Science Monday, July 16, 2012

Lilies blooming too early for hummingbirds seeking nectar

Glacier lilies, whose yellow flowers can be seen in mountain meadows throughout western North America in the early spring, are now appearing even earlier in the spring.

The hummingbirds that depend on the lily’s nectar, however, are still returning to the meadows around the same time they used to.

Broad-throated hummingbirds complete their migration from Central America to the mountain meadows where they breed just before the lilies bloom, but the earlier springs mean that lilies are now blooming 17 days earlier than they were for decades, according to researchers based at the Rocky Mountain Biological Laboratory outside Crested Butte. Hummingbirds, however, are in general arriving only a few days earlier.

If the trends keeps up, the birds will miss their flower food source altogether within two decades. Bird populations that breed at northern latitudes would be most at risk, according to the study, which was published in the journal Ecology last month.

Other studies have observed similar gaps in timing between the emergence of butterflies and the blooming of their mountain wildflower food sources, as well.

■ New research has provided more evidence that the North American continent was colonized by at least two different human cultures with distinctive technology and that the Clovis culture, once thought to be the hemisphere’s oldest human inhabitants, might not have been the first.

The research comes from analyses of dried prehistoric feces in the Paisley Caves of eastern Oregon and marks a milestone in the work of the University of Oregon’s Dennis Jenkins, nicknamed Dr. Poop, who has spent years studying the caves, home to some of the oldest remains of human civilization in the Western Hemisphere.

His team’s analysis also suggests that not only did two distinct cultures co-exist on the continent more than 13,000 years ago, but that the occupants of the Paisley Caves might actually have arrived from Siberia ahead of those of the Clovis culture.

■ Climate change is expected to affect everything from sea levels to crop yield. But what about dairy cows, you may ask. Your answers are finally here.

Heat stress can impact milk production, and as average temperatures gradually warm, that production will gradually decline, but that much was already known. Now, researchers from the University of Washington have shed light on just how that decline might look in different counties throughout the country.

In some places, like cheese heavyweight Tillamook, Ore., dairy cows become less productive once temperatures are around 59 degrees, for instance, whereas in parts of much drier Arizona milk production does not drop off until 77 degrees. But the rate at which production drops off or frequency at which it does also varies widely from place to place.

In general, though, cows are less productive in the southern U.S. where summer heat slows their production, and climate change is expected to make those southern cows even less so.

But while milk production is expected to decline 6 percent by 2080, the researchers note that management and breeding improvements should more than make up for that decline.


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