These Migrating Birds Take Turns at the Hard Work of Windbreaking

A flock of Northern bald ibis over the Adriatic Sea during their migration.
(Photo: A.G. Schmalstieg)

When flying in formation, the lead bird does the aerodynamic heavy lifting, and everybody else benefits by following in the aerodynamically sheltered path of another bird.  So why does the lead bird do it? And do they take turns? A new study of Northern Bald Ibises tests that question with multiple observations of migrating flocks.

They find that these birds travel in stable flocks, often including many related individuals. So they know each other and have ample motive for reciprocation. The result is that

How Monarch Butterflies Found (and Lost) Their Migration

Monarchs at their overwintering site cluster against the cold (Photo: Jaap de Roodee)

As the monarch butterfly migration faces a worsening risk of extinction, a research team has discovered the basis of that legendary migration in a single gene. Genetic analysis also suggests that monarch butterflies originated here in North America, not in the tropics, as previously thought.

Here’s the press release:

The monarch butterfly is one of the most iconic insects in the world, best known for its distinct orange and black wings and a spectacular annual mass migration across North America. However, little has been known about the genes that underlie these famous traits, even as the insect’s storied migration appears to be in peril.

Sequencing the genomes of monarch butterflies from around the world, a team of scientists has now made surprising new insights into the monarch’s genetics. They identified a single gene that appears central to migration — a behavior generally regarded as complex — and another that controls pigmentation. The researchers also shed light on the evolutionary origins of the monarch. They report their findings Oct. 1 in Nature.

“The results of this study shift our whole thinking about

Saving the Monarch Migration

Here’s my latest blog item at TakePart:

It’s been a dismal year for North America’s favorite migratory species, the monarch butterfly, beginning with the report that populations at overwintering sites in Mexico were down 59 percent from the previous winter. When researchers there measured the total area of trees occupied by monarchs—the stock for most of the continent—it added up to less three acres, an all-time low.

Nothing about the spring migration, which recently ended, gave new cause for hope. Monarch numbers are now so low that any catastrophic event could “send the population spinning downward even more,” says University of Kansas insect ecologist Chip Taylor, whose advocacy group Monarch Watch works to protect and rebuild monarch butterfly populations. The thin population could weaken conservation efforts, he says, “because if you don’t see them, you don’t have the motivation to do something about it.” He expects that the numbers will probably go even lower this coming winter.

The tendency is to blame the problem on Mexico, where logging of critical forests has been a perennial issue. Taylor says Mexico has made “a terrific effort to control illegal logging” and has largely put a stop to “the organized mafia-like groups that go in there with guns and cut down a hectare of forest in one night.” But serious incidents still sometimes occur.

A far larger problem, though, is the increasing intensity and efficiency of agriculture in the United States. Taylor dates the dramatic decline in monarch butterflies to the introduction of Roundup Ready corn and soybeans by the Monsanto Co. in the late 1990s. Until then … to read the rest of this post, click here.