Tennessee Warbler

                                                    Tennessee Warbler Male  [Internet Photo]

The Tennessee Warbler, Leiothlypis peregrina, is a common summer resident and migrant in New Brunswick.  It is an indicator species for spruce budworm since it feeds heavily on forest insects.  In past years during our budworm outbreaks it was very common here.  Although not in such high numbers it is still found here during its breeding season and those that breed north of here pass through during migration.

The Tennessee Warbler is rather inconspicuous compared to some of our other common warbler species in breeding plumage.  It shows no brilliant oranges, blacks or reds.  It is, however, a very beautiful, sleek warbler.  It is small (12 cm), sharp-billed, short-tailed, and has a long wing primary projection.  Of special note for identification is its lack of streaking on the breast and flanks, the prominent supercilium and white undertail coverts.  Occasionally the undertail coverts can be tinged with yellow but they are still whiter than the breast.

The male in breeding plumage is shown above.  It has bright yellow-green upperparts with a greyish crown and nape.  Note the white supercilium and black eye stripe.  The underparts are white including the undertail coverts. 

The breeding female plumage shows a more yellowish wash over most of the bird.  This makes her appear duller and the crown and nape are not as contrasting.  The yellow shows on the breast and flanks but the undertail coverts are still white.  The supercilium is often yellow and the black eyeline is still prominent.

Warblers can often be difficult to distinguish from one another.  Tennessee warblers can be confused with some vireos, especially Philadelphia and Warbling vireos.  These can be differentiated by their thicker bills which have a hook on the end.  Fall individuals can be confused with Orange-crowned warblers.  Tennessee warblers usually migrate earlier from our area so the date can help in identification.  The best way to tell one from the other is to check the head pattern, the underparts and the shape.  

The fall Tennessee warbler shows a long whitish or yellowish supercilium with a dusky eyeline.  The Orange-crowned shows a short indistinct yellowish supercilium and a narrow whitish or yellowish split eyering.  Regarding the underparts, the Tennessee warbler is dull whitish or yellowish and unstreaked with white undertail coverts.  The Orange-crowned has dull yellowish underparts and sometimes shows faint olive streaks.  It shows bright yellow undertail coverts which are always brighter than the rest of the underparts.  The Tennessee has a shorter tail and a longer primary projection.  Some confusion may arise in distinguishing the juvenile Tennessee warbler from the juvenile Nashville warbler.  The Nashville has yellow undertail coverts, a gray head and no wing bars which should make differentiation easy (the juvenile Tennessee warbler shows faint wing bars).

                                    Tennessee Warbler Male  [Jim Carroll Photo]

In the photo above note the grayish wash on the white breast of this male, the relatively short tail and the narrow sharp bill.

The breeding range of the Tennessee warbler is most of Canada except British Columbia west of the Rocky Mountains, and the extreme north.  It does, however, include some of Yukon, Northwest Territories, Nunavut and northern Quebec and Labrador.  This is truly a Canadian species!  The Tennessee warbler winters from southern Mexico to Venezuela.  Most migrate south over the eastern US and the Gulf of Mexico.  

The preferred habitat of this species on the breeding territory is mixed and boreal forests and bogs.  On the wintering grounds it prefers coffee plantations (a big reminder to buy bird-friendly coffee).  The Tennessee warbler loves our boreal forest.  It contributes greatly to the control of forest insect damage.  One study estimated that some areas during a spruce budworm outbreak could have up to 610 breeding pairs per square kilometre.

This species nests on the ground usually in grassy tussocks, under bushes or in a mossy hillock.  The nest is made of fine grasses and in it are laid 4 to 7 creamy white eggs spotted and blotched with brown.  The female incubates the eggs for 11 to 12 days.  Tennessee warblers eat all forms of insects and arachnids but also sumac seeds and poison ivy berries.  In the past this species was frowned upon for the destruction that it allegedly did to vineyards.  Further study showed that the birds were actually piercing the grapes and drinking the juice.  They were getting a drink, not intentionally destroying the grapes.

So why is this beautiful warbler species named the Tennessee warbler (unless that is another one designated to be changed)?  The naming goes back to 1832 when Alexander Wilson discovered the species on the banks of the Cumberland River in Tennessee and named it thus.  But, it is inappropriate for a bird to be named after a state when its main breeding range is in Canada!  Wilson obtained only two specimens and thus concluded it was a rare warbler.  Hence he gave it the specific name peregrina which comes from the Latin word, peregrinus, meaning 'wanderer'.  Another appropriate name for the Tennessee warbler might be 'Coffee Warbler' since it spends its winters in coffee plantations.  I vote for 'Canadian Boreal Warbler'.  Another interesting fact is that the breeding range for this species was not known until 1901 when they were discovered breeding in Canada.  Where were our enthusiastic birders then?

                                        Tennessee Warbler Male  [Jim Carroll Photo]

Warblers are often identified by their voices.  The Tennessee warbler's song is usually in three parts sometimes two parts.  The song is rapid, loud and described as unmusical.  It has been described in many ways but one is:  tit it it it it it pita pita pita pita pita chit chit chit CHIT.  It can be confused with the song of the Chipping Sparrow.  In my experience I found that when you hear the 3 parts to the song you have learned it and will recognize it in the future.  

The Tennessee Warbler is a plain, little warbler but when you learn how important it is to the ecosystems of New Brunswick and Canada, it moves well up on the list of our favourite birds.  We will be looking forward to seeing it when late April and May arrive.  Check our mixed forests, our boreal forests and our bogs for this little gem.