Wintery Knight

…integrating Christian faith and knowledge in the public square

New study: how the hummingbird performs stunning feats of aerobatics

Hummingbird in flight

Hummingbird in flight

New study reported by Science Daily.


The sight of a tiny hummingbird hovering in front of a flower and then darting to another with lightning speed amazes and delights. But it also leaves watchers with a persistent question: How do they do it?

Now, the most detailed, three-dimensional aerodynamic simulation of hummingbird flight conducted to date has definitively demonstrated that the hummingbird achieves its nimble aerobatic abilities through a unique set of aerodynamic forces that are more closely aligned to those found in flying insects than to other birds.

The new supercomputer simulation was produced by a pair of mechanical engineers at Vanderbilt University who teamed up with a biologist at the University of North Carolina at Chapel Hill. It is described in the article “Three-dimensional flow and lift characteristics of a hovering ruby-throated hummingbird” published this fall in the Journal of the Royal Society Interface.

For some time researchers have been aware of the similarities between hummingbird and insect flight, but some experts have supported an alternate model which proposed that hummingbird’s wings have aerodynamic properties similar to helicopter blades. However, the new realistic simulation demonstrates that the tiny birds make use of unsteady airflow mechanisms, generating invisible vortices of air that produce the lift they need to hover and flit from flower to flower.

You might think that if the hummingbird simply beats its wings fast enough and hard enough it can push enough air downward to keep its small body afloat. But, according to the simulation, lift production is much trickier than that.

For example, as the bird pulls its wings forward and down, tiny vortices form over the leading and trailing edges and then merge into a single large vortex, forming a low-pressure area that provides lift. In addition, the tiny birds further enhance the amount of lift they produce by pitching up their wings (rotate them along the long axis) as they flap.

Hummingbirds perform another neat aerodynamic trick — one that sets them apart from their larger feathered relatives. They not only generate positive lift on the downstroke, but they also generate lift on the upstroke by inverting their wings. As the leading edge begins moving backwards, the wing beneath it rotates around so the top of the wing becomes the bottom and bottom becomes the top. This allows the wing to form a leading edge vortex as it moves backward generating positive lift.

According to the simulation, the downstroke produces most of the thrust but that is only because the hummingbird puts more energy into it. The upstroke produces only 30 percent as much lift but it takes only 30 percent as much energy, making the upstroke equally as aerodynamically efficient as the more powerful downstroke.

Large birds, by contrast, generate almost all of their lift on the downstroke. They pull in their wings toward their bodies to reduce the amount of negative lift they produce while flapping upward.

Awesome design in nature!

So the question I have from reading the article is this. Do birds and flying insects have a recent common ancestor? I don’t have too many friends who can answer this for me, but I asked one of them and they both said there is no recent common ancestor for hummingbirds and flying insects. So this looks like another example of convergence – common design in two animals that don’t share a recent common ancestor.

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Shorebird’s beak inspires researchers to design new water collection strategy

The shorebird's beak is more interesting than you might think

The shorebird’s beak is more interesting than you might think

Dr. Fazale Rana of Reasons to Believe tweeted this cool example of biomimetics from Science Daily.


A UT Arlington engineering professor and his doctoral student have designed a device based on a shorebird’s beak that can accumulate water collected from fog and dew.

The device could provide water in drought-stricken areas of the world or deserts around the globe.

Xin Heng… a doctoral student in Mechanical and Aerospace Engineering, and Cheng Luo, MAE professor, have made a device that can use fog and dew to collect water.

Cheng Luo, professor in the Mechanical & Aerospace Engineering Department, and Xin Heng, PhD candidate in the same College of Engineering department, published “Bioinspired Plate-Based Fog Collectors” in the Aug. 25 edition of ACS’ (American Chemical Society) Applied Materials & Interfaces journal.

The idea began when Heng saw an article that explained the physical mechanism shorebirds use to collect their food — driving food sources into their throats by opening and closing their beaks. Luo said that inspired the team to try to replicate the natural beak in the lab.

“We wanted to see if we could do that first,” Luo said. “When we made the artificial beaks, we saw that multiple water drops were transported by narrow, beak-like glass plates. That made us think of whether we could harvest the water from fog and dew.”

Their experiments were successful. They found out they could harvest about four tablespoons of water in a couple of hours from glass plates that were about 26 centimeters long by 10 centimeters wide.

Now, if we are lifting designs out of nature, then shouldn’t we give honor to God for putting the designs in there in the first place? I really think it’s important to give God credit where due for his clever designs, even if you’re not a big fan of the shorebird. I also think it’s interesting that it’s engineers who made this application of something in nature, not biologists.  Also, I feel I have to mention that the birdy is also cute, which is not insignificant, if you like birds as much as I do.

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Target acquisition and interception in dragonflies

Here is a fascinating post about some of the capabilities of dragonflies from Evolution News.

Selective attention

First, dragonflies have “selective attention” – the ability to focus on a single prey and ignore other distractions:

Dragonflies are among the best flyers in the insect world. Their twin pairs of paper-thin wings allow them to hover and move in all directions, even in mating. When the time comes to dart after prey at high speed, they rarely miss.

What’s their secret? One is “selective attention” — a trait previously known only in primates, according to new research from the University of Adelaide, Australia. Selective attention is the ability to focus on one object and exclude others. Just as a tennis player must focus on the ball and ignore the cheers of the crowd, a dragonfly must pick out one target from a swarm of insects and avoid being distracted by all the others.

Here’s a snip from the research paper:

Our data make a compelling case that CSTMD1 reflects competitive selection of one target. We emphasize “competitive,” because the attended target is not always the same between trials or even within a trial, as seen in strikingly perfect switches from one to the other…. Competition is further suggested by rare examples where the activity observed under Pair stimulation initially lags both T1and T2 responses… suggesting initial conflict in the underlying neural network before resolution of competition by a “winning” target.

We previously showed that CSTMD1 still responds robustly to a target even when it is embedded within a high-contrast natural scene containing numerous potential distracters. Taken together with recent evidence that the behavioral state of insects strongly modulates responses of neurons involved in visuomotor control, our new data thus suggest a hitherto unexpected sophistication in higher-order control of insect visual processing, akin to selective attention in primates.Perhaps the most remarkable feature of our data is that once the response “locks” onto a target (or following a switch), the second target exerts no influence on the neuron’s response: the distracter is ignored completely.

In order to succeed at the task of catching its prey, the dragonfly has to tune out all other distractions.

Target selection

In addition, dragonflies have the ability to intercept a target in mid-air – similar missile defense systems on AEGIS cruisers and destroyers.

The Evolution News article explains:

Another paper on dragonflies shows that these marvels of the insect world are equipped with navigational equipment that can do vector calculus. In the Proceedings of the National Academy of Sciences, Gonzalez-Bellido and a team at the Howard Hughes Medical Institute discerned “Eight pairs of descending visual neurons in the dragonfly [that] give wing motor centers accurate population vector of prey direction.

Intercepting a moving object requires prediction of its future location. This complex task has been solved by dragonflies, who intercept their prey in midair with a 95% success rate. In this study, we show that a group of 16 neurons, called target-selective descending neurons (TSDNs), code a population vector that reflects the direction of the target with high accuracy and reliability across 360°. The TSDN spatial (receptive field) and temporal (latency) properties matched the area of the retina where the prey is focused and the reaction time, respectively, during predatory flights. The directional tuning curves and morphological traits (3D tracings) for each TSDN type were consistent among animals, but spike rates were not. Our results emphasize that a successful neural circuit for target tracking and interception can be achieved with few neurons and that in dragonflies this information is relayed from the brain to the wing motor centers in population vector form.

What did I make of this? Well, evidence like this always causes me to think aboutthe reality of God, and the disturbing thought that we do not live in an accidental universe where I can do whatever I want and be accountable to no one. It’s easier to believe that – it requires less work and it frees us to be our own boss and make our happiness the first priority. As individuals, it’s very tempting for us to think that we are number one, and to resent our obligations to anyone else. The problem is that the scientific data doesn’t support that worldview. The facts are what they are and it is up to us, now, to try to find out who the designer is and what he wants from us.

Filed under: News, , , , , , , , , , , ,

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