Birding Through the Seasons - April
With the arrival of April showers and the swelling of buds on trees and shrubs comes an increase in spring migration. Lingering winter residents are leaving, moving to their northern breeding territories. Herons, egrets, bitterns, and rails are peaking in migration this month, occupying area marshes. Most hawks also are at their peak migration, seen mostly along mountains such as the Kittatinny, because their northward migration is less tied to summits and ridges than in the fall. Spring hawk migration also is evident along the south shore of Lake Erie, where hundreds of hawks – up to 10 species – may be counted in a day, especially when a storm front approaches from the southwest.
Most waterfowl have moved north by the end of this month, but a few lingering ducks such as Blue-winged Teal and Northern Shoveler may still be present and Wood Ducks, Canada geese and Mallards are now nesting. Shorebird migration is well underway and peaks by the end of the month and into early May. Most of these plovers and sandpipers are winging their way to the boreal forests and taiga of Canada and Alaska where they only have a few weeks to nest before returning on their impossibly long journeys back south. These shore-birds visit shallows of rivers, lakes, and ponds but will also alight on flooded, muddy fields in surprising numbers.
A noticeable increase in bird song is evident as arriving males are establishing territories and seeking mates. Several local residents are now nesting; cardinals, titmice, and song sparrows. Robins also are in song and building their first nests of the breeding season. Early migrants such as swallows, Eastern Phoebe, and Chipping Sparrow arrive this month from the south and quickly will be staking out their territory around rural homes. Yellow Warblers, arriving in the third or fourth week of April, are among the first warblers to return, and add a touch of color to the brown shrubby thickets they inhabit. By the end of April most gulls have moved north and a new wave of birds begin to awaken Pennsylvania's woods.
Songbird migration is increasing and will peak in May. Many seed-and bud-eating migrants, such as the Indigo Bunting and Rose-breasted Grosbeak, welcome bird feeding stations as a rest stop and a place for a quick energizing meal as they continue their journey northward or search for a nesting territory. The fields and thickets can be thick with sparrows and towhees on their way north. Sometime the messiest looking thicket has the most birds. Local resident nesters like cardinals, titmice and chickadees also use feeders as a source of food, for wild seed crops will not be available until summer.
Hummingbird and oriole feeders also should be stocked by the end of April. But, many of these birds feed primarily on arthropods found on natural vegetation and respond to their availability and switching their diet from seeds to insects. Even by late April, some forest warblers such as Black-throated Green Warbler have returned to their nesting grounds and staking a claim to territories and attracting a mate with their songs. By the last week of April, many of the woods are alive with migrating warblers, vireos, tanagers, and grosbeaks.
Many raptors are nesting in April. American Kestrels will adopt either farm buildings such as barn and silos or nest in a tree cavity far from any farm. Red-tailed Hawks are often well into nesting season by this time, usually nesting in a tree near open field. Broad-winged and Red-shouldered Hawks are forest raptors often nesting far from people but some Red-shouldered Hawks nest in well-treed towns.
Usually unseen but sometimes heard by observers, the small owls are charismatic denizens of Pennsylvania's woods. Eastern Screech-Owls will adopt a large nest box as a nest or roost site, chortling and whinnying their song at night. The diminutive Northern Saw-whet Owl nests deep in the woods, often at higher elevations, and can be heard at night "tooting" almost like the sound of truck backing up.
Pennsylvania Game Commission