Swainson's Thrush

I wrote about this thrush in my blog of 9 May 2010.  To those comments, let me add the following (inspired by banding several Swainson's Thrushes during this first week of September).

This species was first described by Thomas Nuttall in 1840 from specimens taken in Washington State. Nuttall (1786-1859) was an English botanist and zoologist who explored much the United States and Canada.  Among his many publications was the first inexpensive, popular guide to North American birds.  The English ornithologist William Swainson (1789-1855) published prodigiously and studied birds from around the world.  Nuttall was probably especially recognizing Swainson's work on Canadian forest birds when he commemorated Swainson with this thrush's common name. Note, however, that the scientific name for this bird is Catharus ustulatus.

The common name for Swainson's Thrush used to be Olive-backed Thrush.  The problem is that many western birds have russet backs. Olive-backed and russet-backed birds differ in breeding habitat, vocalizations, and wintering grounds.   Nevertheless, to the best of my knowledge, the splitting of these birds into distinct species has not been proposed.

Lance-tipped and Common Green Darner

The Lance-tipped is able to regulate its body temperature (both by shivering and by retaining heat in its abdomen produced in the thorax by its flying) which enables it to fly in temperatures too cold for most dragonflies.  Thanks to Scott King for help with identifying this critter.

During last month's heat, Erika and I strolled in the Carleton College Arboretum.  As we walked, we kicked up many Common Green Darners.  (I wrote about this dragonfly on 6 August 2010.)  On this 90 degree day, the darners were regulating their body temperatures by resting in the shade of the bushes and under the leaves along the trail.

Magnolia Warbler

As you can see in this photograph, I banded this wind-blown Magnolia Warbler during yesterday's winds. Alexander Wilson discovered this species in 1810 in a Mississippi magnolia tree.  He named it the Black-and-yellow Warbler.  This warbler is a common nesting bird near the ground in spruce and Eastern Hemlock. Populations appear to be stable (Dunn and Hall 2010).  For the first time ever,  I missed seeing a Magnolia Warbler this spring (although I stood along side two companions who saw one that I could not find).  Despite this bird's being in drab fall plumage, the species is relatively easy to identify if you can see the broad, incomplete, white band near the base of its tail.

Northern Parula

Although I have enjoyed listening to this warbler's trill at the Lower Basswood Falls in the Boundary Waters Canoe Area of northern Minnesota, I have always considered this warbler to be a denizen of the southeast.  Actually, it is both.  Indeed, the northern and southeastern ranges may not be contiguous.  I wondered if northern and southern birds might be distinct subspecies.  The American Ornithologists' Union considers the Northern Parula to be monotypic--not dividable into distinct races.  Researchers have noticed, however, that many eastern birds are heavier than western ones and, furthermore, sing distinct songs.  DNA evidence, on the other hand, does not support these two populations as being different.

Increasing air pollution has reduced the numbers of epiphytes (plants that hang on trees) that Northern Parulas use for nesting.  Old Man's Beard, a lichen that hangs from the boughs of many northern conifers, is an example of an epiphyte. This decimation of epiphytes is especially severe in the northeast United States, where Northern Parulas are now very rare, if not extinct.  Elsewhere in North America, deforestation threatens this species.  Most of this information is from Moldenhauer and Regelski (1966).  I banded this bird on 4 September and caught it again on the 7th.

Tennessee Warbler

This weekend I banded my first Tennessee Warblers of the fall.  This species is quite variable in the amount of yellow in the plumage.  The bird above is similar to a Bay-breasted Warbler, but lacks wing bars.  The bird below is less yellow, and shows more typical contrast between its greenish back and grayish head.  The thin, pointed bill of the Tennessee places it in the genus, Vermivora; the thicker billed Bay-breasted is a Dendroica.

Tennessee Warblers were named by Alexander Wilson, who discovered this species in Tennessee in 1811.  Actually this warbler is more typical of boreal Canadian forests.  Like Bay-breasted Warblers, Tennessee Warblers are spruce budworm specialists. Their numbers fluctuate with budworm outbreaks.  Tennessee Warblers are often the most abundant breeding bird in Canadian forests.  Because this warbler is often found in secondary habitats that grow after logging, this warbler is probably more common now than in recent history.  Nevertheless, its breeding biology is poorly known.  The winter ecology is better studied. Because of its predilection for shade coffee plantations in Central America, this bird might be better named the Coffee Warbler (Rimmer and Mcfarland 1998).

Bay-breasted Warbler

Saturday noon my bird nets finally intersected with a mixed species flock of warblers.  The most interesting of these were two Bay-breasted Warblers, one of the most difficult to identify Confusing Fall Warblers.  Even experienced birders can have trouble telling apart Bay-breasted, Blackpoll, and Pine warblers.  Blackpoll warblers will almost always show at least some yellowish on their legs, even if restricted to the underside of their soles.  The other two birds have gray feet.  This warbler definitely sported gray feet and toes.

Pine Warblers, unlike Bay-breasted, usually show brighter "spectacles"--eye rings with a line attched to the bill area.  Pine Warblers also usually show at least faint streaking on their flanks.  Finally, Pine Warblers in comparable plumage are usually not as bright as Bay-breasted Warblers. My photo shows none of these field marks.  Finally, Bay-breasted Warblers often show a hint of chestnut on their flanks, which can almost be seen on my bird.

Bay-breasted Warbler numbers fluctuate with outbreaks of spruce budworms in the north woods.  The spraying of Canadian forests for budworms have hurt Bay-breasted Warbler populations.  Bay-breasted Warbler migrate across eastern North America. They continue to northern South America across the Gulf of Mexico.  Blackpoll Warblers, on the other hand, migrate across the western Atlantic Ocean.  Consequently, Bay-breasted Warblers are less often observed in the southeast United States (Williams 1996).

American Toad

As we strolled through the Carleton College Arboretum, Erika and I came upon this American Toad.  This is the only toad one would expect to encounter in Rice County.  In Minnesota, American toads usually breed in the spring.  According to the Minnesota Department of Natural Resources, "females lay up to 20,000 eggs which normally hatch within one week. Large schools of tiny, black tadpoles feed together along the edge of shallow wetlands, emerging as a mass of tiny toads within approximately six weeks. Maturity occurs in two to three years."

The general consensus on the Internet is that kissing toads will not give you warts (although touching toads may cause skin irritation, especially around the eyes or in the mouth).  Kissing (or more general contact with) princesses (or princes) may, on the other hand, pass wart-causing viruses between people.

Gray Catbird

I wrote about the Gray Catbird's mimicing abilities in my blog of 16 May 2010.  For the past couple of weeks I have been banding very young catbirds.  Indeed, the catbird above in in a dusky mottled juvenile plumage that I have infrequently seen (usually young birds, like adults, are more uniformly gray).  Note also this bird's gray iris--this is another bird with gray eyes as an immature, eyes that change to a rich chestnut as a breeding adult.

One of the surprises of recent DNA research is the discovery that catbirds and other members of the family Mimidae are not related to thrushes or wrens.  Apparently they are so closely related to starlings that some researches place catbirds and starlings in the same family, Sturnidae.

Gray Tree Frog

This Gray Tree Frog is green, but that is OK.  This frog is able to change colors, from gray to green and from nearly black to nearly white. According to the Minnesota Department of Natural Resources, Gray Tree Frogs create their own antifreeze, by converting glycogen into glycerol, which prevents ice formation within this amphibian--a handy adaptation to Minnesota winter!  I brought this critter into the garage on a bag of charcoal.

Black Swallowtail

A dozen Black Swallowtails are newcomers to our Community Supported Agriculture farm.  They are butterflies of open fields and gardens.  Males are territorial, often chasing rivals away from flowers.  This species is found in across the eastern United States and into northern Mexico.  Some internet sources claim they are found in South America and even Australia--there seems to be some confusion here.  Australia is so distant from North America; one wonders how an unaided butterfly might make that leap.  In any case, they are partial to dill, carrots, parsley and fennel.