As summer rolls in breeding passerines are settling down to guard, warm, and feed their nests, eggs, and chicks. It's an opportune time to look for fledglings, but otherwise, the trees can be a ghost town for birders. Which is why you have to learn to love vireos. With up to 14 species to choose from in North America, the fun—and frustation—never ends with this chatty songbird family.

The rub with vireos, though, is that they're a hassle to ID. Their grayish, brownish, yellowish plumage doesn't do you any favors when trying to distinguish them from the equally grungy empid flycatchers. Their eye rings are kinglet-like at first glance. And their prowling habits among the leaves are nearly identical to those of some warblers.

But there are tricks to avoiding these mix-ups. Use the pointers on the photos below to reveal the biggest differences between vireos and their twinning families.

Vireo

Hutton’s Vireo. Photo: Aaron Maizlish/Flickr CC (BY-NC 2.0)

At first glance, vireos might seem like all of the other small, perching birds you know (they were thought to be related to warblers for a while). But the large feet, long legs, broad breast, and beak on this Hutton’s Vireo illustrate that the family is more closely related to shrikes and crows. The best way to know if a bird is a vireo, however, is to gauge how often it sings; the males are like broken records, belting up to 20,000 tunes in a single day.

Warbler

Tennessee Warbler. Photo: FLPA/Alamy

Warblers can be very similar to vireos in posture, shape, size, feeding style, and even name. (Yes, there’s a species called the Warbling Vireo.) Let’s take the Tennessee Warbler, for example. This bird has an olive-green back, tail, and wings and a pale breast, belly, and undertail—a typical palette for vireos. But like other warblers, Tennessees have a thin, pointy bill, while vireos have a thick bill with a small hook at the end.

Flycatcher

Eastern Wood-Pewee. Photo: Nature Photographers Ltd/Alamy

Both flycatchers and vireos are voracious insectivores, but their hunting strategies differ. North American flycatchers tend to sit and wait on an exposed perch, darting out to catch insects in mid-air. Vireos, in contrast, are more active; they search leaves and flowers, moving from branch to branch to find their next meal. Check out the foraging posture of this Eastern Wood-Pewee: It sits upright, while vireos hold themselves more horizontally.

Kinglet

Ruby-crowned Kinglet. Photo: Fyn Kynd/Flickr CC (BY 2.0)

Things get trickier with kinglets; they feed and pose almost identically to vireos. But no bird can rival the stamina of kinglets, which seem to be in constant motion as they search for food. The bigger vireos, meanwhile, move slowly and methodically. Upon closer inspection, the bill on this Ruby-crowned Kinglet is also much smaller and thinner than a vireo’s. Plus, the bird is more round and compact, almost like a butterball.

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Four Other Vireo Clues

1. Spectacles

Unlike most songbirds, many of the vireos have white rings around their eyes. The White-eyed Vireo, however, has yellow ones (baffling, we know).

2. Wing Bars

Species like the Blue-headed or White-eyed Vireo have two obvious stripes across their wings. Others, including the Gray Vireo, have a fainter pair.

3. Mimicry

The White-eyed Vireo is a pro at copying and pasting other birds’ calls into its own. Listen for a medley of woodpeckers, thrushes, and tanagers.

4. Name Tags

There are a few vireos that are aptly labeled. The key field marks of the Black-whiskered, Blue-headed, and Yellow-throated are revealed in their names.