May
by Master Naturalist Pam Johnson.
The Eastern Phoebe is a bird I frequently see building nests in May. It seems perfectly content to be in and around our house. As one of the first birds to return to the north from southern US and Mexico, it often arrives as early as March. For many years, a pair built a nest of green moss and mud on the logs of our home. They typically lay their eggs in April when the Serviceberry blooms, beating the House Wrens, which arrive later. Phoebes are easy to recognize by their call that repeats their name: fee-bee, fee bay, fee bee, fee bay. They perch on a favorite post as they survey their environment for insects. As they perch, they wag their tails. Often they return to the same location year after year.
By May the eggs hatch and they need a constant supply of caterpillars to feed their young. The fledglings leave the nest around June and the pair often raises a second brood. By October the Phoebes depart again, and I look forward to their return each spring.
The Phoebe habitat is close to woodlands. Look for their nest at Wapello under the gazebo, where Barn Swallows also nest. Watch for their tail-wagging behavior and their habit of catching insects on the wing.
May is warbler time. Some species that wintered in the south are heading back to breeding territories in North America and Canada, while others stay in our region until fall to raise their young.
Bird migration is fueled by insects, rich in fats and proteins. Ecological benefits of migrating north during the spring to breed –and then back south to the tropics for the fall and winter– must outweigh the costs; otherwise, birds would not have evolved this behavior. As Douglas Tallamy notes, migrating north historically offered birds an “inexhaustible supply of insect caterpillars” for raising their young. (The Nature of Oaks, Tallamy, p. 73)
But what happens when we replace native plants with non-native plants? Tallamy’s research shows that insects decline dramatically in non-native plantings –caterpillars alone by 91%. If I were a bird, I would leave the neighborhood!
Do we need to replace every non-native plant? Not necessarily. Another study suggests that if at least 70% of the plants are native species, we can still support breeding birds. (The Nature of Oaks, Tallamy, p. 76) During May migration, where do we see the most warblers? In oaks because oaks support more insect species than any other local native trees.
The breeding season for migrants lasts from mid-April through August. Many bluebirds nest in human-made boxes, though they naturally choose tree cavities or old woodpecker holes. The female builds a nest of grasses in four or five days, lays four or five pale blue or white eggs and incubates them alone for 13-15 days. They typically raise two broods per year.
Fall migration, when birds head back to their winter homes, begins in late September. Some bluebirds, but not all, winter as far south as eastern Mexico. Eastern bluebirds eat insects in summer and fruits in winter.
You can see bluebird boxes at JDCF’s Wapello and Casper Bluff preserves. JDCF and The Natural Area Guardians before them, have managed one of the most continuously successful bluebird recovery programs in the Midwest. Volunteers monitor bluebird boxes– counting eggs and fledglings, cleaning the boxes in fall and checking for black flies that can kill the young birds. The National Bluebird Society has been instrumental in recording this recovery effort. Landowners can install bluebird houses on their property. For information on this rewarding activity, contact JDCF at info@jdcf.org.
One of the unusual birds of the prairies is the Grasshopper Sparrow. You won’t see him at your backyard bird-feeder. He nests on the ground and relies on insects for food. Grasshopper Sparrows live in grasslands, prairies, hayfields, and open pastures with little scrub cover and patches of bare ground. True to their name, they eat grasshoppers in summer, along with beetles, caterpillars, bugs, and spiders. Watch for their ground nest, often tucked at the base of a clump of grass within tall grasses or sedges. The nest is usually domed with overhanging vegetation and has a side entrance. It is lined with fine grasses and sometimes hair. A completed nest is about 5 inches wide and 3 inches tall.
Grasshopper Sparrows are small, compact birds with a flat-crowned head, a conspicuous bill, a very short tail, and a yellow spot between the eye and bill (the lore). Grasshopper Sparrow Identification, All About Birds, Cornell Lab of Ornithology
May Phenology to look for on JDCF preserves:
Birds:
Yellow Warbler
Redstart
Prothonotary Warbler
Ovenbird
Kentucky Warbler
Common Yellowthroat
Yellow-breasted Chat
Warbling Vireo
Yellow-throated Vireo
Scarlet Tanager
Rose-breasted Grosbeak
Indigo Bunting
Bobolink
Ruby-throated Hummingbird
Eastern Kingbird
Great Crested Flycatcher
Plants:
Indian Paintbrush
May Apple
Beardtongue
Wild Geranium
Wild Strawberry
Sweet Cicely
Golden Ragwort
Creamy Wild Indigo
Spiderwort
Blue Phlox
Caterpillars: Caterpillars are just “walking leaves” because of how many leaves they eat, according to Doug Tallamy. There are far too many species to list, but start watching for them –and use iNaturalist to identify what you find. You may have competition in finding them, because birds are capturing them to feed their nestlings. Their favorites are the smooth-skinned tasty inchworms. Think twice before spraying caterpillars in your yard; your birds may have to go elsewhere to raise their young!
Butterflies: The caterpillars of these butterflies are mostly found around their host plants which are listed in parenthesis. Females lay eggs on host plants whose leaves support the larvae stage. These are the most common adults seen in May.
Tiger Swallowtail (Wild Black Cherry, various ash, various willows, Wafer Ash, Cottonwood, Basswood)
Black Swallowtail (parsley family, Queen Anne’s Lace, Golden Alexander)
Giant Swallowtail (Prickly Ash, Wafer Ash)
Red Admiral (nettle family)
Pearl Crescent (asters)
Meadow Fritillary (native violets)
Eastern-tailed Blue (clovers, vetches, legumes)
Reference reading:
The Nature of Oaks by Douglas W. Tallamy.
Tallamy explores the ecological importance of oaks, which support a vast web of wildlife above and below ground. He takes readers month by month through the relationships among birds, insects, and oak trees.
Architecture by Birds and Insects by Peggy Macnamara, artist in residence, Chicago Field Museum
App Recommendations:
NestWatch by Cornell
eBird by Cornell
Merlin by Cornell
iNaturalist by National Geographic
Indian Paintbrush
Beardtongue
May Apple
