Aggressive Communication By Larus Glaucescens Part Vi: Interactions of Territory Residents With a Remotely Controled, Locomotory Model

[Defenders maintaining a territory utilize similar strategies in defense when responding to a locomotory model as they do to intruders entering a territory. Model directional movement, body posture, and orientation were found to be highly correlated with subsequent behavioral response by the defender. Directional model movement caused an immediate position adjustment by the defender in most cases. Model towards movement resulted in a defender movement away and subsequent Display (Choke), while model movement Away caused a defender's Approach and subsequent Attack. Body posture was found to influence Attack rate as well as alter other behavioral responses by the defender. The lower head-neck posture was correlated with fewer attacks, thus showing that the low head-neck posture may convey greater threat to interacting birds. The orientation of a defender to the model during Attack was most common at angles greater than 90°. Thus the independent evaluation of orientation using the model shows that defenders as well as intruders are responsible for maintaining a particular orientation. The sex of defending birds interacting with the model was not distributed randomly. Males tended to interact more than females. Evidence supports the observation that male defenders are more aggressive than females. The non-correlation of certain behaviors during normal intruder-defender and model-defender interactions may be significant. It may be that the defender Upright Still and other behaviors are a "waiting" condition during which the defender plans its strategy under the influence of external threat conditions (i.e., movement, posture, orientation and sex recognition)., Defenders maintaining a territory utilize similar strategies in defense when responding to a locomotory model as they do to intruders entering a territory. Model directional movement, body posture, and orientation were found to be highly correlated with subsequent behavioral response by the defender. Directional model movement caused an immediate position adjustment by the defender in most cases. Model towards movement resulted in a defender movement away and subsequent Display (Choke), while model movement Away caused a defender's Approach and subsequent Attack. Body posture was found to influence Attack rate as well as alter other behavioral responses by the defender. The lower head-neck posture was correlated with fewer attacks, thus showing that the low head-neck posture may convey greater threat to interacting birds. The orientation of a defender to the model during Attack was most common at angles greater than 90°. Thus the independent evaluation of orientation using the model shows that defenders as well as intruders are responsible for maintaining a particular orientation. The sex of defending birds interacting with the model was not distributed randomly. Males tended to interact more than females. Evidence supports the observation that male defenders are more aggressive than females. The non-correlation of certain behaviors during normal intruder-defender and model-defender interactions may be significant. It may be that the defender Upright Still and other behaviors are a "waiting" condition during which the defender plans its strategy under the influence of external threat conditions (i.e., movement, posture, orientation and sex recognition).]