Pleistocene Survivors–The Corvids

As I noted in the very first blog entry I wrote for this website, every animal and plant speciess alive today survived and had an ecological niche during the Pleistocene.   Perhaps one of the most remarkable and successful families of Pleistocene survivors are the corvids–a bird family that includes crows, ravens, jays, magpies, and nutcrackers.  Today, only three species of corvids inhabit Georgia regularly.  In addition to those,  ravens may occasionally appear in the mountains of the northern part of the state, but their numbers have drastically declined in the region for reasons I discuss later.  But during the Pleistocene, there were seven species of corvids that lived within what’s now the state boundaries, though not necessarily simultaneously.  Here’s a look at each.

Illustration by Louis Agassiz Fuertes

Northern Raven–Corvus corvax

This is a bird of the deep wilderness.  Because Georgia Before People was nothing but wilderness, they were a common species in the northern half of the state and probably in the southern half too.  They are large–about the size of a small hawk.  I’ve never seen one in the wild but was impressed with the size of a mounted specimen I saw at a nature center in the Nantahala National Forest.  Some large crows fall within the size range of ravens, but there are some other features that can help one discern the difference between the two–ravens have a kind of beard under their chin, a more rounded tail, and a different call.  Though they’re omnivorous, they favor meat more than common crows.  Whereas this species thrived scavenging from the Pleistocene megafauna carrion and later from the herds of bison that once roamed across the Great Plains, they were unable to adapt when man converted grassland to fields of grain, nor did they like forests converted to suburbs, and therefore their range has contracted to remote wilderness areas.  Raven fossils have been recovered from Kingston Saltpeter Cave in Georgia (Bartow County) and Bell Cave in northern Alabama, suggesting they were once even more widespread in the southeast than they were when Columbus discovered America.

Common Crows–Corvus brachyrhyncos

The range of these intelligent, adaptable birds has expanded, while that of the raven has contracted.  They’re more omnivorous than ravens and actually prefer the company of man, thriving on our grain fields and garbage dumps.  They love nesting in suburbs which provide the perfect habitat for them, and they require much smaller nesting territories than ravens.  But they did live during the Pleistocene too.  Genetic tests show they diverged from European carrion crows 2 million years ago, about when they colonized North America.  Specimens of crows are also common in the fossil record.

Fish Crows–Corvus ossifragus

Scientists debate whether this is even a different species than the common crow.  Genetic tests show common crows are ancestral to this one.  They live along waterways, eating fish, shellfish, and sea bird eggs.  They also have a different call than the common crow.

Illustration by Louis Agassiz Fuertes

Blue Jay–Cyanocitta cristata

These common, noisy jays prefer oak forests and suburbs.  Oak forests existed throughout the Pleistocene, though their extent fluctuated with climatic conditions.  Fossils of blue jays were discovered at Kingston Saltpeter Cave, dating to about 13,000 years ago.

Florida Scrub Jay–Aphelocoma coerulescens

This species no longer lives in Georgia, but it must have inhabited this area sometime during the Pleistocene.  Currently, this bird’s range is a discontinous one with a population from Nebraska west to California, and another in central Florida where it inhabits scrubby prairie, alongside the burrowing owl.  During some climatic fluctuation of the Pleistocene, this scrubby habitat was more widespread across the continent, as I discussed in my blog entry entitled, “The Disjunct Range of the Burrowing Owl.”  When the climatic phase favorable to the development of scrubby prairie maximized across the region, scrub jays lived in south Georgia.

Gray Jay or Canada Jay–Perioreus canadensis

This species no longer lives anywhere near Georgia, but during the Pleistocene its current range was under miles of glacial ice, rendering that area uninhabitable.  Today, it lives in Canada and the Rocky Mountains, preferring deep wilderness areas, consisting of coniferous forests, where they’re known as “camp robbers,” because they frequent logging camps and are so tame, being unaccostomed to people, they scavenge human food and miscellaneous items without fear.  During the Ice Age the Laurentide Glacier depressed this species range south.  Fossils of gray jays were discovered in Cheek Bend Cave in Tennessee, and I’m certain this species inhabited north Georgia during the last glacial maximum.

Magpie–Pica pica

Today this species inhabits the far west; its range is nowhere close to Georgia.  It’s a scavenging bird, heavily dependent upon carrion.  Large carcasses of dead megafauna supported populations of magpies in Pleistocene Georgia.  Magpie fossils were discovered in Georgia’s Kingston Saltpeter Cave and in Bell Cave in northern Alabama.

Interesting Facts about Crows

–Besides parrots and macaws, crows and other corvids are the most intelligent birds.  Their skull to body ratio is similar to that of mammals rather than birds.  Their intelligence rivals small monkeys.

–Crows build fake nests to fool predators.

–Experiments prove crows can count to six.

–Crows use tools.  They use splinters to impale insects hidden in crevices.  They drop nuts, clams, and small turtles on hard surfaces.  Some crows even place nuts under rolling car tires.  In experiments they learned to bend wire into hooks which they use to draw small containers of water.

–Crows crush ants and rub them on themselves to ward off parasites.

–Pet crows give their owners names.

–Crows can mimic humans, other animals, and machine noises.  They have dozens of calls, denoting predators, food, and family members.

–Crows living within 3 miles of human beings have a 2.3% annual mortality rate.  Crows living more than 3 miles from people have a 38.9% annual mortality rate.

–Wild crows can live 14-20 years.  Captive crows can live 40-80 years.

–Crows mate for life, but males will cheat.

–Male crows have no penis.  Their sperm is transferred from their cloaca to the female cloaca.  Copulation lasts 15 seconds.

–Crows living in suburban areas require only 10% of the nesting area of crows living in wilderness areas, and they’re more tolerate of range overlap.

–Crows have been reported to eat over 1000 food items, including insects, worms, berries, birds eggs and nestlings, small mammals, bats, fish, snakes, frogs, salamanders, animal dung, grain, nuts, carrion, fried chicken, hamburgers, Chinese food, french fries, and human vomit.

–Crows chase sparrows into buildings, stunning and eating them.

–An experiment showed crows prefer French fries in a McDonalds bag over those in a brown paper bag.

–A nestling can eat 100 grasshoppers in 3 hours.

–Crows sunbathe for Vitamin D.

–Mobbing crows can seriously injure hawks.  Scientists suspect one eagle was even killed by mobbing crows.

–Healthy crows help crippled crows.

–Crows occasionally murder each other for reasons that mystify scientists.

–Crows can learn to distinguish between different people.  On the campus of the University of Washington with 40,000 students and professors, crows learned to specifically avoid the few scientists who had captured them.

Cheek Bend Cave

Northern ravens, magpies, and gray jays weren’t the only northern and western fauna that lived in the southeast during the last Ice Age.  In the late 1970’s scientists excavated Cheek Bend Cave in Tennessee before it was flooded by the Columbia Dam Reservoir.  They found many fossils of species with affinities for cooler climate, including 13-lined ground squirrels, pocket gophers, arctic shrews, water shrews, red-backed voles, yellow cheeked voles, red squirrels, northern flying squirrels, heather voles, wood turtles, hawk owls, boreal owls, saw whet owls, gray jays, pine grosbeaks, prairie chickens, pine siskins, and red-breasted nuthatches.  All of these today are normally found in boreal forests of Canada or western grasslands.  Fossils of some of these species have been recovered from caves in north Georgia as well, providing interesting evidence of cooler climates in the south where a patchwork of open woodland and prairies wilderness existed.  These species lived side by side with those that prefer more temperate conditions.

References

Forbush, Edward

A Natural History of American Birds of eastern and central North America

Houghton Mifflin 1939

Marzluff, John; and Tony Angell

In the Company of Crows and Ravens

Yale University Press 2005

Parmalee, Paul; and Walter Kleppel

“Evidence of Boreal Fauna in Middle Tennessee during the late Pleistocene”

The Auk V. 99 1981

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5 Responses to “Pleistocene Survivors–The Corvids”

  1. Two Pine Siskins – Alameda, NM Says:

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  2. All Around the World News Says:

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  3. Renee Says:

    I live in GA and I saw a bird that I swear was a magpie. I had never saw a crow with white on its wings so I looked it up on the internet. I could be wrong, but I think it was a magpie.

    • markgelbart Says:

      Maybe it was a pileated woodpecker. They are as big as a crow and have white on their wings.

      • Renee Says:

        No I looked at the picture-it was no wood pecker, we do have those but this is not what I saw. It was in my driveway (dirt road) right in front of the house and I was on the porch watching it take a bird bath in the mudhole. Hope it comes back – I am watching and I will take a picture.

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