MOS logo and Tundra Swans flying
Search Site What's New? Site Map Contact MOS Travel Resources Call Notes

Activities & Events
About MOS
Birds of MD and DC
Birding Sites
Species Counts
Breeding Bird Atlas
Member Resources
Records Committee

You are here: Home - Atlas - Species Notes

Breeding Bird Atlas Logo

Atlas Species Notes

Green Heron (5/1-7/15)

Often nests in thickest vegetation (e.g., willows, vines) around ponds or along streams 8 to 20 feet up; young can be very vocal when being fed; nests of sticks are flat and frail, perhaps 15 to 22 inches across. (JSh)

Herons -- In General

Presence of immatures at ponds does not indicate local nesting. Adults and young may wander far after breeding. An actual nest must be found for a confirmation. (HC)

Black Vulture (5/1-7/31)

Courtship and territory defense displays start in March (Black) or earlier, TVs start a little later; look for birds soaring around or sitting on abandoned farm buildings. (JSh)

Turkey Vulture (5/15-8/20)

As above.

Accipiters -- In General (Late May Onward)

Any accipiter calling or screaming in a frantic way as you walk through the woods is defending its nesting territory. As you get closer to the nest, they often dive at you. (JSh)

Red-shouldered Hawk (5/10-8/10) and Red-tailed Hawk (5/10-8/20)

Territorial displays (calling and legs dangling, etc.) start in late winter on warm days. Nest building starts usually by the end of March; note birds carrying sticks. Pairs can be defensive when you walk near their nest. (Jsh) Nests may be quite near houses or roadside. Start looking well before leaf-out or safe date. (HC)

Broad-winged Hawk (6/15-8/10)

Mature forest, often upland but not always. Tough bird to find. Watch for territorial hawk displays and calling over tops of forest. Courtship is well after leaves have come out. May carry snakes to young. (JSh) Uncommon and local but should be sought. Learn distinctive call from tapes.

Wild Turkey (4/15-9/30)

Watch for family groups from early May into late summer. (JSh)

Killdeer (4/20-6/25)

Nests on flat roofs, along edges of gravel parking lots, driveways and roadsides, and in the middle of barren fields. (JSh)

Woodcock (4/15-8/31)

May nest before March 1 in mild winters; residents return very early (February); listen for calling and displaying males in March and early April then follow up after 4/15 for continued calling or displays. Best time is about 20-45 minutes after sunset. Males prefer old fields with openings between young trees with moist soils and may display from middle of old road or trail; or even from edges of play fields next to woods. Check out any pipeline cuts or even power line rights of way. Second growth forest from earliest stages to mature forest is preferred nesting habitat. Flood plains of small to large streams are favored, especially as late spring arrives, for nesting and brood rearing. Broods often seen at dawn on paths through woods or old fields. Females usually give distraction display when observer close to the young. (JSh)

Owls -- In General

Recently fledged young are very vociferous, especially at dusk and dawn; listen for high-pitched whines or similar noises. (JS)

Great Horned Owl (12/15-8/31)

Loves old Red-tail's nests; watch for old hawk nests in fall and winter. Tops of large stumps also favored. Usually uplands, but does nest in floodplains. Woodlot for nesting may be small and isolated from other woods. (Barred Owl does not use stick nests.) (JS)

Ruby-throated Hummingbird (5/15-7/31)

Learn the little chip notes of the hummer; listen and follow nest building female as she gathers spider webs and lichens from trees and other vegetation. Spotting the female picking up spider web is confirmation in itself. The nest is a tiny cup astride a horizontal branch, so camouflaged as to seem part of it, and usually within a few hundred yards of water. (JSh)

Chimney Swift (5/15-8/10)

Though seen everywhere, swifts are nonetheless a challenge to confirm, and conversely, some reported confirmations are probably over-confident. The reason for this is that the chimneys being used must be accessible to the atlaser, and that excludes most of those actually being used. Ingress and egress is not sufficient evidence of nesting since unmated swifts roost in chimneys, sometimes in small groups or even singly or in pairs.

Viewed from outside, the behavior to watch for is repeated entry and egress by single birds during the day, several times per hour. During nest building, the birds may be seen carrying small twigs in either bill or feet. If a swift is seen plucking a twig from a tree as it passes over, that too is confirmation.

From indoors, one need not see the birds as they come and go; their exit makes a distinct "whoosh" as the vibrating air resonates in the chimney. After the young are hatched a loud, high-pitched chatter ensues as the adult enters, then quiets as the young receive the regurgitated food; then follows the "whoosh" as the adult flies out. The exit is so swift that it is easily missed when viewed from outside. These sounds are usually quite evident from within the room to which the chimney opens and require no special effort to detect. Take-offs and landings continue all day from sunrise to after sunset.

Chimney Swift young are cared for in the nest for nearly 4 weeks, so there is plenty of time to detect them after nesting season starts. Nests may be active as late as the first half of August.

Fledglings on the wing are indistinguishable from adults. It is said that at the time the young emerge (first half of August), the adults are undergoing molt and so show a gap or two in the wings, whereas the young will not show such gaps, but this is a dubious basis for confirmation. Nor is group size diagnostic - as soon as the young are air-borne, swifts begin congregating in loose, constantly re-forming flocks. So "FL" is not a valid confirmation code for swifts; it is nesting itself that must be observed.

A useful strategy is to have a network of friends and neighbors in each of your quarter-blocks alerted to the possibility of hearing the distinctive sounds of swifts using their chimneys. The atlaser would then follow up on these candidates to rule out mere roosting and confirm the presence of breeding. It is not necessary - nor sometimes even possible - to view the nest itself. Ten feet is given in Bent as the average distance of the nest from the top of the chimney. The chatter of the young may be too high pitched to hear easily from the ground floor of a multi-story house, so leaving the flue at least partly open during summer may be aid detection. (FF)

Belted Kingfisher (4/1-7/20)

Nests in vertical banks along streams; kingfisher nest arched about 3 inches high, with flat bottom and two distinct RUTS at bottom. Occasionally nests are excavated in banks not bordered by water, e.g. in quarries. Kingfisher may carry small minnows for one-half mile along a stream course. (JSh)

Acadian Flycatcher (5/25-8/5)

Nests almost exclusively over water, if only a small vernal pool; often on horizontal branch of a maple, etc. Flycatcher perhaps 5 to 15 feet over water. Nest may look like some flotsam from a previous flood; always festooned with hanging strings of moss. Not usually very neat and compact as in vireos. Sometimes the eggs or young may be seen through the bottom. (JSh)

Eastern Phoebe (5/1-8/31)

Well known for building nests on man-made structures such as bridges, porches, door lintels, etc. But less known is that they have now advanced to the point of nesting well inside such structures as sheds, barns, and abandoned houses. (I have come across such a nest so far inside an old house that the phoebes had to actually fly thru several rooms in order to get to it, and at times even seemed a little confused themselves as to how to navigate out again!) Barns and outbuildings may also contained phoebe nests. So atlasers should investigate the interiors as well as exteriors of buildings where phoebes are present but the nest not obvious. (And of course the usual precautions regarding permissions and safety apply when entering any structure, even on public property). (FF)

Willow Flycatcher (6/16-7/20)

Late arrival; wet or damp areas with shrubs. Nest may not be near water. (JSh)

Great-crested Flycatcher (5/25-7/31)

Calls close to or while in nest, especially when feeding young or mate. Nest is often in the hole left by a broken-off branch. (JSh)

Eastern Kingbird (5/25-7/25)

Hitherto, kingbirds have built their bulky nests near the tops of trees, often alongside a pond or waterway; and these aggressive birds making no attempt to conceal their comings and goings, their nests are not hard to spot. Recently, however, this species has developed an adaptation to that makes finding their nests even easier - building on power-line towers. A recent survey of a transmission line through PWRC's North Tract, for example, found kingbirds defending nearly every other of the towers. Therefore, the easiest place to confirm kingbirds is along power-lines.

The nests are located atop a cross-member, tucked against some intersecting vertical component, perhaps in a somewhat shaded corner. They tend to be rather high up (say 50-80 feet), but not so high as to preclude your seeing the young, or at least the parents tending them. The female can be followed flying directly to the nest, relying as she does on the regal self-assuredness of her mate to repel any predators. (FF)

Vireos -- In General

Pairs often become very agitated when observer is near their nest; learn these agitated calls. All nests are in "Y" fork of a small branch, hang suspended, and are a compact small structure -- an unique nest (orioles are 4X larger, Acadian Flycatcher not compact and neat). 2 to 30 feet high. (JSh)

Horned Lark (4/1-9/5)

May nest as early as March 1; look for activity in last year's crop fields or on sod farms with lots of barren soil and a few sprigs of vegetation. Might nest in old corn stubble, but more likely with less overall height to vegetation. May need scope to sit back and watch birds from greater than 200 yards away as they carry food; young fledge in about 6 to 7 days! QUICK nester! Fledglings may be seen running on plowed fields after parents. (JSh)

Tree Swallow (5/25-6/25)

Check bluebird boxes! Nesting may start by April 15-20; goes to end of June. (JSh)

Rough-winged Swallow (5/25-6/20)

Nests in banks same as Belted Kingfisher (above). May also nest in drain pipes, culverts. (JSh)

Swallows -- In General

Recently fledged young very often line up on fence or power line to be fed. Any small group of 3 to 5 swallows sitting close together are suspect from early May to late June. (JSh)

Purple Martin (6/1-6/25)

Less common now; check houses located in wide open areas, not back under trees. Watch for feeding birds in air and then check houses in immediate area. Ask landowners with martin houses. (JSh)

White-breasted Nuthatch (5/10-8/15)

Favors mature woods with decaying trees. Nests in natural cavities (often with a knothole entrance) or old woodpecker hole. Once the female begins incubation, as early as 4/10, the male makes frequent trips to feed her uttering soft "yank" calls as he arrives. (HC)

Blue-gray Gnatcatcher (5/15-7/31)

Another bird that starts nesting long before safe-date. Nests can be found as early as approximately 4/15. The nest appears to be a knot on top of a horizontal branch. Tent caterpillar silk is a component, used to cement the nest to the branch and blend one into the other. Pairs are noisy as they build and can sometimes lead you to the nest. (HC)

Veery (6/10-8/10)

Deep mature woodland with dense understory, more often on north-facing slopes; listen for distinctive singing at dawn and dusk and alarm note rest of day; nest building may start in mid-May. (JSh) Its range distinctly limited by the fall line, the Veery is unlikely to breed in PG County.

Warblers -- In General

Breeding birds VERY territorial; might try tapes to locate territories during safe dates-use sparingly. Breeders return early and may commence nesting 10 to 15 days before safe dates start, so don't wait until safe date to start looking. (JSh)

Blue Grosbeak (5/25-8/10)

Can fledge young as late as Labor Day! (JSh) Note 2nd year male resembles female.

Rufous-sided Towhee (5/20-8/31)

Note the juvenile's striped, sparrow-like plumage with more white in the wings than shown in most field guides; Robbins' guide illustrates it best. (FF)

Orchard Oriole (6/1-7/5)

Two or more pairs may nest in same or adjacent trees (colonial!); old orchards or fields with fruit trees up to 25 feet tall and scattered; note narrow safe dates! Not always as noisy or obvious as Baltimore; try tape. (JSh) Often nests near kingbirds.

Baltimore Oriole (6/1-7/25)

Watch sycamores over streams, roads, paths, lawns, etc. for nests; very noisy when nest building or feeding young. (JSh)


  1. Simply LISTEN more for begging and alarm calls or other non-singing type calling. Most songbirds can be noisy when building nests and feeding young. Most are far more active building and feeding in first few hours of the day, and last hour or two of day.
  2. Breeding activities usually start well before earliest safe date for local nesting pairs. Do not wait until first safe date to look for nesting birds nor stop looking after last safe date for fledged young of most species.
  3. Almost the easiest way to confirm is when adults are carrying nesting material or food to nest or recently fledged young; so watch an adult for 5 to 10 minutes as it forages. Most feeding rates by an adult songbird are 6 to 20 times per hour. Similar rates for nest building. Females, in particular, are often easy, as they do not spend time singing. So if you find one foraging when it could have young, you often have to wait less than 5 minutes before it starts to carry some food or nest material.
  4. A couple of hours right after dawn are usually far more productive than 4 to 5 hours in the heat of the day; on the other hand, most singing stops in mid-day, so most call notes you hear are more likely to be related to nesting activity or feeding young.
  5. Watch for repeated flights of a silent bird going to or from a particular spot. Many foraging adults use the same general route to and from the nest for an hour or more at a time; route will change over time.
  6. Get some bird recordings. Chase the early arrivals of potential breeding species if you do not know their song.
  7. Look for patches of habitat that are not common in most of that block. Survey extra well. Ask landowners for permission to access such unusual habitats if not on public property.
  8. Make a list of some of the target species and/or habitat patches you want to focus on each day. Know which species you need to ignore in that block and quarter block and vice versa. That is, go into the field with a current list of all species and their status in that block.
  9. COMMUNlCATE! If others are working in your block, keep everyone immediately advised of your finds so that others do not have to spend their valuable time focusing on those same species. Stay alert while traversing other blocks for the unusual and report them immediately.


  • FF -- Fred Fallon
  • HC -- Howard chapter MOS
  • JS -- Jo Solem
  • JSh-- Jay Sheppard