Mayslake Vertebrate Action

by Carl Strang

The season’s progress can be measured in many ways. One is through vertebrate activities.

A fox squirrel feeding on flowers

A fox squirrel feeding on flowers

Song sparrows, among other birds, have been singing like crazy.

Song sparrows, among other birds, have been singing like crazy.

Migration is accelerating. This unusually pale savannah sparrow stopped by Mayslake Forest Preserve a couple weeks ago.

Migration is accelerating. This unusually pale savannah sparrow stopped by Mayslake Forest Preserve a couple weeks ago.

Pied-billed grebes have been regulars on Mays’ Lake.

Pied-billed grebes have been regulars on Mays’ Lake.

And the Cooper’s hawks are happy to exploit the stopovers of migrants who don’t know the territory.

And the Cooper’s hawks are happy to exploit the stopovers of migrants who don’t know the territory.


Species Dossier: Pied-billed Grebe

by Carl Strang

Grebes are cool. I love the way pied-billed grebes can sink without diving, and come to the surface with just the top of their head showing as they check out whether the coast is clear. They also have proven to have odd and unexpected evolutionary relationships. A recent study confirmed that the grebes are closest to the flamingos. Once you get your head around that one, add this result: among our local birds, the next closest relatives to the grebe-flamingos are the doves. Here are my observations on this species:

Grebe, Pied-billed

Pied-billed Grebe

Pied-billed Grebe

Common migrant on Maxinkuckee and ponds around Culver, generally appearing as individuals either isolated or on the fringes of duck or coot rafts. Breeder at McKee Marsh in DuPage County, IL. By mid-July the young were foraging with the parents, catching newly metamorphosed bullfrogs. Sings from water, a strange pumping song. “Ah-ah-ah…ah-ah-ah’dool-ah’dool-ah’dool…” The “ah” syllable increases in pitch untill it is very high when compared with the lower-pitched “dool” syllable.

4AP99. First of year seen, Culver.

10SE99. A single youngster spent a day on the Willowbrook marsh. This is the first one to stop at Willowbrook, perhaps because this was the first year with significant emergent vegetation along the edge. Still had some pied markings on the face.

30OC99. 3 on a lake at Fermilab.

8NO99. Lots of pied-billed grebes scattered among coot and duck rafts at Lake Maxinkuckee. Horned grebes outside, separate, and a few of the pied-billeds as well.

2AP00. One individual at Lincoln Marsh, Wheaton.

1JL00. An adult with at least 2 swimming small young, Brewster Creek marsh at Pratts Wayne F.P.

24SE00. Several migrants at McKee Marsh.

28OC09. Mayslake. A pied-billed grebe on May’s Lake swallowed a small fish.

23NO09. Mayslake. A dozen mallards diving for food in May’s Lake, coming up with aquatic vegetation after being completely under water 3-5 seconds. The grebe that has been staying close to them for a week still is present, and also diving.

5AP10. Mayslake. In the stream corridor marsh, 6 hooded mergansers and a pied-billed grebe diving for tiny prey, insect larvae and/or chorus frog tadpoles. Two of the mergansers were first-year males, with nearly white, indistinctly defined boundaries, in crests.

15OC. Mayslake. Two pied-billed grebes in the NW corner of May’s Lake. One flew when I came up on them, the other dove.

7SE12. Maylake. In the SE corner of May’s Lake, 25 mallards accompanied by a single immature pied-billed grebe that at times appeared to be dabbling.


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.

Chorus Frog Population Jump

by Carl Strang

Our most abundant frog, locally, is the western chorus frog. They are small, and well camouflaged, so we know them mainly from their loud singing in the early spring. Their song is reminiscent of the sound of a thumbnail run slowly over a comb’s teeth, and often they gather in numbers so large that counting them is tricky. Even when concentrated in the small ponds they prefer for breeding, they are difficult to see.

Chorus frogs are sensitive to motion and vibration, and quick to shut up. Holding still, with only the head protruding from the water and often sheltered by overhanging vegetation, they are a challenge to spot.

Last year, my first at Mayslake Forest Preserve, chorus frogs gathered in only one location, the stream corridor marsh. My highest count of singing males was 12. This year I was pleasantly surprised to find many more. Conservative counting has given me a minimum of 22 male frogs at the stream corridor marsh. Furthermore, 3-5 have been singing in each of two other locations. The closest of these is at least 1000 chorus-frog-hops in a straight line from the stream corridor marsh, the other at least twice that far.

A little digging produced the fact that chorus frogs can reach sexual maturity within one year. This allows them to make a rapid response to favorable environmental conditions. While it is true that last spring was relatively wet, keeping the stream corridor marsh well filled for the entire season, some of the credit for this goes to Mayslake’s volunteer restoration stewards, Conrad Fialkowski and Jacqui Gleason. They have been clearing brush and girdling trees around the marsh for several years.

This removal of woody plants eliminates most of the water-sucking transpiration that otherwise would dry out the marsh. The result has been improved conditions for marsh and wet-prairie plants in that part of the preserve and, I believe, a jump in the western chorus frog population.

On Monday there were further ecological ramifications. A group of 6 hooded mergansers and a pied-billed grebe spent much of the day on the stream corridor marsh. They were actively diving for food, and coming up with tiny items too small for me to identify. These could have been insect larvae, as there have been diverse and abundant dragonflies at that marsh in summer. The birds’ food also may have included some recently hatched chorus frog tadpoles.

Incidently, the stream corridor marsh attracted the attention of nature enthusiast Ed Teune, who posted a nice video of the marsh and a singing chorus frog (close up, with audio) on U-Tube.

The Grebe and the Mallards

by Carl Strang

For more than a week, a migrating pied-billed grebe stayed on May’s Lake in late November.

This bird was constantly in the company of a group of mallards. Even when the ducks were standing on fallen logs near shore, the little diving bird floated close by. Here the grebe is at the far edge of a feeding mallard group.

The ducks were diving for aquatic plants. Mallards are not very good divers. The splash in the following photo is characteristic of their inefficient plunges.

They stayed beneath the surface 3-5 seconds, which in the relatively shallow water was enough for them to acquire a snack. If I were a children’s book author, I might be inspired to write a story about how the grebe was lonely, made friends with the ducks, then taught them how to dive for food in exchange for their companionship. While that story has emotional appeal, I’m pretty sure none of it was taking place.

Notice how two of the mallards are taking a peek below the surface before diving. The area where they are feeding is only a little farther out from depths where they can get food by tipping up. Mallards don’t dive often, but do so occasionally when bathing or when chasing one another. I’m pretty sure the ducks would be diving for food even if the grebe weren’t with them.

So what of the grebe’s behavior? This is a fairly solitary species, except during the breeding season. They don’t travel in flocks, or even family groups. Young make their way south on their own, entirely by instinct. Nevertheless, a grebe wanting others to hang out with could find them, and wouldn’t need to affiliate with ducks (grebes are now known to be more closely related to flamingos than to ducks, thanks to genetic comparisons made at the Field Museum).

Pied-billed grebes frequently can be seen in the vicinity of flocks of diving ducks or coots on larger lakes during migration, and my impression is that this is more than a random association, though some grebes also are off by themselves. I think the affiliation probably is more like what we see in mixed flocks of migrant songbirds than a social expression. There is evidence that mixed flocks have two advantages for their members. First, they provide more sets of senses for detecting the approach of predators (and the lucky bird that first spots such an approach can place itself on the far side of the flock). Second, the activity of so many birds foraging in close proximity stirs up prey which may escape the individual that first flushed it, but then can be caught by one of the others. It seems likely to me that something like this is going on with the grebes, too.

The Ducks Stop Here

by Carl Strang


This spring I have been impressed by the variety of migrant ducks stopping at Mayslake Forest Preserve. They haven’t come in large numbers, and haven’t stayed long, but the diversity has been interesting. So far I have seen (in addition to local mallards) shovelers, wood ducks, pintails, lesser scaup, hooded mergansers, and this bufflehead pair.




In addition, last fall a ring-necked duck spent a day. The brief stays and low numbers suggest that the habitat quality may be limited in some way. On the other hand, two pied-billed grebes have stayed on one of the lakes for several days, now, so there is food at least for carnivorous divers. The migration has just begun, and I look forward to discovering which species give Mayslake a try as their daytime stopover site.

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