Migratory Songbirds Have a Specialized Night-Vision Brain Area

Jun 08, 2005

Research shows special molecules help the birds navigate at night

Neurobiologists have discovered a specialized night-vision brain area in night-migratory songbirds. They believe the area might enable the birds to navigate by the stars, and to visually detect the earth's magnetic field through photoreceptor molecules, whose light-sensitivity is modulated by the field.

The researchers published their findings May 23, 2005, in the early online edition of the Proceedings of the National Academy of Sciences. The collaboration was led by Henrik Mouritsen of the University of Oldenberg in Germany and Erich Jarvis of the Duke University Medical Center. Other co-authors were Gesa Feenders and Miriam Liedvogel in Mouritsen's laboratory and Kazuhiro Wada in Jarvis's laboratory. The research was supported by the VolkswagenStiftung to Mouritsen and the National Science Foundation's Waterman Award to Jarvis.

To migrate successfully over thousands of miles at night, night-migratory birds need to see where they fly, as well as navigate by stars and the earth's magnetic field. Surprisingly, Jarvis said, recent scientific evidence has suggested that birds have specialized molecules in their visual system that translate magnetic compass information into visual patterns. Thus, , the researchers hypothesized that night migratory birds would need a specialized night-vision brain area.

"There was no evidence of such a specialized region in night migratory birds before we began this research," Jarvis said.

In their study, the researchers compared two species of night-migratory songbirds -- garden warblers and European robins -- with two non-migratory songbirds -- zebra finches and canaries.

Using a transparent cylindrical cage in Mouritsen's laboratory, they first accustomed the birds to the illumination equivalent of moonlight. They waited until the birds were sitting quietly to eliminate brain activity from movement. The researchers then quickly preserved the birds' brains, and in Jarvis's laboratory analyzed the brain structures for the active expression of two genes called ZENK and c-fos that signal activity in a particular brain region.

The researchers found that the night-migratory species showed strikingly high activity in a particular cluster of cells located adjacent to a known visual pathway. According to Jarvis, what excited the researchers was that the area, which they named Cluster N, was not active in the migratory birds during the daytime. Furthermore, non-migratory songbirds did not show strong activation in the Cluster N even under moonlight conditions.

To determine whether the brain cluster is really specialized for night-vision, the researchers performed the same gene expression analysis on the night-migratory songbird species with the birds' eyes covered. The researchers found that blocking night-time vision dramatically reduced gene activity in cluster N.

"This result confirmed that night-migratory birds seem to have a brain area specifically adapted for seeing during their night-time flight," Jarvis said. The researchers suspect that the newly discovered brain region could be involved in processing and integrating light-dependent magnetic compass information and star compass information; and thus may be responsible for the impressive navigational abilities of birds migrating during the night. In future studies, Jarvis, Mouritsen and their colleagues plan to test this hypothesis in more detail, they said.

Source: Duke University

Explore further: Oceans apart: Study reveals insights into the evolution of languages

add to favorites email to friend print save as pdf

Related Stories

Smarter than a first-grader?

Jul 24, 2014

In Aesop's fable about the crow and the pitcher, a thirsty bird happens upon a vessel of water, but when he tries to drink from it, he finds the water level out of his reach. Not strong enough to knock over ...

Recommended for you

Modern population boom traced to pre-industrial roots

1 hour ago

The foundation of the human population explosion, commonly attributed to a sudden surge in industrialization and public health during the 18th and 19th centuries, was actually laid as far back as 2,000 years ...

Researcher looks at the future of higher education

1 hour ago

Most forecasts about the future of higher education have focused on how the institutions themselves will be affected – including the possibility of less demand for classes on campus and fewer tenured faculty members as ...

Now we know why it's so hard to deceive children

2 hours ago

Daily interactions require bargaining, be it for food, money or even making plans. These situations inevitably lead to a conflict of interest as both parties seek to maximise their gains. To deal with them, ...

How financial decisions are made

4 hours ago

Jayant Kale didn't grow up dreaming of becoming a leading expert in corporate finance and mutual fund investment. But he's happy he invested in that market early in life.

User comments : 0