Something to crow about
Although the rooster's strident wake-up call just before sunrise feels as regular as an alarm clock, the evidence that the birds are somehow driven to herald the dawn has long been anecdotal. After all, a rooster is rarely shy about making his presence known regardless of the time of day.
Now, Japanese scientists have quite literally shed light on the phenomenon. To see whether roosters simply crow in response to external stimuli or according to a circadian rhythm -- an internally driven, cyclical pattern of behavior that occurs over a 24-hour period -- the team put one group of birds into a room with continuously dim lights and tracked the birds' crowing over the course of a month. Even in the absence of a daily cycle of light and dark, the authors report in Current Biology, the roosters continued to crow near dawn, suggesting that the birds' racket is indeed controlled by an internal clock. However, over time their crows became more scattered, suggesting that the rhythm eventually faded as they adjusted to a new regime of perpetual twilight.
The perks of being a wildflower
On April 3, the PBS series Nature will delve into the silent, secret conversations between plants. Plants can't talk, you say? Well, according to the documentary What Plants Talk About, flowers, trees and seedlings may not have brains or mouths, but they have other ways of communicating -- to cooperate, to compete and ultimately to survive.
For example, it's well known that plants compete for food and light, but some species, such as the Douglas fir, share resources. Using a massive underground fungal network, the trees supply nutrients to seedlings and other organisms.
The wild tobacco plant, meanwhile, defends itself against caterpillar attacks by communicating with the insect's predators. The plant releases a toxin that, when ingested, makes the caterpillar stink. This odour attracts animals that eat the caterpillar before it finishes eating the plant.
The parasitic dodder vine, unable to produce its own food, "sniffs" out the chemical scents of nearby plants to find a suitable host, from which it can suck water and nutrients. The program features time-lapse video that demonstrates how the vine tendril twirls around on itself, circling in the air for hours until it homes in on the right scent.
Plants and trees, says experimental plant ecologist JC Cahill, are "actively engaging with the environment in which they live. They actively respond to the nutrients and the predators and the herbivores that are around them. It's a really dynamic system."
-- The Washington Post