Purple Coneflower in Winter

by Carl Strang

One of our most striking prairie plants is the purple coneflower.

Purple coneflower, rays just starting to expand

Purple coneflower, rays just starting to expand

The stem is strong enough to remain up through the winter, but the leaves are gone.

The overall impression is a naked stem with the seed head at the top.

The overall impression is a naked stem with the seed head at the top.

The spiky looking head, an inch or more in diameter, remains the distinctive feature of purple coneflower in winter.

I like the twisted stem of this plant.

I like the twisted stem of this plant.

The seeds are long gone, most of them probably taken as food by goldfinches. In my garden I have found that some seeds survive, and are capable of dispersing at least 20 feet.

Advertisements

Buds as Food

by Carl Strang

 

Spring is a time when buds are an attractive food for some animals. Here is my most recent record, a fox squirrel eating willow buds at Mayslake Forest Preserve.

 

fox-squirrel-buds-2b

 

Going back through my dossiers  I find records of 3 bird species and both local diurnal tree squirrels as occasional bud eaters. The summary follows.

 

Goldfinch: silver maple buds (1 observation).

 

Cardinal: elm buds (1).

 

Purple Finch: silver maple (several birds on each of 2 occasions).

 

(Bird observations all were at Willowbrook Forest Preserve).

 

Fox squirrel: American elm (5 occasions), mulberry (3), box elder (3), sugar maple (3), silver maple (2), cottonwood (1), and now willow (1).

 

Gray squirrel: American elm (7), mulberry (1), box elder (1), silver maple (1), cottonwood (1), willow (1), green ash (1), black cherry (1), and hawthorn (1).

 

(Squirrel observations were from 6 forest preserves plus the Morton Arboretum).

 

Buds have a relatively high protein content, which presumably is the attraction, but they are protected by bud scales which may be why their consumers appear to be limited to herbivorous species with relatively strong biting capabilities. The two squirrels select similar tree species for their menus, with both apparently preferring American elm above all others. Fox squirrels in addition seem to favor maples, including box elder. All my observations range from January to May, a time when alternative, perhaps preferred foods are relatively scarce. Any generalizations in a compilation like this have to be regarded as tentative, but I will continue to record new instances and see what if anything emerges.

The Birch Birds Came Back

by Carl Strang

 

Two days ago I described how the Mayslake paper birch had opened its cones and dropped some seeds. Yesterday morning that tree was the focus of attention for around 30 goldfinches and 30 pine siskins, all busily digging into the opening cones for dinner.

 

birch-goldfinches-siskins-b

 

Goldfinches and siskins are close relatives, with goldfinches abundant DuPage County residents, and siskins mainly winter visitors from the North, though the odd pair has been known to nest locally. At this time of year, goldfinches are pale greenish yellow and white with darker wings, the males having molted out of their bright yellow summer plumage.

 

birch-goldfinch-b

 

Pine siskins have bits of yellow here and there, but are distinctive with their dark stripes. The voices of these two finch species are different from one another as well, but I don’t believe I can describe the difference adequately in words. Seek out reference CD’s or a website with recordings of their calls, if you are interested.

 

birch-siskin-b

 

The sudden appearance of so many of these birds brings out an observation I have made about Mayslake. The birds I encounter there have been highly variable from day to day. Yesterday I also saw the first American tree sparrows I have observed at that preserve. In both of my two previous office locations, Willowbrook and Fullersburg Woods Forest Preserves, tree sparrows have come and gone at widely spaced intervals through the winters. Tree sparrows do not make use of bird feeders as consistently as many other species. I am beginning to wonder if the variability of small winter birds at Mayslake is connected to the lack of bird feeders there. Willowbrook and Fullersburg both have feeders, and both have a more consistent presence of birds through the winter than I have observed at Mayslake so far. I resist drawing conclusions so soon, but I find myself asking whether birds undisturbed by human influences are inclined to wander over wider areas, so they appear in a given location less frequently.

 

There is more to report from yesterday at Mayslake. I’ll share the rest tomorrow.

Seeds on Snow

By Carl Strang

 

There is a magnificent paper birch near the entrance of Mayslake Hall which has managed to evade the bronze birch borers long enough to become robust and beautiful.

 

paper-birch-2b

 

Yesterday I noticed that the birch had dropped seeds onto the snow.

 

paper-birch-seeds-2b

 

For a moment I was a little surprised that there were any seeds left. A couple weeks ago that tree was filled with goldfinches, juncos and pine siskins pigging out on seeds they were digging out of the tree’s cones. Obviously they missed some, for the snow was covered with yellow-brown seeds and shed cone scales.

 

paper-birch-1b

 

After taking some photos, I thought about the timing. Now, with leaves dropped from deciduous trees, the little winged seeds have their best chance of being carried away on the wind. Furthermore, if there happens to be snow on the ground, the wind can further push the seeds, increasing the area over which they are spread. This might improve the possibility that some will find suitable places to grow.

 

That thought brought out a memory, of a presentation decades ago at an Ecological Society meeting. Someone had studied Queen Anne’s lace and found that its seeds are contained within the closed umbrella of its flower/fruit support struts.

 

qa-lace-closed-b

 

The struts remain closed when the air’s humidity is high, but open as humidity drops, so that seeds are released in the dry air of winter when there is a good chance the ground will be snow-covered, allowing the seeds to be wind dispersed over a smooth surface.

 

qa-lace-open-2b

 

Later during my lunchtime walk I found some Queen Anne’s lace, and sure enough, though some were closed, others had opened and begun to drop their seeds onto the snow.

 

qa-lace-and-unknown-seeds-2b

Mixed Flocks

by Carl Strang

 

Yesterday at Mayslake I saw 15 juncos, 2 song sparrows, 3 downy woodpeckers, a goldfinch and a white-breasted nuthatch apparently moving together as a mixed flock. I’m more accustomed to seeing such behavior in the fall, so today I want to provide some background for this phenomenon.

 

 

 

At the September peak of the fall songbird migration, I have found that the quickest way to the greatest diversity of warblers and other migrants is to listen for the chickadees.

 

chickadee-1b

 

Black-capped chickadees are on the verge of forming their winter flocks and are very vocal at that time of year. From the standpoint of a naïve migrant, tired and hungry from the night’s migratory jump south, the chickadees represent a familiar bit of normalcy in an unfamiliar location.

 

Yes, I know, I’m projecting human emotions onto distinctly non-human animals that in fact are closer to dinosaurs than to us. But hear me out. I’ve gone north in the late summer and early fall, and I have seen how the black-capped chickadees up in Canada attract other birds to them like dung beetles to, well, dung. Chickadees are active and vocal, easy to find in the quiet autumn forests. Other birds easily can keep track of where the flock is going just by following the chickadees. When the migrants drop down out of the sky at dawn they are entering unfamiliar territory. Where’s the food? Where do the local predators hang out? The chickadees know. They are in the area year ‘round. They are active, vocal, and easy to follow.

 

chickadee-2b

 

There is evidence in the scientific literature supporting both predator avoidance (lots of eyes and ears on the watch, also the ability to hide in the flock) and improvement in individual foraging efficiency (for instance, one bird may catch an insect that is flushed by another) as reasons why mixed flocks form. I see no reason why both advantages can’t play a role, perhaps with different importance at different times.

 

I have thought that it would be an interesting inquiry to see if there are consistent patterns in the structure of mixed flocks. Patterns could be spatial, with different species or individuals holding consistent places within the arrangement of the individuals of the moving flock. There could be rules governing the number of species, number of individuals, or distribution of individuals among species. But so far, I just have some partial counts of the members of a few mixed flocks.

 

How to collect the data? In September the trees still are fully in leaf, and it’s a challenge just to find all the members of a flock let alone keep track of them all. But it’s fun to find the flocks and tally their members, keeping alert to possibilities, hoping a hint of a pattern might show itself.

 

Here are just a few examples of flocks I’ve seen:

 

  1. Algonquin Park, Ontario, Mizzy Lake Trail, 29 August 2001, at an edge between mixed forest and a lake. Black-capped chickadees, several black-throated green warblers (appear to be sticking together to form their own group within the flock), at least 1 blue-headed vireo, 1 female or young blackburnian warbler, 1 chestnut-sided warbler, and 1 Tennessee warbler.
  2. Algonquin Park, Bat Lake Trail, 30 August 2001. Black-capped chickadees, red-breasted nuthatches, golden-crowned kinglets, 1 or 2 black-throated blue warblers, at least 1 Tennessee warbler, yellow-rumped warbler. The first three species are the vocal ones. These flocks are distinctive: you go for hundreds of yards seeing or hearing no small birds, then suddenly there is one of these diverse groups in a small area.

 

Golden-crowned Kinglet

Golden-crowned Kinglet

 

 

 

  1. West DuPage Woods Forest Preserve, West Chicago, Illinois, 7 May 2000. Several blackpolls in a mixed flock with yellow-rumps, chestnut-sideds, a golden-winged, a blue-winged, some Tennessees, a couple black-and-white warblers, several scarlet tanagers and rose-breasted grosbeaks of both genders, a Swainson’s thrush or two, a couple indigo buntings. No chickadees in this flock, but in spring migration many birds are singing so flock cohesion is easier.
  2. First mixed flock of the 2008 fall migration observed at Fullersburg Woods, Oak Brook, Illinois, on 25 August has 2 chickadees, a downy woodpecker, a Tennessee warbler and a Canada warbler.
  3. Fullersburg, 29 August 2008, a mixed flock with 3 chickadees, 3 Tennessee warblers, a white-breasted nuthatch, a magnolia warbler, a parula. Chickadees were doing a lot of hanging upside down, Tennessees less acrobatic running along tops of branches and reaching, magnolia and parula more rapid movements, hopping between branches, nuthatch on bark, all in top half of canopy.
  4.  Kettle Lakes Provincial Park, Ontario, 13 September 2008. Large mixed flock in an area around 75 yards in diameter: at least 2 black-capped chickadees, 5 golden-crowned and 4 ruby-crowned kinglets, 4 yellow-rumped warblers, 2 red-eyed vireos, downy woodpecker, black-and-white warbler, black-throated green warbler, redstart, red-breasted nuthatch. I’m hearing white-throated sparrows, but they seem all near the ground rather than up in the trees with the others. Weak songs from ruby-crowneds, the black-throated green and the black-and-white. This is mainly an area of aspens with some jack pines.

 

Clearly there are many species that can be found in these mixed flocks, and resident birds like downy woodpeckers and white-breasted nuthatches are common members. Descriptions like these are the only data I have so far, but it’s fun just to find the flocks and try to account for all their members. Maybe some day a pattern will show itself.

 

 

 

For now, I’ve got yesterday’s mixed flock to ponder. No chickadees were present, but with the vegetation open, now that leaves have dropped, maintaining visual contact is easier especially with so many individual birds involved. Yet another observation for my growing files on the subject.

%d bloggers like this: