The Bird Family with an Attitude: The Corvids

The Corvids are probably the most notable family of birds with an attitude. They are loud, pushy and act like they are the boss, running off other bird species and often eating other birds’ eggs and hatchlings. The Corvids found in our area include Common Raven, American Crow, Western Scrub-Jay, Pinyon Jay, Blue Jay, Steller’s Jay, Gray Jay, Clark’s Nutcracker and Black-billed Magpie.

Each species has a special habitat or niche. All Corvids have stiff, bristle-like feathers covering their nostrils. They are omnivorous; they’ll eat most anything. In addition to the bad habits they often get blamed for, they do a good job of eating large quantities of harmful insects. They also harvest and store tree seeds, which they sometimes forget about, and the seeds then grow into new forests. Bird watchers thank them for finding owls and hawks which they noisily mob, giving away the raptor’s hard-to-see perch. Corvids often mate for life, each assisting with nest building, and feeding hatchlings and fledglings. Often young birds from a previous hatch will help with feeding the young of a later hatch. Many Corvids live more than 20 years. Some stay on home territories and some migrate in family groups or large flocks, either to lower elevations or by short migrations to warmer climates for the winter. They often become quiet and secretive when nesting. The “bad” in their behavior earned them places in the folklore of many cultures. In Europe they were considered “Devil’s birds.” Some cultures, such as those in the Pacific Northwest, revere them. Corvids are considered to be among the most intelligent of all bird groups. Many will recall with unerring accuracy where they have stashed food for the winter. Flocks of Corvids have been known to post one of their own to watch for danger while the others eat, sleep or loaf. David Sibley informs us that recent DNA-hybridization studies suggest that Corvids arose from an Australian ancestor. The same ancestor also gave rise to many distinctive Australian bird families, including wren-like, warbler-like, and flycatcher-like groups. North American shrikes and vireos are thought to be offshoots of the same line. Many Corvids contracted the West Nile virus when it first appeared in the U.S. in 1999, decimating populations. In the last few years population numbers have begun to recover.

Steller’s Jay is usually found in Colorado between 6,000 and 9,000 feet elevation. They are named after George Steller, a German naturalist who accompanied Vitus Bering on his Russian-sponsored expedition to see if the coasts of Siberia and Alaska were contiguous. George Steller collected the first Stellar’s jay specimen in 1741. Steller’s Jays are excellent mimics. Multiple times I have been fooled into thinking a Red-tailed Hawk was present and calling, when in fact it turned out to be a Steller’s jay. They can also do a reasonably good job of mimicking the sound of a rattlesnake. They were formerly known as Longcrested jays because of the long crest of black feathers on the head. The Steller’s jay nests are hard to find and they are often incubating eggs by early May. Lt. Abert on Fremont’s third expedition described this jay well in 1845 when he wrote “a jay whose plumage partook of the color of the darkest blue of a clear sky.”

Common Ravens are probably the most famous of the Corvids. They soar in elaborate, twirling displays during courtship. They prefer rocky ledges as hangouts and for nesting. Ravens never retrieve sticks from the ground for their nests, preferring to break dead branches from trees for nest building. Ravens, like owls and raptors, regurgitate pellets of indigestible parts of things they eat. When trying to differentiate them from American Crows, it helps to look for the raven’s wedgeshaped tail, to listen for the raven’s hoarse, croak call, and to watch for mostly soaring flight, with very little wing-flap. They have a larger bill than crows. In folklore, the raven flew off from Noah’s ark to find land. A story in the Bible tells of ravens bringing food to a prophet who was starving in the wilderness. Old Testament laws forbid eating ravens and crows because they were considered unclean. They are depicted on many totem poles of the Inuit, Tlingit and Haida cultures. In merrye olde England, it was believed that if the resident ravens left the Tower of London, King Charles II’s kingdom would fall. Since that time, the ravens are fed and cared for by a Ravenmaster to prevent any such disaster from occurring. The Ravenmaster clips a few flight feathers from one wing of each bird regularly to keep the birds from flying away. When these particular ravens die, they are buried in a special grave by the Middle Drawbridge, and each has a plaque with its name and age at death. One of the most famous Colorado ravens belonged to Catherine “Birdie” Hurlbutt. Catherine took in hundreds of injured and sick birds and nursed them back to health, rescuing them in a very old car painted white with “Bird Ambulance” printed on the side. In 1971 she decided to do some research on teaching birds to talk. She mail ordered a young raven from another state (a practice outlawed the next year). She spent many hours teaching “Edgar” the raven to say “nevermore.” In Edgar’s first few years he learned to say, “Nevermore, Hi-ya, Edgar, you’re a bad boy and hello.” Catherine called Edgar a he in most of her book, Edgar and I. In the later years of writing the book she discovered Edgar was a she because of certain courtship behaviors Edgar displayed. Edgar lived for 24 years. Catherine’s book is a fun read relating her stories of Edgar in addition to other bird rescue tales.

American Crows are usually found in open and semiopen habitats. They have straight, square-ended tails and a clearer, higher-pitched call than a raven. They are smaller than ravens and flap their wings a lot when flying. Opening up roads and creating forest clearings has helped them move into new areas. During the winter, crows often gather in large flocks, flying in one day from roost to eating areas, then on to loafing areas, then to another eating area and at the end of the day back to the communal roost. Crows love to hoard bright objects. They also regurgitate pellets of indigestible material. The Tillamook Native Americans have a story about the Thunderbird (who was responsible for making thunder and lightning) not liking its voice and working a deal to trade its voice with the crow. In exchange, the Thunderbird would make lower tides along the coast so the women of the Tillamook clan could gather more clams. We have many sayings about crows: “Eat crow” when one finds it necessary to retract a deed or quote. “Straight as the crow flies “illustrates the crow’s habit of flying in a straight line to their roost. Age puts “crow’s feet” wrinkles around the eyes. During courtship the male spreads his wings and tail, fluffs body feathers and bows several times to the female while singing a rattling song. Many crows have been poisoned, shot and even dynamited when they gather in large flocks of thousands to eat farmers’ crops.

Western Scrub Jays are found along the Front Range in the Transition Zone from the plains to the mountains. They hang out in scrub (Gambel) oak. They are usually found in small family groups and stash the oak acorns for food so they can have them later. They will come to a bird feeder, run off all the little birds, and proceed to pick up as many as 20 sunflower seeds in one visit, which they will then stash in their hide outs in the ground, in cracks and bark crevices, even in snow banks. They may migrate short distances south, especially in years when the acorn crop is poor. They have no crest and look grayish until the sun touches their feathers. They were once called Woodhouse’s Jay. They will also hoard bright objects

Pinyon Jays are sometimes found in small flocks in our area. Like the Western Scrub jay, the Pinyon jay has no crest, however, they are bluer than Scrub jays, especially on the breast. Their calls are very different than the calls of Western Scrub jays. Pinyon jays prefer Pinyon pine/juniper habitat but sometimes show up along the lower foothills in Ponderosa pine areas. They often walk instead of hop as other jays do. Crows and Clark’s nutcrackers also walk. Genetically Pinyon jays fit intermediately between jays and crows. They are one jay that does not have bristles covering their nostrils giving them their scientific name Gymnorhinus which means naked nose. They were discovered by Alexander Philip Maximilian, Prince of Wied, noted German traveler who first found them in Montana in 1883. They breed in colonies. Breeding is triggered by availability of Pinyon nuts which they cache for food in late winter, often when snow is still on the ground. If you find seedling trees uphill from a parent tree, most likely a Pinyon jay cached and forgot. Pinyon nuts cached by squirrels and birds and then forgotten can sprout and grow.

Blue Jays have crests. They were originally found in states east of Colorado, however, when we created their favorite habitat by planting Eastern region trees and shrubs, they gradually moved up river courses to Denver (the first record in Jefferson County: September 24, 1917). They love to stash seeds from bird feeders. I have watched one in my backyard poke holes in the sod and place the seed in the hole, and then put a leaf over the hole to hide the stash. I then noticed a squirrel who had figured out the ruse, looking under leaves on the ground for gifts left there by the blue jay. Blue jays usually don’t migrate south in winter except for the extreme northern bird populations. They will announce the arrival of a fox, cat, owl or other raptor by loud calls as they mob the intruder. In addition to this loud raucous call they have a quieter flute-like call. In Colorado the blue jay has been known to hybridize with Steller’s jays.

Gray Jay has also been called Rocky Mountain Jay, Canada jay, Jackdaw and Camp Robber. Another name “Whiskey Jack,” is believed to have come from their Cree name of “Wisca Chan.” They are the only Old World jay present in the New World. They have a large round head and small bill. They are very tame and will snatch up food left unattended. They are also known to carry off such items as matches, tobacco plugs, pencils, soap and candles. They can store food in a sticky bolus mixed with saliva and placed on a limb or tucked under tree bark for use in lean times. Some jays have been known to remember as many as 1,000 separate caches.[Is this the gray jay, or jays in general?] Gray Jays are mostly silent and are usually found in pairs or small groups. Their habitat is the Montane Zone and Boreal Forest of Engleman spruce, Douglas fir and Lodgepole pine. Any migration is usually to a lower elevation in winter. They usually start nesting in late March while snow is deep; the eggs hatch in early April.

Clark’s Nutcracker, which was once known as Clark’s Crow or the Woodpecker Crow, is named after Captain William Clark of the Lewis and Clark Expedition. The Clark’s Nutcracker is like a combination of a woodpecker and a crow. It has a long, stout bill which it uses to open pine cones and eat the seeds. It often walks instead of hopping. They are found near timberline along crests of higher mountains, usually in small groups. They can do a good mimic of the calls of the Great Horned Owl and the Pygmy Owl. Their nests are seldom found because they nest during March and April when there is still deep snow on the ground. Female birds loose feathers on their breasts during incubation to enable them to keep the eggs warmer. Clark’s Nutcracker males are unusual in that they also develop these “brood patches.” Research has shown males incubate the eggs as much as 20% of the time. They have been known to collect as many at 30 – 100 seeds at once in a sub-lingual pouch to stash for use in the spring to feed new hatchlings. These caches on south-facing slopes have been known to contain 22,000 to 33,000 conifer seeds.

Black-billed Magpie is a common bird in Colorado open country [and in the foothills, too—at least judging by the numbers that hang around my house on Lookout Mtn!]. Colorado often gets the highest count of Magpies on the annual National Audubon Christmas Count totals by state. Magpies are very noisy birds and they love to steal dog food left outside. Their nests are elaborate, hollowed-out piles of sticks, lined with mud and soft materials , usually containing several entrances. They may spend 40-50 days building a nest. Sometimes, after the Magpies finish nesting, the dome collapses and hawks or owls will take over the location. Magpie eggs are often lain by the third week of April. They usually travel in small, family flocks occasionally increasing to larger flocks in winter. They will perch on livestock, elk, deer and eat ticks or other parasites. The name Magpie may come from the sound of their call. Legend has it that the Magpie was the only bird that refused to enter the Ark, preferring to perch on its roof, from which it could complain about the plights of those caught in the rising flood. Their numbers are increasing after declining dramatically following the onset of the West Nile Virus.

Copyright © 2011 Ann Bonnell

Birds of Jefferson County: Accipiters

“What is that hawk who comes into my yard and eats ‘my’ birds?”

These hawks are probably Accipiters, a sub-group of the birds of prey most easily distinguished by their long tails and short, broad, rounded wings which allow them to maneuver in and out of trees. Their normal hunting ground is in the forest, but Accipiters have been loosing out to houses, commercial developments and highways. The many small birds that consititute their prey base have adapted to urban living and bird feeders, so seeing these Accipiters hunting in your back yard and nesting in urban settings is becoming more and more commonplace.

The two Accipiters most often seen in the Denver area are the Cooper’s Hawk (Accipiter cooperii) and the Sharp-shinned hawk (Accipiter striatus) – the Sharpy. If you’re in your yard and suddenly you notice that all the birds are fleeing from the feeders, and then everything suddenly gets quiet, search the trees close by. You may see a Cooper’s Hawk or Sharpy quietly sitting and waiting for some small bird to fly into harm’s way.

In my yard I have seen an Evening Grosbeak, which measures just over 7 inches tip to tail, taken by an Accipitor. I have also watched as a Cooper’s Hawk stepped into my 2″ deep birdbath and spent 15 minutes deciding whether or not to take a bath. Then he splashed about for another 30 minutes, spreading his wings and bending over sideways to bathe. The Cooper’s Hawk is about 17″ long. The Sharpy is smaller, about 12″ long, however – because the female Sharpy is larger than the male, a Sharp-shinned female can be about the same size as a male Cooper’s Hawk.

Photo - AccipitersTelling the two species apart can be difficult, the accompanying photo is representative of either species, although, by consensus of opinion, we think the Accipiter is a Cooper’s Hawk and his prey a sparrow of some sort. As adults, both are dark gray above and lighter below with buff-colored stripes on the breast. The most distinguishing feature of both species is the tail…long, wide and banded, alternating dark and light brown, with white tipping at the end. A Sharpy has a straight-edged tail with a little white at the outer end. The Cooper’s Hawk has a rounded tail with more white showing at the end. Feather wear can modify the appearance of the tail feathers, causing identification confusion. Adult birds of both species have red eyes while their youngsters have yellow eyes. Sharpys often have some white blotchy feathers on the back.

In flight, the Sharpy tucks its head into its wings, while the Cooper’s Hawk extends its head – some have described a Cooper’s Hawk in flight as “a flying cross.” A Cooper’s Hawk weighs about a pound while a Sharpy weighs only about half a pound.

One day I was at my bird feeders when one came at me chasing a sparrow – couldn’t tell if it was a Cooper’s Hawk or a Sharpy, they were moving so fast. The sparrow went to my right and the Accipiter to my left. The sparrow got away. In the bird world there are predators and there are prey…don’t be too alarmed if you witness an Accipiter doing what he’s supposed to be doing at your feeder or in your yard. This is just part of the way of the wild.

Copyright © 2011 Ann Bonnell

Big Bluestem: Plant of the Future

This fall I had an email from a botanist friend: “What’s going on with big bluestem?” After he pointed it out, I noticed that, sure enough, this species, one of the dominant grasses in the tallgrass prairie (as in the source of the original Kansas sods that once housed the homesteaders), is bustin’ out all over the foothills! Big bluestem typically occurs on the slopes of our mountain front, but has been expanding in recent years. In 2010, this warm-season grass had an extraordinary year. Its abundance first drew attention at Lookout Mountain, on the slopes of Windy Saddle Park and adjacent areas, where you can probably still spot patches of its russet fall color when the ground is free of snow, even if you’re driving by on 6th Avenue. If you’re on the Lariat Trail, big bluestem borders the south side of the road east of Windy Saddle. This time of year, when it might seem there’s little to interest plant lovers, big bluestem and its cousins in the grass family provide color in the landscape.

Tallgrass prairie, whether here or in the East, is a tattered remnant of what it was in its glory days. We’re lucky to have sizable patches in Jeffco; efforts to protect some have been underway for more than 20 years. It’s been years since we talked tallgrass prairie here in the PJ newsletter, but the Board has continued to monitor and comment on developments in the Rocky Flats area, where our best examples of this rare ecosystem survive, including the Ranson/Edwards and Jewell Mountain properties. Boulder conveniently protected several hundred acres of the latter. Patches of big bluestem on the foothills slopes are fine, but limited, reminders of the more extensive remnant prairie that once rolled out across the county but has retreated to a fringe along the mountain front. Most of what you see just northwest of Highways 93 and 72 is also tallgrass prairie.

Big Bluestem in Jeffco’s Landscape

Look for these foothills patches primarily on unforested south- and east-facing slopes: on most central slopes visible west of Highway 93, and on the north sides of our canyons, from Bear Creek to Golden Gate. In Mt. Galbraith Park, you can see the colorful auburn patches across the canyon as you make your way up the trail. Driving west on I-70, look for it to the north as you enter the foothills, on the slopes in Matthews-Winters Park. In the southwest part of Red Rocks Park, it occurs on level sites, more prairielike, because that area has been protected and contains isolated spots where the Rocky Flats alluvium has managed to persist on lands that would otherwise have been cultivated or developed. In fall, big bluestem blends perfectly with the outcrops of the Fountain Formation.

Lack of development and a somewhat inhospitable climate have also protected the Rocky Flats area. The extremely cobbly soils, beloved of gravel companies, hampered agricultural attempts on much of the area and enhanced the available moisture content for the growth of these taller species. Because the area is unplowed, in part, these soils are considered among the oldest in Colorado, with some estimates placing their age at 2 million years. But big bluestem’s expression/visibility in the landscape of any given year reflects how we’re doing on overall precipitation and temperature.

The Water Year and Other Influences

Based on the 30-yr average precipitation, our wettest month of the year should be May. When it is, that’s about perfect for big bluestem and other warm-season grasses (including blue grama, sideoats grama, little bluestem, and switchgrass), which are just getting started as the weather warms toward summer. By June, the cool-season grasses (such as the common lawn grasses, including Kentucky bluegrass, which take advantage of early season moisture to start growth) will be ready to flower and set seed, but you’ll still have to hunt around on the ground to find evidence that big bluestem is even alive. Large clumps of hairy, velvety blue-green leaves will be your hint.

In July, those spreading clumps send up tall flowering shoots, which produce the “turkey-foot” seed heads by August. When cool-season grasses are giving it up and their seed has scattered, big bluestem ripens into the terra cotta masses that reveal its presence even from a distance.

This seasonal habit represents an entirely different metabolism (called “C4”) in these plants, which use carbon along different pathways than many familiar plants. According to some researchers, this may give them an advantage under conditions of elevated carbon dioxide (think global climate change), especially during drought. Like many grasses, big bluestem is also adapted to grazing and fire, but not if they occur too frequently.

Interestingly, although it seemed, until recent snows, that it’s been droughty for several months, 2010 was an above average moisture year during its first half, giving big bluestem the start it needed. In fact, rainfall in this part of the county has been at or above normal every month from April 2009 through last June. (Later records have not yet been posted online.) Average temperatures have also hovered a degree or two above normal for several years (except 2008); most of the past decade has been warm. Temperature and moisture conditions have apparently encouraged big bluestem, a species that prefers a little more moisture and warmth than is the rule in Colorado. If we get too dry and warm, we’re apt to see more of its cousin, little bluestem, but as long as it finds a moist spot, big bluestem will remain a part of the county’s natural prospect. If you haven’t seen it, this winter is a great time to go looking for it.

To see temp/precip data go to: http://ccc.atmos.colostate.edu/coloradowater.php

Big Bluestem (grass),
Andropogon gerardii

  • Warm-season sod-forming grass.
  • Height: 4-5 feet in Colorado, occasionally taller; to 8 ft in prairie states.
  • Occurs in all but the five westernmost of the lower 48 states, as well as the central provinces of Canada. Most abundant in eastern Great Plains.
  • Dominant and characteristic grass of the tallgrass prairie ecosystem.
  • Flowering heads are 4-5 inches long, with 3 (or more) spreading branches, suggesting its other common name: turkeyfoot

Copyright © 2011 Sally L. White