Why Evolution is True is a blog written by Jerry Coyne, centered on evolution and biology but also dealing with diverse topics like politics, culture, and cats.
I am still asking for readers to send their photos in, as at most I have a week’s contributions in reserve. Thank you!
Today is Sunday, and that means another batch of themed bird photos from biologist John Avise. I particularly like this week’s theme, which involves two groups of animals. (As you’ll see, John knows his fish as well as he knows his birds.) His notes and IDs are indented, and you can click on his photos to enlarge them.
Piscivorous Birds with Their Fish
Many birds are piscivorous (fish-eating), so it’s common to see piscivores in action. Occasionally, I’ve managed to photograph a bird and its piscine prey with sufficient detail to reveal the general type or even the species of fish recently captured (this is often helped by knowing the piscine species that inhabit the body of water where the bird was feeding). In this batch of photos, I try to identify not only the piscivorous bird but also the type of fish it is about to consume. The White Tern was photographed in Hawaii; all other pictures were taken in southern California.
Thanks to several readers for sending in photos. I still can always use others, though, so keep this site in mind.
Today’s photos come from Andrew Furness, whose IDs and captions are indented. Click on his photos to enlarge them.
All these photos were taken in the last 6-months in South Florida. They showcase some of the wildlife of the region, including species introduced from elsewhere in the world and now firmly established. If readers are interested, I have a Flickr account where more of my photos can be seen.
A brown pelican (Pelecanus occidentalis) stretches while waiting for an easy meal on a fishing pier.
A male green iguana (Iguana iguana) bobs his head as a warning.
A pike killifish (Belonesox belizanus) lurks just below the water surface. This species, native to Central America, was introduced into Miami-Dade County in 1957 and is now established in South Florida’s waterways. It is a livebearer in the family Poeciliidae, the same family that includes guppies, mosquitofish, mollies, and swordtails. Remarkably, this single species has evolved a pike body shape and specializes in eating other fish.
Closeup of the head of the pike killifish (Belonesox belizanus) revealing large jaws and needle-like teeth.
A common snapping turtle (Chelydra serpentina) with several leeches just above the head.
Brown water snake (Nerodia taxispilota). The snake was stuck in the plastic erosion-control netting. After taking a few photos I carefully cut the netting and freed the snake.
Muscovy duck (Cairina moschata) mother and her chicks. These ducks are a very common in the greater Miami area.
Black ctenosaur (Ctenosaura similis), a large lizard in the family Iguanidae introduced to Florida from Central America.
A male peacock (Pavo cristatus) spreads and waves his impressive plumage.
A male sailfin molly (Poecilia latipinna) showing an impressive sail-like dorsal fin.
Close-up portrait of Florida softshell turtle (Apalone ferox).
American alligator (Alligator mississippiensis) surfacing amongst the water lilies.
American alligator (Alligator mississippiensis) in a drying pool. The alligator, around 5 foot in length, appeared to be attempting to capture and eat schools of small poeciliid fishes swimming near the surface in the muddy oxygen-deprived water.
Southern water snakes (Nerodia fasciata) gathered at high density in the shallow waters to hunt fish.
Today we have some lovely osprey photos from Doug Hayes of Richmond, Virginia. His captions are indented, and you can enlarge the photos by clicking on them.
Still learning the ins and outs of the new camera. I wanted to try my hand at photographing birds in flight, so I went down to Mayo’s Bridge which connects Richmond’s downtown to the Southside. Most mornings you can see dozens of ospreys (Pandion haliaetus) fishing. In between dives, they roost in the nearby trees to eat, rest and dry out. The camera’s bird eye detection autofocus + tracking works as advertised! Once it locks on the subject (instantly), you can guarantee that your pictures will be in focus.
Scanning the river for fish. This osprey dropped down to about 30 feet or so – just within the closest focus range of the 200-600 zoom lens I was using. I actually think he was more interested in what I was doing than fishing at that moment. Keep in mind that I’m holding a nearly ten pound lens/camera combo vertically while tracking the bird which is directly overhead!
When prey is in sight, ospreys can hover for a better look, then dive, nailing their prey most of the time.
The operative word is “most” of the time. Sometimes they just get wet for their trouble. This osprey is rising from the river after an unsuccessful dive.
Circling around the river for another attempt.
Shaking off excess water.
This osprey managed to snag an American shad (Alosa sapidissima) nearly as big as it was. Believe it or not, the bird was able to fly across the river and into the trees to enjoy its feast!
Another pass over the river.
Catfish for breakfast!
This osprey managed to snag two fish with one talon!
Showing the human fisherman how it’s done.
Camera info: Sony A1, FE 200-600 zoom lens + 1.4X teleconverter, crop sensor mode for an additional 1.5X reach (converting the 600mm maximum focal length to 1,260mm equivalent), bird eye detection autofocus with tracking, ISO 2000 – 5000, 1/2500 – 1/3200, f/9 – f/11, all shots hand held – camera body and lens image stabilization on, high speed electronic shutter (maximum burst rate 30 fps).
Thanks for the response to my importuning you for photos: I got several sets, one of which is below. But don’t neglect sending in your good photos, as I always have a need for more.
This set comes from reader David Campbell, whose captions are indented. Click on his photos to enlarge them.
A few photos for the hopper. As usual, a diverse lot.
Great Egret (Ardea alba) photographed at St. Marks National Wildlife Refuge. The bird is gliding within one half of one wingspan above the water, a condition known as ground effect. This reduces the drag on the wing because the fixed surface (in this case the water) breaks up the wingtip vortices. Less drag increases glide efficiency. If the bird gets close enough to the surface of the water on a calm day, you can actually see the ripples where the vortices meet the water. This egret did not oblige.
Spotted Sunfish (Lepomis punctatus). Male coming into breeding color photographed in Silver Glen Springs in the Ocala National Forest. Spotted Sunfish are among the most common of the Lepomis in the St Johns River drainage and the most approachable. If a swimmer is motionless and patient the fish will swim up within inches and hover. Look closely and you can see the teeth in the lower jaw and a leech attached to the fin rays.
Wilson’s Snipe (Gallinago delicata) photographed at Payne’s Prairie Preserve south of Gainesville, Florida.
Horned Spanworm (Nematocampa sp. Probably N. resista.). This larva dropped down from an oak canopy on a silk thread. The dorsal threads can be extended until straight.
Eastern Garter Snake (Thamnophis sirtalis). This is a quartet of photos showing how a nonvenomous snake can intimidate perceived threats by changing its appearance to look like a venomous snake. When grabbed, garter snakes respond by biting and smearing musky feces on the attacker. The experience is both unpleasant and memorable. When threatened they try to flee. When cornered, like many other snakes, they vibrate their tails, inflate the body to look larger and fatter, and flatten the head to make it wider and more triangular while elevating the front third of the body in an S shaped coil. It is a pretty impressive mimic of a small viper.
This is a close up of the front part of the snake.
The first photo shows a normal eastern garter snake as it would look minding its own business.
The second shows a snake that is in almost full defensive posture with inflated body and flattened head.
The fourth photo shows a snake in full defensive threat posture with head elevated for a strike.
Florida Softshell Turtle (Apalone ferox). The trash can lid with legs and an attitude. This is one of the largest freshwater turtles in the United States, with large females having carapace lengths approaching 40 cm long. They spend most of their time under water except when basking or seeking mates/laying eggs. They have very long necks and extended nostrils, allowing them to sit on the bottom waiting for food but still reach up to the surface to breathe. The neck is long enough that the turtle can bite a careless human grabbing the shell behind the middle of both sides. Turtle rescuers grab (VERY carefully) the front edge and rear edge of the shell to transport softshells.
Eastern Coral Snake (Micrurus fulvius). I found this little beauty crawling next to my house. Coral snakes are elapids, related to cobras, with short fixed fangs and primarily neurotoxic venom. We used to see them a lot more frequently, but drought and a large feral cat colony down the road have decimated populations of lizards and snakes that coral snakes feed on. These are shy snakes that tend to be very nervous. When threatened many (but not this one) curl the end of the tail into a small ball and wave it around, supposedly mimicking a head, while burying the real head under a coil of snake. Several species of nonvenomous snakes mimic coral snakes, but their banding patterns are a bit different. The late Dr. Roger Conant suggested thinking of a traffic light. Red means stop, yellow means caution (except around here where a yellow light means floor it). If the danger colors touch, it’s a coral snake. In North America.
Clouded Leopard (Neofelis nebulosa) This is not “wild” life but the picture shows one of my favorite cats in a beautiful pose. It was photographed at the Central Florida Zoo in Sanford, Florida.
For today’s post we return to the New York City Subway 8th Avenue local (B and C trains) station at 81st-Museum of Natural History,this time for the amphibians.
81st St.-Museum of Natural History station, New York subway, July 17, 2019.
My favorite of the amphibians is this brooding caecilian, curled round its eggs. These legless, short-tailed amphibians are found only in the tropics, and there is no real English vernacular name for them. (You can find a Sicilian in the subway, but I prefer Neapolitan.)
Brooding caecilian. 81st St.-Museum of Natural History station, New York subway, July 17, 2019.
What appears to me to be a reed frog (Hyperolius sp.), an African tree frog of sorts, hangs on the wall next to a station identifying sign.
Reed frog. 81st St.-Museum of Natural History station, New York subway, July 17, 2019.
This looks like a ranid frog to me– a member of the family Ranidae, perhaps intended to be a Rana proper. Many species in this and related genera look much alike the world over. Note the nicely delineated tympanic membrane.
Frog. 81st St.-Museum of Natural History station, New York subway, July 17, 2019.
This generic frog (I won’t even try to name a family for it) is leaping out of the Signal Room. Interestingly, the subway workers here believe in free will, apparently of the libertarian sort. A scratched note on the door reads, “Use other door→ | or this one– up to you”.
Frog. 81st St.-Museum of Natural History station, New York subway, July 17, 2019.
These well-rendered salamanders provide detail enabling specific identification. On the left we have a Marbled Salamander (Ambystoma opacum), a species of eastern North America (including the New York area), and on the right we have a Fire Salamander (Salamandra salamandra), a species widely distributed in Europe. The American Tiger Salamander (Ambystoma tigrinum; found in the New York area) is also black with yellow markings, but the yellow markings (quite variable in both species) look more like Salamandra to me, and the evident parotoid glands at the back of the head (making it look wide) are conclusive. Ambystoma and Salamandra are similar in size and body shape, and are sort of continental ecological analogues.
Salamanders. 81st St.-Museum of Natural History station, New York subway, July 17, 2019.
The Coelacanth (Latimeria chalumnae) is one of the few surviving lobe-finned fishes, and as such is one of the tetrapods closest living relatives, and so is included here as an honorary amphibian. I don’t know why there is a question mark on its tail; in fact I never noticed it there before till just now.
Coelacanth. 81st St.-Museum of Natural History station, New York subway, July 17, 2019.
Finally, we have a group of patently Paleozoic fish. The artist has rendered them neither strictly from above (as though we were looking down on them in the ‘water’ of the paving tile) nor from the side, but in a sort of twisted view, allowing us to see various aspects. The bottom four may be intended to be the same type of fish (I’m not sure what kind), but the top one (which seems to be more of an exclusively side view– see the partly opened mouth) looks like one of those strange Paleozoic sharks, with a spiny first dorsal fin, and a heterocercal tail. You can also see more clearly in this photo how the lighter brown granite-like stone is integrated with the darker paving tile.
Fish on the floor. 81st St.-Museum of Natural History station, New York subway, July 17, 2019.
There are other taxa represented in the tiles (e.g., ants), and other forms of art, including larger tiled murals, and casts of in-situ fossils projecting from the wall. Many of these works are depicted in a gallery at www.nycsubway.org, a subway fan/history site. Some of those depicted I’ve never seen in person, because I always exit the station at the south (Museum) end, not at the north (81st Street) end.
(Looking at one of the pictures in the gallery now, I see the undersea mosaic mural has a coelacanth-shaped gray silhouette in the otherwise colorful tiles; could the question mark noted above be related to the coealcanth’s absence here?)
Big Mouth Billy Bass is an adult toy consisting of a plastic bass that sings music and moves its head and fins (see here for an early example).
This videomaker apparently connected Billy Bass up to an Alexa and managed to synchronize its mouth and head with the words. Ergo, you can ask Billy anything.
I have a bad feeling about running out of photos, so now is the time to send them in!
Today we have the second part of Mark Sturtevant’s February 4 post on a spider that lives on water lilies and eats fish. Have a look at the earlier post first, then this one. Mark’s notes are indented, and you can enlarge the photos by clicking on them.
I had recently introduced the six-spotted fishing spider (Dolomedes triton). This species is widespread, and can be found on floating vegetation on lakes and ponds or on river areas with minimal current. From there they will hunt a variety of prey, including small fish. This will be a special post since it is that latter talent that you will see today.
I had brought home a fishing spider, and she was kept for a time in a glass-bottomed aquarium with water and some lily pads. Here she is again. For scale, her leg span was a bit over 2 inches. They do get larger.
The aquarium was put in my backyard for a time, and I could park myself underneath it to photograph activities from below. One tries not to imagine what the neighbors were thinking. Minnows (fishing spider food) were introduced, and I really had no idea if she would even go hunting for one. But from time to time she would extend her legs out onto the water. As I understand it, this is how they monitor for moving prey below, so that was encouraging.
By the way, all of these pictures from the underside were extensively processed since I had put a screen cover over the aquarium to keep her inside while I was directly below. The screen was plainly visible in the pictures, though, so it had to be digitally removed. That was a lot of work!
Anyway, it took a little while, but then something started to happen. At this point I was freaking out!
The actual attack was very fast, and these are among the few pictures that I have of it. What I saw was that the spider strode out onto the water, and suddenly “clawed down” to gather up the fish before retreating quickly back to the lily pad.
The shadow tells the tale.
Here she is again up top. The photographs were taken through glass which was by now rather steamy with the summer heat, and so the pictures required some de-hazing treatments in post-processing to rescue them.
She was deftly turning her prey over and over with her chelicerae and pedipalps, working in the venom. In just a few minutes the tissue dissolving effect of spider venom was very obvious.
Fishing spider hunting has been captured in video. Here are two examples. They really seem to go after fish! [JAC: don’t miss these videos!]
Stephen Barnard from Idaho is back with some lovely photos—and two videos as lagniappe. His captions and IDs are indented.
The first four are mallards (Anas platyrhynchos) in flight. Migratory mallards are pouring in from Canada and parts north. There will soon be thousands. Duck hunting season, popular here, starts October 19. You’ll be happy to know I don’t hunt ducks or allow it on my property. [JAC: Yes, I am delighted at this!]
Next is a photo of Hitch (Canis familiaris), two more mallards, two Canada geese (Branta canadensis), and a moose (Alces alces). It’s not much as a photo, but funny.
This bald eagle (Haliaeetus leucocephalus) sometimes perches in this tall blue spruce (Picea pungens) in my back yard, scanning the creek for fish. This is probably Lucy.
Rainbow trout spawn in the spring, and brown trout (Salmo trutta) spawn in the fall, which is convenient when they coexist because they use the same spawning beds, called redds. These brown trout are on a particularly nice redd, which is also what anglers call a “prime lie” — a favored spot for fish to feed and rest. They compete with each other, and drive away the rainbows that threaten to eat their eggs. The bird calling in the background is a marsh wren (Cistothorus palustris).
Thanks to the several readers who responded to my plea for wildlife photos. I now have at least a week’s worth.
One of the kind respondents was Stephen Barnard, who hasn’t been here for a while. He sent a batch of lovely photos, and I’ve indented his notes below.
A few “wildlife” photos for you (except for the last).
The wildlife on Loving Creek is micro-seasonal through the summer. Species come and species go, on a weekly or even daily schedule/
The first three photos are, obviously, hummingbirds. I get two species: Black-chinned (Archilochus alexandri) and Rufous (Selasphorus rufus). Both are migrating through and not breeding. The Black-chinned arrive first, but the Rufous come soon after, and fireworks ensue. The Black-chinned are pugnacious and defensive of their territory, but the Rufous eventually overwhelm them with numbers. The first two photos show each in a defensive posture, and the third shows the Black-chinned’s purple gorget. Sadly, they’re all gone now.
The next two photos are action macros. The flower in the first photo is Cleome serrulata, commonly known as Rocky Mountain beeplant/beeweed, stinking clover, bee spider-flower, skunk weed, Navajo spinach, and guano. “Navajo spinach” is problematical, so please don’t tip Titania off. Sadly, all the flowers and bees are gone now.
Next three are trout-themed photos. Loving Creek gets several different mayfly “hatches”. The Tricos are the most impressive in numbers and biomass. Sadly, they’re over. Happily, the Callibaetis are thriving. The first photo is a Callibaetis “dun” — a recently emerged mayfly, drifting on the surface drying its wings, vulnerable to a trout, or even a swallow. The third photo is a rainbow trout (Oncorhynchus mykiss) consuming a Callibaetis “spinner” — a spent fly that’s fallen dead in the water.
Finally, not wildlife, but some cows. I’m trying to rejuvenate the soil with a varied cover crop and grazing.
I’m happy to report that Stephen Barnard is back with a spate of pictures—of fishing. Stephen’s notes are indented:
During the seemingly endless pandemic I’ve been doing little more than fly fishing and farm chores, and photographing fish. All these are rainbow trout (Oncorhynchus mykiss). The exceptions are mayflies: a Callibaetis dun and a comparision of an artificial fly and a natural Trico spinner. Anglers refer to newly emerged adult mayflies as a “duns”, and to the spent insects that fall into the water after mating and egg-laying as “spinners”. One photo is of a oddly colored trout that I’ve been seeing for at least three years, and that I’ve caught three times. I used to think it had an abnormally dark head, but after bringing it to hand I realized it had an abnormally light body, but only on one side.
JAC: A very realistic fly!
When I pointed out that I liked the second photo best, with the fish’s head above the water, Stephen replied:
That’s what they do when they take tricos on the surface. There are so many mayflies that they kind of sweep their heads around to take as many insects as possible. Here’s another photo of a fish eating a callibaetis dun.
