On Labor Day let’s honor working birds. This year … domestic geese.
A couple of domestic geese are often kept with chickens to guard them from predators. Geese are always alert and will naturally honk and shout when they see danger. The chickens run for cover while the large and aggressive geese may attack the threat. Some geese are so aggressive that they’ve injured people. (By the way, Canada geese will attack if you approach their young.)
When you see geese with chickens you can be sure those geese are at work.
p.s. When seen in Pennsylvania, geese like those pictured above are barnyard escapees. Here are some tips on their background: Chinese geese have long necks and knobs on their heads (top photo) and were domesticated from swan geese (Anser cygnoides). Domestic geese in white or gray with faces like snow geese (the attacking goose above) are descended from greylag geese (Anser anser).
For more than 173 years humans and dolphins have worked together to catch fish on the coast of Laguna, Brazil. Dolphins initiated the cooperation some time before 1847 and taught humans what to do.
The dolphins hunt by herding shoals of mullet in the estuary. The fish would escape into shallow water except that the humans are helping.
Fishermen stand in the water with cast-nets and wait for a dolphin to signal them. When the signal comes, the fishermen throw their nets and catch many fish. The rest of the fish flee to deeper water where the dolphins are waiting to eat them.
Humans and dolphins both catch more fish than they would working alone.
Did you know that, when threatened, this Eurasian woodpecker uses the same distraction display as a South American flycatcher? Though the birds aren’t related their similar behavior looks like convergent evolution.
Convergent evolution is when similar traits evolve in unrelated species because they’ve had to adapt to similar environments.
A classic example is the body shape of sharks and porpoises. Both have long streamlined bodies, dorsal fins and flippers because both must swim fast to catch underwater prey.
But sharks are fish and porpoises are mammals. They aren’t related.
The eastern meadowlark of North America (a member of the blackbird family Icterid) and the yellow-throated longclaw of Africa (a member of the wagtail/pipit family Motacillidae) live in similar habitats on separate continents. Though strikingly similar they are not related.
So what do you think? Is the neck-turning behavior of the Eurasian wryneck (Jynx torquilla) …
Meanwhile at Frick Park the goats and their guard donkey are back in the large enclosure at Clayton East, munching away at invasive plants. The black goat at the fence is eating mile-a-minute weed on the fencing. Yay!
Mathematicians spend a lot of time working on problems in their heads, imagining solutions and proposing theorems. Sometimes an engineer is inspired to flesh out a proposal in real life to prove it’s true. Thus was born the gömböc, pictured above.
In 1995 Russian mathematician Vladimir Arnold described a theoretical object that has just one stable and one unstable point of equilibrium. When it sits on a flat surface it always rights itself like a roly poly toy except the gömböc is not weighted (the toy is).
The gömböc was harder to flesh out than you’d think. Hungarian engineer Gábor Domokos discussed the theory with Arnold in 1995. In 2006 he presented the real life solution. This 5 minute video shows why a gömböc is unique and describes Domokos’ quest.
During the quest, Domokos looked for gömböcs in nature and found tortoises that are shaped this way.
If an Indian star tortoise ends up on his back, he draws into his shell and automatically rights himself because his shape closely resembles a gömböc. (He has to use his limbs sometimes due to less than flat ground conditions and shell imperfections.)
Life imitates math imitates life.
(photos from Wikimedia Commons; click on the captions to see the originals)
The Nazca Lines are hundreds of enormous lines and figures in the Nazca Desert, created about 2,000 years ago when people cleared the reddish pebble surface from the underlying soil. The desert’s stable windless climate has kept the lines visible to this day, helped by the fact that the underlying soil contains lime which hardens when exposed to morning mist.
Many of the Nazca Lines are long straight lines or geometric patterns but more than 70 are animals. The most frequently depicted are birds. Some of the birds are local, some from far away. Naturally the Nazca people depicted an Andean condor though it appears to have a hummingbird’s beak.
But perhaps they’re forgetting how recently those species evolved from mallards. The Mexican duck (Anas diazi) that occurs in Mexico and the U.S. Southwest was thought to be a subspecies of mallard until 1957.
Mallards are just working on creating new species. 😉
Read more about mixed up ducks in this vintage article: Ugly Ducks
Did I say peregrine falcons? Here’s a view from the high-rise roof deck (not from our apartment). When I took this photo I saw two peregrines perched on the Cathedral of Learning, one on the north face, one on the east.
Today we’ll be really busy moving from one side of Schenley Park to the other.
The movers come at 8:45am. Gotta run!
(photo by Kate St. John. Moving Day cartoon from Wikimedia Commons, click on the caption to see the original)
One of the biggest challenges facing the U.S. during the coronavirus pandemic is our poor ability to quarantine to stop the spread. This summer’s COVID-19 surge in Pittsburgh was sparked by travelers who returned from vacation (Myrtle Beach, Hilton Head, Florida, Raleigh, Nashville) but did not quarantine for 14 days.
Perhaps we could learn from ants. An April article in Treehugger described how social species avoid each other to stop the spread of disease. This includes black garden ants.
Ants are very social creatures, always working together to feed and protect the colony. Nurse ants stay inside the nest and tend the larvae; workers forage outside for food. A study of black garden ants found that when workers contract a fungal infection they know to stay outside the nest and avoid contact with other ants. Meanwhile nurse ants move the larvae deeper inside the nest to avoid infection. Ants basically quarantine themselves.