In North America, it's easy to enjoy sparrows. You can find them in almost any habitat. They can occur in large (although decreasing) numbers, sing beautifully (for the most part), and reliably cheer up backyard feeders.

What's not so easy is identification. For starters, there are more “sparrows” than names might suggest. Juncos and towhees, for example, are sparrows, too. Add them up and you get 48 sparrow species in the United States and Canada. And when you include subspecies and groups — which aren't insubstantial — the list is even longer.

This diversity may be impressive, but it's not ostentatious. Differences can be subtle (white vs. gray chins) and recognizing specific species can be difficult, especially for beginners. The workaround for many is to simply call these birds as they see them: “little brown jobs.”

The truth, of course, is much more complicated and interesting. Each sparrow species has a unique story to tell, based on distinctive features, behaviors, survival strategies, songs, and much more.

Profiling all, or even a majority, of North America's sparrows in a single blog isn't feasible. Instead, we've picked seven of the most fascinating sparrows, in no particular order, to illustrate how minor differences in small birds can be a big deal.

7) Song Sparrow

The Song Sparrow lives up to its name, its sweet voice ringing out in gardens and countryside continent-wide from late winter into summer. Young males develop unique song patterns, which they learn by listening to adult males. Songs become more complex as the young bird matures, then attempts to establish a breeding territory the following spring.

The Song Sparrow is a very widespread and varied bird species, boasting an incredible 24 to 38 subspecies. Song Sparrows of the Southwest, for example, are pale, while those in Alaska's Aleutian Islands are darker and larger — nearly a third longer than eastern subspecies.

With so many subspecies, it's not surprising that Song Sparrows are common throughout North America. However, their numbers have declined by more than 30 percent over the last 50 years. Song Sparrows face the typical gamut of human-caused threats as they move within their territories or from place to place, including collisions (particularly with glass), outdoor cats, and pesticides. Also, Song Sparrow nests are one of the most frequently parasitized birds by the Brown-headed Cowbird.

6) Saltmarsh Sparrow

Saltmarsh Sparrow. Photo by When Photographed/Shutterstock

The Saltmarsh Sparrow's life is intimately connected to the sea. These marsh-dwelling birds, which nest near high tide lines, synchronize their breeding with the moon to provide chicks with sufficient growing time between lunar high tides.

Unlike other birds, male Saltmarsh Sparrows don't defend a nesting territory; instead, they occupy large, often overlapping home ranges and mate with any females that enter. Females also rove around and mate with many different males. The male's only investment to his offspring is his genetic material. Females raise their young alone, and most broods have mixed parentage.

Climate change and associated sea-level rise are major concerns for this bird. Habitat loss has also taken a toll; the species now exists only in small, fragmented populations. As a result, the Saltmarsh Sparrow was listed on the 2016 State of North America's Birds Watch List, and the U.S. Fish and Wildlife Service is reviewing whether the species should be listed under the Endangered Species Act.

5) Black-throated Sparrow

The handsome Black-throated Sparrow, also known as the “desert sparrow,” is most often found on dry desert hillsides and salt flats of the American Southwest, while some birds also migrate to or live year-round in Mexico. Its sweet song, a mix of tinkling notes and musical trills, is a characteristic sound of the region.

Like other desert species such as the Greater Roadrunner and Cactus Wren, this bird can survive long periods without water, getting the moisture it needs from its food. Extra-efficient kidneys also help these birds retain water.

Although still relatively common in some areas, Black-throated Sparrow populations have declined by 54 percent over the last 50 years due to habitat loss and degradation. In and near settled areas, the Black-throated Sparrow's ground-nesting habits make it vulnerable to cat predation. Pesticide use and hotter, more frequent brush fires ― caused by a combination of climate change and current fire management practices ― have reduced habitat throughout the bird's range.

4) Vesper Sparrow

The Vesper Sparrow's melodic song, a combination of clear whistles and trills, can often be heard at twilight — roughly the same time as vespers, thus earning the bird its name. This unique sparrow is the only member of the genus Poecestes — which translates as “grass dweller.” True to their name, these birds prefer grasslands and fields across much of the north-central United States and Canada. During winter, most of these sparrows migrate to the southern and central United States, as well as Mexico.

Although Vesper Sparrows are fairly adaptable — they can nest on reclaimed mine sites and recently burned areas — their populations have declined by 37 percent during the last 50 years. This is primarily due to habitat loss on both breeding and wintering grounds. In addition, modern farming practices, including pesticide use, hedgerow clearing, and early hay harvesting, have been detrimental. The Oregon Vesper Sparrow, one of four subspecies, is in particular trouble.

3) Grasshopper Sparrow

More often heard than seen, the secretive Grasshopper Sparrow gets its name for the buzzing, insect-like quality of its songs. This is one of the few sparrow species in which the male sings two different songs: one to attract a mate and another to defend a breeding territory.

This species forages mainly on the ground, keeping a low profile as it moves through grasses. True to its name, the Grasshopper Sparrow feeds on grasshoppers during the breeding season, along with other insects, spiders, earthworms, and snails.

Over the last 50 years, Grassland Sparrow populations have undergone a dramatic decline, tumbling by nearly 70 percent. Habitat loss and degradation are the greatest threats. Increased use of pesticides, brood parasitism by Brown-headed Cowbirds, and loss of wintering habitat have also contributed to their decline.

Twelve subspecies of Grasshopper Sparrow are recognized. Fewer than 200 birds remain in the federally Endangered Florida subspecies, all in the dry prairie ecosystems of that state.

2) Dark-eyed Junco

Nesting in open forests across much of North America, the Dark-eyed Junco is one of the continent's most familiar birds. Many of these dark sparrows migrate over long distances within the continent, and people commonly think of them as “snowbirds,” as they seem to arrive in backyards just as winter settles in. When spring comes, they move northward in most areas.

While all Dark-eyed Juncos have some features in common — white outer tail feathers, darker upperparts, and pale bills — they can vary drastically in appearance depending upon location. As a result, they were classified as five separate species until the 1970s. These species are now recognized as six subgroups: Slate-colored; White-winged; Oregon; Pink-sided; Gray-headed; and Red-backed.

Although the Dark-eyed Junco is still considered common, Partners in Flight data show that populations declined by over 40 percent in the last several decades. Like many other bird species, this species is vulnerable to habitat loss and is a frequent victim of window collisions.

1) White-throated Sparrow

The White-throated Sparrow breeds mostly across Canada, but it's a familiar winter bird in most of eastern and southern North America. During colder months, the bird's sweet whistled song, described as “Poor Sam Peabody Peabody Peabody” or “Oh Sweet Canada Canada Canada,” can be heard throughout the day.

White-throated Sparrows have two adult plumage variations: tan- and white-striped. The variations, which can be seen on the bird's eyebrows and central crown, occur in approximately equal number. Interestingly, opposite color morphs almost always breed with each other. Stranger still, White-throated Sparrows sometimes mate with Dark-eyed Juncos, even though they look different and aren't very closely related.

Although White-throated Sparrows remain common, their U.S. population has declined by 63 percent over the last 50 years. Frequenting suburbs and urban parks in winter, they are also frequent victims of window collisions and attacks by cats.