared, birds in original groups called more often, but paused longer
between calls. Anti-predator behaviour differed in that assorted groups were less vigilant and aggressive toward the predators
and panicked more frequently. In these groups, a failure to transfer the predation threat information might have caused the
group to stop behaving cohesively and reliably. The manipulated experiments carried out in this study indicated that Bronze
Mannikins were able to communicate predator size risk to conspecifics, but not as successfully to unfamiliar group members,
showing that the investment, probability through altruistic payback, is greater in stable groups.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:tut/oai:encore.tut.ac.za:d1001767 |
| Date | 09 December 2009 |
| Creators | Malan, G, Seoraj-Pillai, N, du Plessis, MA |
| Publisher | Taylor & Francis |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | |
| Rights | © NISC Pty Ltd |
| Relation | Ostrich Journal of African Ornithology |
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