Bird Egg Shape Determined By Flying Ability?

Owls’ are spherical, hummingbirds’ are elliptical and sandpipers’ are pointy. All bird eggs have the same function — to protect and nourish a growing chick. But they come in a brilliant array of shapes. This variety has puzzled biologists for centuries. Now, in the most comprehensive study of egg shapes to date, a team of scientists seems to have found an answer.

The researchers cataloged the natural variation of egg shapes across 1,400 bird species, created a mathematical model to explain that variation, and then looked for connections between egg shape and many key traits of birds. On a global scale, the authors found, one of the best predictors of egg shape is flight ability, with strong fliers tending to lay long or pointy eggs.

In the new study, the authors conducted a multistep investigation that brought together biology, computer science, mathematics and physics. They first wrote a computer program, named Eggxtractor — who says scientists have no sense of humor? —, that classified eggs based on their ellipticity and asymmetry. Elliptical eggs are elongated and round on both ends, like cucumbers, and asymmetric eggs are pointier on one end, like mangoes. With Eggxtractor, the researchers plotted nearly 50,000 eggs, representing all major bird orders, from a database of digital images by the Museum of Vertebrate Zoology in Berkeley, Calif.

Next, the researchers attempted to answer how eggs might acquire varying shapes. Rather than looking at the shell, as one might expect, they focused on the egg’s membrane (the film you see when peeling a hard-boiled egg), which is essential to the egg’s shape.

The scientists identified two parameters that could influence egg form: variations in the membrane’s composition and differences in pressure applied to the membrane before the egg hatches. By adjusting these parameters, they were were able to completely recover the entire range of observed avian egg shapes.

Finally, the researchers looked into why egg shapes might be so spectacularly diverse. One popular hypothesis centered on nest location: Cliff-nesting birds, it was thought, lay pointy eggs so that if the eggs are bumped, they spin in a circle rather than rolling off the cliff. Another suggested that birds lay eggs in shapes that pack together best in different-size clutches.

But when the authors related egg shape to these and other variables, they were surprised to find that none of them fit on a global scale (though they may still play important roles on smaller scales). Instead, egg shape was strongly correlated with a measure of wing shape, called the hand-wing index, that reflects flight ability.

So what connects flight to egg shape? In general, birds want to pack as many nutrients as possible into their eggs. But, in order to fly, they must maintain sleek bodies — meaning their eggs can’t be too wide.

Common murres, for instance, are fast, powerful fliers and have asymmetric eggs, as do least sandpipers, which migrate long distances. Wandering albatrosses are one of the most far-ranging fliers (some have been known to circumnavigate the Antartic Ocean three times in a year) and they have elliptical eggs.

Eastern screech owls rarely move beyond their small territory, where they tend to fly in short, low-powered glides, and have almost spherical eggs.

“Perhaps, evolutionarily, birds stumbled upon this very natural, geometric solution, which is to increase the ellipticity and asymmetry of their eggs,” Dr. Mahadevan said, since doing so allows for greater volume without increasing girth. This explanation requires further research, he added.

Ultimately, this study shows that “we can challenge old assumptions,” Dr. Stoddard said. ”In something as familiar and common as a bird egg, we are still discovering new truths.”

Why Whales Are So Big…A Mystery No More?

Whales are the largest animals on the planet, but they haven’t always been giants. Fossil records show that ancient whales were much smaller than the currently living behemoths. The largest whale on record is held by the great blue whale–a species that can be found in every museum around the globe.

It can weigh as much as 24 elephants and grow longer than two school buses. Its jawbone is as big as a telephone pole, its heart is the size of an oil drum and it can consume up to two tons of food in a single day. But exactly when whales became the largest animals on the planet — and why — has been a mystery. Until now.

A new study suggests it might be due to changes in climate that affected the food that some whales eat: krill and small fish. Instead of being spread throughout the ocean, lots of krill started being packed into a small area. Bigger whales were simply more efficient at eating the dense pockets of krill, and they beat out their smaller cousins.

These whales use filters to feed on the tiny krill. Known as baleens, they include the largest whale on Earth — the blue whale. The baleen filter looks like bristles of a comb and is made up of keratin — the same stuff in our fingernails. To eat, the whale opens its mouth and takes in a huge gulp of water. Then it spits the water back out, and food like krill are caught in the baleen filter. It’s a highly efficient way to eat, allowing whales to pack on the pounds.

This has been met with some resistance, however. Stanford University researcher Jeremy Goldbogen says Baleen can’t be the only reason why whales got so big. He goes on to say: “Baleen evolved about 20 million years ago, and we didn’t see the evolution of gigantism until about very recently, about 3 million to 5 million years ago.”

Goldbogen’s group looked back to see what was happening in the ancient oceans, and if there were any clues about what caused the massive growth spurt.

They found that around the time baleens began growing larger, the ice ages started. The researchers think changes in climate led to increased runoff and more nutrients pouring into the coasts. Around the same time, there was an increase in ocean upwelling–which occurs when wind pushes surface waters off-shore and causing deeper ocean waters underneath surface waters to replace it. Those deep waters are often full of nutrients and food for the whales.

The combination of the ice ages and more upwelling resulted in dense patches of food in the ocean — setting the stage for massive whales to win out.

“As animals are getting bigger, they’re getting much more efficient. So for every gulp, they’re getting tremendous amounts of energy” Goldbogen says.

Think about it this way: It takes a lot of energy for a giant whale to open its giant mouth. If a lot of food is packed into a small space, those whales can swallow it up in one big gulp and it’s worth all the energy it takes. But if the food is spread out and the whales have to swim around opening and closing their mouths a lot — then it’s not great to be a big ol’ whale. So big whales are more efficient at eating the dense patches of food, while smaller whales might be more suited to eating food dispersed throughout the ocean.

The changes in the ocean also allowed to whales to get really big, really fast. The researchers reported in the journal Royal Society B that the whales increased in body mass from 10 tons to 100 tons in just a few million years.

While it is hard to draw a direct connection between whale size and ocean dynamics 3 million years ago, other studies support the hypothesis. “There are cases where food limitation or food production can basically control body size changes on very short time scales,” Goldbogen says referring to a 2013 study published in the ICES Journal of Marine Science.

Therefore, “the inference here is that if you have enough food available and very very efficient animals, that perhaps they can evolve larger and larger body sizes.”

Goldbogen is more than a little excited to be studying these ocean giants. “We’re totally living in a time of giants. Unlike no other time in Earth’s history” he says. “We have a unique opportunity to study how the largest animals of all time function in these different ecosystems, and that’s a lot of fun.”

Goldbogen thinks the next question is, “Are whales still getting bigger? If we fast-forward a few million years into the future if food is not limiting, can they evolve even greater body sizes?”

We’ll have to wait to find out.

Colorado Wild Animal Sanctuary Euthanizes ALL Its Animals Following Relocation Dispute

If you ever needed another reason to believe that our world grows a little darker each day, this is a good one. A wild animal sanctuary in Colorado has euthanized all its animals after a relocation dispute.

The Lion’s Gate Sanctuary put down its three lions, three tigers and five bears on April 20 after local county commissioners denied their request to move about 20 miles from its site southeast of Denver. The sanctuary owner and local psychologist, Dr. Joan Laub, said that she had “no other option” as the site had repeatedly flooded over the past two years–making it impossible for them to care for the animals properly.

The Elbert County Commissioners said that they were “shocked” and “saddened” by the decision after the sanctuary’s owners had promised to continue to care for the animals at the center if their proposal was turned down. “The decision by the operators of Lion’s Gate to euthanize all their animals comes as total surprise,” they said in an official statement.

“Only two weeks earlier, the operators of the facility assured the County in a public forum that if the application was denied, they would still continue to operate at their current location as they had for the previous 10 years.”

Laub, however, vehemently denies ever giving such an assurance, calling the statement a “blatant lie”. In a statement to an online publication, Laub stressed “We want to be clear we did not put our animals down because we were denied by the Elbert County Commissioners. We put our animals down because it was NO LONGER SAFE FOR THEM AND NO LONGER SAFE FOR THE PUBLIC. This was made abundantly clear to the Elbert County Commissioners. The commissioners were not concerned with the safety of residents around the Sanctuary–only the residents at the relocation site.”

The commissioners added that the nearby Keenesburg Wildlife Sanctuary, which is home to 450 animals, had publicly offered to care for the animals at their facility if Lion’s Gate was unable to do so.

The founder and executive director of Keenesberg park, Pat Craig, mentioned that Lion’s Gate had so few animals that “they would easily be able to place every animal with another wildlife sanctuary”. This comes along with his surprised reaction that the owners of Lion’s Gate did not try to find a new home for their animals.

“Given these facts, the news that Lion’s Gate euthanized all 11 animals at the same time and so shortly after the decision to deny the move comes as an absolute shock” the county commissioners added.

Dr. Laub argued that she was not able to move the animals–some of which were endangered–to another sanctuary because they were already old and vulnerable. “We did think long and hard about relocating these animals,” she said “However, due to their ages and disabilities, they would not have survived a move to a new facility. Our vet agreed to this.”

Given this information, it is unclear why she would have asked to have the animals relocated to begin with. The Colorado Parks and Wildlife official Facebook page says that their purpose was to “rescue and protect exotic animals” but said that the sanctuary owners are within their legal rights to work with their vets to decide when to put down animals.

All 11 animals have since been buried since being euthanized.

Plausible Sightings of Extinct Tasmanian Tiger Sparks Search in Queensland

Zoologists in Queensland are in a tizzy. It seems that plausible possible sightings of a Tasmanian tiger in Northern Queensland has triggered scientists to undertake a search for the species long thought to have died out more than 80 years ago.

The last Tasmanian tiger was thought to have died in Hobart Zoo in 1936. It was also widely believed to have become extinct on mainland Australia at least 2,000 years ago. As of late, sightings of some large dog-like animals that are neither dingoes nor foxes have spiked in the recent decades despite the common skepticism that surrounded the accounts.

It was the recent eyewitness accounts of potential thylacines in the far Northern Queensland that became the catalyst for scientists from James Cook University to launch a search for the animal.

It is Professor Bill Laurance said that he had spoken, at some length, with two people about the animals they had seen in Cape York peninsula that could potentially be Tasmanian tigers. The accounts of the sightings were quite plausible as the descriptions of the animals were quite detailed.

One was a long standing employee of the Queensland National Park Services and the other was a frequent camper in the north of the state. The professor said all the potential sightings to date had been at night. “In one case, four animals were observed at close rage–about 20 feet away–with a spotlight.”

The detailed descriptions of the eyes, shape, and behavior were inconsistent with the known attributes of other large species in the north Queensland. The common animals in the area are dingoes, wild dogs, or feral pigs.

The sightings occurred at two separate locations on the Cape York peninsula but the specific details of the locations are being kept confidential. “Everything is being handled with strict confidence,” says Laurance.

He mentioned people who claimed to have seen a thylacine were “quite nervous about relating their tales for fear of being branded kooks or fringe types”.

Even English ethologist, evolutionary biologist and author, Richard Dawkins has tweeted hopefully regarding news of the study. “Can it be true? Has Thylacinus been seen alive? And in mainland Australia not Tasmania? I so want it to be true.”

Sandra Abell, a researcher with James Cook University’s Center for Tropical Environmental and Sustainability Science who was leading the field survey has said that they had been contacted with more possible sightings since their intentions were made known to the public. She was in the process of deciding on sites for more than 50 cameras that will be set up on Cape York peninsula. Their target date shall be at the onset of the dry season in April or May.

Abell also said even if a thylacine was not detected, the survey would inform the center’s understanding of the status of rare and endangered mammal species on the peninsula. It seems that several mammals, including the northern bettong, were at risk from introduced predators.

“It is a low possibility that we’ll find thylacines, but we’ll certainly get lots of data on the predators in the area and that will help our studies in general,” she said.  It was “not impossible” there were thylacines to be found. “It is not a mythical creature. A lot of descriptions people give, it’s not a glimpse in the car headlights. People who say they’ve actually seen them can describe them in great detail–so it’s hard to say they’ve seen anything else. I’m not ruling it out at all, but to actually get them on camera will be incredibly lucky.”

We’re all hoping the rediscovery of a thriving Tasmanian tiger, aren’t you?

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