For decades, biologists studying migratory songbirds maintained that magnetic reception served as their sole primary mechanism for long-distance navigation. Early laboratory experiments supported this view by demonstrating that altering artificial magnetic fields disoriented captive birds during their migratory season. Consequently, prevailing models treated geomagnetic orientation as the complete and sufficient explanation for avian migration routes.
However, field research in the late 1990s began to reveal anomalies that the geomagnetic model could not adequately explain. Researchers tracking free-flying birds observed that they maintained accurate trajectories even through geographic zones with severe magnetic distortions. Furthermore, temporary disruption of the birds' olfactory receptors caused disorientation under cloudy nighttime conditions, despite their intact geomagnetic sensitivity. These findings indicated that magnetic sensing alone was insufficient to guide precise nocturnal travel.
In response to these conflicting observations, contemporary avian biologists have developed a multi-cue integration model. According to this framework, migratory songbirds do not rely on a single compass system; instead, they calibrate magnetic inclinations against visual cues at sunset and use olfactory cues for regional navigation. By framing avian navigation as a hierarchical, multi-sensory process, this new model reconciles earlier laboratory findings with recent ecological data.
Which one of the following most accurately describes the organization of the passage?
- A traditional scientific explanation is outlined, empirical evidence challenging its adequacy is introduced, and a new integrative model that resolves the conflict is described.Answer
- BA long-standing theoretical paradigm is introduced, all previous experimental evidence supporting it is proven fraudulent, and an unrelated biological phenomenon is explored.
- CTwo competing hypotheses are evaluated against experimental data, both are rejected as unscientific, and a call for entirely new laboratory methods is issued.
- DA biological process is defined, several competing evolutionary explanations for its origins are debated, and one historical perspective is firmly endorsed.
- EAn experimental technique is detailed, the specific equipment used to gather field data is defended against criticism, and future applications of the technology are projected.