One of my all-time favorite field-guide lines came from the old classic Golden Guide by Chandler Robbins et al. In reference to Pine Warbler, he writes, “female and immature are hard to recognize when not in pines.” What a brilliant line! It alludes to several important facts. First, that we often use habitat as a key field mark for identifying some species. Second, that female and immature Pine Warblers can look a bit drab. And third, that Pine Warblers really like pine trees.
Pine Warbler is a very common bird in southern New Jersey. In spring, all you need to do to find one is go to a stand of White Pines and listen for a minute or two. Early on in the breeding cycle they sing like crazy, and their lazy musical trill is one of those heartwarming signs of spring. But before they get to their pine forest breeding sites, migrant Pine Warblers do show up in a wide variety of places. Though they are amazingly good at finding the only pine tree in the neighborhood, they will also use other habitats, sometimes even when pines are present. They regularly visit suet feeders in cold weather and, in winter, often join flocks of bluebirds, traveling wherever the bluebirds go–including open fields, telephone wires, and fences.
As Chan Robbins taught us, it is always helpful to consider habitat as a clue to bird identification. Likewise, it is just as important to consider the calendar. Pine Warbler is one of our earliest songbird migrants. Some are already on territory by the beginning of March, and by late March and early April local pine forests are full of them. Away from breeding sites, most migrants are found between about mid-March and late April. This is earlier than one would normally expect most of Pine Warbler’s look-alike cousins to show up.
In the photo captions below, we’ll take a look at plumage variation in Pine Warbler and also examine a number of species that can be mistaken for Pine Warbler. We’ll pay specific attention not only to what they look like, but also to when they are likely to be seen.
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Figure 1 – Adult Male Pine Warbler, April, New York.For a warbler, Pine is a rather bulky bird with a heavy bill, chunky body, longish tail, and relatively sluggish movements–all characters recalling a number of non-warbler species. Adult males are quite snazzy–bright yellow below and bright green above, with bold white wing bars. Such birds may be easily identified without scrutinizing details, but to learn the dull ones, it helps to study the bright ones more closely. Notice in particular the precise pattern of the face and breast–weak “spectacles” (broken eye-ring and pale supraloral line) and dark cheeks merging into blurry streaks at the breast-sides. Notice also how the cheek and breast makings outline a very rounded (in this case, yellow) throat patch. Although not obvious at this angle, Pine Warblers have a rather distinct notch at the end of their longish tail. Photo by Cal Vornburger. |
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Figure 2 – Immature female Pine Warbler, January.This plumage represents the other end of the spectrum for Pine Warblers. The dullest ones have no yellow or green at all and the wing bars are much duller. But focus on the similarities–same structure, same face and breast patterns as brighter birds. The broken eye-ring can be particularly obvious on duller birds but the “spectacled” look is often still there. The dark cheeks merge into blurry dark smudges on the breast-sides, outlining a rounded (in this case, dull buffy) throat patch. Photo by Giff Beaton. |
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Figure 3 – Female Blackpoll Warbler, May, Illinois.Dull Pine Warblers are sometimes thought to be female Blackpolls. In fall, Blackpolls look quite yellowish below and greenish above but spring females are much grayer. Notice the Blackpoll’s shorter tail, longer wings, and smaller bill, as well as its thinner wing-bars, streaked breast and upperparts, and prominent dark lateral throat stripes. Blackpolls are among the later migrants, with males first arriving at the very end of April and females seldom showing up before the second week of May. Spring migrants are most often seen in flowering trees, especially oaks early in May and Black Cherries later in the month. Photo by Rob Curtis/VIREO. |
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Figure 4 –Yellow-throated Vireo, October.A bright male Pine Warbler may sometimes be mistaken for a Yellow-throated Vireo but notice the vireo’s even heavier bill (a tiny hook at the tip is visible at close range), larger head, shorter tail, thicker spectacles, and blue-gray legs. The yellow on the vireo’s underparts is very bright but a bit less extensive than on a Pine Warbler, extending about half way down where it sharply cuts off to the white belly. It is also worth noticing that Yellow-throated Vireos are very methodical feeders. They tend to stay on one perch and look around for a few long moments before hopping to the nest branch. Pine Warblers, though more sluggish than mot warblers, are usually more active than that. Yellow-throated Vireos typically arrive in southern New Jersey during the last week of April, where a few remain to nest in open oak forest. Photo by Giff Beaton. |
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Figure 5 –Female Orchard Oriole, April, Texas.Orchard Orioles are surprisingly small and females are very often mistaken for warblers. Compared to Pine Warbler, notice the sharply pointed, slightly decurved bill, plain face-pattern, usually a fully yellow-washed underparts (Pine Warbler has a white belly and undertail coverts), and longer, yellow-washed tail. Orchard Orioles typically arrive in south Jersey during mid or late April though they are usually not common until the first week of May. They occur in a wide variety of open and edge habitats. Photo by Brian Small/VIREO. |
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