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).

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.)

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.

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.

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!

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.

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.

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).

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).