Marking Loons, Making Progress
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Common the common loon may be, but it’s behavior remained enigmatic until the emergence of bird-marking techniques that have now begun to yield long-term findings. Almost two decades reveal that loons do not mate for life, as so long supposed, that breeding pairs may be intruded upon by both male and female invaders, and that territorial fights between males can lead to fatalities 30 percent of the time. In fatal fights, the invader is always the victor. Sonogram studies reveal that the signature of these territorial birds, their yodel, is both characteristic of individuals yet also changes as their physical state and circumtances change.