Tuesday, August 31, 2010

Buff-breasted Sandpiper

Sunday afternoon Dave B. e-mailed that he found a small flock of Buff-breasted Sandpipers east of Faribault.  Never having "ticked" this species on my Rice County list, I somewhat belatedly set out in search.  I easily discovered this single bird feeding in a sod farm where the original flock was reported.  This sandpiper often prefers dry, short-grass habitat.

Buff-breasted Sandpipers breed sporadically across the western Canadian and Alaskan Arctic shores and into western Arctic Asia.  The Asian birds presumably migrate with the North American ones to the pampas of Argentina, Uruguay, and Paraguay.  They migrate over the central United States. The species seems to be fairly picky about its habitat.  I have observed this sandpiper only about a half dozen locations.  Erika and I saw them regularly in Louisiana, but only in the same well grazed pasture in Cameron Parish.  We encountered them on a grass DC 3 landing strip in the Amazonian Ecuadorian jungle. I saw them twice in South Dakota, once along a weedy drained shoreline and once in grazed pastureland.  Finally, I have found them twice in Minnesota, both times in sod farms.

The first time I saw these birds in South Dakota we found a flock of several hundred in May.  Despite their migrating, the males were already displaying.  Buff-breasted Sandpipers have bright white under-wings.  Males display by extending one or both wings, trying spasmodically to flag down the interest of females.  This species are the only North American breeding shorebird to breed on leks.  Males defend small display sites.  Females pick the sexiest mate and then nest elsewhere without male assistance.  Check out this video.

Once abundant, Buff-breasted Sandpiper numbers have greatly declined since the late 1800s.  Grassland habitat in the United States and in southern South America has gone under the plow.  Before the Migratory Species Act, this sandpiper was also commercially hunted.  Buff-breasted Sandpipers are usually tame and have the unfortunate habit of returning to wounded flock members.  Despite legal protection, recent surveys suggest the species is still declining.  The Handbook of Birds of the World estimates the total world population to be no more than 25,000.  In contrast, the Stilt Sandpiper, which has a similar migration route but different habitat preferences, enjoys as many as 100,000 individuals.  (I am not exactly sure how these estimates are made.)

Monday, August 30, 2010

Eastern Pondhawk

My dragonfly stalking began this fall.  This Eastern Pondhawk is the fifth species I have found in our garden. This fierce predator eats anything it can catch, including other dragonflies. The species is common over much of eastern North America.

Sunday, August 29, 2010

Red-eyed Vireo

Back on 18 June 2010, I posted a photo of an adult Red-eyed Vireo showing its red eye.  I promised to look for an immature bird.  I caught this one last Thursday--a brown-eyed Red-eyed Vireo.  Age is told by eye color.  Perhaps the brown eyes reduce aggression from red-eyed adults, indicate breeding condition or readiness, or perhaps just identify young vireos.

Saturday, August 28, 2010

Mourning Warbler

On Thursday I was surprised to band a fairly bright Mourning Warbler. Usually by now both sexes would be in their drab fall plumages. Little is known about the breeding biology of this warbler.  One reason is that this species prefers tangles and thickets and so is hard to observe.  Because of its predilection for dense habitat--the sort that often appears after lumbering--the Mourning Warbler is one of a few of our neotropical migrants that may be more common now than in relatively recent history.

Friday, August 27, 2010

Golden-winged Warbler

On Thursday I banded a Golden-winged Warbler, our first for the Dundas banding site. I previously observed the species there but never banded it.  In my 14 June 2010 blog, I discussed some of the genetics and population dynamics of this bird.  But this warbler has more fascinating biology.

I caught this Golden-winged Warbler with four Black-capped Chickadees, perhaps not a coincidence.  These two species are often found with each other, especially in the late summer and during the fall migration.  This association may be to the benefit of both species.  The warbler learns from the resident chickadees where the best feeding areas are located (and the chickadees are familiar with local predators).  The warbler may be better able to open insect-laden buds that the chickadee would otherwise miss (the chickadee then steals from the warbler).  The somewhat similar plumage of the two species (black throats, gray bodies, and similar song pitch) may reduce aggression and thereby enable the species to occupy the same flocks (Eastman, Birds of Field and Shore).

Thursday, August 26, 2010

Autumn Meadowhawk


Autumn, or Yellow-legged Meadowhawks are common dragonflies across much of North America. This dragonfly is the fifth species of Odonata that I have found in our backyard.  I am amazed at their crimson eyes. The meadowhawk in the photo above is an immature male.  It will become brighter red as the season progresses.  The photo below is of a female.  The yellowish legs and the downspout ovipositor are good field marks.  Thanks to Scott King for identification help.

Wednesday, August 25, 2010

Black-throated Green Warbler

The parade of confusing fall warblers continued on 24 August, when I banded this first-year fall Black-throated Green Warbler.  The male (see below) is one of the more handsome of the spring birds.  Fall males have more black on their throats than this female, which also showed a yellowish wash on its lower flanks.

The Black-throated Green Warbler's spring song is distinctive and easily learned by beginning birders.  On its northern breeding grounds, one male sang 466 songs in an hour.  This species is thought to be monogamous.  Silent males, however, have been observed within another pairs' territories, which may indicate that extra-pair copulations occur (Morse and Poole 2005). Genetic testing of siblings would indicate if such shenanigans were taking place.

Tuesday, August 24, 2010

Spreadwing Species

I have just begun chasing dragonflies around the backyard and am finding them exceedingly difficult to identify.  I am somewhat confident that the damselfly in this post is a species of spreadwing.  According to the Mississippi National River and Recreation Area website, the distributions of the Minnesota spreadwings and damselflies are not well known.  At least six species might be found in this region of the state, but identification requires closely examining a captive.  Whatever species this may be, I was amazed by the intensity of its azure eyes and by the yellowish racing stripe along its sides.
Resting spreadwings hold their wings back in a V-shape, unlike dragonflies that hold their wings straight out and damselflies that keep their wings against each other. Unlike most dragonflies that survive as larva under water during the winter, some spreadwings inject their eggs into vegetation just above the waterline.  In winter, the eggs go into a suspended state. After winter, as water levels rise, the eggs begin growing again.  Thus spreadwings are among the first dragonflies to appear in the spring.

Since posting this blog, I received a note from Scott King.  He writes "The spreadwing is even more exciting. I'm fairly certain it's a Great Spreadwing (Archilestes grandis) and a new state record...The closest records for this species are for Iowa and are from August and September. Take a look at the dot map for the species at Odonata Central (http://www.odonatacentral.org/): type in Archilestes grandis for the taxa. It's a significant find. One reason for recent survey work is to document range expansions to the north due to climate change; this would certainly suggest such an expansion.

Monday, August 23, 2010

White-faced Meadowhawk

White-faced Meadowhawks hunt near the forest edge from low perches usually near streams or ponds. Fifteen species comprise the genus Sympetrum, and many are difficult to distinguish.  This species, obtrusum, is identified by its white face and the black diamonds on the red tail. This meadowhawk is found across much of northern North America. It is a late season dragonfly, observed in Minnesota even in late November. These dragonflies eat most soft-bodied insects, including mosquitoes, flies, small moths, mayflies, and flying ants and termites.

Sunday, August 22, 2010

Jack-in-the-pulpit

Many folks are familiar with Jack-in-the Pulpit (Arisaema tryphyllum), which gets its name from the spadix that looks like a preacher in a pulpit (see Erika's photo below).  The spadix contains tiny flowers. Fewer people know the bright red fruit, which appear in the fall as the foliage withers.  In the photo above, the fruit is changing from green to a ripe crimson.

If properly prepared, the Jack-in-the-Pulpit is edible.  But beware--the plant contains calcium oxalate, which can create burning sensations and rashes, irritate the digestive system and adversely affect breathing.  Native Americans used the plant to treat rheumatism, bronchitis, asthma, snakebites, and to induce sterility. On the other hand, 17th century Europeans thought plants were put on this earth with signs for how humans should use them.  (The liver shape of liverworts was a sign that these plants could be used to cure liver ailments.)  The Jack-in-the-Pulpit's spadix was seen as a sure sign that the plant is an aphrodisiac.  The Minnesota Department of Natural Resources wisely considers the Jack-in-the-Pulpit to be toxic.

Saturday, August 21, 2010

Monarch Caterpillar

Monarchs live as caterpillars for 10-14 days.  During this time they grow and consume mostly milkweed.  From here they enter a chrysalis stage, and emerge as an adult butterfly.  I assume the gaudy colors of these caterpillars serve as a warning to predators that the caterpillars are poisonous.  This type of warning is called aposematic coloration.  I found this caterpillar on a milkweed we planted in Erika's garden in hopes of attracting monarchs.

Friday, August 20, 2010

Chestnut-sided Warbler

Today's Confusing Fall Warbler is this young Chestnut-sided Warbler. In the spring, both sexes, like the male in the photo below, are more striking.  In the fall, both sexes have varying amounts of chestnut on their sides.  The female above had no chestnut.  But fall birds have a remarkable back color, which I have barely captured in my photograph.  This color is a bright, grass-green color that I have seen in some tropical tanagers, but not in other North American birds.  According to Richardson and Brauning (1995), Chestnut-sided Warblers have benefited from deforestation in North America--the species prefers disturbed secondary growth.  This species was almost never recorded in Audubon's time, but now it is common.

Wednesday, August 18, 2010

Black-and-white Warbler

Finally a not so confusing fall warbler.  This Black-and-white Warbler visited our water feature on Tuesday afternoon.  She is a young female, as indicated by her buffy cheeks. (Not visible in this photo are her buffy flanks.)  Contrast the sides of her face with the black and white head of a winter-plumaged male below. 

Only in 1859 did ornithologists recognize that this bird is not a creeper, but, rather, an aberrant warbler.  Its generic name, Mniotilta, means "moss-plucker."  This species is the only warbler that forages like a nuthatch or creeper along tree boughs, searching for small arthropods under the bark.  Hence its bill is relatively long for a warbler, and slightly down-curved.  Another creeping adaptation is this bird's unusually long back toes (at least among warblers). The toes are almost equal in length to the tarsus (again, see the photo below).

Because it winters along the Gulf Coast and in Florida (and all the way down through northern South America), this warbler is one of the first warblers to appear in the spring.  Last January, Erika photographed this Black-and-white Warbler foraging in Florida.


Monday, August 16, 2010

Canada Warbler

Awaiting me on the last net check of Sunday evening was the second confusing fall warbler of the season: a hatching-year female Canada Warbler.  I startled at the white eye-ring: a Connecticut Warbler?  No, the very faint gray necklace and grayish back proclaimed Canada Warbler.  How subdued this plumage is compared to the brilliant spring male below!

This warbler winters from Columbia and Venezuela south to Peru and Brazil.  Although a fairly common breeder in northern Minnesota, and a common migrant elsewhere in the state, Canada Warbler populations have been declining in North America at a rate of about 2% a year, presumably due to deforestation in both the breeding and wintering range (Reitsma et. al 2010).

Sunday, August 15, 2010

Monarch Butterfly

Yesterday I finally caught up with a Monarch Butterfly.  Reading about Monarchs in Wikipedia, I was surprised by two statements.

I thought that Monarchs make their marvelous migrations in a single flight. "But no single individual makes the entire round trip. Female monarchs deposit eggs for the next generation during these migrations...The length of these journeys exceeds the normal lifespan of most monarchs, which is less than two months for butterflies born in early summer. The last generation of the summer enters into a non-reproductive phase known as diapause and may live seven months or more. During diapause, butterflies fly to one of many overwintering sites...It is thought that the overwinter population of those east of the Rockies may reach as far north as Texas and Oklahoma during the spring migration. It is the second, third and fourth generations that return to their northern locations in the United States and Canada in the spring. How the species manages to return to the same overwintering spots over a gap of several generations is still a subject of research; the flight patterns appear to be inherited, based on a combination of the position of the sun in the sky."

Next Wikipedia cited the similar-looking Viceroy Butterfly as an example of Mullerian mimicry, which is when two poisonous creatures look similar, thereby not taxing predators' learning curves.  I always thought that the mimicry here was Batesian, wherein a palatable species (the Viceroy) masquerades as the poisonous one (the Monarch).  The Viceroy is less common than the Monarch, which is essential for Batesian mimicry to work.  But Wikipedia claims that both species store heart-stopping cardenolide aglycones in their bodies, ingested when the caterpillars feed on milkweed.

(A third type of mimicry, Aggressive, occurs when predators appear to be "safe" species.  Zone-tailed Hawks have a flight silhouette similar to Turkey Vultures.  The hawk soars with the vultures, and surprise their unsuspecting prey when the hawk swoops from the vulture flock.)

Saturday, August 14, 2010

Yellow-bellied Flycatcher

This morning I banded a Yellow-bellied flycatcher.  I tend to band this species late in the spring (often in June) and early in the fall. These observations are collaborated by Gross and Lowther (2001), who comment that, of the neotropical migrants, the Yellow-bellied Flycatcher spends one of the shortest nesting periods in the northern forests (often less than 70 days).  The winter range is from central Mexico through Panama.

Even with birds in hand, I find it difficult to photographically capture this flycatcher's colors.  Often photographs miss either the greenish back or the intensity of the yellowish underparts.  This photo comes close, although it is not perfect.

Thursday, August 12, 2010

Blackburnian Warbler

This noon I caught the first CFW (Confusing Fall Warbler) of the season.  I had hoped to share with you the brilliant birds of spring, but the migration proved to be poor.  The field marks for this first-year female Blackburnian Warbler include the dark cheek patches, white wing bars, and streaked sides.  Older birds will show more of an orange-yellow color on their throats, although not as intense as the neon orange or yellow of spring birds (like the male bird below).  Blackburnian Warblers winter from Panama through northern South America.

Wednesday, August 11, 2010

Tree Swallows

On Wednesday I birded as the wind blew and large thunderclouds appeared from the west.  I came upon a few dozen swallows perched on a wire.  Most were easily identified as Tree Swallows.  As you can see in the photo below, Tree Swallows are blueish above and white below, making identification fairly easy.  Unlike other swallows, this species can survive on fruit in the winter.  Therefore they winter further north than many other swallows and are the first swallows to appear in the spring. Tree Swallows are not universally admired, since they depend on nesting cavities of other birds, like woodpeckers and bluebirds.
A few of the birds gave me pause.  They appeared to be smaller than the Tree Swallows and brown-backed.  Because their throats were definitely white, my first thought was that these smaller birds were Bank Swallows.  (Rough-winged Swallows have dusky throats.)   They lacked, however, any semblance of a breast band.  If you look closely at the next photo, you may notice a few blueish feathers molting into this juvenile Tree Swallow's back.
The young Tree Swallows had difficulty keeping their balance when they faced the wind.  In this last photo the young bird almost toppled off the wire!

Tuesday, August 10, 2010

Horned Lark

My blog entries may appear to be random.  In fact, the subjects are usually inspired by my most recent encounters with wildlife.  This note is an exception--I took this photograph of a Horned Lark last May and have just returned to it this rainy Tuesday morning.  The Horned Lark is a common but often overlooked North American bird.  Horned Larks are thought to be monogamous, at least within a breeding season, although if a female loses her mate, an adjacent, but already mated, male may mate polygamously with her. (Beason, Robert C. 1995.  http://bna.birds.cornell.edu.bnaproxy.birds. cornell.edu/bna/species/195.)

When I lived in South Dakota, I figured the Horned Lark was perhaps our most common bird species.  It breeds commonly in the prairies, is an abundant migrant, and even survives the Dakota winters.  But much of northeast Minnesota's forests are inhospitable to larks. The honor of Most Common Bird Species in Minnesota, and in the United States as a whole, may go to the Red-winged Blackbird.  All the blackbirds need is a marshy wet area or weedy field (both of which can be scarce in western South Dakota).  Highway construction with roadside "borrow" pits has probably benefited Red-winged Blackbirds.

Friday, August 6, 2010

Urban Green Herons

In my 50-years of birding, I do not believe I ever observed Green Herons on a city sidewalk or, for that matter, perched in a conifer. But that is exactly what we found as we toured Minneapolis with out-of-town family on Friday morning.  These recently fledged herons were in the Walker Sculpture Garden.  (Unfortunately I did not pack my camera and resorted to taking these photos with my cell phone.)
Adequate habitat and food sources did not seem to be at hand, except, perhaps, in Loring Park on the far side of busy Hennipen Avenue.  Perhaps the herons were feeding on dragonflies in the grass.  The dragonflies appear to be Common Green Darners, found across most of Minnesota.  These darners are interesting because they one of the few dragonflies that are migratory. Many (but not all) populations migrate from Canada and the northern states to southern parts of the United States. We did not observe the herons feeding, and although the species primarily eats fish, the literature does mention their occasionally consuming insects.

Thursday, August 5, 2010

Tiger Swallowtail

Today this Tiger Swallowtail landed on a Long-leaf Speedwell in Erika's Garden.  Long-leaf Speedwell is a common garden plant, and is attractive to butterflies, bees, and birds.  The plant is resistant to deer browsing. I do not know if this speedwell is native to North America, as I have read conflicting accounts on the internet.  The butterfly is native, and was drawn by John White who was commander of Sir Walter Raleigh's third expedition to North America in 1587 (University of Florida, 2007).

Monday, August 2, 2010

Butterflies

I continue to chase butterflies, finding both their photographic capture and subsequent identification to be difficult.  The critter in the upper photograph is a Common Sulphur.  The clue here is the small black dots on the back side of the upper wing. This butterfly is common across most of the United States.  The flower is Purpletop Vervain, Verbena bonariensis.  The plant is native to South America and has been introduced worldwide.  It is a common garden plant and has escaped into the wild, especially in the southern United States.  Butterflies love them.
Among the Common Sulphurs, I noticed a few much more orange individuals.  These are probably Orange Sulphurs.  Historically Orange Sulphurs have moved north, hybridizing with Common Sulphers along the way. The hybrids do not survive as well as either parental stock (Alexander Klots. 1951. A Field Guide to the Butterflies.)

I am less confident about the identification of this third butterfly.  I am fairly certain it is one of a group of six or so species called Angle Wings.  The species are difficult to tell apart, but I concluded, due to its relatively dark hind wings, that the lower photo is of a Comma Butterfly.  Commas are also widespread and common.  Commas feed on nettles and elms, both of which grow nearby.

I welcome any input from those of you who know more about butterflies than do I!

Rock Pigeon and Psittacosis

Last week a Rock Pigeon (used to be named Rock Dove) spent two days in the garden. This species was introduced to North America by the first European settlers in the early 17th century.  Wild Rock Pigeons roost and nest on rocky cliffs, but have found human buildings an adequate substitute.

Our garden bird was banded with an orange band on the right leg.  Federal banders do not usually ring pigeons.  This band is not a Federal issue, rather one used by a private individual. Information on reporting pigeon bands can be found at http://www.pigeon.org/lostbirdinfo.htm.

Although our visitor did not appear to be able to fly,  I did not get the band number.  I will not handle pigeons.  I worry about psittacosis, a disease caused by a bacterium, Chlamydophila psittaci.  The infection is transmitted to humans from parrots, turkeys and pigeons.  Psittacosis is usually contracted by inhaling dust from dried droppings from cages or from handling infected birds.  This disease is rare, only 100-200 cases are reported annually in the United States.

Human symptoms range from none to death (older folks), but usually are flu-like and not fatal.  Complications include brain disfunction, pneumonia, heart valve infection, and hepatitis.  People with compromised immune systems should not handle imported parakeets or other birds that may carry psittacosis. Birds may die from the disease, but can carry the bacterium and show no symptoms.  Bird symptoms include a ruffled appearance, eye or nose discharge and diarrhea.  Our pigeon looked fine, but did leave messy droppings in the garden.  I do not know the pigeon's fate, but suspect raccoons or neighborhood cats.

A medical doctor can administer tests to see if you have the disease, which usually shows symptoms in five days to two weeks.  Antibiotics usually cure psittacosis.  Previous infection does not give you immunity.

My sources for this information are the New York Department of Health website  (http://www.health.state.ny.us/diseases/communicable/psittacosis/fact_sheet.htm) and from A.D.A.M. (https://health.google.com/health/ref/Psittacosis).