I haven’t yet decided whether to post wildlife photos for the week I’m in Boston, as photos sent to me there to replenish my waning stock might get lost. If you have some good photos to send, and I hope you do, please hold onto them until late next week.
Today’s photos come from Peter Sansun in England, whose ID’s and caption are indented. You can enlarge the photos by clicking on them:
Here are a few sample nature pictures that you may wish to consider for publication. The bird pictures were all taken within a short walk from my home here in the UK, on the outskirts of London.
I have included the Linnean names (where known) in the picture titles.
When I was a kid in Virginia, I knew where there was a pawpaw tree in the woods, and at the right time of year I’d gather the ripe ones and gorge myself. They are superb: the American equivalent of mangos. Here’s a post from reader Leo Glenn about the American pawpaw and its fruit. They’re not much grown commercially, as far as I know, so try to find a wild tree—or plant one yourself, as Leo did.
Leo’s captions are indented and you can enlarge his photos by clicking on them.
In heeding your call for more wildlife photos, I thought I would offer something a little different. The photos themselves are no great shakes, but hopefully the subject matter will be informative and of interest to your readers. After acquiring our house and property in western Pennsylvania 15 years ago, we began to look for interesting and unusual native trees and shrubs to plant, particularly ones which provide food and/or wildlife habitat. I’ve had a keen interest since childhood in edible and medicinal wild plants, so I was very surprised to learn of a native tree that I had not heard of before, apart from a vague memory of a childhood song. The Pawpaw tree (Asimina triloba) is indigenous to the eastern United States and Canada, and its fruit is the largest native tree fruit in North America. It’s also the only species in its family (Annonaceae) that is not tropical. It’s related to the custard apple (Annona reticulata), soursop (A. muricata), and the cherimoya (A. cherimola).
We have been growing pawpaws now for over 12 years, and have around 20 trees, eight of which are bearing fruit. We also discovered a wild patch along a river bank about a half-hour drive from our home.
Here is a map of the pawpaw’s native range, including some of the Native American names for it. Prior to the ice ages, the species was propagated by megafauna, which ate the fruit and distributed the large seeds. After the extinction of the megafauna and the introduction of Homo sapiens, the fruit was widely eaten and propagated by Native Americans. Thomas Jefferson grew them at Monticello, and they were supposedly one of George Washington’s favorite desserts. Lewis and Clark survived on them during part of their travels, and Mark Twain extolled their virtues. At some point, however, they were all but forgotten.
Pawpaws are understory trees that form clonal patches, which may partly explain their scarcity in Pennsylvania, as the majority of woodland was clearcut here by the early 1900s. The only remaining wild patches here tend to be along river banks. They are more common in Ohio, Michigan, Indiana, and elsewhere in their native range, where they are sometimes called “Prairie Banana.” Here is a pawpaw tree, surrounded by its clonal “children.”
Pawpaw blossoms are perfect, containing both male and female parts, but are protogynous—the stigma matures before the pollen—generally requiring two genetically different trees for pollination (though some self-fertile trees have been found). This is why many clonal patches often produce little or no fruit. The blossoms are pollinated primarily by flies and beetles, have a fleshy color and a slightly fetid odor. Some pawpaw growers hang animal carcasses on the trees to attract pollinators, a practice I have not been tempted to try.
Pawpaws are often compared to bananas, partly because of the flavor and the fact that they are highly perishable, but also because of the manner in which the fruit grows.
Pawpaws growing in a wild patch along the Allegheny River.
Some of our pawpaws:
Pawpaws have few insect pests (the bark and leaves contain annonacin, a natural pesticide), though they are the exclusive larval hosts for the Zebra Swallowtail butterfly (Protographium marcellus). I have yet to find one on any of our trees or at the one wild patch I know of, so sadly I cannot offer a photo. I did notice some signs of caterpillar damage on the leaves, but was unable to discover the culprit, until I ventured out at night with a headlamp and caught this fellow, a Tulip-Tree Beauty caterpillar (Epimecis hortaria), happily munching away.
Pawpaws ripen in late August and September in the warmer parts of their range, but here in northwestern Pennsylvania, we have to wait until early October, and keep our fingers crossed that we don’t get an early hard frost. They can be picked when the surface gives slightly to the touch and they begin to emit a sweet aroma.
The flesh of pawpaw fruit varies in color, from a pale, cream color to bright yellow-orange, and has a rich, custard-like consistency, often described as a vanilla or banana custard, though it can have hints of mango, cantaloupe, and other flavors. Some find it too cloying, but my family and I consider it to be one of the most exquisite fruits we have ever tasted. Unfortunately, it is highly perishable and, like bananas and avocados, can go from under-ripe to perfect to over-ripe in the blink of an eye. This has presented formidable challenges to the efforts of some people to commercialize the fruit. Interest in the fruit has been building, however. You can find them at some farmers markets, and there are small-scale pawpaw growers in parts of the U.S., Europe, and Asia.
For those seeking additional information about this remarkable native species, I recommend looking up R. Neal Peterson (petersonpawpaws.com). As a plant geneticist in the 1970s, he came across some pawpaw trees, tasted one of the fruits, and had an epiphany. He has since devoted his career to studying the species and promoting it as a commercial crop. He is almost single-handedly responsible for the revival of interest in the fruit and has developed a number of exquisite cultivars. I had the great pleasure of meeting him, and he very kindly and patiently endured my many questions. A good book to read is Pawpaw: In Search of America’s Forgotten Fruit, by Andrew Moore. There are a handful of festivals devoted to the pawpaw, but the first and by far the biggest is the Ohio Pawpaw Festival (ohiopawpawfest.com), in Albany, Ohio, which is happening soon (Sept. 17-19). It’s a wonderful mix of educational presentations, live music, and fantastic food, including pawpaw beer. We first attended in 2008 when, after planting a half dozen young pawpaw trees, it occurred to me that it would be a great disappointment if, after waiting for 7-10 years for our trees to bear fruit, we discovered that we hated pawpaws. So we went to the Ohio Pawpaw Festival to try one, and went back every year after that for the next 10 years.
We are at a seriously low level in the photo tanks, so please send me your good wildlife/travel/street photos. Thanks!
Today’s photos come from John Egloff. His captions are indented, and you can enlarge the photos by clicking on them.
Although I’m certainly not a professional photographer, since you always seem to be in need of photos for the “Readers’ wildlife photos” posting on your website, I thought I’d offer up the attached photos I took last month while visiting two different parks.
The first photo is of a Small Skipper(Thymelicus sylvestris) visiting the flowers of a Prairie Ironweed(Vernonia fasciculata). This was taken at Eagle Creek Park in Indianapolis. Eagle Creek Park is one of the largest municipal parks in the United States, with 1,400 acres of water and 3,900 acres of forest.
The remaining photos were taken at the Morton Arboretum in Lisle, Illinois. As you probably know, the Morton Arboretum is about 30 miles east of downtown Chicago, with 1,700 acres of prairie, woodlands and ponds. The Arboretum was established in 1922 by Joy Morton, founder of the Morton Salt Company, whose estate formed the core of the Arboretum’s original property. The first picture is of a Common Eastern Bumble Bee(Bombus impatiens) visiting a White Turtlehead(Chelone glabra).
The next picture is of a Monarch Butterfly (Danaus plexippus), looking a bit worse for wear while sharing a Musk Thistle (Carduus nutans) with another Goldenrod Soldier Beetle (Chauliognathus pensylvanicus).
Next is a photo of a group of quite striking Purple Asters(Symphyotrichum patens).
Here are two photos of a Great Blue Heron(Ardea herodias), who allowed me to approach it quite closely, although in the second photo it seems to be eyeing me with some suspicion.
Last but not least is photo of a green heron(Butorides virescens), with his beak open and displaying his crest.
Caught some early morning light on an Arbutus tree whose peeling bark seems to be sending out a message. About what I can’t say, but they have been stressed by fungal organisms and warmer, drier weather in recent years. Ours seem to be doing pretty well, but we do see a lot of mangy looking trees in the area.
And some travel photos by Jean Greenberg:
We went to Tibet in the summer of 2009. It was when Michael Jackson died, because we learned about it while we were there. We traveled with my former postdoc and her husband, who was all about taking fancy pictures and connecting with people everywhere even though he could not speak the language. To get pictures of people, he often posed with them. The pictures below, except for a few, were taken by my late husband Adam Driks.
We have about a week’s worth of photos in the tank, so, if you have good pictures, please top it up.
Today’s photos come from Tony Eales in Queensland. His captions and IDs are indented, and you can enlarge the photos by clicking on them.
It’s coming into Spring in the Southern Hemisphere, and many of the early spring flowers are opening up. An I noticed that a number of the ones around now are purple, so I thought I would send a collection of purple blooms from the east coast of Australia.
Thysanotus tuberosus,Common Fringe Lily. These lovely plants are fairly common in undisturbed grassy forest. The small tubers were collected and eaten by Aboriginal Australians.
Viola betonicifolia,Mountain Violet. This was a new one for me, and despite the common name it was nowhere near a mountain.
Utricularia dichotoma, Fairy Aprons—one of the lovely flowering Bladderworts that can be found in the right habitat.
Desmodium rhytidophyllum. Rusty Tick-Trefoil, one of the numerous small pea flowers that scramble through the grass in open forests around here.
Hovea heterophylla, Common Hovea. Another small pea plant that flowers profusely in September:
Murdannia graminea,Grass Lily. Another plant of the grassy understory that has small edible tubers:
Patersonia sericea,Silky Purple Flag, looks like nothing in the grass through most of the year. Then, in Spring, you realise they’re everywhere, with their large flowers that often last just for a morning.
Today’s photos and a bonus video, come from reader Jim McCormac, whose “massive photo website” is here and whose blog is here. His captions and IDs are indented, and you can enlarge the photos by clicking on them.
Here’s some stuff from a recent West Virginia trip, most notably perhaps, bumblebees caught in the act of pollinating one of the bottle gentians.
Sunrise at Bear Rocks at Dolly Sods, West Virginia. I was at a conference in the nearby Canaan Valley recently, and tacked on time to visit this amazing mountaintop on August 22.
Although I saw no bears at Bear Rocks, I did see this beautiful American Black Bear (Ursus americanus) in the Canaan Valley. Bears in this region tend to be quite wary, as they are hunted (seasonally), and people train their dogs using bears year-round. I spotted this one a ways off, was able to get in a good position for photos as he approached, but as soon as he made me, he quickly disappeared into the forest.
A tough Red Spruce (Picea rubens) ekes out an existence at Dolly Sods. Strong prevailing winds from the west, often accelerating to gale force, pound the trees relentlessly and those that are prominently exposed exhibit one-sided branching. This is known as the Krummholz Effect (German = “twisted wood”). Branches on the upwind side are stunted by the constant strong winds.
Fireweed (Chamaenerion angustifolium) still had some flowers, but mostly had passed to the fruiting stage. This elegant member of the Evening-primrose Family (Onagraceae) is one of the most photographed wildflowers of northern and montane habitats, where it can form breathtakingly large colonies.
Long-fruited Sedge (Carex folliculata) with its distinctive elongate fruit (in sedge-speak, the fruit are termed perigynia). In my neck of the woods – flatland Ohio – this species is absent and it was a treat to see it again. Long-fruited Sedge is a northerner, extending southward at higher elevations of the Appalachian Mountains.
Glimmering dewdrops of death adorn the specialized hairs of Round-leaved Sundew (Drosera rotundifolia) leaves. I saw many of these plants in a bog at Dolly Sods. The sticky droplets lure small insects, who are stuck fast in the viscid liquid. This triggers a reaction in the leaf, which slowly enfolds the victim. After extracting nutrients from the insect, leaving a desiccated husk, the leaf unfurls and is ready for more action. This carnivory is an adaptation for life in nutrient-deficient bog substrates.
A botanical highlight of Dolly Sods was a colony of Narrow-leaved Gentian (Gentiana linearis). It is another northerner whose range extends southward in the Appalachians at higher elevations. Dolly Sods is near its southern limits. As it was the first time that I had clapped eyes on this species, I was particularly pleased to encounter the beautiful gentian.
It got even better when I saw that numerous bumblebees were seeking nectar at the odd flowers. This group of “bottle” gentians are primarily if not exclusively pollinated by large bumblebees in the genus Bombus (I think the one in the photo is the Common Eastern Bumblebee, B. impatiens). The blue petals are fused together forming a tube, with a small opening at the summit. Colorful stripes acting as nectar guides adorn the interior of the flower, and while we cannot see them, the bees certainly do.
The following video shows bumblebees working a flower cluster. Once a bee spots the internal nectar guides, it works hard to enter the flower. Experienced bees quickly push their way in via the small pore at the flower’s summit, but it takes a powerful insect to open this “door” and gain access. Naive, young bees (presumably) will literally bumble about the flower’s exterior, seemingly baffled as to how to gain entrance. I saw this behavior several times. But once they have figured it out, they too quickly tap the nectar at the flower’s base and in the process provide pollination services.
“Senescence” is defined as “deterioriation with age”, and, in biology, usually refers not to an accumulation of external injuries over one’s life, but to an inherent process of going downhill physically and physiologically, as many of us are experiencing now. In humans, things start going wrong, you get creaky, or your mind might go and diseases of age will occur. The evolutionary reason why animals aren’t immortal are not completely clear, but there are evolutionary theories. (One of them is that genes that make us reproduce early, but have the side effect of hurting us as we’re older, will be subject to positive natural selection.)
But what about plants? Do they senesce, too? Well clearly some plants are genetically programmed to live only a year or so, but the paper at hand is concerned with trees. Do they senesce, too, or do they have a limited life span simply because, over time, bugs, fires. lightning, climate change, and so on eventually cause them to die?
This new paper, which has sixty-one authors (!) says “yes”, but answering a bit more limited question: do larger trees have reduced fecundity (i.e., seed production)? Since we don’t know the age of a tree without counting its rings, the authors use size as a surrogate of age, though in many species the correlation between tree size and age is not tremendously strong. Another issue is that even in single trees, much less species, seed production varies tremendously from year to year, being huge in so-called “mast years.” Every squirrel knows this. So you can’t just look at seed production in one tree in one year, or even in an entire species in one year, to find out if it goes down as a tree ages. (“Size”, by the way, is estimated as the diameter of the trunk.)
We’d like to know this for several reasons: ecological prediction, use of trees to produce fruit or nuts (do they need to be replaced at a given time? and, if so, when?), and for studies of what truncates life spans in various organisms.
Up to now the assumption has been that log of fecundity goes up with the log of a tree’s diameter, but the data from various species has been conflicting. This new paper in Proc. Nat. Acad. Sci. USA uses data from 597 species of trees, with measurements taken from 585,670 individual trees and 10,542,239 tree-years (this explains why there are so many authors). The conclusion? Yes, in general fecundity declines with tree size. (Fecundity is measured via standardized methods of seed sampling.
Click on the screenshot below to read the paper, or get the pdf here; the full reference is at the bottom.
The results are simple, and can be shown in one graph (below). Of all the tree species tested, 63% showed a decline in fecundity (relative to trunk diameter) as they age (actually, as they get bigger), while another 17% show an increase in seed production that slows down as the tree ages. The conclusion, then, is that “80% of the 597 species tested here show declining rates of increase in fecundity with diameter. . . and 63% of the total actually decrease.” They consider this “empirical evidence for declining fecundity with size”, ergo with age. In other words, the reproductive effort of trees, like that of many animals, slows down as the organism ages. Trees get old and less functional.
Here are some figures showing that decline. Subfigures A-C are for temperate regions, and D-F are tropical regions. Each plot shows the standardized (by diameter) fecundity versus standardized diameter (see paper for how these were calculated), and each line represents one species of tree.
Plots A and D show a pattern of declining relative fecundity with diameter (age surrogate), and these have most of the data for both regions. Standardized fecundity is taken to be fecundity relative to maximum fecundity, which is why in A and D, it peaks at 1.0.
Plots B and E show a pattern whereby fecundity first increases with diameter and then, as the tree gets bigger, the rate of fecundity increase begins to level off (a “sigmoid” graph), showing that the increase in reproductive effort slows down as trees get bigger (and older).
Finally, plots C and F show a pattern in which standardized fecundity continually increases as the tree gets bigger. (It’s possible that if they kept measuring or found the very largest trees, the increase might slow down.)
Clearly, A and D represent most of the trees surveyed.
I’ve put the journal’s caption below the figure; click to enlarge it.
So if anyone asks you if trees get old, you can tentatively answer: “Well, they appear to, at least insofar as older trees reduce their relative investment into seeds.”
Qiu, T., M.-C. Aravena, R. Andrus, D. Ascoli, Y. Bergeron, R. Berretti, M. Bogdziewicz, T. Boivin, R. Bonal, T. Caignard, R. Calama, J. Julio Camarero, C. J. Clark, B. Courbaud, S. Delzon, S. Donoso Calderon, W. Farfan-Rios, C. A. Gehring, G. S. Gilbert, C. H. Greenberg, Q. Guo, J. Hille Ris Lambers, K. Hoshizaki, I. Ibanez, V. Journé, C. L. Kilner, R. K. Kobe, W. D. Koenig, G. Kunstler, J. M. LaMontagne, M. Ledwon, J. A. Lutz, R. Motta, J. A. Myers, T. A. Nagel, C. L. Nuñez, I. S. Pearse, Ł. Piechnik, J. R. Poulsen, R. Poulton-Kamakura, M. D. Redmond, C. D. Reid, K. C. Rodman, C. L. Scher, H. Schmidt Van Marle, B. Seget, S. Sharma, M. Silman, J. J. Swenson, M. Swift, M. Uriarte, G. Vacchiano, T. T. Veblen, A. V. Whipple, T. G. Whitham, A. P. Wion, S. J. Wright, K. Zhu, J. K. Zimmerman, M. Żywiec, and J. S. Clark. 2021. Is there tree senescence? The fecundity evidence. Proceedings of the National Academy of Sciences 118:e2106130118.
Today’s batch is quite diverse in content, and comes from reader Leo Glenn, whose notes are indented. You can enlarge the photos by clicking on them.
I haven’t been able to take many photos lately, and my archive is fairly disorganized, so here is a somewhat random collection of photos. The only thing tying them together, really, is that they were all taken within walking distance of my house in western Pennsylvania. I’ve also included a “macro” photo that you could use as a “What am I?” quiz, if you so desire. The subsequent photo is the reveal. [JAC: I’ll put it below the fold.]
Gray treefrog (Dryophytes versicolor), so named because they can change color from gray to green or brown. Far more often heard than seen, this one was down near the ground and politely lingered long enough for me to take its picture:
Our mulberry tree had a bumper crop this year, which attracted many bird species, including this Black-billed cuckoo (Coccyzus erythropthalmus), seen here, though, on a neighboring red maple (Acer rubrum).
Today we have prairie photos from reader Jim McCormac. His captions are indented, and you can access his photos by clicking on them. (Jim’s “massive photo website” is here, and his blog is here.)
Here’s a pictorial tour of a particularly notable southern Ohio prairie. I also included image files as separate attachments, thinking they might be easier for you to work with. But if embedded files within the email are sufficient, let me know and I won’t attach them separately in the future.
A snippet of Chaparral Prairie in southern Ohio’s Adams County. I went there on August 5 to find the prairie in peak bloom. It is a botanist’s – and entomologist’s – dreamscape. In this photo, the round white flower clusters of rattlesnake-master (Eryngium yuccifolium) punctuate the foreground. Purple wand-like inflorescences of spiked blazing-star (Liatris spicata), golden pyramidal floral arrangements of early goldenrod (Solidago juncea), and the huge basal leaves and towering flower stalks of prairie-dock (Silphium terebinthinaceum) fill out the scene.
Lush stands of spiked blazing-star are especially conspicuous, both to human visitors and pollen-seeking butterflies.
The discerning botanist will find much of interest beyond the showy mega-flora. This small wildflower is bluehearts (Buchneria americana), a species of dry prairies and barrens. It is a member of the broomrape family (Orobanchaceae), whose members are hemiparasites. They derive some sustenance from tapping into the roots of surrounding plants, although I am not sure which species the bluehearts pirates nutrients from.
Careful searching is required to find the diminutive pink milkwort (Polygala incarnata). A six inch tall plant would be a whopper, and it grows in sparsely vegetated zones of the most barren areas within the prairie.
Far more conspicuous is nodding wild onion (Allium cernuu), one of the showiest members of the onion family (Alliaceae).
The rich botanical diversity of Chaparral Prairie attracts legions of pollinators, both obvious and obscure. This monarch(Danaus plexippus) was one of many that I saw. They are especially smitten with the blazing-star. Habitats such as this are critical way stations fueling this insect’s amazing migration to wintering grounds in oyamel fir forests in central Mexico.
Many other butterfly species were present, although most were not as conspicuous as the monarchs. This is a tawny-edged skipper (Polites themistocles) nectaring at nodding wild onion.
Scores of small native bees worked the flowers, and the rattlesnake-master blooms were especially attractive to this group. This is an orange-legged furrow bee (Halictus rubicundus). Many other bee species were present.
Beetles of many stripes formed an important component of the pollination crew. This is a wedge-shaped beetle (Microsiagon limbata).
Many wasps also are also important pollinators, and many of them are spectacular. This is a huge species of spider wasp known as Entypus unifasciatus. When not nectaring at flowers – rattlesnake-master in this case – the females hunt large wolf spiders. They square off with their formidable eight-legged prey, and soon sting the spider. Powerful neurotoxins are injected which nearly instantly paralyzes the victim. The wasp then drags it to a burrow and encrypts it along with some eggs. When the wasp grubs hatch, they enjoy fresh spider meat.
This insect greatly resembles a spider wasp and is just as large. But it is a fly, a mydas fly (Mydas tibialis) to be exact. It even frequents the same flowers as the spider wasps. The fly world is awash in remarkable mimicry. Looking like an insect that can pack a venomous punch, such as a bee or wasp, presumably dissuades birds from trying for a meal.
A tachinid fly (Juriniopsis adusta) rests and grooms on a leaf in between nectar forays. Tachinid flies are parasitoids, and this one preys on the caterpillars of certain butterflies and moths. Parasitoids generally kill their hosts, and in grisly fashion. In this case, eggs are deposited on the caterpillar, the maggots soon hatch, bore into the victim and ultimately eat it alive from within. Horrific as this may seem, tachinids are vital to ecological balance (other than those species unwisely introduced for “biological control”) and serve as important pollinators.
The “lesser” bugs fuel a fascinating web of predation, and of the insect predators this may be king. It is a cannibal fly (Promachus hinei), and it might be thought of as the peregrine falcon of the fly world. Cannibal flies have been documented taking prey the size of hummingbirds, although they more typically stick to their invertebrate brethren. This one has a European honey bee (Apis mellifera) in its grasp. They often take large bumble bees, and I have seen them grab big wasps with potent stings. We can be grateful that cannibal flies are not the size of sandhill cranes, or our field trips could become quite perilous.