Why hummingbirds love sweets


This video from Alaska is called Hand feeding [Rufous] Hummingbirds.

From Live Science:

The Surprising Reason Hummingbirds Love Sweets

By Megan Gannon, News Editor

August 21, 2014 02:00pm ET

Nectar-slurping hummingbirds clearly ­have a taste for sweets — but they shouldn’t. Like all other birds, they lack sweet-taste receptors on their palates and long tongues, so in theory, they should be immune to the temptations of sugary foods.

However, new research reveals why hummingbirds feast freely on nectar: At some point in their evolution, the birds transformed a taste receptor that’s typically used to detect savory or umami flavors into one that’s used to taste sweets instead.

Hummingbirds are constantly wavering between a sugar rush and starvation. Their metabolisms are hyperactive, their hearts can beat 20 times a second, and they often need to eat more than their body weight in food each day to stay alive. [Images: Beautiful Hummingbirds of the World]

The small birds eat the occasional insect, but they largely subsist on nectar from flowers, which is not a typical source of food for most other birds. As a result, hummingbirds have been able to carve out a distinct environmental niche. The birds can now be found throughout North and South America, in habitats ranging from high-altitude mountains in the Andes to tropical rainforests, and they’re quite diverse. They have split into more than 300 species in the estimated 42 million years since they parted from their closest relative, the insect-eating swift.

Scientists have been puzzled by the fact that hummingbirds maintain such a sugary diet without a sweet-taste receptor. For most mammals, the sweet-taste receptor that responds to sugars in plant-based carbohydrates is made up of two proteins: T1R2 and T1R3. The taste receptor that detects savory, or umami, flavors found in meat and mushrooms is made up of the proteins T1R1 and T1R3.

But after the chicken genome was sequenced in 2004, researchers noticed the birds lacked the gene that encodes T1R2, a crucial component of the sweet-taste receptor. This same pattern was seen in other bird genomes.

“If a species is missing one of those two parts, then the species can’t taste sweet at all,” said Maude Baldwin, a doctoral student of evolutionary biology at Harvard University and one of the researchers on the study.

When scientists sequenced the genomes of cats, lions, tigers and cheetahs — true carnivores that also don’t have a taste for sweets — they found these species still have a nonfunctional “pseudogene” (a nonfunctional gene that’s lost its protein-coding powers) for the sweet-taste receptor. But in bird genomes, scientists never even found a trace of a pseudogene for a sweet tooth, Baldwin told Live Science.

To figure out what made hummingbirds like sweets despite their lack of the sweet-taste receptor, Baldwin and colleagues cloned the genes for the T1R1-T1R3 taste receptors from omnivorous chickens, insectivorous swifts and nectivorous hummingbirds. The researchers then tested how the taste-receptor proteins produced by these genes reacted to different “flavors” in a cell culture.

For chickens and swifts, the receptor had a strong reaction to the amino acids behind umami flavors. The hummingbird receptor, on the other hand, was only weakly stimulated by umami flavors, but it did responded strongly to the sweet flavors of carbs, the researchers found.

Then, to look for the molecular basis for this change in function, Baldwin and colleagues made taste-receptor hybrids using different parts of the chicken and hummingbird receptors. They found that by mutating the chicken receptor in 19 different places, they could get it to respond to sweets, but the researchers suspect there are more mutations that contributed to the change in hummingbirds.

Further research could eventually show where this change for hummingbirds arose in the evolutionary process — and how other nectivores like orioles and honeyeaters developed a taste for sweets. It’s still not clear why birds lost their sweet receptor in the first place, but perhaps it was due to the loss of sweets in their diet.

“Birds are the descendants of carnivorous dinosaurs, so maybe this gene was lost early on because of the diet of their ancestors,” Baldwin said. “That would be very cool, but we’re still not sure.”

The findings were detailed today (Aug. 21) in the journal Science.

See also here. And here.

Young snowy owls in Alaskan summer


This video says about itself:

Cornell Lab Staff Member Visits Snowy Owls with Denver Holt. July 22, 2014

Cornell Lab staff writer Pat Leonard travelled to Barrow, Alaska, to visit owl researcher Denver Holt of the Owl Research Institute, who has been studying Snowy Owls for more than 20 years. They visited the owl nest that’s featured on the explore.org and Bird Cams site. The nest originally had seven owlets, but the researchers know of only two that are still alive. Pat Leonard describes how the nest checkup went in her blog.

Alaska grizzly bears on webcams


This video is called Battle Of The Giant Alaskan Grizzlies.

From eNature.com in the USA:

Watch Live As Grizzlies Catch Salmon

Salmon are running in Alaska and Brooks Falls in Katmai National Park may be the best place to watch local bears gorge themselves on fresh caught salmon.

Explore.org has a number of webcams on the scene and you can almost always observe a bear or two (or three or four!) in action.

Snowy owl nest in Alaska on the Internet


This video says about itself:

Arctic Snowy Owl Prey Delivery by Male

9 July 2014

A pile of four owlets await their mother’s arrival on the tundra outside Barrow, Alaska. Soon after she alights, the male owl flies in to deliver a lemming, exchanges it with the female, and departs while she begins to provision the owlets.

Learn about the Owl Research Institute’s work with Snowy Owls here.

From the Cornell Lab of Ornithology in the USA:

Watch Snowy Owlets in Alaska

In the tundra around Barrow, Alaska, Snowy Owls nest in the 24-hour sunlight. Now you can watch one of these nests, featuring seven growing owlets, live on our Bird Cams. The camera is located a respectful distance from the nest, so be aware that the owlets are not always visible (they tend to hunker behind a low rise). But their parents visit regularly with meals of lemming and duck—as you can see in this video highlight. What are the owlets up to now? Check in on the Snowy Owl cam.

Got Snowy Questions? We’re holding live-chat Q&A sessions every day through Friday this week, from 4:00 to 5:00 p.m. Eastern time.

Alaskan shorebirds nest earlier because of climate change


This video is called Celebrating Alaska’s Shorebirds. It says about itself:

21 May 2014

In Alaska, hundreds of diverse species from tiny songbirds to the much larger sandhill cranes and majestic trumpeter swans all share the same rich nesting grounds.

The fact that these shorebirds, some weighing in at a fraction of an ounce, travel up to 20,000 miles annually simply gives us humans a profound sense of awe when they arrive each spring, right on schedule. Celebrating Alaska’s Shorebirds chronicles this amazing migration against the spectacular background of Alaskan scenery. Produced over a two and a half year period of field work this stunning film has captured many stunning images in a variety of locations with in Alaska where these birds land to feed, rest, nest and breed.

From Wildlife Extra:

Arctic birds nesting earlier to catch advancing springs

Snow melt in the Arctic Alaska is causing migratory birds to breed nearly a week earlier than ten years ago, a new study shows.

For nine years scientists have monitored 2,500 nests of four shorebird species and one songbird, across four sites, recording when the first eggs were laid in each.

They discovered that the birds have advanced their nesting by an average of 4-7 days over the nine years, and snow melt, over other contributory factors such as abundance of nest predators and the seasonal flush of new vegetation, was the main cause.

“It seems clear that the timing of the snow melt in Arctic Alaska is the most important mechanism driving the earlier and earlier breeding dates we observed in the Arctic,” said lead author Joe Liebezeit of the Audubon Society of Portland in the USA.

The four sites ranged from the oilfields of Prudhoe Bay to the remote National Petroleum Reserve of western Arctic Alaska, and the species monitored included the semi-palmated sandpiper, red phalarope, red-necked phalarope, and pectoral sandpiper.

“Migratory birds are nesting earlier in the changing Arctic, presumably to track the earlier springs and abundance of insect prey,” said Wildlife Conservation Society Coordinator of Bird Conservation Steve Zack.

“Many of these birds winter in the tropics and might be compromising their complicated calendar of movements to accommodate this change.

“We’re concerned that there will be a threshold where they will no longer be able to track the emergence of these earlier springs, which may impact breeding success or even population viability.”

Climate change threatens 314 North American bird species: here.

Steppe bison discovery on Texel island


This video says about itself:

BBC Monsters We Met – 1 of 3 – The Eternal Frontier

Episode 1: Eternal Frontier (Alaska, United States, North America, 14,000 years ago) Woolly Mammoth (Mammuthus primigenius) American Lion (Panthera leo atrox) (live-acted by a African Lioness) Homotherium (Scimitar-tooth Cat) Smilodon (Saber-tooth Cat) Megalonyx (Jefferson’s Ground Sloth) Camelops (Giant Camel) (live-acted by a Dromedary Camel) Arctodus (Short-Faced Bear) American mastodon (Mammut americanum) Steppe Bison (live-acted by an American Bison) Hagerman Horse (live-acted by a Grevy’s Zebra) American Cheetah (live-acted by a Snow Leopard) Wild horse (live-acted by a Przewalski’s Horse) Grey Wolf (live-acted) American Bison (live-acted) Andean Condor (live-acted) Brown Bear (live-acted) Muskox (live-acted) Caribou (live-acted) Saiga (live-acted) California Condor (live-acted) Dall Sheep (live-acted) … Wolverine (live-acted).

Steppe bison are an extinct species, ancestral to both today’s American bison and European bison.

Recently, a former employee of Ecomare museum found a steppe bison astralagus bone in the dunes of Texel island. Probably, it had landed there from the North Sea; which was land when steppe bison were still alive.

The discoverer gave the bone to Ecomare.

Wildlife biologists recently scanning photographs taken by a trail camera in the Uinta Mountains last winter, saw something never before captured in Utah: the first official photographs of a wolverine: here.

Leaked Document: Scientists Ordered to Scrap Plan to Protect Wolverines: here.

How polar bears survive the Arctic


This video from Alaska is called Grizzly vs. Polar Bear.

From Wildlife Extra:

Gene study reveals how polar bears cope with killer lifestyle

A study of the genes of polar bears reveals how quickly they evolved to handle the extremes of life in the high Arctic, and why, and how they cope with being profoundly obese. A comparison between polar and brown bears has found that the former is a much younger species than previously believed, having diverged from brown bears less than 500,000 years ago to spend life on sea ice. There, the bears subsist on a blubber-rich diet of marine mammals that would result in cardiovascular diseases in other species. The relatively short time that has passed in its evolution and how it evolved was what interested the scientists.

The study, published in the journal Cell, was a collaboration between Danish and Chinese researchers and a team from the University of California Berkeley, including Eline Lorenzen and Rasmus Nielsen.

Unlike other bears, fat comprises up to half the weight of a polar bear. “For polar bears, profound obesity is a benign state,” said Lorenzen. “We wanted to understand how they are able to cope with that. The life of a polar bear revolves around fat. Nursing cubs rely on milk that can be up to 30 per cent fat, and adults eat primarily blubber of marine mammal prey. Polar bears have large fat deposits under their skin and, because they essentially live in a polar desert and don’t have access to fresh water for most of the year, rely on metabolic water, which is a by product of the breakdown of fat.”

The genome analysis comes at a time when the polar bear population worldwide, estimated at between 20,000 and 25,000, is declining and its Arctic sea ice habitat is rapidly disappearing. As the northern latitudes warm, the polar bear’s distant cousin, the brown or grizzly bear is moving farther north and occasionally interbreeding with the polar bear to produce hybrids that have been called ‘pizzlies’. This is the possibly the same process that led to the emergence of polar bears in the first place.

The bears’ ability to interbreed is a result of a very close relationship, Nielsen said, which is one-tenth the evolutionary distance between chimpanzees and humans. “It’s really surprising that the divergence time is so short. All the unique adaptations polar bears have to the Arctic environment must have evolved in a very short amount of time.”

These adaptations include not only a change from brown to white fur and development of a sleeker body, but big physiological and metabolic changes as well. The genome comparison revealed that over several hundred thousand years, natural selection drove major changes in genes related to fat transport in the blood and fatty acid metabolism. One of the most strongly selected genes is APOB, which in mammals encodes the main protein in LDL (low density lipoprotein), known widely as “bad” cholesterol. Changes or mutations in this gene reflect the critical nature of fat in the polar bear diet and the animals’ need to deal with high blood levels of glucose and triglycerides, in particular cholesterol, which would be dangerous in humans.

What drove the evolution of polar bears is unclear, though the split from brown bears coincided with a particularly warm 50,000-year interglacial period known as Marine Isotope Stage 11. Environmental shifts following climate changes could have encouraged brown bears to extend their range much farther north. When the warm interlude ended and a glacial cold period set in, a pocket of brown bears may have become isolated and forced to adapt rapidly to new conditions.

There is potential for the polar bear research also to have applications in the study of human’s lifestyles. “Polar bears have adapted genetically to a high fat diet that many people now impose on themselves,” said Nielsen. “If we learn a bit about the genes that allows them to deal with that, perhaps that will give us tools to modulate human physiology down the line.”

See also here.

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