2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

We hypothesized that supplementary feeding has a positive effect on the time course
of breeding, on reproduction success and on nestling condition. Isotopic analysis
revealed that parents indeed provided nestlings with supplementary food. We could
detect an increase in clutch size and body measures of nestlings fed with artificial
food, but we found negative effects on hatching rates resulting in a dramatically
reduced reproductive success, particularly in supplemented great tits. We discuss
possible causes and consequences of our findings and recommend further studies to
investigate the complex effects of supplementary feeding on bird reproduction.
����30 Eva Heeb
Context-specific colony defense in the red wood ant Fromica rufa: Social
interactions modulate aggressive behavior
Authors: Eva Linda Heeb 1 , Christoph Kleineidam 1
Affiliation: 1 University of Konstanz
Colony defense requires reliable discrimination of colony members (nestmates) from
members of other colonies (non-nestmates). Nestmate recognition in ants is based
on chemical recognition of cuticular hydrocarbons (CHC) that originally served as
protection against desiccation. The CHC profile of a colony (colony-label) is uniformed
through trophalaxis and frequent exchange of CHCs between nestmates. This
promotes colony cohesion and chemical separation of neighboring colonies, which
consequently are treated as ?aliens? that evoke aggression (Wallis D.I. (1964) Animal
Behaviour). The ants? aggressive response is negatively correlated to the distance to
its own nest: Ants show a lower level of aggression when they are further away from
their nest (Wilson E.O. (1971) The Insect Societies). Furthermore, a relation between
path integrator information and aggression to non-nestmates has been described for
desert ants (Knaden M. and Wehner R. (2004) Science). However, it is unclear
whether indeed information of the path-integrator, as suggested, or more direct
measures, like e.g. (reduced) social interactions between nestmates is used to
modulate aggressive responsiveness.
We addressed the question how separation form colony members versus recent and
frequent social interactions affect aggressive responsiveness to non-nestmates. In
behavioral tests, we separate workers and groups of workers of Formica rufa for
different time spans and subsequently test their aggressive responsiveness under
laboratory conditions and in the field. In addition, we use dummies, loaded with
extracts from the postpharyngeal gland (containing the CHCs) to investigate the ants’
response under highly controlled experimental conditions that also allow a detailed
analysis of the behavior based on high speed video recordings.
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