Prairies are home to a diversity of grassland birds. Many species of grassland birds have been declining throughout the continent since the first prairies were plowed up. This decline has continued in recent decades as agriculture has intensified. The loss of native prairies is a major contributor to this decline. Some of the grassland bird species that use Neal Smith National Wildlife Refuge include Northern Harrier, Short-eared Owl, Upland Sandpiper, Sedge Wren, Henslow’s and Grasshopper Sparrow, Common Yellowthroat, Dickcissel, Eastern and Western Meadowlark, and Bobolink. During spring and fall migration the Refuge hosts Clay-colored, LeConte’s, and Savanna Sparrows and Smith’s and Lapland Longspurs. During the winter American Tree Sparrows are abundant. Grassland birds require large areas of grasslands such as tallgrass prairie and sedge meadow. Treeless areas are preferred by grassland birds because trees provide habitat for predators such as hawks, skunks, raccoons, foxes, and coyotes. Brown-headed cowbirds are also more common along the edges between trees and grasslands. Cowbirds are nest parasites, laying eggs in other birds’ nests to raise as their own. Many studies have shown that grassland birds are able to produce more of their own offspring in larger blocks of grasslands at greater distances from trees.
Depending on the species, grassland birds eat insects, seeds, or rodents, all of which are plentiful in a thriving prairie. Grassland birds are adapted to nesting on or close to the ground. Individual habitat requirements vary, with some species preferring grazed areas of shorter grass, some preferring dense vegetation that has not been burned, some preferring scattered shrubs or thickets, and others requiring large areas of grassland without trees.
Viewing grassland birds:
Northern Harriers are usually present fall through spring, with an occasional bird seen during the summer. They are easily seen as they soar low over the prairie hunting for rodents. Their wings generally form a “V” as they soar, and they spend much of their time soaring rather than flapping. Their distinctive white rump is another notable field mark. They may be seen almost anywhere on the Refuge, especially where there are the fewest trees.
The best time to see Short-eared Owls is between October and April, generally around dusk and dawn. They are sometimes active during the day. Look for their irregular moth-like wing-beats as they fly low over the prairie. If you’re lucky you may see one perched on the road or on a signpost. The “ears” are not usually visible, but the disk-like face and tawny coloration are distinctive. There are usually only up to a handful present on the Refuge at any time, and numbers fluctuate as they migrate through in spring and fall. Their abundance in winter may be related to the snow depth, since deep snow makes hunting for rodents more challenging. Some of the best places to observe Short-eared Owls have been along the auto tour route including the bison enclosure.
The Sedge Wren is a tallgrass prairie species easily found on the Refuge. These tiny brown birds can be found in dense, tall grass, often in low, wet areas. Their staccato bouncing-ball song accelerates at the end and can easily be heard across the prairie. They may be more difficult to see than other birds, but with patience can be seen perched above most of the tall grasses. They are curious so may come to investigate if you stand quietly.
Henslow’s Sparrow is one of the most sought-after species by birders visiting the Refuge. Each year there are usually several dozen Henslow’s Sparrows on the Refuge during the breeding season. They generally arrive in mid-April and remain until at least September. They are most easily seen when they are singing, generally mid-April through July. Henslow’s Sparrows prefer areas that have not been burned for at least a year, so look for them where there is standing dead grass from last year’s growth. Listen for their short, high-pitched songs (often described as a hiccup-like tsee-lik). The males often perch high on a plant with a stiff stem as they sing, so scan the tops of plants in the direction you hear the sound. As with most grassland birds, they are most easily heard early in the morning when they are most vocal and conditions are usually less windy.
Grasshopper Sparrows are most often found in the bison and elk enclosure, where the vegetation is kept shorter by grazing. Although you must remain in your vehicle, Grasshopper Sparrows are often quite close to the road so can be seen without getting out. Be sure to pull over to the side to prevent collisions. Grasshopper Sparrows have a soft, long-drawn buzzy trill for a song. Look for them perched up above the shorter vegetation as they sing.
Bobolinks can be a challenge to find as their distribution seems to be patchy across the Refuge. Listen for their bubbly song that is reminiscent of R2D2 from Star Wars. Bobolinks often sing in flight, so look in the air when you hear them sing. The males are black with white on their backs and yellowish on the back of the head. Females are drab brown and much more difficult to spot. Bobolinks are often found in the bison enclosure or in other areas of the Refuge with mid-height vegetation. Bobolinks arrive in late April or early May and complete their nesting earlier than other birds, often by late June, when they begin travelling in flocks. Oak savanna birds
Although many species of birds require trees, some species are most associated with oak savannas. Some of these will also use the edges of dense woodlands or strips of trees, but historically these conditions were found primarily in oak savannas. Bird species that are often associated with savannas include American Kestrel, Barn Owl, Wild Turkey, Red-headed Woodpecker, Northern Flicker, Loggerhead Shrike, Blue Jay, Gray Catbird, Great Crested Flycatcher, Eastern Bluebird, Eastern Towhee, Indigo Bunting, and Orchard Oriole. Sadly, the bird that was once the most abundant oak savanna species is now gone forever: the Passenger Pigeon.
Several species associated with savannas nest in cavities. Red-headed Woodpeckers and Northern Flickers excavate cavities in trees that may later be used by other species like Black-capped Chickadees, White-breasted Nuthatches, Tufted Titmice, Great Crested Flycatchers, and Eastern Bluebirds. Blue Jays may be seen carrying acorns in the fall. Wild Turkeys also take advantage of acorns. Eastern Bluebirds nest in cavities (such as bird boxes) and forage in grassy areas—similar to conditions that were historically associated with oak savannas.
During spring and fall migration, many species of warblers, vireos, and other songbirds use the oak savannas as stopover sites. They feed on insects found on the leaves of oaks and other trees. May is an excellent time to walk the Savanna Trail to look for migrating songbirds, as well as the resident birds.
Another group of birds uses shrubs for feeding and nesting. These include Bell’s Vireo, Gray Catbird, Brown Thrasher, Yellow-breasted Chat, and Orchard Oriole. Others such as Loggerhead Shrike, Willow Flycatcher, Eastern Kingbird, Vesper Sparrow, Field Sparrow, Lark Sparrow, and American Goldfinch use scattered shrubs surrounded by grasslands. Some of these have specific habitat requirements such as sparse vegetation for Vesper and Lark Sparrows. Bell’s Vireo and Yellow-breasted Chats can be found (more often heard than seen) from May through August along the Tallgrass Trail in the trees and shrubs inside the loop at the east end of the trail.
Insects and other invertebrates are vital to the life of the prairie, oak savanna, and sedge meadow ecosystems. They are the largest group of grazers in the prairie, transforming plant matter into protein (in the form of their bodies) that can be eaten by a large number of vertebrate species. However, their value goes far beyond their use as food for other species. Insects such as bees and moths pollinate many prairie flowers. Insects, worms, and other creatures decompose dead plants and return the nutrients to the soil. Ground-dwelling species like ants aerate the soil. Some insects and spiders prey on and parasitize plant-eating species, keeping their populations from devastating the plants.
After a prescribed fire, visitors to the Refuge may notice mounds of dirt scattered throughout the prairie. These are ant mounds, built by some of the many ant species on the Refuge, such as Formica montana. Ants serve important roles in the prairie, including mixing and aerating soil, feeding on other invertebrates, and aiding in the decomposition process. They have symbiotic relationships with some species of plants such as sunflowers. The plants produce nectar outside of their flowers that the ants feed on. In exchange, ants will attack plant-eating insects that approach them on the plant, protecting the plant. Ants build mounds to collect the sun’s heat and regulate the temperature inside the nest chamber. Ant mounds are important to a variety of small animals including other invertebrates that live inside ant tunnels. Here is a link to a very informative web site about ants in prairies:
Bison and Elk
Bison also create wallows, or depressions devoid of vegetation, by rolling on the ground to deter biting insects, rub off hair when they are shedding, and cool off when it is hot. Bulls also wallow to leave their scent and display their strength. Large wallows collect water during rainfall, which creates habitat for species such as amphibians and aquatic insects. Some species of plants and invertebrates are found associated with the soil disturbance found around wallows. Another way bison shape the prairie is through the transport of seed. Nomadic bison could move great distances, carrying seed with them both internally in their stomach contents, and externally on their hair. This helped plants disperse throughout the prairie ecosystem.
Bison are weighed and their body condition is scored. As they are scanned, the computer displays where each bison is to go: back out onto the prairie or into the chute for disease testing or removal from the herd. Typically if any bison are to be removed they are yearlings and two-year-olds.
White-tailed deer were actually hunted to the point of being entirely eliminated from Iowa. They were re-introduced by the Iowa DNR in the 1950s. They are now an abundant species. Deer are commonly seen on the Refuge, and may be hunted during the hunting season.
In the oak savanna, keep an eye out for fox squirrels. They play an important role in the life cycle of the oak tree—they plant acorns! Fox squirrels gather acorns in the fall and cache them, poking them into the ground. Throughout the winter they return to eat the acorns they cached. Fortunately for the oaks, the squirrels don’t recover all of the acorns, so some of them grow into trees.
The Indiana bat is an endangered species found in the oak savanna and along Walnut Creek. Indiana bats roost under the bark of dead trees or under the shingles of shagbark hickory. At night they forage for insects around the creek. During the winter they roost together in caves, probably far from the Refuge. They have been found on the Refuge during the summer months. Several other species of bats are also present on the Refuge. Many species of mammals create burrows on the Refuge. One of the most common is the thirteen-lined ground-squirrel. They can be seen around the visitor center and along the gravel roads. Pocket gophers, wood chucks, badgers, foxes, and coyotes also dig burrows but because of their habits are rarely seen.