Literature Review: Muskrat Ups and Downs

by Carl Strang

One of the classical sources of data in vertebrate wildlife ecology is the Hudson Bay Company fur records in Canada. Those were used, for instance, to establish the dramatic cyclical pattern of lynx relative to showshoe hare populations, inspiring much subsequent research as to the underlying causes. There still are data to be mined from those records, as was demonstrated in a 2011 study [Estay SA, Albornoz AA, Lima M, Boyce MS, Stenseth NC. A Simultaneous Test of Synchrony Causal Factors in Muskrat and Mink Fur Returns at Different Scales across Canada. PLoS ONE 6(11): e27766. doi:10.1371/journal.pone.0027766].

The muskrat, primary focus of this study, is common across North America, including northeast Illinois.

The researchers examined Hudson Bay Company fur records from 81 posts across Canada, looking at muskrat numbers, mink numbers, and bringing in climate data. They concluded that mink had an important impact on muskrats all across Canada, but the greatest and most direct effect was in the west.

Mink, also common in our area, are predators of muskrats.

In the east, variation in winter precipitation also was important, with drought in particular affecting muskrats. Interactions among these factors could be important here. For instance, drought could force muskrats to disperse longer distances over land, reduce their watery escape space, and concentrate them, exposing them to greater mink predation.

Lessons from Travels: Desert Plant Spacing

by Carl Strang

One of the important characteristics of our climate in northeast Illinois is the relative abundance of moisture. This feature is driven home when we visit the deserts of the southwestern United States. Today I want to focus on how the relative lack of moisture there forces the plants to space themselves out.

Here you can see how the desert shrubs and cacti form a regular spacing, with bare soil between.

The roots of established plants are so effective at grabbing what rain comes, that new ones cannot succeed in the spaces between. This does not mean that plant size is limited, however. There are the Joshua trees for instance.

Their foliage connects them to the smaller yuccas.

Saguaros, likewise, can be huge.

Note again, though, how widely spaced they are. Such large plants need many years to reach this size.

Other plant species with smaller stature increase the local diversity.

They also add to the beauty and charm of these ecosystems.

The bare soil can increase the ease of tracking.

Facing the sun increases the reflection from the compressed soil.

Plants have other adaptations allowing them to live in such places, and there are animals as well, so we’re not done with the deserts.

Great Horned Owl Species Dossier

by Carl Strang

Today’s species dossier is one of my largest. Great horned owls simply attract my attention and interest more than most other animals, and so I have accumulated more notes on them. Great horned owls haven’t been as easy to follow in the years since West Nile virus came into our area. Formerly the crows were reliable blabbermouths as to where the owls were. If our local crows develop resistance to the disease, those days will return.

Owl, Great Horned

Great horned owl

My earliest memory of young great horned owls was in a forest near Purdue, after they had branched one spring [branching is the term for owlets leaving the nest; it is different from fledging, because they reportedly climb down to the ground, walk to another tree, and climb up it]. I know this species primarily from observations in DuPage County, IL, where it is the common large owl, occurring in forests, even small ones. A pair nested annually in the Willowbrook riparian strip for many years, staying as year-round residents. They nested in large willows, 20-30 feet up, first in a nest on branches, then after a storm dislodged the nest, on a provided platform until that tree fell. Incubation begins January or February. The non-incubating male bird usually perches nearby in the daytime, flying away apparently to draw off people or mobbing crows. Owlets (usually 2) branch in May as trees are leafing out, can fly between trees by late May. Young have a distinctive begging call, a rising squeaky-scraping or -grating loud “scaip!” Young disperse usually by the end of October. Before then, they fly all over their parents’ territory, usually staying fairly close together. Branched young mostly sit still, observing all that goes on around them. November brings frequent late afternoon and evening territorial calls: the female’s call is a higher-pitched “WHO-whowhowho-whowhowho-who.” The male’s call has fewer syllables and a lower pitch.  Deep, booming voice. Willowbrook’s territorial birds had a running, never-ending conflict with the caged birds. I also heard calls during childhood campouts on the Tippecanoe River, Indiana, in summer, and later in the woods near the Boiling Springs, Pennsylvania, house in spring.

Pellets and food remains in late winter 1986 at Willowbrook were heavy in rabbit fur and bones in February, meadow voles in March. There were feathers of a gull in May. They covered a territory that included Willowbrook, adjacent residential neighborhoods, and much of the College of DuPage campus, for a total of perhaps 100 acres.

In the Basin of the Chisos Mountains, Big Bend National Park in Texas, they were calling around 5:30am in late July. We saw others there on the road in early evening in the upper desert. They were a bit paler than Midwestern birds.

Some contents of owl pellets at Mayslake, 2009. Prey species are meadow voles, white-footed mice, and a short-tailed shrew.

12FE87. Lots of recently molted breast feathers in Willowbrook Back 40.

8AP87. Photos of branching young owls.

Great horned owl, soon after leaving the nest.

29AP87. Crow remains found under nest area.

5MY87. The pair’s own nestlings now branching, in a willow 50m from nest tree.

6MY87. Remains of a consumed pigeon.

7MY87. The young are in another willow, closer to the nest tree, the one used most by last year’s young when branching. The third (foster, added by Willowbrook staff) youngster is on another branch of the same tree.

8MY87. Another tree change.

1JE87. The young are flying.

5OC87. Adult male beginning to hoot, in afternoon, Willowbrook Back 40.

9JA88. McDowell. Owl flushed from pine grove at south end of north field.

16JA88. McDowell. A great horned owl flew to tree on the west bank of the river, just north of where trees thin to a thread of willows, and where a housing development comes down to the river. There’s a top-blown tree nearby, also several large oaks. Then crows began raising a ruckus nearby in another direction, as though pestering a great horned owl. From that direction a red-tailed hawk soared, but they paid it no heed. It circled an adjacent riparian strip, but when the owl finally broke and flew with a flock of 10 crows in pursuit, the hawk fell in between, and also began to chase the owl. Once it got above the owl and swooped at it, brushing the owl’s back with its feet, but about then the crows caught up and chased both raptors down toward where I had seen the first owl perched, now out of my sight.

30MR88. Willowbrook. Fresh pellet with remains of 2 meadow voles.

25AP88. Both great horned owls off the nest, though in nearby trees.

17MY88. I hadn’t seen great horned owls of Willowbrook Back 40, or heard harassment by crows, in some days. Today I saw 2, upstream of their nest. Crows didn’t harass them for long or in numbers (2-3), apparently too occupied with their own nesting activity.

18JE88. Harassment of owls by crows gradually has increased this month at Willowbrook. Today I observed heavy harassment of a great horned owl by a large number of crows at McDowell Grove F.P. Owls branch at the same time crows are starting to nest, and becoming too busy to harass owls.

22FE89. Owl on a nest at Willowbrook (started incubating within the past 10 days).

26AP89. For the first day since February, there is no adult owl in the nest tree at Willowbrook (have been brooding several days, then a few days of adult perched beside nest with a youngster visible. 2 young. A fox squirrel climbed the nest tree. When it was just below the nest, the adult female flew from a nearby willow, and landed on the nest. The squirrel turned around and began to climb down as she flew in, but was not panicked.

31AU89. Jays vigorously “jay”-ing at an owl well hidden among leaves in a willow top. Chipmunks chucking nearby, below.

30NO89. Great horned owl flying, viewed from behind. Wingbeat of remarkably little amplitude, compensated by its more rapid rate. A fluttering sort of appearance. Wings kept straight. (A behavioral quieting of flight?)

14DE89. Willowbrook nature trail. The owl caught a mouse, according to tracks. Slight blood drops in snow. Many steps trampled snow just beyond the mouse burrow. Then the owl walked, either having swallowed mouse or transferred it to bill. Tracks: landed on mouse tunnel, then walked 5m. Noticeable straddle, up to 1 inch. Track 4 inches long, 3.5 wide, right angle toe pointing to outside distinctive for species. 8 inches center to center for length of step between tracks.

Sketch of great horned owl tracks.

3JA90. The Willowbrook owl pair perching near nest platform.

29JA95. Following a tip, I found a great horned owl on a nest at Maple Grove F.P. Stick nest was built last year by Cooper’s Hawks, according to informant. Nest solidly based in a main crotch 15-20 feet up. Owl had head and ear-tufts up, very noticeable but only from the front. Nest tree right beside a regularly used trail, but not a main trail, less than 200 yards from Maple Ave. and less than 100 yd. from the private school on the east border of the preserve. The owl reportedly has been on the nest less than a week.

18FE99. At Willowbrook, I found this year’s great horned owl nest (they probably have used this site before; not easy to find) in the top of a dead tree trunk, with most of branches gone, a large hollow with little in the way of a roof. Only part of the owl’s head is visible, and only from certain angles. A single fuzzy feather tuft was the give-away. Once while I watched, the bird appeared to stand and turn or shift eggs by moving feet, stepping from one to the other. The owls had been advertising consistently in the area around this tree in the early winter. Crows mobbing nearby earlier in the day (presumably after the non-incubating bird nearby) drew my attention to this area. Only one other candidate tree is nearby.

A sketch I made after finding the nest on February 18.

11MR99. The great horned owl was standing in the Willowbrook nest in the morning.

15MR99. A young bird was seen on the afternoon of the 12th. Today at least 2 young are visible. They were being fed between 3 and 3:30pm.

18MR99. The 2 young owls frequently are standing in the sun in the nest.

12AP99. The Willowbrook great horned young have branched.

A pair of branched young.

16AP99. One of the owl young somehow crossed the rain-swollen Glen Crest Creek to perch between it and the Nature Trail. Flew?

4MY99. At mid-day, a flock of 8 crows pursuing an adult great horned owl over much of Willowbrook Preserve.

27MY99. Both Willowbrook owl young still alive.

11AU99. Only one of the Willowbrook owl young remains.

18AU99. The young owl calling at mid-morning.

8MR00. A neighbor near the north edge of the Willowbrook preserve reported that the pair of great horned owls have been calling in his yard nightly since late January. He gave us permission to look for a nest, and we found it, in the top of a large blue spruce, built on an old crow or squirrel nest. 20 minutes were required to find a small hole through which to confirm the bird’s presence. The tree, perhaps 40 feet tall, is close to a dead‑end side street, in between his house and garage (the 2 buildings less than 20 feet apart), with no other tall trees right there though several others were in the yard. The bird appeared still to be incubating, occasionally turning eggs. We did not see the non‑incubating owl, but numerous potential roosting sites are nearby.

30MR00. We checked the nest again. After a few minutes the brooding bird flew away (sunny, warm afternoon). We could see one young bird clearly; there may have been more. Development seems behind last year at this date by at least a week. Still all white down, as far as we could see.

14AP00. In central Kane County, in a bur oak woodlot of perhaps 10 acres, a great horned owl nest. The nest is an appropriated crow or hawk nest in the top of a large oak. At least one young bird still is inside. The presence of the owls was made clear when the adult male flew past us, pursued by crows. He was small, appearing no larger than the crows. Later I found the nest when walking through the woods. The female flew a short distance, and a few crows called, but she settled in against the trunk of an oak, well camouflaged, and they left her alone.

17JL00. No sounds of great horned owl adults or young at Willowbrook in the evening.

2001: No signs of nest or young around Willowbrook this year, though in the spring an adult seemed to be decoying crows.

Great horned owl tracks. Owl tracks are distinctive in having one of the toes protruding out to the side at an odd angle.

14SE01. An owl called several times in the early dusk at Herrick Lake, south of the former youth campground. I see that this is my earliest record of territorial behavior, by about 3 weeks.

3NO01. Saw an owl, probably a male, at Herrick Lake F.P. in the forest behind a house, north of the big trail loop and south of the former youth group camp. That was in the morning. In the late afternoon, heard one hooting along the Fox River somewhere around Red Oak NC.

27SE02. While walking after a run at Herrick Lake, heard both members of the pair duetting strongly for at least 5 minutes (same area as previous 2 entries).

13FE07. At mid-day in the middle of a winter storm with heavy blowing snow, a great horned owl at Fullersburg holding a recently caught gray squirrel.

3AU08. Great horneds called for a long period, early morning, in my neighborhood. This continued into the dawn hour and overlapped with a cardinal’s singing, past 5 a.m.

21JA09. Mayslake. An elm branch, apparently broken from tree by storm, with bark being consumed by cottontails. Near there, one of the rabbits caught and consumed on the spot last night by a great horned owl (impressions of wing and tail feathers in the snow). Head, feet, a couple bones, and fur all that remain.

29JA09. Mayslake. I found where a great horned owl had walked on the frozen stream surface, heading S out of the woods, taking off before reaching the bridge. The tracks led back to a feeding site, with much cottontail fur and a bone, but no rabbit tracks. Continuing downstream 20 yards I found another area against the bank with fur and blood, and a couple great horned owl footprints again from last night, but again no rabbit tracks. On downstream another 30 yards I found yet a third such site, but again no rabbit tracks. Here there was no feeding, mainly just the impression of the rabbit in the snow. As the owl had walked a few steps before that impression, it must have had the rabbit in its beak. The owl had come from the N or NW. I searched all around but did not find a clear kill site. All of this was under trees with moderately thick brush that makes it seem unlikely the owl would carry prey in there from outside. The shift of location twice would seem to reflect a sense of vulnerability. I wonder if the owl would have removed the head and feet at the actual kill site. The body impression where it first landed on the stream ice was bloody.

Here is one of the stops made by the great horned owl described in the January 29 entry. There is an oval depression where the rabbit’s body was placed.

14FE09. Fullersburg. This year the great horned owls are nesting in last year’s Coopers hawk nest, just west of the Amphitheater. That nest has been available both the past two years, but the owls have chosen to use other hawk nests close to 31st Street in all of the previous 4 years but 1. In that year there were reports of a nest well south of the preserve, but I could not find one on the preserve.

19FE09 Mayslake. I found the great horned owl nest in a hollow willow near the west boundary of the preserve close to May’s Lake. It is not high up, and exposed thanks to the brush clearing, but facing away from the lake may limit its discovery by fishermen.

Great horned owl incubating nest in tree cavity, Mayslake, February 2009.

6MR09. Mayslake. Great horned owl is standing in the nest cavity, apparently brooding.

13MR09. Mayslake. The great horned owl nest tree snapped off at the point of the nest cavity, presumably in the wind storm 3 nights ago (gusts reached 45mph). A dead owlet at the base of the tree, none others nor adult seen, no sign of hurt adult but nest apparently abandoned (cold enough today that an adult would be brooding). There has been enough time that scavengers could have removed other young.

Dead nestling beneath storm-broken nest tree.

10DE10. Neighborhood. I heard a great horned owl calling early this morning.

27JA11. Mayslake. Great horned owl incubating on last year’s red-tailed hawk nest. It was not there yesterday.

Great horned owl incubating nest, Mayslake, January 2011.

10MR11. Mayslake. The owls have abandoned the nest. No sign of disturbance or dead nestling beneath, best guess is the eggs didn’t hatch, either infertile or perhaps the female was forced to abandon during the fierce blizzard at the beginning of February.

18MR11. Mayslake. At a bright mid-day, the great horned owl pair duetted for more than 15 minutes, the male in the west end and the female in the east end of the area 9 hilltop pines.

29MR11. Mayslake. A single hoot from GHO in pines, mid-day, the first I’ve heard since the 20th.  (In September I heard the pair duetting at Mayslake, so they remain at the preserve.)

Singing Insects Guide Revision

by Carl Strang

I have updated my guide to the singing insects of northeast Illinois and northwest Indiana. The revision has new pages for three species (moved from the hypothetical list thanks to this year’s research), adds several new photos along with bits of new data here and there, and expands the information on species in the hypothetical list after a review of literature and records.

It is available for free as a 7mb pdf file. To get it, send a request to me at The conditions under which it is made available include the need for all copies to come from me. The document is not to be copied to others; simply have them contact me in the same way. One advantage here is that no one who got an earlier edition need miss out on annual updates. If you are on my mailing list you will get the update automatically.

Species Dossier: Common Nighthawk

by Carl Strang

This week’s species dossier features a bird which in DuPage County is a migrant rather than a breeder. That is unfortunate, because the spectacle of a hunting nighthawk in summer was a special delight in my younger days.

Nighthawk, Common

Generally these are seen in the air. They also roost (nest?) on buildings, large horizontal tree branches near woods edges, temporarily on deserted streets in early morning, and on rocks in the prairie. They were summer residents in Culver and Lafayette, Indiana, there were a few in Carlisle, Pennsylvania, but they are essentially absent as breeders in DuPage County although they are abundant migrants there, with rivers of them passing over in spring and fall. They feed on aerial insects, sometimes chasing them spectacularly high above the ground. They show some evidence of territoriality when breeding, with aerobatic chases, steep dives with sudden upward turns and twists. Many were brought to the wildlife hospital at Willowbrook in the early 1980’s, wings broken by wires. Adults almost always died; they had to be force-fed and didn’t take the stress well. Some young birds would beg, however, and a few made it. In the clinic they showed an impressive threat display, opening the enormous pink-lined mouth and hissing.

14AU86. First fall migrants in DuPage County, IL.

15MY87. First of year (several) passing over Geneva.

16MY87. One resting on fence rail in front of house at Summerlakes subdivision, Warrenville. I approached within 7 feet and took several photos before it suddenly popped into flight.

Nighthawk roosting on decorative fence rail in a Warrenville subdivision.

10SE87. Bulk of fall migration over. An occasional individual in the evening, yet. 3 seen on 16SE the last noted for 1987.

10SE88. Still a few migrants.

27MY99. Nighthawks migrating over Willowbrook, evening.

JE99. Horsethief Trail, central Kansas. Nighthawk flying and calling at 1pm.

18AU99. First migrating nighthawks, DuPage County.

27AU00. Nighthawks have been common, passing through Warrenville the past week. Today at Illinois Beach State Park in the Natural Area I photographed one sleeping on a horizontal branch of an Austrian pine.

Autumn migrant roosting on a tree branch, Illinois Beach State Park.

23MY02. The first evening I’ve noticed many passing over. At Elsen’s Hill, some were flying low over the river to feed.

25MY02. At Meacham Grove after 10a.m., one flying over marsh area.

29SE11. Mayslake. An unusual group of 5 nighthawks passing over the preserve at mid-day, late for them.

Lessons from Travels: A Most Unconventional Raptor Show

by Carl Strang

Hawks, owls and other raptors are unquestionably charismatic. You probably have seen some form of raptor show at some time, in person or on TV, if nothing else perhaps a falcon or eagle flown at a sporting event. Zoos and other educational facilities, including DuPage County’s own Willowbrook Wildlife Center, have trained staff, volunteers and birds which together provide members of the public with up-close learning opportunities. I did not fully appreciate, until I visited the Alice Springs Desert Park in central Australia in late 2000, the significance of one unspoken message that all these examples have in common: they all involve a relationship in which the bird is, or appears to be, subordinate to the handler. I expected much the same when I saw that there was a raptor presentation on the daily schedule at the Desert Park, and so I allowed myself to be distracted along the way and missed the first few minutes. I really wish now that I had seen how it was introduced.

The presentation was set in an outdoor amphitheater, with the cliffs of the MacDonnell Range in the background.

View from the audience. Notice the separation between the presenter on the right, and the bird, which had flown into the arena and perched on the branches to the left.

Interested in the mechanics of the program, I saw how a handler, out of ready view of the audience, released each bird on cue. The bird clearly was trained to fly to the perch in the arena. The speaker did not overtly point out that the birds wore jesses and, significantly, did not distinguish between their birds and free-flying ones. His presentation on the natural history of the trained birds was expertly mixed with commentary on other free raptors and other birds (including a bronzewing pigeon) that came into view.

They flew a brown falcon, which eventually came to the perch in front of the grandstand. The speaker tossed tiny bits of meat, and the bird hopped off the perch and fetched them on foot, all to illustrate the bird’s long legs and walking agility (they perch on treetops and hunt reptiles, mainly).

Brown falcon at Uluru.

He commented that the falcon looked agitated, possibly indicating the presence of a rival on the cliffs above. The best moment came when a wedge-tailed eagle appeared, one of a free-living pair that nest on the cliffs. Only a speck at first when pointed out by the speaker, who evidently expected it, the eagle approached the areana, perhaps in response to its conspecific in the show, which was sent out flying shortly after the free one arrived (had it been exposed to the free one’s view to bring it in?).

The program’s wedge-tailed eagle after it eventually came to rest on the arena perch.

The resident swooped at the program bird, but neither eagle was hurt. The presenter said that the introduction of disease, which is knocking back the rabbit population, is allowing the vegetation and native herbivores to recover. That rebound hasn’t happened, yet, and for the time being the eagles are having it harder than when rabbits were abundant.

This was a thoroughly masterful and creative approach to a program, integrating free-living wildlife with trained animals. I am willing to say that this remains the best interpretive program I have ever seen.  I especially liked the carefully orchestrated separation between the presenter and the birds, which avoided the undesirable (in my opinion) subliminal message of subordination of wildlife to people. When I mentioned the Alice Springs Desert Park in a recent post, Gary Fry, the park’s current Director, made a supportive comment. Gary, if you notice this one as well, and can recognize the presenter from my photo, his name deserves mention.

Mayslake Update

by Carl Strang

With the onset of winter, things have slowed at Mayslake Forest Preserve. Bird activity has diminished as the migration season winds down.

This sharp-shinned hawk was one of the later migrants to stop by the preserve.

Winter bird activity hasn’t quite settled into a consistent pattern.

A few blue jays continue to hang around, but they may yet move on if the winter turns frigid.

The weather itself has seemed indecisive. The lakes froze over about a week later than they did last year.

May’s Lake had an inch of ice on December 12.

Then we had renewed warmth, and heavy rains that opened the lakes again.

May’s Lake on December 15.

I look forward to expanding my collection of winter botany photos.

Recently I took some pictures of swamp milkweed.

The big push there will need to wait until there is snow on the ground to provide a contrasting backdrop.

Swamp milkweed in winter resembles some of the other milkweeds, but the pods are narrower and more delicate than common milkweed, but wider than those of butterfly weed. There’s also the habitat association.

Snow also will provide for easier tracking, and I’ll renew my acquaintance with the preserve’s mammal activities.

Literature Review: A Surprisingly Carnivorous Plant

by Carl Strang

Among the most insidious of our invasive plants are two species of teasels, unfortunate imports from Europe.

Here’s one of them, the cut-leaved teasel.

One of the studies which caught my eye this past year demonstrated that the other species behaves like a carnivorous plant (Shaw PJA, Shackleton K (2011) Carnivory in the Teasel Dipsacus fullonum — The Effect of Experimental Feeding on Growth and Seed Set. PLoS ONE 6(3): e17935. doi:10.1371/journal.pone.0017935). Dipsacus fullonum, AKA D. sylvestris, the common teasel, has water-holding leaf bases. Shaw and Shackleton experimentally added insects to these little cups, and found that this led to improved seed set and a higher proportion of plant biomass in seeds. Plant growth and total biomass were connected more to rosette size, which in turn is indicative of first season, non-carnivorous growth in this biennial.

Literature Review: Butterfly Range and Diet

by Carl Strang

This week’s literature review note is about butterflies. Usually we just think of butterflies as delightful, beautiful bits of nature, but those qualities also attract the interest of scientists. The scientists in this case are J. Slove and N. Janz (2011. The Relationship between Diet Breadth and Geographic Range Size in the Butterfly Subfamily Nymphalinae – A Study of Global Scale. PLoS ONE 6(1): e16057. doi:10.1371/journal.pone.0016057). The butterflies they studied are 182 species in the widespread subfamily Nymphalinae. Our local members of this subfamily include such familiar butterflies as the mourning cloak, question mark and red admiral.

Mourning cloaks pass the winter in the adult form, hibernating in a sheltering refuge.

Slove and Janz were interested in seeing if there is a relationship between the diet breadth and the geographic range of these butterflies. They wanted to test a prediction that species which eat more kinds of plants have larger ranges. The diet of interest is not that of the adult butterfly, but rather of the caterpillar.

Mourning cloak caterpillars eat the leaves of trees in several families, so they would be regarded as having a wide diet breadth.

It turns out that the prediction holds. The point is that there are a lot of different kinds of plant-eating insects. Some have broad diets, others have narrow ones. How did this diversity come about? The possibility being considered is that some insects have large geographic ranges, in part because by eating a number of kinds of plants they can spread over the collective ranges of those plants. Over the course of time, circumstances such as climate change (interposing a glacier or desert, for instance), geological events (raising a mountain range or sea, for example) and chance isolations (a few representatives driven to a remote island by a storm, perhaps) divide a wide-ranging species into separate groups that no longer can interbreed. Each group may then specialize on the reduced menu of plants available to them, and over time can evolve into separate species. This is called the oscillation hypothesis, because over a long period of time it predicts an alternation between wide diets and narrow diets within a genetic line.

Mallard Species Dossier

by Carl Strang

Today I share my dossier on one of our most familiar birds, the mallard duck. This is one case in which my initial entry in the 1980’s was large enough that it remains the bulk of the file.


Adult male mallard

Widespread, common marsh bird, also frequenting suburban ponds, lakes and streams. Singles and pairs occasionally appeared in western Alaska, but the mallard was not a common species there.

Adult female mallard and ducklings

Courtship begins in September in Illinois and Pennsylvania, as drakes come out of eclipse, but (at least in northeast Illinois) may not peak until January. The male has a large variety of courtship displays, generally preceded by preliminary shakings of the head from side to side, tail shaking, and lifting and shaking the entire front half of the body (the last seems to represent a higher intensity). The most common of the male’s displays is the Grunt Whistle, beginning with lifting the front half of the body (note similarity to the most intense form of the Preliminary Shake). While the body is lifted the neck is arched forward and down, and the tip of the bill is used to flick out an arch of water drops. As this happens the bird emits a high-pitched peeping sound. Frequently several males Grunt Whistle together, and in fact courtship displays generally occur when several males plus at least one female are close together on the water.

Mallard Preliminary Shake

Down-Up is another display, in which the male lowers the front of his body into the water while lifting the tail end. The bill points down as the bird dips, then it is pointed upward. This is an especially beautiful display when several males, facing one another, bow simultaneously.

In Head-Up-Tail-Up, the body is contracted while the neck stretches upward (bill kept level). This always ends with a bout of Nod-Swimming, with the bird swimming rapidly low in the water, neck stretched low and forward, pumping slightly as the bird swims.

Sometimes several courtship displays may be performed simultaneously. Here, the two males on the left are performing the Down-Up display, the one on the far right is performing a Grunt-Whistle, and the one just left of him appears to be in a Head-Up-Tail-Up.

Males and females can be seen together more and more in pairs as winter and spring pass. The female continues to test the drake with Inciting, a display in which she mechanically waves her bill back and forth to point toward another nearby mallard. The male commonly responds by chasing that bird away. Rarely and inexplicably, drakes perform the Inciting motion.

Female mallard performing the Inciting display.

Copulation begins usually with the male performing an exaggerated vertical pumping of his neck with the bill held parallel to the water surface. If the female is receptive, she identically pumps her head. After the two have done this together a few seconds, the male swims behind her, then climbs onto her back. Head pumpings cease as the male achieves a grip on the back of the hen’s upper neck with his bill. She sinks low in the water, he swings his tail around to the side of hers as she pulls hers out of the way, and genital contact is made. Post-copulatory displays are bathing motions by the female and Nod-Swimming by the drake.

The presence of a male with the brood may be a sign that these birds have some domestic mallard in their ancestry.

Pairs appear on land in mid-spring, usually with the female leading the search for a nest site. The nest is built of grasses mixed with down. Generally one pale blue-green egg is laid per day until the 8-13 egg clutch is complete, then the female incubates the eggs and usually raises the young alone. After the ducklings hatch and dry, they follow the hen on an early-morning trek to water, sometimes a mile or more distant. On 8JE86 I saw a drake with a female and large downy ducklings on land, an exception to the rule that males stay away from broods which females raise alone. This was in DuPage County, where ducks are unusually dense because of artificial feeding, and there is considerable domestic mallard in the gene pool. Single failed-nest females sometimes become injured from rape attacks by multiple males. Possibly this male was insuring against the loss of the brood. Young ducklings are distinguished from those of wood ducks by a dark line between the eye and bill, and a darker yellow base color.

Female incubating a nest

General vocalizations include peeps of ducklings, loud call of adult females (series of quacks, first one long and successive ones shorter), and a chuckling continuous call occasionally performed by flocked birds on the water. Mallards winter in DuPage County. Occasional large flocks spent the early winter in the center of Lake Maxinkuckee in Indiana, flying out to harvested corn fields to feed. Mallards feed on the surface of water or tip up to take food from the bottom.

Occasionally an incubating duck leaves the nest for a time. When she does so, she covers it with the mixture of down and grass for camouflage.

Once a hen had a nest in my fenced-in yard in Warrenville, but abandoned before incubation was complete.

Mallard eggs are a pale green in color.

19AP99. Mallard nest at Willowbrook under a columbine, against east wall of garage/bird nursery building (was gone, abandoned or destroyed, by 30AP).

14MY99. Mallard female with 7 young ducklings in stream at Willowbrook.

17SE99. Some mallards at Willowbrook appear to be in eclipse plumage, or perhaps young are molting into their first adult plumage.

29OC00. McKee Marsh. A green-headed male with a group of black ducks has a very dark gray body, no curly tail feathers, and no white neck band, apparently a hybrid.

4MY09. Mallard male with female and duckling chased away another male that showed interest in the female.

Mallard ducklings approaching maturity

23NO09. Mayslake. A dozen mallards were diving for food in May’s Lake, coming up with aquatic vegetation after being completely under water 3-5 seconds. A pied-billed grebe was with them, also diving.

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