Author: Don

For the past week, we have been hearing warbling sounds from high overhead as sandhill cranes return to their spring breeding areas from their winter stay in Mexico and the southern U.S.  Even though their large size makes it possible to see these birds for long distances, they fly at such high altitudes that their size looks deceptively tiny, making them hard to find in bright daylight skies.  Flying in a ‘V’-shaped pattern, flocks from a dozen to several hundred noisy birds pass by repeatedly during the day. 

Sandhill cranes, Antigone canadensis, are classified into five subspecies.  Lesser sandhill cranes, A.c. canadensis, and greater sandhill cranes, A.c. tabida, both overwinter in Florida and Mexico.  In spring, they migrate north to breeding grounds in the northern U.S. and across Canada into the Arctic, Alaska and northeast Siberia.  There are two separate flyways, one from Florida bearing slightly northwest and passing through Indiana and Illinois.  The second is from Mexico heading due north through Texas, Nebraska, and Colorado.  Three quarters of all the cranes will pass through the Sand Hills region of Nebraska from which their name is derived.  This flock, crossing the Platte River area in spring, is comprised of 250,000 to 500,000 birds.  There are three small populations of non-migratory birds named for their respective locations including the Florida sandhill, A.c. pratensis; the Cuban sandhill A.c. nesiotes, and the Mississippi sandhill, A.c. pulla.

Sandhills are large birds, standing between 3’6″ and 5′ tall.  Their broad wingspans of up to six feet provide enough power to lift their considerable weight, for a bird, of six to fourteen pounds.  They have a small head, long straight bill, a long neck, and a short tail covered by drooping feathers called a “bustle”.  Cranes are slate gray with pale cheeks and black legs.  Adults display a bright red crown and some rusty tones in their backs from mud used in preening.

Birds fly during the day when the sun is up and air currents are strongest.  The birds will use thermals, a column of air that is heated by the sun and rises upwards, to carry them aloft.  As cranes ascend, they are searching for air currents blowing in the direction they want to fly.  Typically, they will fly between 4,000 and 5,000 feet high, but may ride a thermal all the way up 12,000 feet.  Cranes are able to cover 150 to 400 miles each day at speeds of 15 to 50 miles per hour.

Upon reaching their summer breeding grounds, both sexes will engage in courtship displays that includes a dance involving outstretched wings and head pumping, bowing and leaping into the air.  Males and females will call in unison as part of their bonding.  They mate for life, only taking another partner if one dies.  A normal life span is a little over twenty years; the oldest recorded bird was 36 years 7 months old.  Females may begin breeding as early as age two, but most are seven years old and up.  They will lay 1-2 eggs, but normally only one survives.  The juvenile, called a ‘colt’, will remain with the parents for 10-12 months, until leaving for their own life the spring following their birth.

Fossils found in Nebraska date from the Miocene period about ten million years ago.  The bone structure of the fossils is the same as what is found in today’s birds, making the sandhill crane one of the oldest species of birds.  In the late 19th century, they were hunted for the wild meat market until they were considered extirpated east of the Mississippi River.  The Migratory Bird Treaty Act of 1918, passed with support of several early conservationists, is considered to be the critical step that saved the sandhill crane.  Current populations are doing well, but growing slowly since only one chick is born annually.  Conservation of all five species, especially the non-migratory birds, is tied to the preservation of wetlands for migratory staging and breeding.

Now is the time of year to get outside in late morning through the afternoon and listen for their warble, then see these great flocks heading northward overhead.  To learn more, take a look at the International Crane Foundation website at: https://www.savingcranes.org/

Winter is quickly turning into spring in our area.  Freezing temperatures that were here just two weeks ago have passed, and daytime temperatures are warm with temperatures often  staying above freezing overnight.  In the local bird communities, we are beginning to hear males singing for mates.  This will begin the cycle of courtship, mating, nest building and raising a new family.

As birds evolved from cold-blooded to warm-blooded animals several million years ago, they started to build nests to help keep their eggs warm.  Researchers think that the first nests were simple piles of twigs on the ground in depressions or among rocky or sheltered areas.  The first nests built off the ground were also made from loosely arranged twigs.  There are species today who still use both of these types of nests.

Nests have several functions.  They create a place to hide and guard the eggs from predators.  They  provide protection for the parent who remains with the eggs while incubation takes place.  They create a place where incubation is easier in variable weather conditions.  Eggs can be kept warmer and out of the wind and rain.  Many nests are built in places that are already sheltered, such as lower branches of trees where wind effects are less, under large limbs or next to tree trunks that provide protection from both wind and rain.  In urban areas, as well as woodlands containing a heavy shrub layer, most nests are less than ten feet off the ground.  The most complex nest construction is that of a cup nest, built of mud and grass, in a tree fork or hanging from a branch or plastered to the side of a building.

Robins build a cup nest of twigs and mud in the fork of a tree or on a horizontal branch close to the trunk.  Sparrows, of all species, make small cups of grass built either on or near the ground.  Goldfinches build a small nest lined with soft milkweed or grasses in the crotch of a tree. Hairy and downy woodpeckers, like all woodpeckers, prefer holes in trees.  Hairy woodpeckers will drill an oval-shaped hole in a dead branch of a living tree, while downy woodpeckers drill a perfect circle in a branch of a dead tree.  Most woodpecker holes face east or south under a branch to gather warmth from the sun and protection from the rain.  Geese build a large nest on the ground near water, typically lined with down for warmth and comfort. 

Finding nests in late spring and throughout the summer can be quite difficult.  You may try to follow a bird back to its nest, but many nests are only built by one partner, and you could follow the wrong one  and be disappointed.  Many birds will build a nest in one place, but will forage for food in an entirely different location.  If you should walk near a nest, birds will sing or make a display to distract you.  Getting out at this time of the year lets you see where many of last year’s nests were located.  Take a walk before leaves are out and see how many nests you can still find from last year.

Want to learn more?  There are many field guides that will have information on building nests and nesting behaviors.  You may want to consider a specialty volume such as “Eastern Bird Nests” by Peterson Field Guides for explicit information on nests of all kinds.

There are numerous species of birds that spend the winter in Illinois, but two that are infrequent visitors to northeastern Illinois can be easily seen in other areas of the state during this season.  The Bald Eagle, Haliaeetus leucocephalus and the Golden Eagle, Aquila chrysaetos.  They are both members of the family Accipitridae, which includes birds of prey that have broad wings and short tails which produce a distinctive flight pattern consisting of several short wing strokes followed by a long glide.  Members of this genus are all predators and use their talons to kill by repeatedly puncturing their prey.  They are able to stretch their long legs to keep the prey away from their head and eyes for safety.  All members of this family  have fearsome-looking, large, curved, sharply pointed beaks which are used strictly for plucking and tearing the food into bite-sized chunks.

Eagles form long-term pair bonds and both contribute to building their nests, constructed from twigs and vegetation, which are located in tree tops or on cliff ledges.  Softer, finer vegetation is used to line the nests so eggs do not drop through the twig cavities, and the vegetation provides insulation to keep the nest dry and warm.  Starting at about five feet in diameter, nests are reused over many years and may grow to nine feet or more and weigh several hundred pounds.  Eagles typically have more than one nest in an area and may move to another site if they feel threatened or they may use other nests for resting closer to hunting areas.  Eagles that migrate into the southern United States start nest construction and cleanup as early as November.  In Illinois, nest construction takes place in January and February.

Golden Eagles are the only member found in Illinois of the group known as “true eagles”.  They are closely related to buteos, a genus of broad-winged, soaring hawks.  Their main habitat includes mountains and rugged terrain where temperature and wind conditions are conducive to creating numerous updrafts.  They have a light brown head with a dark brown body, brown wings, and a tail of light grey-brown with a dark brown band across the end.  Juveniles may have white spots under the wings in flight, making it easy to misidentify them as Bald Eagles.  Golden Eagles hunt from the air for small mammals and flying birds.  They are mostly migratory visitors to Illinois, but a small population can be found in winter in the far southern part of the state.

Bald Eagles are members of the group called “fish eagles,” closely related to sea-eagles on other continents, but not at all closely related to Golden Eagles.  Adults have a dark brown body with a bright white head and tail, yellow feet and beak, and pale yellow eyes.  Juveniles have a dark head with mottled brown and white bellies and do not sport the distinctive white head until they are at least three years old.  A mature adult stands about three feet tall with a wingspan of 80″-90″.  This species is found only in North America with a population of about 70,000 birds of whom half live in Alaska.  Bald Eagles are always found near large bodies of water that support the abundant fish and waterfowl they feed on. 

As rivers, streams and lakes in Canada and parts of the northern United States freeze and open water becomes scarce, Bald Eagles move southward looking for open water to support fishing.  The Illinois Department of Natural Resources estimates that there are about 3,100 eagles that reside in Illinois in winter, the largest group in the lower 48 states.  They will remain in the area throughout January and February before migrating north as more northerly bodies of water begin to open during the spring thaw.

Thousands of people enjoy eagle watching during the winter months.  The fourth Saturday in January is Illinois Eagle Day, a celebration of the Bald Eagle across the state.  According to the DuPage Forest Preserve District, there have been several sightings in area forest preserves that have large water reservoirs including McDowell Grove, West Branch, Hidden Lake and Blackwell preserves.  There are also several places along the Illinois/Iowa shores of the upper Mississippi River with great viewing opportunities.  A list of many sites and celebration activities can be found at https://www2.illinois.gov/sites/eagles/Pages/EagleWatching.aspx.

Please be aware that we can easily disturb the birds by getting too close.  Stress and our presence can change the behavior of the birds, possibly putting them in danger, especially during nesting periods.  The U.S. Fish and Wildlife Service suggests maintaining a distance of about 330 feet for the birds’ comfort.  I have been to several areas along major rivers.  Viewing from a safe distance is exciting when you can see all of the activity including where the birds are sitting among ledges, flying out over the fishing areas, swooping low to pick up a large fish and flying back to a ledge or tall tree to eat.  Consider bringing binoculars, a spotting scope, or a camera to make it a fun day.

Hawks and their allies are members of the Accipitridae family.  We have several commonly seen species in DuPage County including Cooper’s Hawk and Red-Tailed Hawk, which are year-round residents and Sharp-Shinned Hawk, a species here only in winter.  Other species that may be seen in the area include Broad-Winged Hawk, a summertime only resident, Northern Harrier and Red-Shouldered Hawk, both seen year-round, and Northern Goshawk and Rough-Legged Hawk, also here only in the winter.

Hawks in our area are medium-sized birds, active during the day, with hooked beaks for feeding, and long, sharp talons for catching, holding and killing prey.  The Red-Tailed Hawk, Buteo jamaicensis, is often seen gliding on winds high aloft over open fields.  The  Sharp-Shinned Hawk, Accipiter striatus, and Cooper’s Hawk, Accipiter cooperii, are mostly seen zipping among the trees in open woodlands or in our backyards.

Hawks are among the top avian predators in this area.  They have excellent eyesight and can see clearly four to eight times farther than our human eyes.  As hunters in mainly terrestrial habitats, their coloring blends in with their environments.  Most are brown, grey or black, with pale underparts often streaked or barred in shades of brown.  Combining their coloration with their ability to fly very quietly, most prey are unaware of the hawk until they have already been set upon.  Hawks eat a wide variety of foods including other birds, mammals, fish, reptiles, amphibians and invertebrates. 

Many hawks show a distinct size difference between the sexes, with the female being larger.  There is no consensus as to why this difference exists.  In birds of the accipiter group, including Sharp-Shinned Hawk and Cooper’s Hawk, the males and females will select prey of different sizes and habitats.  This allows a mated pair to find food in two different ecological niches.  Members of the accipiter group feed mostly on other bird species and are just as well adapted to chasing smaller birds through open woodland areas as they are to attacking perching birds from available cover around backyard feeders.  Species in this group have long tails to increase maneuverability, particularly in open woods and forest edges.

Hawks in our area all mate for life, unless a partner is lost.  All species use display flights to attract a mate, and displays may be used by either sex.  Red-Tailed Hawks are unusual in that both sexes have display flights that are started individually, but end together.  Hawks in DuPage County are solitary nesters.  They actively defend the territory that includes their nest as well as nearby feeding habitat from other hawks of their own species.  Nests are built from vegetation, mostly sticks, and a pair may have more than one nest in an area, and nests may be used for many years.  Switching among nests occurs if breeding fails or a nest is infected by parasites.  Whenever possible, fresh vegetation or pine needles are placed in the nest, possibly to provide concealment, serve as a natural coolant, reduce odor or fungal growth, or to signal that the nest is currently occupied.  Nests are further insulated with finer material to keep the occupants warm as well as to keep eggs from falling between sticks.  Nests are very important, and hawks tend to spend several weeks or months building and constantly improving them. 

As egg laying time approaches in early to mid-spring, males will keep supplying nesting material, as females construct and shape the interior.  Egg laying consumes a lot of energy, so females tend to lay an egg every other day.  The number of eggs in a clutch varies from two to six depending on species and tends to increase in breeding locations farther north.  Both male and female will incubate the eggs for a period of 28 to 35 days.  Incubation starts as soon as the first egg is laid, so earlier chicks may be born first and tend to be stronger than later chicks.  After hatching, males do most of the hunting, and females spend all of their time with the chicks.  Chicks can hold up their heads, open their eyes and feed by sight within minutes of hatching.  Females will wave a bit of prey in front of each chick until the chick snatches it from the mother’s beak.  If the bit proves too big for the chick to swallow, the mother may take it back and eat it herself and start with a new bit of prey.  In the nest, chicks are very susceptible to weather changes, and females will spread their wings to protect them from both rain and hot sun.

In northern Illinois, the Broad-Winged Hawk migrates to Central America for the winter.  Several species from summer breeding grounds in central Canada, including Sharp-Shinned Hawk, Northern Goshawk, and Rough-Legged Hawk, migrate into northern Illinois for the winter.  All migrating species fly during the day when winds are more favorable for long distance flight.  Juveniles and adults will fly at different times and different speeds, coming together at their destinations.  Some species may flock together, but most are solitary flyers.  However, none will attempt long water crossings, tending to follow land for the whole journey.  Fall migration starts in mid-August and lasts through November, normally on days following the passage of a cold front, when the air is cooler, drier and more stable.

Over the past few decades, hawks have faced a number of threats including hunting, pesticides and loss of habitat.  However, they have been able to adapt well to their changing environment.  Breeding bird survey statistics indicate that most species have seen increasing populations in the past twenty years, assisted by reduced pesticide use, increased dedication of rehabilitation facilities, and better education, altering the views of hawks held by the general public.