We have two contributions today from regulars: a video from Tara Tanaka (her Vimeo site here and Flickr site here) and one photo (with scientific analysis) from evolutionary ornithologist Bruce Lyon. First the video from Tara, with her caption:
Last August a Wood Stork that had hatched here two months before took what was probably his first flight. When I first saw him he was on the little island out in our swamp that we’ve dubbed “gator island.” He was sopping wet and shivering, despite it being a hot morning. I think he had landed in the water and must have swam to the island and pulled himself up. I grabbed my digiscoping gear and started filming from the living room – he was about 700’ away. It wasn’t long before not one, but two large alligators saw him and immediately started moving in his direction. The storks are like my children, so I watched in horror as our large female gator moved slowly closer and closer, using vegetation to hide herself. After storks bathe, they walk around with their wings out to dry, occasionally flapping, almost always followed by an adorable tail wag. The gators were taking their time so as to not be discovered, giving the stork time to partially dry. Adrenaline is a magical potion.
All ends up well, though. Be sure to watch the video on full screen with sound on:
Bruce sent a his photo of a dorsal view two mallard drakes, and I have to admit that I hadn’t noticed the pattern he did. But, on the other hand, he’s a trained ornithologist and keen observer of nature. His analysis is indented:
At a local pond yesterday, lots of mallards [Anas platyrhynchos] were dozing on the lawn. When they sleep they show a feature I hadn’t noticed before—their backs are jet black and velvety—almost like a black hole where no light escapes. The tan scapular feathers (side of upper back) and tertials (wing feathers lower down) frame the back and make the effect even more striking. It is interesting that the curlicue black feather over the rump is at the end of this black stripe. I had not noticed this pattern when viewing the birds from the side. The photo below shows this for one male and since he was alert even here the effect was muted compared to when they are sleeping.
In your readings about the birds have you come across any discussion of this pattern? I am increasingly convinced that a lot of male sexual signals are shaped by their effects on female sensory systems so I suspect there is an element of such ‘signal design’ here.
That was spectacular! The alligator missed the bird’s foot by inches. Lucky Stork.
Fantastic scary footage! Maybe a lttle Jaws music over it? That’s what was playing in my head.
The way she propelled herself into that island was amazing. I didn’t realize there was much purchase in the water.
Many years ago I witnessed a ridiculous little dog harass and annoy an alligator who was only sunning himself. The alligator finally had enough and went after the little dog. Holy smokes, I had no idea they could move that fast. The dog was very lucky there was a dock within 10 feet to jump up onto.
My brother in laws young dog jumped into a canal in Florida to take a puppy swim. He was quickly grabbed and dragged under by a ‘gator. The two young sons were heartbroken. They soon got another dog of the same breed.
Great video!
I would guess it is not sexual selection per se, but some fine-tuning of sexually selected traits to break up the outline of the duck from the air. It is very similar in principle to many at-rest moth patterns
“from the air” -> “when viwed from the air” (as by a predator)
It was pretty intense to watch the subtle signs of gator approaching.
There is a spate of interest in the ‘blackest black’ feathers in male birds. The one that gets the most attention is a bird of paradise called Victoria’s riflebird. You’ve all seen it.
The very blackest black (though not naturally occurring) is Vantablack, which absorbs 99.965% of radiation in the visible spectrum: https://en.m.wikipedia.org/wiki/Vantablack
A paper I tracked down on this topic called ‘Convergent evolution of super black plumage near bright color in 15 bird families’ has some interesting information. It has independently evolved in 15 different taxonomic bird families. The photo composite of these birds show that in most cases the super black occurs in species where males are dramatically more colorful than females (suggesting sexual selection is at play). Also noteworthy is that the black is always adjacent to very colorful plumage and seems to function mechanistically to enhance the appearance of the color in an optical illusion.
Not for the alligator.
Whoa…tough being a wild animal…always a threat it seems. I was rooting for the stork, yay!
Thanks all for the comments on the video. I witnessed that gator eating two recently fledged storks last year (fortunately I didn’t see it happen), but the act of dismembering them was brutal. Jerry may have already posted this — I recorded itin 2017:
I remember it well. It is imprinted in my visual cortex.