Have you tried counting robins lately? This week it’s been a challenge.
Though it may seem pointless I usually count birds when I’m outdoors. The reward comes later when I look back at the numbers.
Based on my counts I know that a first wave of migrating American robins came through Pittsburgh in September. Their numbers dropped, but a second wave arrived last week to feast on the fruit in the city’s trees and bushes.
Unfortunately these birds are camouflaged by the autumn foliage. Rust-and-brown robins match rust-and-brown leaves. On walks in Brookline, Oakland and Squirrel Hill I counted 20, 50, 100 robins. Why the round numbers? I don’t know exactly how many there were.
All I know for sure is: There are lots of robins right now.
Last week’s sensational bird video showed a red-tailed hawk attacking a personal drone in Cambridge, Massachusetts (above). The drone lost.
Drones are popular because they’re easy to fly and come with onboard videocams. Open the box, assemble a few pieces, turn on the camera, and fly it up and into … trouble, if you aren’t careful. Novices don’t realize who owns the sky.
When Amazon Prime announced plans last December to deliver packages using drones it sounded simple but the initial hype failed to mention the regulatory, mechanical and natural hurdles. Blog posts at Slate and The Atlantic immediately set the record straight.
The FAA limits personal drones to a 400-foot ceiling — that’s below the 30th floor of the Cathedral of Learning — but birds of prey limit flying threats to a much lower level than that. Red-tailed hawks near the Cathedral of Learning are frequently reminded that peregrines own the airspace above the treetops. Drone pilots could learn a valuable lesson from a bald eagle who strayed into Dorothy’s zone.
If you’re a Swainson’s thrush of mixed parentage you’ll probably pick a bad migration route. It’s in your genes.
In eastern North America we see only one subspecies of Swainson’s thrush, the olive-backed (above), but in British Columbia there are two. The russet-backed subspecies breeds along the Pacific coast and follows the coast to spend the winter in Mexico and Costa Rica. The olive-backed subspecies breeds in the interior and migrates across the continent and the Gulf of Mexico to winter in South America.
Where their breeding ranges meet the thrushes pair up without regard to these distinctions. Their hybrid offspring inherit a mixture from their parents, including mixed coloration.
The data proved that their migration routes are inherited and that those of mixed parentage inherit a blend. While each parent would have followed the Pacific coast or a safe route across the continent, the hybrids chose novel and dangerous compromises between the two paths.
“Instead of taking well-trodden paths through fertile areas, these birds choose to scale mountains and cross deserts,” said Delmore.
The dangerous routes probably cause more hybrids to die on migration than their pure counterparts, thus keeping the subspecies distinct. Says Delmore, “The self-destructive behavior of hybrids could be helping to maintain the great diversity of songbirds we enjoy.”
Before Columbus, the human population in the Americas was larger than Europe’s and the landscape, animals and birds were balanced by the pressure of so many people. Europeans arrived and accidentally left behind pigs carrying human disease. Native Americans, who had no immunity to European disease, encountered the free-range pigs and spread the plagues through human contact.
The Western Hemisphere suddenly lost 95% of its human population in only 150 years. Remove the keystone species and you get some pretty weird results. European settlers didn’t see the transformation so they thought what they found was normal including the endless forest, huge bison herds and billions of passenger pigeons.
So I wonder …
If Native Americans had not died off, would passenger pigeons have boomed at all?
If there hadn’t been so many passenger pigeons, would we have hunted them to extinction?
Though shaped like a green rose this knob is not a flower. It’s a goldenrod bunch gall.
A search at BugGuide.net(*) indicates:
The gall was made by a midge, Rhopalomyia solidaginis, that lays its egg at the tip of the goldenrod stem. “Its larva secretes a chemical that prevents the goldenrod stem from growing although it continues to produce leaves, thus a shortened bunch of leaves is formed.”(*)
The resulting rosette provides shelter for many insects as well as the midge.
This fall I’ve seen many bunch galls in goldenrod fields. This one was at Wingfield Pines in southern Allegheny County.
Click here to read more about the midge at BugGuide.net.