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.  

Bell's Vireo

 

                                                        Bell's Vireo    [Photo by Mark Morse]

A Bell's Vireo was seen and photographed on October 2, 2023 by Mark Morse, previously found by Karen Miller across from the Anchorage Road on Grand Manan.  This is a significant event because it is the first record of this species for New Brunswick.  The photos above and below in this post were taken by Mark Morse.  Birds of New Brunswick: An Annotated List lists six vireos found in New Brunswick and, of course,  Bell's Vireo is not one of them.  The story of its discovery follows.

Sometime in September Jim Wilson and his birding friends were discussing vireos and commented that we were overdue for a rare vireo.  Specifically they were thinking about Bell's Vireo and Cassin's Vireo.  If Maine and Nova Scotia have had autumn records of these species over the years, why not us?  Well, fate would have its way.

On September 28, 2023, a vireo was seen on Grand Manan by Karen Miller which was not easy to identify.  She thought at first it was a Blue-headed Vireo and thus did not report it since that species is common.  She saw it again over the weekend and then thought that it might be a juvenile White-eyed Vireo.  That was when Mark Morse decided to get some photographs for identification.  We are thankful they were able to get them!  The bird was identified as a Bell's Vireo.

                                                   Bell's Vireo   [Photo by Mark Morse]

So what is a vireo that is supposed to be in the southwestern US doing in New Brunswick?  The range of this species is expanding but we are way off its normal range.  The Bell's Vireo's normal breeding range includes southern California, Colorado, the Dakotas and Indiana southward.  It is not found at all in the eastern third of the US.  It winters along the Pacific coast from northern Mexico south to northern Nicaragua.  Its preferred habitat is thickets in forests and along streams.  It also likes woodland edges and overgrown fields.

                                                   Bell's Vireo   [Photo by Mark Morse]

The Bell's Vireo is a small vireo, 12 cm long, compared to the Blue-headed Vireo which is 13 cm long and the Red-eyed Vireo which is 15 cm.  The plumage varies geographically, the eastern population being yellower and the western population grayer.  Two indistinct wing bars are present, the upper one sometimes very indistinct.  The white spectacles and lores are also sometimes indistinct.  Both of these features are seen in the photos above.  Notice that the eyering is broken.  The bill is thick and slightly flattened.  The bird's upper parts are green to gray and the underparts are white with a wash of pale yellow on the sides.  The Eastern race has more gray-green on the upper parts and distinctly yellow on the underparts.  The bird flicks and bobs its tail frequently.  Both genders are similar.  

                                                   Bell's Vireo   [Photo by Mark Morse]

The photo above gives a clear view of the gray-green on the dorsum.  Notice the gray head.  The Bell's Vireo is a very active species.  It feeds low to the ground in dense underbrush.  It eats insects, spiders and fruit.  Given the indistinct plumage features, this species can be difficult to identify.  Its song, however, is the way it is mostly identified.  The song is distinctive among vireos.  It is described as rapid, complex, harsh, squeaky, sharp.  We, here in NB, have not heard this species but would quickly learn it.  Given that the bird prefers dense thickets and is reluctant to show itself, the song is the best way to identify it.  

Karen has already told us what species we might mistake this one for, Blue-headed Vireo and White-eyed Vireo.  In the west one would have to distinguish it from the Hutton's Vireo and the Gray Vireo. The Bell's Vireo was named by John James Audubon after John Graham Bell (a taxidermist from Tappan, NY) who was with him on a trip up the Missouri River in the 1840s.  The Least Bell's Vireo is an endangered subspecies in southern California and is endangered due to habitat loss and parasitism by the Brown-headed Cowbird.

Bell's Vireos nest in dense shrubbery often along streams.  The nest is well camouflaged and made from grasses, leaves, bark and spider webs.  It is lined with fine grasses, coarse hairs, feathers and wool.  Brown-headed Cowbirds often parasitize the nests of this species throughout most of its range.  Three to five white eggs are laid and incubated for 14 days by both adults. 

                                                   Bell's Vireo   [Photo by Mark Morse]

We are unlikely to see a Bell's Vireo nest here in NB but the appearance of this individual will make us all look more closely at vireos in the future.  It has been a learning experience for all serious birders.  Thanks go to Karen and Mark!