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.
Thanks to several readers’ contributions, we’re limping along here and may not run out of photos for a while. One of the contributors is regular Doug Hayes of “The Breakfast Crew” fame, who lives in Richmond, Virginia. His captions and IDs below are indented, and you can enlarge his photos by clicking on them:
The Breakfast Crew is back! The yard is quite busy with all the regulars plus a few newcomers who stay around for a few days, then move on to the park and wooded areas along the James River. We’ve also had quite a bit of rain, but that doesn’t stop the Crew from coming for a free meal!
A male American Goldfinch (Spinus tristis). These birds are found all over the neighborhood, especially in yards where the owners have planted sunflowers. This little guy is a bit soggy from the rain:
This American Robin (Turdus migratorius) is damp but not deterred from visiting the yard:
I think I’ve mentioned that mourning doves (Zenaida macroura) are not the brightest of birds. It looks as if this one didn’t have enough sense to get out of the rain:
This house finch (Haemorhous mexicanus) doesn’t mind a bit of rain when there is free food to be had:
Peanut girl, a red-bellied woodpecker (Melanerpes carolinus), does not let a little rain stand in the way of her and her favorite food:
Pretty Girl is the most brilliantly colored female Northern cardinal (Cardinalis cardinalis) that visits the yard – although her colors are a bit hard to see when she’s drenched. Her red crest, red wing markings and bright orange beak make her stand out from the other more drab-looking females. She has been around for at least three years:
This Carolina wren (Thryothorus ludovicianus) is one of the regulars. Seeds or suet, this little guy enjoys it all:
We get quite a few Eastern bluebirds (Sialia sialis) throughout the neighborhood as the park service has set up a number of nesting boxes for them in Forest Hill Park:
White-breasted nuthatches (Sitta carolinensis) are frequent visitors to the yard. They’re tricky to photograph as they tend to zip in, grab a seed or peanut and quickly take off to eat in the trees. They never linger like finches or doves:
A male rose-breasted grosbeak (Pheucticus ludovicianus). This is only the second time these birds have visited the yard. They came by for about a week, then left for parts unknown. I never saw the males feed, preferring to chase each other away from the feeders:
A female rose-breasted grosbeak (Pheucticus ludovicianus). This female came by a couple of times a day for a week or so, eating greedily. She may have been getting ready to lay eggs or had babies to feed:
I put out a bowl of peanuts hoping to attract bluejays and woodpeckers, but this house finch (Haemorhous mexicanus) decided that she wanted some too!:
A male house finch (Haemorhous mexicanus). Mother Nature loves making male birds flashier than the females!:
A tufted titmouse (Baeolophus bicolor) decides to get in on the peanut feast too:
A quick trip to the Chamberlayne Swamp revealed that the anhingas (Anhinga anhinga) are back. This is the second year for them to nest in the area:
Camera info: Sony A1 and A7R5 dslr bodies, Sony 200-600 zoom lens + 1.4X teleconverter, photos either hand-held or the camera supported with an iFootage Cobra 2 monopod and Neewer gimbal head. The anhinga photo was shot with the aid of the camera’s Clear View digital zoom for added reach.
Mark Sturtevant has rescued us from a day with no wildlife photos (I have about four batches left and will have to do this only sporadically if I run out). PLEASE send in your good photos.
Mark’s IDs and notes are indented, and you can enlarge his photos by clicking on them.
Here are pictures from the previous summer. The pictures were taken generally in May, near where I live in eastern Michigan.
First up is a lettered sphinx, Deidamia inscriptum. The larvae will feed on wild grape and Virginia creeper:
European pine sawfly larvae, Neodiprion sertifer. These were accidentally introduced into the U.S. in the early 1900s, and they feed, en masse, on several species of pines. I regularly see them by the thousands in some areas. This group of early-season youngsters are in a defensive posture where they are ready to collectively spit toxic chemicals if necessary:
Next is a flower chafer beetle, Trichiotinus sp. I always find them on white flowers. Always:
I have been using my 2.5-5x Venus/Laowa super macro lens to try to get facial portraits of arthropods. The next picture is an early effort. This bizarre spider is a female long-jawed orb weaver, Tetragnathaelongata, and they are super common near water. People recreating on rivers and lakes may learn to hate them for their scary jaws and habit of dropping in on you from where they concentrate near shore. But they really are as benign as ladybugs, and their long jaws are used as forceps to delicately pluck small flying insects from their webs. Getting this manually focused stacked picture took a lot of work since these spiders can pretty much fly. By that I mean they will run away, clamber up high, and stand on their head to send away delicate silk draglines into the air currents. As soon as they get a tether on something across the room, they secure the near end and off they go – a flying Wallenda on a tightrope. I had to chase after this one dozens of times to return it to its perch, and so this picture required a determined sense of humor. Right now I am fixing to exhaust myself again with a male spider, simply because they have an even more gnarly face:
Late last summer I had collected several egg cases (oöthecae) of one of our largest insects, the Chinese mantis (Tenodera sinensis). The plan was to photograph them while hatching, as that is quite a sight. Over and over, the oöthecae would hatch in the pre-dawn hours and I would miss the whole thing. But one batch was slower and I managed to get something of it as shown in the next two pictures. The babies all wiggle out while wrapped in a tight membrane. They will later break free of that, and soon they are moving around:
And here is a youngster that is about the size of a mosquito posing on a tiny mushroom. I released all of them in a field near home:
Finally, here is a fuzzy bumble bee bum. It is a small internet meme to get pictures of bees deep in a flower, with their cute little butts sticking out, and here I finally got one! I am not sure about the species:
Well, we’re running out of photos, so after tomorrow I’ll post them when any arrive. If you have some on hand, please send them!
Today we have varied bird and mammal photos from Christopher Moss, taken in northern Nova Scotia, near the New Brunswick border. His captions are indented, and you can enlarge the photos by clicking on them.
He first announces this:
The teleconverter arrived, so my 500mm lens is now a 700mm lens.
Ardea herodias, I mean. Apparently a redundancy too, as “ardea” means “heron” in latin, and ἐρῳδιός (erodios) means the same in Greek. The sun is on the pond today, and each time I go out to feed the crows (they come and caw—did you know ‘cawe’ is Anglo-Saxon for crow?—on the deck rail when they are ready for their peanut. There are too of them chattering out there now hoping for a third handout. They have me well trained!) the heron flaps a few feet further away, but comes stalking back slowly and purposefully to the deeper water closer to me. I don’t know if it is true, but my father told me they secrete some kind of attractant from glands on the legs that entices fish to come within reach.
And the first wood duck since the winter, Aix sponsa:
Today I found the blighter swimming close to the deep hole we dug out to fill watering cans for the garden. With 200mm focal length:
. . . and as quick as I could twist the lens to 500mm:
At which point the muskrat dived, and I waited as long as I could, until my bladder said I’d done enough. Either it is true that they can dive for 17 minutes, or he has made a burrow with the entrance, sensibly, in the deep pool next to the bank adjacent to the house (even when the pond is frozen there will be access).
A Green-Winged Teal drake (Anas carolinensis, and mainly no longer thought conspecific with A. crecca, the Eurasian Teal) preening:
Today we have another photo-and-text story, this time on earthworms (a favorite of Darwin), concocted by Athayde Tonhasca Júnior. His captions are indented, and you can enlarge the photos by clicking on them.
Underground influencers
“Everything is connected” is the sort of vacuous New Age twaddle churned out by the self-help industry. And yet, stuff and nonsense often holds a grain of truth. For example, we would have to look hard to find a connection between earthworms and bees. But such an association exists, and it is of consequence for pollination services.
Earthworms (mainly of the family Lumbricidae, which includes most European species) are immensely important for the functioning of some terrestrial ecosystems. Their tunnels channel air, water and nutrients into deep layers of the soil, and facilitate root penetration. Their work improves soil structure and reduces runoff, thus decreasing the rates of erosion. By eating soil, plant litter and other materials (depending on the species), earthworms break down organic matter, helping decomposers such as bacteria and fungi release nutrients into the soil. Their food intake, 2 to 20 tonnes of organic matter/ha/year, ends up as castings (worm excrement), which are rich in nitrogen, phosphorus, potassium, magnesium and calcium, all minerals essential for plant growth. Thanks to their relentless burrowing, soil mixing and fertilizing, earthworms are important to soil formation, and consequently vital to plants and every organism that depends on them. You can learn a great deal more about these indefatigable diggers from The Earthworm Society of Britain.
The value of earthworms was not lost on Charles Darwin. His 1881 book, The formation of vegetable mould, through the action of worms, published a few months before his death, was a revelation to the general public about the importance of these secretive and poorly known animals. The book was a huge success, selling 6,000 copies in the first year, more than On the Origin of Species when it was first published.
Darwin and his worms in a caricature from Punch, 1882:
Darwin calculated that in 10 years, castings from 0.4 ha (one acre) of soil would form a 5 cm-thick layer of top soil (what he called ‘vegetable mould’). In his book’s closing paragraph, Darwin justified calling earthworms ‘nature’s ploughs’: ‘The plough is one of the most ancient and most valuable of mans (sic) inventions; but long before he existed the land was in fact regularly ploughed, and still continues to be thus ploughed by earth-worms. It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organised creatures.’
Diagram of the formation of vegetable mould. Darwin, 1838. Proceedings of the Geological Society of London 2: 274-576:
Considering earthworms’ impressive portfolio as nature’s engineers, we may think they are indispensable, or useful, everywhere. But they are not.
About 10,000 years ago, northern North America was overwhelmed by a vast ice sheet. If there were earthworms in the region, they were killed by the glaciation because there were none when the ice receded. So northern North America was earthworm-free until European settlers started to bring in plants and soil, which inevitably introduced worms such as the ‘night crawler’, the local name for the common earthworm Lumbricus terrestris.
American farmers and gardeners benefited from ‘nature’s ploughs’ as much as Europeans did, but it was a matter of time until earthworms made their way to native habitats such as hardwood forests. And in those environments, earthworms were not welcome at all.
The top layer of the forest floor – known as the litter layer – consists of leaves, bark and stems at different stages of decomposition. In North American native forests, the litter layer is broken down slowly, mainly by millipedes and mites. Organic material accumulates as blanket sheets, which are essential habitats for many insects, amphibians, birds, and flowers.
When earthworms move in, the litter layer is consumed in two shakes of a duck’s tail. Decomposition accelerates dramatically, so that nutrients that have been slowly accumulating are released quickly; plants cannot absorb them all. With the loss of litter cover and nutrients, the understory fauna and flora become depleted. Dwindling understory plant biomass has secondary consequences; deer will have no option but to munch on young trees, and non-native plants may take advantage of the impoverished conditions to spread out. These problems worsened after the arrival of the Asian jumping worm (Amynthas agrestis), an earthworm native to Japan and Korea.
But the negative impact of earthworms is not restricted to the litter layer. In Canada, the abundance, biomass, and species richness of the insect fauna above ground are lower in forest plots with invasive earthworms than in earthworm-free areas. Insect abundance was reduced by 61% where earthworm biomass was highest (Jochum et al., 2022).
The reasons for these effects are not known. Scarcity of some plants or altered soil conditions in earthworm areas may reduce the abundance and survival of herbivore and soil-dwelling invertebrates, which may affect the food chain. Invasive earthworms can decrease the concentrations of some plant metabolites used against leaf-chewing insects, so changes in plant chemistry may be involved.
Even more worryingly, there is strong evidence that earthworm activity increases emissions of greenhouse gases. Dendrobaena octaedra, another earthworm native to Europe, seems to be spreading in Canadian boreal forests, which are important carbon reservoirs. Wherever this earthworm is found, some of the carbon stock in the forest floor is lost in the form of carbon dioxide. So many soil ecologists have rightly voiced their concerns about a ‘global worming’.
The shenanigans of Darwin’s ‘nature’s ploughs’ in northern North America are cautionary tales about species taken to where they do not belong. Few could have expected that earthworms, so beneficial to species and habitats in the Old Continent, are detrimental elsewhere. The buff-tailed bumble bee (Bombus terrestris) and the European honey bee (Apis mellifera) are protagonists of similar tales.
The unpredictability of outcomes is a concern. Only a fraction of invasive species are harmful, but those that are can be disastrous.
JAC Addition: Here I’m posing (in 2008) with Darwin’s “wormstone” at Down House, his home in Kent. As Darwin Online notes, Darwin used this to “measure the rate of sinking of the stone due to the actions of earthworms.” The site adds, “The stone now at Down House was reconstructed by Horace Darwin’s Cambridge Instrument Company in 1929 when Down House became a museum open to the public.”
Today’s batch of large format black-and-white plant photos come from reader Christopher Moss, whose captions and IDs are indented. You can enlarge the photos by clicking on them.
Since you have expanded the definition of wildlife, I thought I send along some plant studies. They are all taken on film, indoors, and the medium format photos (the first four) used a strobe. All are taken on Ilford XP2 Super film, which is a black and white film made with the same chemistry as a colour film. It was produced when black & white developing at the High Street chemist had disappeared, and is usually developed in the same CD-4 process as colour films. I have found a way to develop it with (I think) superior results in traditional B&W chemicals.
Please send in your good wildlife photos, folks. The tank is dropping at a disturbing rate.
Today we’ll feature the second half of Daniel Shockes’s photos from Africa (part 1 is here). His narration is indented, and you can click on the photos to enlarge them. Here’s his original introduction:
Here are photos from our trip to Africa. Started in Livingstone Zambia, traveled through Zimbabwe, and into Botswana.
Male Lion after a kill. This group had just taken down a baby elephant and was methodically eating it. I do have pictures of them eating the carcass but even dispassionate scientific readers might find it a bit disturbing. Happy to share more if you want (also have great video):
We have a special bonus today: DUCKS AND DUCKLINGS! At my request, UC Davis ecologist Susan Harrison took photos and video for this site when she went out yesterday to help a colleague band, chip, measure, and DNA-sample wood ducklings. Susan’s narrative is indented; click the photos to enlarge them.
Notes From a Wood Duck Research Field Trip
In early June 2023, I accompanied UC Davis’ John Eadie, a leading expert on waterfowl biology and conservation, to measure and tag newly hatched Wood Duck (Aix sponsa) ducklings.
For ten years, John and his collaborators have been studying the social lives of Wood Ducks, especially the striking behavior called nest parasitism. Females (‘hens’) may lay some or all of their eggs in the nests of other Wood Duck hens. Why do they do this? It’s probably related to the fact that they nest in tree cavities, which are a scarce resource. But how do hens decide whether and whom to parasitize? What determines the shifting benefits of raising your own kids versus trying to get them raised by someone else? You can read this lively and beautifully illustrated American Scientist article to find out what’s been learned and what’s still unknown.
We went to a private ranch near Davis where John and his lab have set up 100 of their 400 total nest boxes. Nest boxes help boost Wood Duck populations, and when suitably equipped, they also make it easy to collect data on hens and ducklings.
These ‘research’ nest boxes can be raised or lowered for access, and are equipped with instruments that read the output from tiny radio tags similar to pet microchips:
The first step is to lower and open the nest box to see if the eggs have hatched:
Then the entrance hole is covered to keep the hen inside and the ducklings are carefully extracted:
Each duckling is brought to a mini-lab on the truck tailgate:
Being a good mentor, John is letting me ‘help;’ here I’m holding my first duckling:
Ducklings are slid headfirst into the tube to be weighed:
Bill length, bill width, and tarsus length are measured:
A tiny pinprick allows blood to be drawn for DNA analysis:
A radio tag the size of a rice grain is gently and safely slid under the skin:
Foot color is recorded as tan (left), orange (right), or pure black, since John is curious about this variable trait:
Ducklings then go back to their nest and the seemingly calm hen. Using this combination of radiotagging and DNA, John and collaborators have collected around 3 million data points, each one a combination of an individual duck’s identity, parentage and location. These data have shown, for example, that a hen’s tendency to parasitize is pretty strongly correlated with her mother’s tendency to parasitize.
We stopped at John’s aviary on campus. Here I’m holding Konnie, a Wood Duck hen who was hand-reared and named for Konrad Lorenz, to show off her gorgeous iridescent wings:
In this brief video, Konnie and her mate Crookneck like they are eating but they are actually performing a contact ritual, watched by a Mallard (Anas platyrhynchos). Turn the sound up to hear their squeaky calls and John explaining their behavior. He says many pair-bonding behaviors in birds are ritualized versions of feeding: (Photo 13)
This male Cinnamon Teal (Spatula cyanoptera), less friendly than Connie, energetically nibbled at fingers when picked up:
It was great fun comparing notes with John about research. When I was in grad school learning plant and insect ecology, it was often said that you couldn’t really test theory using birds or wildlife, because you couldn’t do experiments or get large amounts of data. But sensor and DNA technologies have since transformed the study of animals in the wild. And with Wood Ducks, a researcher can deploy their most critical resource – nest boxes – and return later to find abundant and accessible study animals. However, since adult male Wood Ducks are hard to catch and tag, their role in the social network is not yet well understood.
Today’s photos are the first of three batches of pictures taken by reader Daniel Shoskes on a trip to Africa. He didn’t supply the scientific names, so I’ll just give a link to the animals (Daniel’s words are indented.) Click on the photos to enlarge them.
Here are photos from our trip to Africa. Started in Livingstone Zambia, traveled through Zimbabwe, and into Botswana.
Today we have the second batch of photos taken by ecologist Susan Harrison on a recent trip to Finland (part 1 of her trip is here). Her IDs and narratives are indented, and you can click on the photos to enlarge them.
Finnish Forest Fauna
While visiting the University of Oulu in May 2023, after enjoying the common migratory birds flooding into the city’s parks, I took two guided day tours to see elusive forest-dwellers such as owls and grouse. On these trips I met British “twitchers” and German “Vogelbeobachters” who’d come to Finland just for this purpose, since it’s one of the best places in Europe to see forest wildlife.
Large old trees with nest cavities are scarce, so nesting boxes are frequently set out by bird-lovers. The nature tour company in Oulu takes it a step further: they put up owl boxes, and take customers to view the inhabitants, but you must sign an agreement not to record the location. I guess on balance this is a good arrangement for the owls and us.
Female Ural Owls (Strix uralensis) sometimes maim people who approach their nests, so we were cautious:
My grouse-oriented tour took place around Kuusamo, a small resort town on the Russian border. Finnish bird tours begin at 3 am, so please forgive some grainy photos taken in dim light.
Domestic Reindeer (Rangifer tarandus) wandering around in radio collars:
On both trips we also saw many interesting songbirds and water birds; here are some of the latter.
Arctic Loon (Gavia arctica), a.k.a. Black-Throated Loon or Diver:
Slavonian Grebe (Podiceps auritus), known as Horned Grebe in North America, and also picturesquely called Devil-Diver, Hell-Diver, Pink-eyed Diver, and Water Witch:
Male Ruff (Calidris pugnax). This shorebird has three types of males, determined by a chromosomal inversion. The common type (85-90%) is colorful and puts on aggressive group displays. A second type is paler and less aggressive, and a third type mimics females and sneaks copulations. The genetics and evolution of this complex mating system are just beginning to be understood. This male is of the common type:
JAC: I’ve added a figure from a paper in BMC Genomic Datashowing the various types of males. “L. L. F.” is Lindsay L. Farrell, and “S. B. M.” is Susan B. MacRae; click to read the caption.
