During the summer corvids stay home to raise their families but as soon as the breeding season is over they move around. In autumn large flocks of American crows return to Pittsburgh to join the winter roost while a few common ravens show up, alone or in pairs.
This month the crows and ravens are back in town. Since August their populations have gone through several phases.
Late August: On 30 August a surprising count of 380 fish crows gathered on rooftops at Fifth & Craig while only 12 American crows were present that evening.
September: By 6 September fish crow numbers dropped to 30 and then zero. American crow numbers rose through the hundreds. No ravens.
October so far: On 10 October a high count 620 American crows flew past “the doorknob” water tower at dusk. By late October no crows were counted because they changed their route. However we now see and hear ravens!
Ravens in town?
Crows migrate. Adult ravens stay home year round. However, young ravens go wandering until they reach sexual maturity at three years old. From fall through early spring a handful of these ravens visit Pittsburgh.
Last Sunday 23 October Andrea Lavin Kossis saw two ravens on Dawson Street dining on some “delicious roadkill.” The pair even had something to say about it.
p.s. In December I’ll enlist your help to find the crow roost in time for the Pittsburgh Christmas Bird Count.
Sometimes an experiment doesn’t work as planned but the results are far better than expected.
Researchers wanted to track Australian magpies (Gymnorhina tibicen), a very social species that lives in groups of 2-12 individuals on permanent territories. Rather than use the typical long-lasting harness that requires recapturing the bird to collect the datapack, they designed a harness that would release when exposed to a magnet placed at a feeding station. Would the new harness design work? The first step was to try it on a few magpies and see.
Researchers led by Joel Crampton captured five magpies at Pacific Paradise, Queensland, banded them and fitted each one with a GPS harness. Then they followed the birds to see the harness release at the feeding station.
Each banded bird immediately tried to remove the harness but it was too well designed for that to work. Instead the unexpected occurred. Unbanded magpies came to the rescue.
On the day of trapping, one individual was observed attempting to remove its own tracker but was then approached and aided by another juvenile (without a tracker or coloured leg-band) once again pecking the harness part of the tracker. The tracker remained but, within the next 10 minutes, an adult female (also without a tracker or leg-band) proceeded to approach and successfully pecked the harness at various points such that the tracker came off the fitted juvenile within c. 10 minutes. This first Magpie that had been tagged had its GPS device removed within 1 h.
Corvids [crows, jays, magpies] occupy virtually every terrestrial habitat on Earth, including Arctic tundra, arid deserts, urban streets, and tropical rainforest. Having likely dispersed around the world over millions of years from an Australasian core, it is odd that they never reached New Zealand or Patagonia or disappeared from them both.
It’s hard to imagine a place without any crows or jays but it is true of the southern end of South America, New Zealand and quite a few Caribbean and Pacific islands. I learned this seven years ago when I visited a place that has none of them: St. John, U.S. Virgin Islands.
In the absence of intelligent omnivorous corvids, other birds fill their niche. The all-purpose crow/jay/predator at St. John is the pearly-eyed thrasher (Margarops fuscatus) …
… an aggressive, opportunistic omnivore that feeds primarily on large insects, but also feeds on fruits and berries, and will occasionally eat lizards, frogs, small crabs and other bird’s eggs and nestlings.
I’ve often noticed that in winter there are more birds in the city than the countryside. Though we may not have “quality” birds we make up for it in quantity with large numbers of fruit-eating birds drawn to our ornamental trees.
In the past two weeks hundreds of American robins have been feasting in Oakland. Some of the fruits were inedible until the deep freeze softened them so the robins circled back to finish the Bradford pears last weekend. This week they started on pyracantha berries and the red fruits of this (hawthorn?) tree next to the Cathedral of Learning.
Was half the fruit wasted when birds and squirrels knocked it out of the trees?
Look closely and you can see that deer walked among the fallen fruit. They must have crossed Forbes or Fifth Avenue after dark to browse on the Cathedral of Learning lawn.
Nearby, the sweetgum balls were coated in snow on Monday, all melted by Wednesday.
American goldfinches arrived to pull seeds out of the balls. Some fell on the snow.
Year after year we’ve counted thousands of crows — up to 20,058! — during Pittsburgh’s Christmas Bird Count so we were stunned when the annual count on 1 January 2022 yielded zero (0!) at the South Oakland roost and only seven crows nearby at dusk. Roosting crows were a No Show at the CBC. Where were they? And why?
The best way to count Pittsburgh’s winter crow flock is to find a good vantage point and count them as they stream into the roost. Before Christmas they roosted in South Oakland, confirmed by my count of at least 5,200 crows near Magee Hospital on 8 December. However on Count Day a number of things went wrong.
Crow counters usually work as a team but my teammate Claire Staples was injured in mid-December and is still recuperating. I tried to recruit others but no one jumped at the chance because …
The weather was warm but extremely rainy and foggy. All the high vantage points were enshrouded in fog so I went to Dan Marino Field in South Oakland where the crows fly by. It poured! I was soaked by relentless rain for an hour while I counted five crows overhead and two cawing in the neighborhood. Yet 220 American robins pulled worms from the mud and sang in the rain. As I drove home I checked the roosting trees near Magee Hospital. No crows anywhere!
Apparently crows change their roosting habits in heavy rain.
Were they still flying to South Oakland? As a partial answer I counted from the roof of my building on 2 January for 20 minutes. In the distance 1,140 crows flew toward South Oakland. Less than I expected. Have they split the roost into several locations?
The crows are here somewhere. Have you seen them? Where?
UPDATE: Gerry Devinney filmed a huge flock of crows near the Petersen Events center on 18 December.
On Throw Back Thursday here’s a look back at the Good Old Days of 2012 when it was possible to count 20,000 crows.
Fish crows (Corvus ossifragus) are a relatively recent addition to the corvid species found in western Pennsylvania. Most people don’t realize they’re here because fish crows look nearly identical to American crows (Corvus brachyrhyncos).