It’s hard to take a bad picture of an American red squirrel (Tamiasciurus hudsonicus). When they pose they look so cute that it’s hard to believe they are asocial, combative and confrontational.
This sleeping squirrel seems to be saying, “I love you, tree.”
Ready to fight? Still cute.
Though they rarely encounter each other — perhaps for their own safety — red squirrels fight when there’s more than one. Most of their battles are a lot of shouting and chasing while the resident squirrel defends his territory.
Defending the midden (food store) is a matter of survival that’s learned in the first year of life. Juvenile red squirrels must find a territory and midden before their first winter or they won’t make it to next spring. Only 22% survive to one year old.
For a few, just 15%, their mothers bequeath them a territory but it still has to be defended. The red squirrels who survive are the most confrontational.
(photos from Wikimedia Commons; click on the captions to see the originals)
Les Leighton had his camera set up at Canada’s Vancouver harbor when a drama played out in front of him. A gull zipped by with both a bald eagle and peregrine falcon pursuing it in flight. What was it about that gull that attracted two predators at the same time?
Watch the chase and notice the difference between the eagle’s and peregrine’s hunting techniques. Why did both of them give up?
Since my last update on 14 March a Big Thank You goes out to everyone who went looking for peregrines in Southwestern PA, especially to Jeff Cieslak, Dave Brooke and Dana Nesiti. Jeff’s photo, above, has a second message. If you ever doubted the sorry condition of Pittsburgh’s bridges take a look at the underside of the California Avenue Bridge. Yikes!
Dante Zuccaro now reports a single peregrine almost every day, seen from the mouth of the Beaver River, most recently on 27 March.
Ambridge-Aliquippa Bridge, Ohio River:
No news since 8 March. If you’re in the vicinity, please take a look.
Sewickley Bridge, Ohio River:
After frequently seeing both peregrines at the Sewickley Bridge Jeff Cieslak found only one on 27 March. I’m encouraged that this bird is perched on the pier rather than the superstructure since the underside of the bridge is a much safer place for youngsters. Perhaps they have eggs in a nest under the bridge.
McKees Rocks Bridge / Ohio River Blvd, Ohio River:
On 22 March Jeff Cieslak saw a peregrine perched near Alcosan (which is near the McKees Rocks Bridge) but could not figure out where it came from. When it flew he followed it as best he could and returned the next day to investigate.
On 23 March he found a peregrine at the Ohio River Blvd bridge (below) which flew to the California Avenue bridge (shown at top). Perhaps this pair is nesting in the area of the McKees Rocks Bridge but not on it. Meanwhile, did you know that the decrepit California Ave bridge (at top) is rated in “fair” condition? Hmmm!
Westinghouse Bridge, Turtle Creek:
At the Westinghouse Bridge on 26 March Dana Nesiti watched the male bring in food and stash it near the nest area. He may have heard the female call from the nest but can’t be sure because a noisy train went by right then.
62nd Street Bridge / Aspinwall Riverfront Park, Allegheny River:
On 15 March Andrew Mumma saw gulls harass a peregrine falcon perched on the Aspinwall Railroad Bridge, shown above. Where did the peregrine come from? We don’t know but the 62nd Street Bridge is not far away.
When Dave Brooke visits the Tarentum Bridge now he sees only one bird at a time, as on 22 March above. On 19 March his distant observation of the nestbox indicated that the female may have laid her first egg. The male was perched alone that day.
We can know this because of the focus on pine cones, how the cones were denuded, and the sizeable midden. Conifer seeds make up the majority of the red squirrel’s diet and he defends his midden territory year-round against every other red squirrel.
Red squirrels are highly territorial and asocial with very few non-reproductive physical interactions. The majority of physical interactions are in male-female matings and between females and their offspring before the offspring disperse to their own territories. The non-reproductive physical interactions recorded (0.6% of all recorded behaviors in one 19-year study) were all instances of chasing an intruder from a territory.
This week the elms, maples, ornamental cherries and northern magnolias began to bloom in Pittsburgh. Their flowers have not yet reached their peak and that’s a good thing. Tomorrow night the low will be 19 degrees F and will devastate the tender petals.
Above, an ornamental cherry shows off its delicate pink-white blossoms in the sun on Thursday 24 March. Below, a northern magnolia flower peeks out of its winter coat in Schenley Park on Tuesday 22 March.
And finally there is the experiential illusion of a “gravity hill.”
A gravity hill, often referred to as a mystery hill, is a spot in the road where the layout of surrounding land and landmarks creates an optical illusion, making a slight downhill slope appear to be an uphill slope.
Skeptics have put the hills to the test, using magnetic detectors and levels. All indications suggest the hills are just illusions.
Because we humans can’t see ultraviolet light we miss the fact that some rocks glow in the dark after exposure to sunlight.
The glowing orange and green rock at top is a composite of willemite (normally brown glowing green) and calcite (normally white glowing orange). On display under normal light it is boring by comparison.
Other rocks can glow, too. Did you know that about 30% of diamonds glow under ultraviolet light? 99% of them glow blue but a few glow white, yellow, green, or red as shown below. See the explanation at Diamond Pro.
On Sunday at Duck Hollow we saw a female mallard with odd plumage. She was paired with a male mallard but she resembled a male in eclipse plumage. Was this duck a hybrid? Or was it something else?
Michelle Kienholz was so intrigued that she took photos and sent them to the Duck ID group where she learned an amazing thing about female ducks. This odd mallard at Duck Hollow is an “intersex hen.” She is becoming male in a process called spontaneous sex reversal (SSR).
Female ducks are born with two ovaries but only one develops. The left ovary actively pumps out hormones to stifle the male genes, making the bird truly female. If a disease damages the only ovary and it stops producing hormones the female duck spontaneously turns into a male. Experiments have shown that the now-male duck is able to breed and fertilize eggs.
Because most ducks are sexually dimorphic a female with a dead ovary eventually looks male as well. The intersex hen at Duck Hollow is partway through her/his outward transformation, which is why she/he is in eclipse-like plumage.
Notice the clues in her/his feathers that indicate the transition:
tail feathers are black and curly white,
green feathers interspersed on head
breast is darkening (top photo)
color line between neck and breast is becoming white
For more information on bird sex chromosomes see Anatomy: W and Z. For photos of eclipse plumage see Mallards in Eclipse. And here is an article about spontaneous sex reversal in chickens, a problem for chicken farmers.