April is a month to watch lakes and reservoirs on a daily basis; migrants can drop in, rest briefly, and depart. The more miserable the weather, the more likely stray migrant waterfowl, shorebirds, and terns will appear. Birding in cold, driving rain is no fun, but the possibility of finding something unusual or truly rare is a powerful goad to the dedicated field birder. Early in the month, days with northwest winds are sometimes dismissed as too early for most passerines and too late for much waterfowl. Although a day spent in the cold wind may produce nothing, the first ten days of April, under stormy conditions, have produced a major waterfowl fallout on Triadelphia Reservoir, an American Bittern at West Friendship Park, a Black Scoter at Centennial Park, and a Short-eared Owl at Alpha Ridge Landfill.
This is a transitional month. Although many birders are used to starting near dawn to catch peak feeding activity and movement, during April almost any time of the day can be productive. If there has been a significant change in cloud cover, temperature, or wind direction during the day (showers in the morning, clearing by afternoon), the late afternoon/evening hours may be more productive than the morning. Terns, gulls, and swallows may appear over lakes in the afternoon; smaller passerines may suddenly become active; and raptors may be seen soaring as updrafts strengthen. If rain or a cold front is forecast to move in during the day, take advantage of early sunshine and favorable winds. After the winds have shifted to the northwest and are blowing steadily, there is a chance that migrating waterfowl will drop onto local lakes and reservoirs until the winds diminish.
Blue-winged Teal are usually passing through during April. Check the shallow end of Centennial Lake as well as Forebay Pond.
Long-tailed Ducks may drop onto the larger lakes and reservoirs during late March and early April, especially during periods of stormy weather.
This is the month to look for Red-throated Loons on Triadelphia Reservoir. Though the heaviest state Red-throated Loon movement occurs in March, most of this county’s few records are in April.
Common Loons migrate well into May and are occasional to regular on county lakes as well as on the reservoirs. Throughout this month and part of May, singles and flocks may be seen as flyovers, mostly from dawn until 10:00 a.m. almost anywhere in the county.
Most Pied-billed Grebes and the majority of mergansers leave by the end of April.
Migrating Double-crested Cormorants will be passing through this month and well into May. Early to mid-morning is the peak time.
American Bitterns should be looked for all month until mid-May. Meadowbrook Park, with its large patches of cattails, has proven attractive to this species. They have also been seen in the Race Road Wetlands.
The first week of April may see the return of the first Green Herons, although the third week is more likely to see a surge in numbers.
Most spring Glossy Ibis records are from the first week of April through the first week of May.
Although the earliest Ospreys begin to drift through in March, many more move this month with migration continuing well into May. An occasional pair nests in the county.
Check main forks of large deciduous trees before the leaves have reached full size for nesting Red-shouldered and Red-tailed hawks. Red-shouldered Hawks, which are a common stream or river valley nester, sometimes may be seen carrying identifiable prey items such as snakes, frogs, and small rodents.
Northward-moving Broad-winged Hawks are most visible from the middle of the month into early May.
Although Soras have been observed as early as the first week of April and as late as the third week of May, late April to mid-May appears to be the peak migration period. Muddy edges of islands at Centennial Park and pond edges with adjacent wetlands at Meadowbrook Park offer accessible places to watch and listen for this elusive species.
Shorebirds (other than Killdeer, an occcasional yellowlegs, Wilson’s Snipe, and American Woodcock, all of which arrived earlier) begin appearing in numbers after the middle of the month. Check muddy areas around the western islands at Centennial Park from late March until the vegetation grows up. At one time the entrance pond at Western Regional Park was highly productive, but its value dropped dramatically when that drainage area was reconfigured. Browns Bridge mudflats are usually covered at this season. Shallow pond and river edges anywhere in the county may produce a few birds. Wet spots in fields, especially on the few remaining turf farms, where the sod has been stripped, may also be suitable habitat. Shorebirds should be found in good numbers throughout the first part of May; few are noted after mid-May.
Bonaparte’s Gulls and Caspian Terns can be seen sporadically this month and into May resting on or flying over the county’s larger lakes and reservoirs. Wilde Lake, for reasons known only to the Bonaparte’s, was the favored lake for these gulls for many years. More recently, Centennial and Lake Kittamaqundi, as well as Triadelphia Reservoir, are also frequently visited. Caspian Terns, although sometimes reported as early as the first week of April, are more often seen later in the month and are likely at any of the central lakes or the reservoirs.
There is a resurgence of Barred Owl calling in late April and May, sometimes during daylight hours.
By late April, watch at dawn or dusk for early Common Nighthawks. Most migrate in May.
Occasionally, someone reports a Whip-poor-will calling at dusk or dawn. These are migrants, normally present only a single night. Nesting (if it still occurs in the county) is probably confined to a few areas in or near Patuxent River State Park; currently, there is no location that can be pinpointed with certainty.
Chimney Swifts begin to filter in around the middle of the month; numbers are often small until closer to the beginning of May.
There are a few Ruby-throated Hummingbird records in early April, but more appear from mid-month on. Most come through in early to mid-May.
Look for Red-headed Woodpeckers late this month and most of May. Areas of mature oaks and hickories with little or no understory and numerous dead trees are primary nesting habitats; in migration they can turn up in almost any mature deciduous woods.
In most years, Yellow-bellied Sapsuckers can be spotted throughout the month.
Eastern Kingbirds begin showing up the last 10 days of the month. Great Crested Flycatchers usually begin to appear the last week of April or the first week of May with arrival continuing into late May.
Most Blue-headed Vireos migrate through the last third of April and the first week of May; numbers taper off rapidly after that.
White-eyed Vireos begin appearing the last third of the month.
The number of swallows over lakes and reservoirs rises dramatically this month. There may be a few days when hundred of swallows of several species are present over local lakes. Barn Swallows nest under the deck at Centennial Park and beneath the bridge at the east end of Lake Elkhorn. Rough-winged Swallows normally nest in riverbanks; however, they have been seen attempting to nest in bridge drains including those at the west end of the lake at Centennial Park.
Most years nesting Cliff Swallows return to Brighton Dam by mid-April. A colony also exists near Sykesville under the MD 32 bridge over the Patapsco River.
Continue to listen and look for Red-breasted Nuthatches until the first few days of May. Areas of pines at Pigtail and Big Branch are possible locations.
House Wrens can arrive anytime this month; most records are after the first week.
Marsh Wrens should be sought the last week of April and the first three weeks of May in any wetland habitat containing even a few cattails or areas of soft rush.
By mid-April the high, thin song of Ruby-crowned Kinglets can be heard. Most Golden-crowned Kinglets (the common winter kinglet) have moved on.
Blue-gray Gnatcatchers begin nest building as soon as they arrive. The beautifully constructed compact nest looks like a knot on a horizontal branch. Nests are often easy to locate because the birds usually choose an open-branched tree like black walnut and build before leaves have emerged completely.
With favorable weather, Eastern Bluebirds may begin nest building the first half of the month.
Heaviest Hermit Thrush migration is the first half of the month, with Wood Thrushes and sometimes Veeries making appearances the last third of the month.
The earliest Gray Catbirds show up by the third week of April, peak numbers do not occur until the first 10 days of May.
The last third of the month may produce early records for some warblers, but only small numbers are present except for a few typically early species. The earliest warblers are Pine (March), Louisiana Waterthrush (usually late March but more obvious in early April), Yellow-throated (late March to mid-April), and Palm (sometimes a few in March, more likely early April). By the last half of the month, watch for Common Yellowthroat, Northern Parula, Ovenbird, and American Redstart, as well as Yellow, Black-and-white, Prairie, Prothonotary, and Hooded warblers.
Although Prothonotary Warblers have been recorded from mid-April through May, the peak period is the last 10 days of April and the first week of May.
Rockburn Branch Park and Pigtail are good places to hear singing Pine Warblers.
For Yellow-throated Warblers, try Marriottsville Road east along the river (especially the first half mile) and west to the tunnel—sometimes it is not even necessary to leave the parking lot! Another location where they have been regularly recorded is in the vicinity of Henryton Road at the river. A few times they have arrived in late March, more often it is early to mid-April. This species and Louisiana Waterthrushes both sing loudly and exuberantly in the Patapsco River floodplain before the trees have leafed out. From a distance, it is possible to mistake one species for the other as the songs have similarities. Seek out the Yellow-throated Warbler high in large sycamores along the river; waterthrushes are more likely to be bobbing along the muddy edge of the river or perched on a relatively low branch.
Generally, the most productive areas for songbird migrants in late April and early May are places not far from water which contain flowering oaks, hickories, box elders, and willows. Southern and eastern locations such as Schooley Mill Park, Rockburn Branch Park, the Avalon/Orange Grove section of Patapsco Valley State Park, and trails near Savage are good options. Sometimes northern areas, such as Daniels or Henryton, can be rewarding despite slow leaf development; on the other hand, they can be devoid of migrants on a clear, chilly morning. By the second week of May, central and northern locations have the edge so that the Middle Patuxent Environmental Area, Patuxent River State Park, and northern sections of Patapsco Valley State Park may be the most rewarding. Early morning birding during the chilly days of early April may not be as productive as the late afternoon.
A few Yellow-rumped Warblers usually winter, but the last two weeks of April see peak numbers of our most common migrant warbler. Sometimes hundreds may be seen along the water’s edge at Centennial Park or Lake Elkhorn.
In late April and early May, check Palm Warblers carefully for the paler western subspecies whose numbers peak in late April. Palm Warblers are frequent along lake edges at Centennial and Lake Elkhorn.
Grasshopper and Vesper sparrows should arrive—the former mostly in late April and the latter from early April on. For both, there is at least one late March arrival date.
Some White-crowned Sparrow migration can usually be detected in late April and early May. Search flocks of White-crowned Sparrows for a Harris’s Sparrow, a choice find in the East in this late April/early May period.
Rusty Blackbirds can normally be found most of the month, although numbers drop in late April.
Orioles (especially Orchard) and Scarlet Tanagers begin appearing late in the month; the majority arrive in early to mid-May.
April, especially the last half, provides the best chance during the year to spot a Purple Finch (or even a Pine Siskin or Evening Grosbeak). Search treetops, like tulip trees whose seeds are favored, or scan flocks of American Goldfinches. Purple Finches may show up briefly at feeders, but are unlikely to be seen with large flocks of House Finches.