Sunday, October 30, 2011

Sandhill Crane

On Friday, Erika and I finally made the drive to Sherburne National Wildlife Refuge, about 90 miles from Northfield and just beyond the northwest suburbs of greater Minneapolis. Comprising over 30,000 acres of wetlands, oak savannas, and prairies, the refuge lies in the transition zones between eastern woodlands and prairie as well as northern and more southern forests. This wilderness, relatively close to the city, amazed us. The lakes and marshes almost reminded me of parts of Florida! One reason to visit Sherburne in October is the refuge serves as a staging area for migrating Sandhill Cranes. On Friday, refuge personnel counted 5352 Sandhill Cranes, and we had no trouble finding them in harvested fields northeast of the refuge. I was surprised how close they allowed us to approach (although we did not leave our car, which we used as a mobile bird blind).
Sandhill Cranes are awesome. Genetic studies suggest that these cranes are an old species without close relatives. They are more closely related to Australian cranes than they are to the Common Crane of Europe. Sandhill Cranes live to over 20 years, do not breed until they are 2-7 years old, remain in stable pairs over at least several years, and provide extended care to their young, staying together for almost a year. They usually only fledge one young per year.
Sandhill Cranes migrate and winter in large flocks. The use of migratory staging areas makes them particularly vulnerable to loss of wetlands. In Sherburne, the cranes roost in marshlands and feed in the surrounding fields during the day. As they fed, we saw several cranes dance. In the fall, these dances are antagonistic displays, protecting feeding space or family groups. As you might predict, antagonistic displays are most often done by males.
Family groups remain together from hatching through the following March. The advantages of family groups for the young include more feeding time, fewer aggressive encounters, and less time spent watching for predators. Juveniles outside of family groups tend to be in poor physiological condition.
Minnesota Sandhill Cranes migrate through the eastern and central United States and winter in Georgia, central Florida, the Gulf Coast and Texas. These cranes, along with others from Canadian breeding grounds, stop at staging areas during migration. Huge crane concentrations form in the spring for up to six weeks in the North Platte and Platte river valleys in Nebraska.
Cranes begin their migratory flights in the morning and usually stop near sunset. They cover about 250 km per day at speeds up to 83 km/hour (depending on wind conditions). They fly at altitudes of up to 2500 m. They prefer sunny days with tail winds. They are often inspired to migrate by seeing crane flocks overhead.
My source for almost all of this crane information is Tacha et al. (1992, The Birds of North America Online).

Saturday, October 29, 2011

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?

Thursday, October 27, 2011

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).

Tuesday, October 25, 2011

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.

Sunday, October 23, 2011

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.

Friday, October 21, 2011

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).

Wednesday, October 19, 2011

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.

Monday, October 17, 2011

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).

Sunday, October 16, 2011

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).

Friday, October 14, 2011

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.)

Thursday, October 13, 2011

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. 

Wednesday, October 12, 2011

Blue-headed Vireo

Genetic studies split the former Solitary Vireo into three species: eastern birds like this Blue-headed Vireo, Rocky Mountain populations, now called Plumbeous Vireos, and far western birds named Cassin's Vireos. Blue-headed Vireos breed across northern Canada, just catching northern Michigan and northeastern Minnesota, to New England, and then south through the Appalachians. Although Eckert considers this species to be common in northeastern Minnesota, throughout most of the breeding range Blue-headed Vireos are widely spaced and, due to their remote habitat, little studied (Ross 1998). This author cites surveys that indicate Blue-headed Vireo populations have increased steadily during the past 30 years. When I banded two Blue-headed Vireos last Saturday, however, I was surprised I have not banded this species since 2008 (when I banded seven). This absence explains why this post is my first for this species.

Tuesday, October 11, 2011

Hagen's Bluet

According to the Wisconsin Odonata Survey, about two dozen bluet species occur in the upper midwest.  All look similar and can only be identified with a hand lens. The Hagen's Bluet is common across the northern United States and southern Canada. Its preferred habitat includes ponds and marshes. Last June I found this stunning damselfly in the grasses along the shore of the small pond on the southern edge of Carleton College's lower arboretum. According to Scott King, this damselfly "can't be identified for sure, but if you labeled it a Hagen's Bluet, I can't imagine any objections."

Monday, October 10, 2011

Busy Banding Weekend

On 8-9 October 2011, we enjoyed a busy banding weekend in Northfield. In all we ringed 69 individuals, comprising 20 species.  Our totals were: American Goldfinch 2, American Robin 13, Black-capped Chickadee 7, Blue-headed Vireo 2, Brown Creeper 1, Dark-eyed Junco 2, Downy Woodpecker 3, Fox Sparrow 1, Golden-crowned Kinglet 1, Hermit Thrush 1, Nashville Warbler 1, Orange-crowned Warbler 2, Red-bellied Woodpecker 1, Red-eyed Vireo 1, Ruby-crowned Kinglet 3, Swainson's Thrush 2, Tennessee Warbler 3, White-breasted Nuthatch 2, White-throated Sparrow 3, Yellow-rumped Warbler 18.  Prior to the weekend, we encountered relatively few migrants. The photograph of a Ruby-crowned Kinglet is left over from this spring's banding.

Saturday, October 8, 2011

Hen of the Woods

Erika called, "Check out the two-foot wide, brain-like fungus under this maple!"  With a bit of research, I identified it as a Hen of the Woods.  Folks who are foolish enough to eat wild mushrooms prize this species, which takes long, slow cooking according to the Edible Wild Mushrooms of North America: A Field-to-kitchen Guide. But never, ever take my word as gospel as far as fungus identification goes! Eating wild mushrooms can be fatal! The Hen of the Woods is primarily an eastern fungus, but is found across the country. Look for this species on the ground near tree bases.  Despite our finding it near a maple, the fungus prefers oaks. The name refers to its reputedly tasting like chicken. I ate Hen of the Woods at a Minneapolis restaurant but found it tasted slightly moldy. Other sources say Hen of the Woods gets the name by looking like a crouching grouse.

Friday, October 7, 2011

Bald Eagle Eats Mallard

On 5 October 2011, while birding near Northfield, I discovered a Bald Eagle perched on a muskrat den.  After a few minutes, a flock of American Crows flushed the eagle, which appeared to be carrying either a prey item or perhaps a stick from the den. As I took these photographs, I did not notice the snow-like covering of duck down across the muskrat den.
With a bit of Photoshop work (see below), I discovered the eagle carried an eviscerated Mallard carcass. Bald Eagles are opportunistic foragers, generally preferring fish. When possible, this eagle scavenges or steals prey from other species. It captures its own prey only as a last resort (Buehler 2000).

Thursday, October 6, 2011

Dot-tailed Whiteface

The Dot-tailed Whiteface is one of the first dragonflies to emerge in the spring.  I photographed this female in Dakota County this June. Young are more colorful than adults, which become quite dark. Dot-tailed Whitefaces like lake country, though they are often found basking in the sun away from their breeding areas.  Males defend small, non-static territories.  Mated pairs often fly in tandem in search of breeding areas (Montana Field Guides). The day I observed them, the air was full of flying whitefaces.

Wednesday, October 5, 2011

Mourning Dove Banding Recovery

A former subpermittee banded a Mourning Dove in Ipswich, South Dakota, on 13 May 2006. Slightly over 5 years later, on 23 September 2011, this bird was shot 15 miles south of Tilden, Texas. This location is about half-way between San Antonio and Corpus Christi.  

The oldest Mourning Dove banding recovery on record is 31 years, 4 months (Bird Banding Laboratory). An interesting recovery reported in  Birds of South Dakota was a bird banded on 1 July 1968 and recovered in El Salvador on 20 October 1968. Another was banded on 18 August 1975 and recovered in Nicaragua on 27 October 1975. Birds banded in South Dakota have also been recovered in Maryland and California.

This Mourning Dove photo was taken several years ago at South Dakota's Sand Lake National Wildlife Refuge.

Tuesday, October 4, 2011

Common Baskettail

The Common Baskettail is found in eastern North America.  They are often seen patrolling ponds and lakes, as is in the photograph above taken in June 2011 in the Carleton College Arboretum (the lower photo is from Erika's garden in 2010). Baskettail identification tends to be tricky, so I am indebted to Scott King for his help with these photographs. According to (Mead 2003), the dark patches on the bases of the hind wings of the individual below cinches its identification.

Monday, October 3, 2011

Dark-eyed Junco

In March 2010, I blogged about aging and sexing Dark-eyed Juncos. Eye color is one key to age. Birds with reddish-brown eyes are adults. Those with grayish-brown eyes are in their first year. This junco, the first of this fall (30 September 2011), is an hatching-year bird. In the photo below, note the grayish-brown eye. Telling junco sex is much more difficult. Check out McGill Bird Observatory's photographic key.  I have always relied on wing measurements, with birds with wing chords over 77 mm being male, and those under 73 mm, female. This individual measured 78 mm--thus a male.

Sunday, October 2, 2011

Cherry-faced Meadowhawk

On 18 July 2011, I found this female Cherry-faced Meadowhawk perched on the edge of a low pile of dead brush near Northfield. Note the orange wing veins. Males are red and difficult to identify in the field. This dragonfly is cold tolerant and found from Alaska and far northern Canada into the United States to California, Missouri, and Pennsylvania. The Cherry-faced Meadowhawk feeds on almost any soft-bodied flying insect (Idaho Digital Atlas, Montana Field Guide).

Saturday, October 1, 2011

Deer Mouse

Deer and White-footed mice are often difficult to identify. This mouse's being young does not help. Note the tail, which is shorter than the body length and white below. The gray back (instead of reddish-brown) also suggests Deer Mouse. Erika and I stumbled upon this individual in a woodland at the edge of the Big Woods State Park. This mouse may have been ill. It did not try to flee, but swayed back and forth in the undergrowth. Such behavior should result in this youngster's becoming dinner for an owl or other predator. If such predation did not exist, the planet would quickly become overrun by mice.