Ever since the first snowy owl showed up at Presque Isle State Park on November 23 Erie’s resident pair of peregrine falcons has been on the warpath. Peregrines hate owls and snowies are no exception. How dare an owl invade their territory!
On November 26 a second snowy arrived and perched near the first at Gull Point. On November 30, a third and darker owl came to Beach 6. The snowies like the banquet at the lake. They’re eating visiting waterfowl.
Their arrival has kept the peregrines quite busy. Many observers have seen the peregrines attacking the owls.
One owl is annoying, two are worth shouting about. On Friday while Shawn Collins was on his way to Gull Point he heard a peregrine whining and warning at Beach 10. The peregrine was so upset and distracted that it remained perched and whining on a telephone pole while Shawn snapped several pictures.
Angry and swift, the peregrines teamed up to convince the owls to leave. Would it work?
The owls are bigger and know about large, powerful falcons. They come from the land of the gyrfalcon.
At this time of year I often forget to retrieve snapshots from the peregrine falconcams because so little is going on. When I finally did so this month I found a surprise at the Gulf Tower.
For two years the Downtown peregrines have shunned the Gulf Tower nest. In the early days Louie visited alone but Dori stayed away. The nest had been so inactive that I forgot the camera was still running.
But look who came to visit on November 16!
The visitor puttered at the nest for about two minutes — a fairly long time for a peregrine in November. Here are two more snapshots.
Assuming this is one of the resident Downtown peregrines, which bird is it? Dori or Louie? Here are links to other Gulf nest snapshots for comparison:
Though juvenile mortality is high, birds are amazingly long-lived if they survive to adulthood. What’s the key to their longevity?
In 2011 scientists at the National Evolutionary Synthesis Center in Durham, NC crunched 27 years of data on more than 1,200 birds to examine mate selection, fertility and aging. They used the rich data set on blue tits, a bird similar to our chickadees, studied on the island of Corsica since the late 1970′s. Aging was easiest to see among female blue tits because their fertility dropped if they lived long enough. They laid fewer eggs and laid them later in the season than females in their prime.
Interestingly the study found that females remained in their prime longer if they had good mates. Their fertility did not wane so soon, they aged more slowly. This was especially true for the ladies whose mates became fathers at an early age.
The good males were better helpers during the nesting season. They shared parenting duties and were solicitous for the females’ well-being. They brought food to their ladies and eased the burden of nest building, incubation and child rearing. The team’s scientists conjectured that the males who became fathers at an early age were not only more experienced at this but were also healthier.
The good mate scenario sounds a lot like Dorothy and E2′s relationship. Every nesting season we see E2 on camera bringing food to Dorothy and the kids, begging to take over incubation duties, and sometimes refusing to give them up. Even in the off season, those of us who watch this peregrine pair see E2 bring food to Dorothy throughout the year. What a guy!
p.s. A study published this year showed this principle is true for humans, too. Happily married couples live longer, healthier lives than their single counterparts. Thank you to my husband on our anniversary.
Since late October, Pittsburgh’s winter crow flock has been big and brash in Oakland. At dusk they flood the sky, gathering on roofs and treetops to choose a place to sleep. Last week they roosted in the trees around Pitt’s Student Union and the Cathedral of Learning. This got them into big trouble!
Every night pedestrians dodged the “rain” from trees filled with crows and every morning the sidewalks were a slippery crow-poop mess. The crows had to go. But how to convince them?
Last weekend Pitt positioned a loudspeaker on the low roof of the Student Union and played very loud bird distress calls over and over all night. They ran it for five nights, Friday through Tuesday, Nov 8-12.
Most people didn’t know it was a recording. In the dark it sounded like birds fighting and dying: a robin in awful distress, an unidentified bird screaming and a peregrine kakking.
Late Saturday night Jason Carson recorded the video above and tweeted me with the question: “What is this? Are the peregrines fighting?”
Initially I was fooled and thought it was real, though it didn’t make sense. Any bird suffering that much would have died after the first assault and the noise would not repeat. Then Pat Szczepanski told me she heard it Sunday night at 6pm and it dawned on me. Duh! It’s a recording.
Usually crows are not impressed by bird distress recordings. They are way too smart to be fooled for long. Sometimes the only thing that will move them are bird-scare firecrackers like the ones they use at Penn State (click here for videos of Penn State’s “crow wars”).
Why were a few nights of noise enough to move Pittsburgh’s crows away from the Cathedral of Learning? I have a theory and I think it’s pretty good.
Crows are afraid of peregrines but they’re more afraid of great horned owls. They know Dorothy and E2 live at the Cathedral of Learning and they know peregrines hate great horned owls so they probably figured “The enemy of my enemy is my friend” and they chose to roost at Pitt.
But last weekend there was an awful ruckus and the sound of peregrines defending their home. “Oh my gosh!” thought the crows, “The owl must be here! I hear the peregrines attacking it!”
In the dark Dorothy and E2 swooped low to investigate the noise. “Oh no!” said the crows, “The peregrines are here! Fly away!”
The crows didn’t move far but they moved far enough. By Monday evening they were avoiding the trees on campus and roosting instead on the roof of Soldiers and Sailors Hall. Just far enough to avoid the owl and the peregrines. Just far enough that Pitt is happy. Just far enough that the noise has ceased and Dorothy and E2 can get a good night’s sleep.
Without real live peregrines at Pitt, the crows would not have been fooled.
And here’s a potential food source — a flock of dunlin.
The peregrine is looking for a bird that’s easy to catch. The dunlin are sitting ducks (er… dunlin) if they stay on the ground so they fly and flock as soon as they see a peregrine. This interaction has made dunlin more fit in the years since the peregrine population has recovered from the DDT crash.
A 2009 study at the Fraser River delta on the Pacific coast backs this up. Peregrines never went extinct on the West Coast but they were very scarce in the 1970′s. During this period wintering flocks of dunlin safely roosted on the sand at high tide and became fat — and a bit slower — in early winter.
The peregrine population began to recover in the 1990′s and soon found tasty dunlin meals as they migrated past the Fraser River delta in fall and spring. The dunlin quickly learned it was unsafe to roost at high tide during the day because peregrines were on patrol. Instead they began to spend high tide flocking over the open ocean, flying and flying for three to five hours. With this exertion they became much more fit and are now are measurably thinner in early winter, the time when peregrines are passing by.
Peregrine falcons have provided dunlin with a fitness program. Be fit or be eaten.
Click here to read more about the Fraser River dunlin study.
Exciting news at Green Tree! Thanks to Shannon Thompson we now know the identity of the female peregrine at the water tower.
Shannon made it her goal this spring to read the female’s bands. It was a challenge! After months of frustration she finally saw “Black/Green 74/AE” last Sunday and sent the numbers to Pennsylvania’s Peregrine Coordinator, Art McMorris, who tells us …
This is a bird we’ve met before. She hatched and fledged at the Cathedral of Learning in 2011, a daughter of Dorothy and E2. Back then she was nicknamed “Blue” because of the blue tape on her USFW band.
Blue barely left home, choosing to nest only 5.25 miles from her birthplace. Her mate is unbanded so we’ll never know where he came from but we do know he was born in 2012 because of his juvenile plumage.
For a month now we’ve had no peregrine nesting news in Pittsburgh. I thought the season was over… right?
Not! This afternoon Art McMorris, Peregrine Coordinator for the PA Game Commission, reported that the peregrine pair at the Green Tree water tower have nestlings! Here’s an excerpt from Art’s email:
“As you know, the peregrines’ nesting attempt this spring failed, and all indications were that they were not re-nesting, so we (PA Game Commission) gave the water company the go-ahead to resume the work they postponed to protect the peregrines. Today the contractors started working — and they saw the adults flying in and out of the nest feeding chicks that they could hear, but not see.
They have agreed to suspend work, again, to protect the peregrines. … Since the workmen could hear the chicks, I think they must be at least 10 days old; but beyond that, I have no idea. For all we know now, they could even fledge tomorrow.”
Art needs our help monitoring the Green Tree site. How many chicks are there? Have they appeared at the nest opening yet? Let’s make sure they fledge safely. Stop by the Green Tree water tower (visit the park behind the Green Tree Borough City Office) and look under the bulb of the water tank at the shelves beneath.
Congratulations to this persistent pair at the water tower. (“Mom” & “Dad” pictured below.)
Why do peregrines nest on buildings and bridges instead of cliffs?
“Raptors imprint on their natal nest sites. Consequently, they choose a similar situation several years later when they reach maturity.”(1)
This explains why they’ve chosen to nest at the Tarentum Bridge, pictured above. The adult female, nicknamed Hope, was born on the Benjamin Harrison Bridge in Hopewell, Virginia. That bridge is such a dangerous place to fledge that Hope was hacked in the Shenandoah Mountains, but she remembered where she was born and picked a bridge when she chose a place to nest.
There are exceptions to the natal imprint rule. Though Dorothy’s daughter Maddy was born on the Cathedral of Learning, a 40-story Late-Gothic Revival building, she chose the I-480 Bridge in Valley View, Ohio. I can’t think of anything less like the Cathedral of Learning than this. (The nest is at a broken patch of concrete on the bridge support.)
The exceptions have saved at least one species from extinction.
Mauritius kestrels used to nest in tree cavities but monkeys were introduced to the island and ate the eggs and young. By the 1960′s the kestrels were down to two pairs — almost extinct — when one of the pairs decided to nest on a cliff ledge where the monkeys couldn’t reach them. That nest was successful, their youngsters nested on cliffs, and the species rebounded.
The exceptions benefit the rule.
(photo of Hope at the Tarentum Bridge (blue structure) by Sean Dicer. Photo of Maddy’s nest site at the I-480 Bridge at Valley View (busy highway) by Chad+Chris Saladin.
Today’s Tenth Page is inspired by and includes a quote(1) from page 444 of Ornithology by Frank B. Gill.)
Late June is an intensely busy time for peregrine parents in North America’s mid latitudes. If their nests were successful they have young about to fledge or already on the wing who must become independent in just four to eight weeks.
If you think that’s fast, consider the life of an arctic peregrine.
Island Girl, pictured above, is an arctic peregrine tagged with a satellite transmitter in southern Chile in 2009 by the Falcon Research Group. They’ve tracked her migrations every year in amazing detail, able to determine latitude, longitude and altitude of her roosts and see the neighborhood where she chooses to sleep via Google Earth.
Island Girl nests on Baffin Island, Canada and spends November to April on the coast of southern Chile. To do this she travels nearly 17,000 miles per year. This spring she left Chile on April 17 and arrived at her eyrie in Canada on June 3, covering 8,868 miles in only 48 days. She got home early.
Here’s a screenshot of her trip. (Click on it to see the real map.) This is the feat of an athlete!
Now that she’s on her breeding grounds Island Girl has a very compressed schedule. She arrived on June 3 (the day Silver Boy fledged) and absolutely must leave in late September. Winter comes quickly on Baffin Island so Island Girl always leaves between September 20 and 24. Always.
This gives her about 111 days to court, lay eggs, incubate, raise nestlings, and teach fledglings.
Her schedule probably looks like this:
Courtship and egg laying: 14-18 days, June 3 to June 19. This is the most optimistic schedule, assuming an established mate, an established territory and no intruders.
Incubation: 33-35 days, June 19 to July 23
Nestling phase, 39 to 45 days, July 23 to September 3
Fledged young dependent on parents, 4-8 weeks, September 3 to October 1 or October 29.
There’s barely time to fledge young and begin to teach them before she has to leave for Chile. In fact her kids might leave with her and learn to hunt while traveling.
Arctic peregrines are certainly on a tight schedule!