Yellow-rumped warbler eating poison ivy berries (photo by Cris Hamilton)
How many of us get a rash from poison ivy? (Raise your hands.)
I know only one person who’s immune to poison ivy. The rest of us get a rash, mild to severe. Most of us avoid the plant so carefully that we haven’t tested the limits recently.
Birds are not only immune to poison ivy’s itchy oils, they eat its berries.
Here, a migrating yellow-rumped warbler (Setophaga coronata) inspects a cluster of poison ivy berries, and then he swallows one.
Yellow-rumped warbler eating poison ivy berries (photo by Cris Hamilton)
Even though New York is the largest city in the U.S. they have a wide variety of habitat and some great places to go birding. I didn’t know about Bayswater until Gintaras Baltusis, a long time follower of this blog, told me about it.
Gintaras was in Queens at Bayswater Park last weekend to photograph airplanes approaching JFK airport. While he was focused on airplanes this osprey came over with a newly caught fish.
Birds love to perch on wires and power poles, the bigger the bird the bigger the wire. Unfortunately this affinity poses a threat to very large birds because their long wings can touch two wires at the same time and electrocute them. Vultures are especially vulnerable because they roost in large gregarious groups. If they jostle their buddies too much … ooops!
Cape vultures (Gyps coprotheres) of southern Africa, like most Gyps species, are declining. They are listed as threatened because of decreased carrion for their chicks, poisoning from medication in livestock carcasses, electrocution and collision with wires, and exploitation for traditional medicine/religion.
Cape vultures live a long time and reproduce slowly so significant losses of any kind pose a problem. There are protected areas in southern Africa where the vultures aren’t exposed to so many threats but there is also a growing power grid.
W. Louis Phipps and his team decided to find out how cape vultures used the power grid so they affixed GPS trackers on nine cape vultures — five adults and four immatures — to see where they would go. The results were somewhat surprising.
The cape vultures’ home range is larger than expected; some traveled more than 600 miles one way. Given the opportunity to travel the power corridors, that’s what they did. Cape vultures are cliff birds so the power towers gave them high perches and clear sight lines in formerly useless habitat. The study also found that the vultures fed more often on private farmland than in protected areas. (The vultures would say, “Well, that’s where the food was.”)
It’s the classic Catch-22. The power corridors have expanded the cape vultures’ range but the wires sometimes kill them. In a declining population it makes a difference.
On Monday I described how American Indians shaped the landscape before European arrival. We shape it too, though we don’t always realize how. Case in point: There are more deer in North America now than there were before Columbus landed in 1492.
Because deer are a prey species, their abundance is tied to their predators. When American Indians ruled the continent they hunted deer for food and to control their population so the deer would not decimate their crops. They knew that no deer and too many deer meant less food.
European Americans are still figuring out how to balance the deer population. We overdid it a century ago by uncontrolled hunting that killed all the deer in Pennsylvania. Then we passed hunting laws and imported deer from Virginia because we missed them.
Now we’ve erred on the other side. We’ve eliminated deer predators and protected them so well that their population has exploded everywhere, even in city neighborhoods. In her conversation with Allegheny Cemetery’s president, Sharon Leadbitter learned that about 300 deer live there in three herds. This is way too many deer for the land to support so they move through Lawrenceville eating gardens, shrubs, flowers and handouts.
Allegheny Cemetery’s deer are almost tame. Sharon says this is both a blessing and a curse, “Some of the blessings are that the deer will eat out of your hand if they know you. The curse would be this great interaction. People feed all manner of things to these animals. White bread, cereal, I’ve even seen a candy bar being fed. It only takes once for someone to be bitten or kicked. These are not pets but because the animals have lost most of their healthy fear, people don’t realize that they are still semi-wild.”
The deer browse and gambol among the headstones, unconcerned by living visitors. Sharon filmed a fawn playing among the tombstones last June while his mother watched.
“The cemetery is a great place to have some quiet time and reconnect with nature,” says Sharon. “Come check it out but always maintain a respectful distance, or even better stay in the car” when you visit the deer among the dead.
When I learned American history in grade school, Christopher Columbus’ arrival on October 12, 1492 was Day One. So little was said of the people and habitat that preceded his landing that it seemed nothing happened until he got here. I learned that North America was an empty wilderness, barely inhabited. By the time the English settlers arrived it was indeed empty, but it wasn’t like that before the first Columbus Day.
My perception of the western hemisphere changed forever when I read 1491: New Revelations of the Americas Before Columbus by Charles C. Mann (Knopf, 2005). Examining scientific, historical and archaeological evidence, Mann describes what the continents were like before European infectious disease unwittingly changed everything in less than 200 years. For example…
In 1491 the human population in the Americas was greater than that of Europe, the Central Mexican Plateau the most densely populated place on earth. Unfortunately American Indians had no immunity to European diseases. Once the flame was lit their contact with each other and with escaped pigs from the Spanish expeditions fanned the plagues across the continents over and over again. In the 150 years between First Contact (the first Columbus Day) and the first English settlers, 95% of the American Indian population died.
This emptied the hemisphere of its keystone species — humans. Without the agricultural and hunting pressure of 100 million people the forest grew and other species took over. For instance, Mann explains that passenger pigeons and bison were not numerous when American Indians ruled the continent but their populations exploded in the sudden the absence of humans. Wow!
Sometimes while hiking I find a trace in the forest of a former homestead — a row of stones that bordered a field, an apple tree engulfed by weeds, a Norway spruce alone in the woods. Nature took over the site but I can see the past because someone told me what to look for. The settlers who arrived in the 1600’s found the continental equivalent of old field succession but no one was there to explain it.
Mann’s book gave me a window on the world before Columbus Day. If you haven’t read 1491 I highly recommend it.
(statue of Christopher Columbus by Frank Vittor, erected by the Sons of Columbus in Schenley Park, Pittsburgh, in 1958. Photo from Wikimedia Commons. Click on the caption to see the original)
During a hike at Parker Dam State Park last year I noticed this hemlock, a tree on stilts.
Hemlocks have shallow root systems and can sprout easily in moist locations. Sometimes they sprout in the moss on top of a rock or stump and their roots follow the contour across the surface and become anchored in the earth nearby.
My guess is that this tree sprouted on a stump that decayed out from under it. The support disappeared after the hemlock’s root system was already established but the hemlock didn’t care. It sent down some new roots and just kept growing in place.
Hemlocks in this position are vulnerable in wind storms but this one is in the understory, surrounded and protected by many other trees.
It will probably surprise hikers on the Beaver Dam Trail for a long time to come.
Take a walk outdoors at this time of year and you’re likely to come home with some of these stuck to your clothing.
These tiny burs are the seed pods of agrimony (Agrimonia eupatoria), a plant native to Europe that was brought to North America for its herbal properties. (See Mark’s comment below! This species doesn’t occur locally but we have similar natives.)
Though the burs look wicked in this close up, they’re actually small and rather weak. Compared to burdock they’re only slightly aggravating.
Click here for a view of a local species (Agrimonia parviflora) when it’s flowering — photos I took at Jennings Prairie last year.
(photo produced using focus stacking, Museum of Toulose, from Wikimedia Commons. Click on the image to see the original)
