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Territorial intrusions are related to the peak frequencies of yodels given by male common loons.

Year: 
2011
Researcher(s): 
Mager, J., Walcott, C., Backus, J., Nebgen, E., and D. Norris
Institution: 
Ohio Northern University
Discipline: 
Ecology, Animal Behavior, Ornithology
In addition to their identity, male Common Loons (Gavia immer) communicate condition-dependent fighting abilities through the dominant frequencies (better condition individuals produce lower-frequency signals), and a heightened aggressive motivational state by lengthening their territorial yodels by adding two-syllable repeat syllables. Through an acoustic playback experiment, we experimentally examined whether the dominant frequencies of either resident or non-resident yodels affected an intruder’s (i.e., conspecifics flying over a territory) propensity to land upon a breeding territory. Among 33 territories from which we broadcast yodels having three repeat phrases, we found that potential intruders were more likely to land on territories when we broadcast higher-frequency yodels to them. These results provide the first empirical support of the idea that conspecific prospectors consider the dominant frequencies of a yodel in deciding whether to land upon a potential breeding territory, and support observational studies that infer that males that communicate poorer fighting ability can hold onto breeding territories by communicating greater aggressive motivation.
Behavior 2011: The Joint Conference of the Animal Behavior Society and International Ethological Conference