Stream Bluet vs. American Rubyspot

Here is an odd damselfly behavior that Scott K. and I observed last July. I was excited to list my first American Rubyspot, the damselfly on the right, which I blogged about on 21 July. The rubyspot faced two Stream Bluets (see 3 August post). The later odonate is common across much of eastern North America. Scott and I were surprised when the rubyspot arched its abdomen in what appeared to be an aggressive behavior. Was this action in response to the bluets?  Or was another rubyspot in the vicinity?

Tufted Titmouse

Much of the thrill of birding is being at the right place at the right time. From Day One at our Dundas banding station, I predicted we would encounter a Tufted Titmouse. The habitat seemed perfect--wood edge with plenty of oaks and nearby bird feeders. Wednesday morning (three years later) my prediction materialized. I knew a bird hit the net, but what a thrill to discover our first Tufted Titmouse! (The word titmouse is "derived from the Old Icelandic titr, meaning 'something small,' and mouse, a corruption of the Old English mase, 'small bird'" (Gruson's Words for Birds)).

Tufted Titmice are very common in the eastern deciduous forests of the United States. Minnesota is at the northwest corner of the species' range (see eBird). During the past 50 years, perhaps as a result of global warming, titmice have been expanding northward. This titmouse was an after-hatching year bird. During their first year, young birds often stay in their parents' territories and help raise second broods. Only in their second year do they disperse into new territories (Grubb and Pravasudov 1994).

Harris's Sparrow

The Harris's Sparrow is a large, handsome songbird with a strange range. This bird is Canada's only endemic breeding bird, nesting from the western shore of Hudson's Bay, north and west almost to Alaska. The winter range is also odd, restricted to a relatively narrow band from southern South Dakota to southeastern Texas. In Minnesota, this species is an uncommon migrant, most likely to be seen the farther west you travel. A few attempt to overwinter in the southernmost part of the state. On Monday, 24 October 2011, I located several Harris's Sparrows in brush piles, two in Rice Co. in Carleton College's Upper Arboretum (thanks to an alert from birding friends) and another in nearby Dakota Co.

The bird above, photographed on Monday, in a first-year bird. The bird below, banded a couple of springs ago near Dundas, is an adult. Harris's Sparrows are sexually monomorphic--males and females look the same (although males tend to be larger and heavier than females). In the spring, birds with the blackest throats are dominant over birds with whiter, more splotchy plumage.

Cedar Waxwing

Surprisingly this scruffy, young, fruit-stained Cedar Waxwing molts into the elegant adult waxwing pictured below. Waxwings are one of North America's few fruit specialists (although they will hawk for insects when arthropods are abundant). Waxwings show a number of distinct behaviors as a result of their love for fruit. They tend to be nomadic, feeding and breeding where fruit is seasonally or locally available. Because fruit is often abundant, waxwings tend not to be territorial and instead breed and travel in large flocks. Finally, waxwings tend to be late breeders, as evidenced by the heavily molting October juvenal above.

Waxwing numbers are increasing, perhaps because we use fewer heavy-duty pesticides on fruit crops. However, waxwings are notoriously susceptible to consuming fermented fruit, one result of which is drunken waxwings colliding with cars and windows. In Aberdeen, South Dakota, we witnessed massive waxwing mortality due to their eating cyanide-laden Caragana (Siberian Pea-shrub) buds in the spring. The pea-shrub is a winter-hearty ornamental plant introduced from Siberia.

Downy and Hairy Woodpecker

I have written about Hairy and Downy woodpeckers several times in this blog, including on 5 March 2010, when I discussed identification of these woodpeckers. In South Dakota, Downys outnumbered Hairys about 10 to one. I assume similar ratios exist here in Minnesota. Generally Downys forage on small, outer tree branches while Hairys specialize on larger branches nearer the trunks.

The first photo is of a female Downy Woodpecker. The second is of a  male Hairy. Curiously many studies indicate these similar appearing species are not closely related. Downy Woodpeckers may be most closely related to Ladder-backed or Nuttall's woodpeckers and one of the few genetic studies with Hairy Woodpeckers indicated a close relationship with Latin American Smokey-brown Woodpeckers (Jackson and Ouellet 2002).

I write about these woodpeckers again because, during the past week, surprisingly I caught a few unbanded individuals. A small fraction of resident woodpeckers show seasonal wanderings, but these movements may be examples of dispersal rather than migration and, in any case, are not well understood (Jackson and Ouellet 2002).

Barred Owl

Barred Owls are fairly common in our woodlands, though seeing one might be difficult. I might have better luck pointing out its call, "Who cooks for you, Who cooks for you?" I hear these owls calling in the early morning as I open my banding nets. Barred Owls are territorial throughout the year, so fall calling is not surprising. (The linked file is used with permission of Thayer Birding Software).

I have enjoyed a few close encounters with Barred Owls. The bird in the first photo was probably at a nest. I found it for a few years near Northfield, and, in those days, I could have guaranteed you a view. But in recent years the nest tree has fallen. Barred Owls nest in cavities in mature trees. They will nest in large trees in secondary forests, unlike the endangered Spotted Owl, which requires old-growth forest. Barred Owls, however, are occasionally seen in other habitats. I found the owl in the second photo, taken with my cell phone, in residential Bloomington, Minnesota.

The last Barred Owl makes a winter roost in a tree above our Dundas banding station. The owl pays little attention to the juncos and siskins at the feeders, and the small birds do not mob the owl. Barred Owls are known to take small birds, but appear to prefer mammals. Apparently this owl ate mice trapped in John H.'s basement and tossed into the woods. 


Although Barred Owls mostly hunt at night, dawn, and dusk, they also hunt during the day. This species' lack of "ear" tufts is typical of daylight-hunting owls. Owls that roost during the day often have these tufts, which apparently make them appear like broken tree trunks. "Eared" owls are less noticeable to birds that would otherwise mob them.

Four-spotted Skimmer

On 21 July 2011, I found this Four-spotted Skimmer defending territory atop a large brush pile at the Northfield compost center. Males defend territories against other males and even other species. This skimmer has a holarctic distribution--it is found throughout Europe, Asia, and North America. The Four-spotted Skimmer is Alaska's state insect.

Unlike the sedentary North American populations, European Four-spotted Skimmers migrate (usually in 10 to 15 year cycles). These migrations, which are in unpredictable directions, may be triggered by parasitic trematodes. Possibly the migrations serve to disperse the parasites (Wikipedia).

Fox Sparrow

This Fox Sparrow, which I banded on 8 October 2010, was the first of this species that I listed this year. Because Fox Sparrows are normally common migrants, I am surprised that I did not list it last spring. Perhaps this lapse was due to last year's harsh winter. Freezing rain and deep snow during the winter and spring migration can cause high mortality for this sparrow (Weckstein et al, 2002). In the long run, nevertheless, Fox Sparrow population trends appear to be relatively stable. In a previous post, on 27 March 2010, I blogged about the complexity of Fox Sparrow races (some of which, within the near future, may be elevated to species status).

Wood Thrush

I banded and released this Wood Thrush on 11 October 2011. This date approaches the late dates for this species in Minnesota (Janssen, Birds in Minnesota). I have written about the beautiful Wood Thrush song on 13 May 2010 and, on 28 September 2010, about this species' declining populations. When you see a black background on my photographs, the reason is often that the photo was taken at dawn or dusk. The camera's flash highlights the bird, but leaves the background dark.


Our warm, dry fall may have induced this individual to linger. Note the pale-tan spots on this bird's wing coverts. These are feathers that the bird retained from its junvenal plumage. This pattern is typical for most thrushes (although some individuals go through a complete molt). These junvenal feathers are even present on some spring birds. When present, these feathers indicate that you are seeing a first-year bird in the fall and a second year one in the spring. (Banders celebrate all birds' birthdays on the first of the year.)

Common Liverwort

Although my students never seemed to share my enthusiasm for liverworts, the reproductive biology of these primitive plants is both strange and fascinating. To avoid the same fate as my glassy-eyed students, if you are interested in learning about liverwort sex, you might study the haploid and diploid generations of this plant on the Internet or in a library book.

Suffice to say here that the Common (or Umbrella) Liverwort is found around the world. It has separate male and female plants. This liverwort reproduces both sexually and asexually. The little gemmae cups visible in my photograph are an example a asexual reproduction. The little balls of cells inside the cups are genetically identical to the parent plant. Rain splashes these balls out of the cups, thereby dispersing the liverwort. 

Since liverworts usually prefer moist habitat, we were surprised to this plant on Erika's garden soil.  We usually find them on rocks along riverbanks. Wikipedia, however, assures us that Common Liverworts are often found in gardens and greenhouses and can be a horticultural weed.

The word "liverwort" comes of the Anglo-Saxon for liver and plant.  At the time, folks believed that God made each plant for human use.  As the liverwort thallus (leaf) is more or less liver-shaped, you could use liverworts to cure liver diseases.  Such a philosophy can easily lead you to cases of plant poisoning, but throughout the history of medicine, and to this day, patients only die from the last disease they contract.