Sometime this summer the Department of Public Works placed a large sandstone rock at the base of the stairs behind the Schenley Park Visitors’ Center. The prominent fossil facing the stairs tells a story about life in Pittsburgh 300 to 330 million years ago.
The sand became sandstone and in the early 21st century the rock separated from its fellows thereby exposing the fossil. This rock many have fallen at the Bridle Trail rockslide.
I have never seen Lepidodendron’s closest living relative, Lycopodium, in Schenley Park …
… but I’ll look for it now that I’ve seen its fossil ancestor.
p.s. If this Lepidodendron had fallen in a swamp instead of on a sandy beach, it would have become coal. Read about similar fossils at Ferncliff Peninsula in Ohiopyle State Park in this vintage article: Fossils at Ferncliff
(photos by Kate St. John, illustrations from Wikimedia Commons; click on the captions to see the originals)
Birds move around on their own but some of our most common species came from a different continent or a different habitat and were introduced here by humans. Now you can see both native and exotic ranges in eBird after they made changes this month to the species maps.
House sparrows and pigeons, both introduced from Europe, are a case in point. In the eBird maps below native range is purple, exotic range is orange.
Captured house finches were illegally transported from California to New York City in the 1940s to be sold as “Hollywood finches” in the pet trade. Just before the law caught up to them, the vendors released the birds on Long Island. The “exotic” house finch population has now spread across the continent. eBird shows it on the map below. Click here and scroll down to see how they spread through the decades.
The northern bobwhite does not do well in urban and suburban habitats but as a game bird it is raised in captivity and released for hunting in gamelands, agricultural fields and open woods. Have you seen a bobwhite in your backyard? It is an escapee within its “exotic” range.
Scallops travel by opening and closing their shells but the direction they move seems counterintuitive. They don’t lead with their hinges. Instead the open edge goes first as they use their eyes to guide themselves.
Scallops’ eyes look like bright beads at the shells’ front edge.
By the end of July in western Pennsylvania, there are patches of orange string draped over plants in moist locations on the edge of the forest. The orange strings are dodder (Cuscata), a native annual parasitic vine that blooms from July to October.
Dodder wraps itself around its host and inserts tiny haustoria to suck out water and nutrients. Last week I found it parasitizing invasive porcelain berry — Go, dodder! — but dodder won’t beat back the grapevine. Dodder doesn’t kill its host.
Look very closely and you can the haustoria clinging and dodder’s tiny flowers that are pollinated by wasps.
Dodder will die at the end of the growing season yet you may find it in the same spot every year. Find out why this happens and other interesting tidbits in this vintage article.
What do you do when your nest and babies sail away without you? A house finch couple on Pittsburgh’s North Shore have learned to wait for the boat to come home.
This spring a pair of house finches (Haemorhous mexicanus) were very quick to build a nest atop a loud speaker on the aft deck of the Rivers of Steel Explorer, docked behind the Carnegie Science Center. By the time the crew caught up with them the female had finished the nest and laid eggs, so the nest had to remain undisturbed until it was empty.
When would it be empty? Not yet. In August? In September?
House finches are masters at back-to-back nesting, raising three to six broods per year. As the young approach fledging the male takes charge of them while the female starts the next round of egg laying. On the Explorer the female doesn’t pause between one brood and the next.
When I met the Explorer finch family on 26 July they had already raised several broods and were caring for young approximately two days old. While our tour waited on deck for the boat to depart the father fed three tiny nestlings. They are growing fast! Here they are three days later on 29 July.
Our tour pulled away from the dock and I forgot about the house finches for 90 minutes while we traveled Pittsburgh’s three rivers. Mother and father house finch were absent but they had not forgotten. Waiting on shore they were so attuned to the habits of the Explorer that when the vessel maneuvered to dock they raced across the channel to the aft deck. “The kids are home!”
The Traveling Nest is one of many birding highlights on Rivers of Steel Explorer tours. Captain Ryan O’Rourke explained, “In addition to hosting a bird-watching cruise with the National Aviary, part of our educational program for students includes a lesson in birding and how birds can be indicators of the health of our rivers.”
This flower head is so spiny and eye catching that we rarely look at the leaves though they’ve been studied intensely at least three times since the 1870s.
Teasel’s (Dipsacus fullonum) paired perfoliate leaves collect rainwater in the cup where they clasp the stem and unwary insects drown in the puddle. Notice the water in the leaf cups below. (Click the first photo to see a marked-up version showing the water line.)
In the mid 1870s Francis Darwin, son of Charles Darwin, hypothesized that teasel digests the decaying insects, then studied and published about the digestive mechanism. Not everyone was convinced. Teasels were studied again and again.