Happy Birthday Project FeederWatch

It’s mid-November and once again I‘m engaged in Project FeederWatch, keeping a record of the number and species of birds visiting my back porch feeder area. As a veteran of this citizen science project started by the Cornell Lab of Ornithology, both they and I are celebrating our 30th year engaged in this unique program.

A male northern cardinal (Photo by Torindkfit in Wikimedia, Creative Commons license)

A male northern cardinal (Photo by Torindkfit in Wikimedia, Creative Commons license)

The rewards have been enormous. Not only have I seen as many as 22 bird species at the feeders during the cold, snowy winter of 2014-15, but I have also observed interactions between small mammals and birds fighting for seeds on the ground. Although last winter, which was unusually warm, was not an exciting year for my feeder-watching, other wildlife observations while feeder watching added to my enjoyment.

This morning, for instance, shortly after 7:00, while glancing out at the feeder birds on the two tube feeders hanging from our back porch, I spot an eight-point buck walking to the edge of the woods and making or, more likely, freshening a scrape, pulling down a branch repeatedly with his mouth to leave his scent and then pawing the ground beneath.

Three does foraging at the edge of the woods (Photo by Dave Bonta)

Three does foraging at the edge of the woods (Photo by Dave Bonta)

Only a few yards from the buck, I see one, two, and finally three does foraging at the border between the woods and the flat area. I think I might see chasing and breeding, but he seems to sense that they are not yet in estrus.

When eight mourning doves feeding on the ground below the back porch steps suddenly take fright and fly, probably because they can see me standing at the kitchen door window staring out at the deer, the buck flees too. The does, though, continue eating placidly with no visible reaction to the buck’s retreat.

An American tree sparrow

An American tree sparrow (Photo by D. Gordon E. Robertson in Wikimedia, Creative Commons license)

Week after week last winter I entered the same bird numbers and species, sometimes seeing as few as 11 species during my weekly, two-day count. But field work often consists of persistence with now and then a breakthrough. Mine came last February 16, when I recorded 18 American tree sparrows on the feeders and ground below, followed on March 3 by 21 tree sparrows. In previous winters my number of these sparrows hovered in the low single digits, and I couldn’t account for so many of these birds.

When the annual Project FeederWatch (PFW) report for the top 25 bird species from 6,498 sites in the northeast was issued, the American tree sparrow was 24th on the list, reported at 36% of sites, and the average flock size was three! All my other feeder birds—black-capped chickadee, dark-eyed junco, mourning dove, blue jay, northern cardinal, American goldfinch, downy and red-bellied woodpeckers, white-breasted nuthatch, tufted titmouse, song and white-throated sparrows and Carolina wren were much higher on the list.

A dark-eyed junco

A dark-eyed junco (Photo by CheepShot in Wikimedia, Creative Commons license)

Chickadee was first at 97% of sites, but that included both Carolina and black-capped chickadees, so dark-eyed junco, second on the list at 94% of sites, continued to be the most common feeder species. The flock size for juncos averaged four, but I’ve counted between 60 and 80 most years.

When I report those numbers, they are flagged during my online reporting as a result of a “smart filter” system the Cornell Lab has developed to root out mistaken observations. Species not usually seen in the area or high counts of a species are questioned. An error message pops up, and I am asked to confirm my number. Then when I do, my report is forwarded for review by PFW staff and regional biologists. Had I reported a rare bird, they would have required more validation, including a description of the site and bird and a photograph, if possible.

Because PFW data is being used by more and more researchers, they had to develop a reporting system that would increase both researchers’ and participants’ confidence in the resulting data. They tested their new “smart filter” system during the three winter seasons of November 2007-April 2010, flagging 50,104 PFW submissions out of a total of 3,924,088 or 1.3%, and reviewers approved 97.7% because a rare species had been confirmed in that region or, in my case, because large flocks of a species occasionally occur here. As researchers concluded in a paper about validating PFW reports, “Our methods ensure that unexpected reports are subjected to expert scrutiny, resulting in a more accurate and reliable data set regardless of the user.”

A pine siskin

A pine siskin (Photo by Hvbirder in Wikimedia, Creative Commons license)

In contrast to last winter’s mild temperatures, the winter of 2014-15, which began late, was the coldest in decades. It was also a pine siskin invasion year. As they poured south from their boreal home grounds, we saw our first ones on November 9, 2014 when three dozen visited our feeder area. They must have headed farther south because our next siskin visitation happened on January 6, 2015. After that, it was every bird for itself and the mammals also, since pine siskins may be small, but they are feisty.

For example, on February 2, a cold, windy day, a sea of birds covered the ground when I threw out more birdseed in mid-afternoon. The siskins fought off all comers. Two on the large tube feeder fought with house finches and won. They scared off chickadees, tufted titmice, and each other as well as American goldfinches. The blizzard of birds, including siskins, continued through February and into a freezing March, with the siskins paying their last visit on March 30.

A black-capped chickadee

A black-capped chickadee (Photo by fishhawk on Flickr, Creative Commons license)

According to a paper about boreal bird irruption, pine siskin irruptions may happen every other year but also may occur in consecutive years or at longer intervals. Using more than two million PFW pine siskin observations from 1989-2012, researchers studied the patterns of pine siskin irruptions from their Canadian boreal homes where they eat conifer seeds to the high elevation Adirondack and Appalachian Mountains.

They concluded that a wet spring in the boreal region leads to a small seed crop, but a dry spring in the Appalachian region leads to a large seed crop. If the winter air temperature is also unusually cold in the boreal region, which even stresses these cold-adapted birds, they will irrupt south where the seed crop is plentiful. “This study,” they write, “is the first…to reveal how climate variability drives irruptions of North America boreal seed-eating birds.”

Tufted titmouse

Tufted titmouse (Photo by Cindy Sue Causey on Flickr, Creative Commons license)

Using PFW data to track changes in winter bird communities has been useful in studying climate change in our backyards according to Karine Prince and Benjamin Zuckerberg. They maintain that since the 1970s, North America’s climate has been changing especially during the winter season with less and shorter snow cover and more variable and heavy precipitation.

Choosing 38 bird species that winter in eastern North America, they tested the influence of changes in winter minimum temperatures over 22 years and found that the winter bird communities became increasingly dominated by warm-adapted species such as mourning doves, Carolina wrens, red-bellied woodpeckers, eastern bluebirds and dark-eyed juncos, which moved northward about 4.2 miles a year.

Pine warbler

Pine warbler (Photo by Andy Reago & Chrissy McClarren on Flickr, Creative Commons license)

Last winter PFW also received several reports of pine warblers as far north as Nova Scotia and growing numbers of hermit thrushes at northeastern feeders visiting two to four percent of sites.

The latest addition to PFW studies is a plea for us to report bird interactions at feeders. They began this project late last season and received 1,994 observations from 200 feeder watchers. Most were of one bird displacing another, 37 of one bird catching and eating another, and 23 of one bird mobbing another. Usually larger birds displaced smaller ones but sometimes smaller birds turned the tables with house finches displacing cardinals and downy woodpeckers displacing mourning doves.

A house finch

A house finch (Photo by Lee Coursey on Flickr, Creative Commons license)

I see many interactions a year, especially the winter of 2014-15. Some are harmonious such as the early January morning when a cottontail rabbit, a gray squirrel and juncos, white-throats, a tree sparrow, two song sparrows and a cardinal pair fed together on the porch and steps. Later they were joined by house finches, and goldfinches. Chickadees, titmice, and white-breasted nuthatches appeared and competed with goldfinches and house finches on the hanging feeders. Mourning doves flew in and out, as many as ten at a time, and a red-bellied woodpecker made several hurried appearances.

But our peaceable kingdom dissolved during a snowstorm two weeks later when four squirrels, the rabbit and 13 mourning doves pushed the small birds from the covered porch floor where I had spread birdseed. Then the birds that only eat from the feeders arrived—nine goldfinches, a couple chickadees and three house finches but goldfinches even displaced the house finches. A pair of cardinals sidled in and scared off as did a female red-bellied woodpecker.

Thus, instead of merely counting and recording my feeder birds I can contribute my observations of such interactions to PFW and help them learn more about what drives the interactions of feeder birds.

Happy 30th birthday Project FeederWatch, and may we celebrate many more birthdays together! A two-minute YouTube video provides an effective introduction to Project Feederwatch.

Not a Snipe Hunt

On a cold, crisp day in late January, my husband Bruce, son Mark, and I set out on our annual Winter Raptor Survey in nearby Sinking Valley. Although a substantial snow had fallen the previous day, all the township roads had been plowed, and Bruce had no trouble driving our usual 35-mile route.

The spot in the stream across from the Little Country Store where we saw the snipes

The spot in the stream across from the Little Country Store where we saw the snipes (Photo by Bruce Bonta, December 12, 2016)

Despite a light breeze, we counted only three red-tailed hawks, three northern harriers, and two American kestrels. When we stopped at the Little Country Store for groceries, we heard killdeer calling across the road. Two killdeer and 13 mallards waded in a tiny stream bisecting a snow-covered Amish field.

Most surprising of all were four Wilson’s snipes probing in the mud beneath an inch or so of flowing water, their long bills stitching like sewing machine needles. The snipes were crowded into a two foot by two foot curve in the stream that had a small rock on one side. Even though I had seen many American woodcocks over my lifetime, I had never seen a Wilson’s snipe.

We walked across the road for a closer look at the short, stocky shorebirds which were studies in brown and beige with three white stripes on their dark brown and gray backs, heads striped white and dark brown, beige-spotted breasts and white bellies. One snipe tried to hide behind the rock when it noticed us, but half of its head and long bill stuck out, reminding me of a small child unsuccessfully playing hide and seek.

Wilson’s snipe

Wilson’s snipe (Photo by Larry Jordan on Flickr, Creative Commons license)

Mark was hoping the snipes would fly so we could see their rapid zigzag flight and hear their rasping “scaipe” calls. But on that cold winter day, they were too busy probing in the mud for worms and other small invertebrates, while their large eyes, set far back on their heads, allowed them to watch us even while they foraged.

Seeing Wilson’s snipes at that time of year in central Pennsylvania was unusual we thought, but when Bruce talked to the bird-watching Amish teenager, who lives next to the store, he told Bruce that as many as five Wilson’s snipes were there every winter. Certainly the small steam in a pasture habitat matched their wintering requirements which also include muddy ponds, ditches, ephemeral pools, barnyard drainage, marshes, beaver ponds, or spring outlets.

A Wilson’s snipe found in a North Carolina marsh

A Wilson’s snipe found in a North Carolina marsh (Photo by DickDaniels in Wikimedia, Creative Commons license)

However, according to Terrestrial Vertebrates of Pennsylvania: A Complete Guide to Species of Conservation Concern, “successful overwintering in Pennsylvania [of Wilson’s snipe] is probably rare except possibly in brackish marshes of the extreme southeastern portion of the state.” Gerald McWilliams and Daniel Brauning, writing in The Birds of Pennsylvania, agree that most wintering snipes are found in Pennsylvania’s Coastal Plain and Piedmont but admit that there are widespread but local winter records most years in our Ridge and Valley province and in southwestern Pennsylvania.

Still, having heard the spoofing stories of snipe hunts, I was amused that while hunting for raptors we had found snipes instead.

A Wilson’s snipe and a northern bobwhite, from Alexander Wilson, American Ornithology: or, the Natural History of the Birds of the United States (1812), volume 6 plate [47]. In the public domain

A Wilson’s snipe and a northern bobwhite, from Alexander Wilson, American Ornithology: or, the Natural History of the Birds of the United States (1812), volume 6 plate [47]. In the public domain

Once our Wilson’s snipe (Gallinago delicata) was considered a subspecies of common snipe (Gallinago gallinago), but, based on recent taxonomy studies, it was classified as a full species in 2002 by the American Ornithologist Union. Named for Alexander Wilson, a Scottish immigrant who lived in Philadelphia, he was a self-trained ornithologist and artist, who traveled throughout the eastern United States, collecting and studying birds. He produced his nine-volume American Ornithology at the beginning of the nineteenth century which earned him the title “Father of American Ornithology.”

Wilson’s snipes breed in wetlands across northern North America and usually winter from the southern United States through Central America to Venezuela. Pennsylvania is near their southern breeding range in eastern North America, and because they are so dependent on wetlands throughout the year, they have been selected as a Species of Maintenance Concern in the commonwealth. Between the first and second Pennsylvania Breeding Bird atlases, their numbers decreased by ten percent. In addition, they are rare breeders here most likely in the wetlands of northwestern Pennsylvania in the counties of Crawford, Lawrence, Mercer and Erie. In fact, back in 1923, George Miksch Sutton, who became a famous ornithologist and artist, was then Pennsylvania’s ornithologist and watched several Wilson’s snipes nesting in Crawford County.

A group of snipes in a pond

A group of snipes in a pond (Photo by leppyone in Flickr, Creative Commons license)

Wilson’s snipes migrate through the state beginning in mid-March, moving in flocks on moonlit nights, the males a week or more ahead of the females. Their extra-large breast muscles that give them their plump appearance enable them to fly as fast as 60 mph.

If any Wilson’s snipes are still here in mid-April through May and early June, they may be breeders. And if any birdwatchers are especially lucky, they may observe their diving flight displays, when their outermost tail feathers spread to make a “winnowing” sound that reminds me of the tremulous calls of eastern screech-owls. Most frequently males display to defend territories and attract mates, but sometimes females also “winnow.” They even “winnow” occasionally during migration as well as on their breeding grounds and at all times, both day and night, but most commonly after sunset.

They have an array of calls and displays as part of forming pairs, even flipping upside down during dives. Finally, once they are paired, they fly close together with their wings held at 45 degrees in a nuptial flight display. Leslie M. Tuck, who studied them on their nesting grounds in Newfoundland and Ontario, published his monograph on them back in 1972 and recorded their many courtship displays.

A nest of a Wilson’s snipe

A nest of a Wilson’s snipe (Photo by rich Mooney on Flickr, Creative Commons license)

A female has her choice of several males and even copulates with a few, only establishing a pair bond with one male after she’s chosen her nest site and begun to lay her eggs. But she spends time, as soon as she arrives in her breeding area, looking for a nesting site and making several scrapes on wet areas such as hummocks or edges of sedge bogs, fens, marshes, willow or alder swamps. She places her nest on the ground, well-hidden by grasses, sedges, or sphagnum moss, lining her shallow scrape with grasses.

She lays two to four olive-brown eggs and incubates them for 18 to 20 days, Twenty-four hours before they hatch, the chicks begin peeping, and the female responds by straddling the nest and clucking softly. Covered with down that dries within an hour, the chicks climb on the female’s back or wander away on their long legs and huge feet.

A snipe chick

A snipe chick (Photo by Guy Monty on Flickr, Creative Commons license)

The male usually takes the first two hatched chicks and the female the second two, leading them to wet areas where they feed them bill to bill. But at six days of age, the young peck at food and probe for it, becoming proficient when they are ten days old, although the parents continue to feed them for at least another ten days and as long as two months, according to researcher K.A. Arnold writing in Tacha and Braun (1994).

Mostly they eat the larvae of crane, horse and deer flies, beetles, dragonflies, crickets, grasshoppers, and ants as well as snails, crustaceans, and worms, using sensory pits near the flexible tips of their bills, to find prey by touch. Their bills are also flexible and open to grasp food without moving from the soil. Sometimes not only their entire bills are covered with water but their foreheads as well in their hunt for food.

Distraction display by a Wilson’s snipe

Distraction display by a Wilson’s snipe (Photo by Kathy & Sam on Flickr, Creative Commons license)

The earth colors of Wilson’s snipes provide them with camouflage, so they only flush at the last minute when confronted by a predator. They also practice a distraction display—the females at their nests and both parents with their young—by fluttering up from the ground or nest, falling back to the ground, spinning and fluttering around, falling on their sides and beating their wings, as if in a drunken rage, or lying on their breasts and beating their wings.

Although there has been no observation of egg or chick predation, great horned owls, peregrine falcons, merlins, northern goshawks, Cooper’s hawks, and especially northern harriers prey on adults.

Wilson’s snipes begin their migration south as early as mid-July in Pennsylvania and may not reach their destination until November if they are heading as far south as Venezuela. Juveniles leave first, followed by females and then males. They don’t always remain in one place, for instance, numbers of snipes in Venezuela increase in January and February at the same time they decrease in southern Louisiana. Apparently, they move in search of food, especially if their chosen spots have dried out.

If Tuck and other researchers are right and at least 40 per cent of Wilson’s snipes return to the same wintering grounds every year, I can look forward to seeing them this winter and subsequent winters as long as the habitat remains unchanged.

To see and hear a Wilson’s snipe calling, watch a video on YouTube from Wild Bird Video Productions.

Owls of North America and the Caribbean, by Scott Weidensaul

If you like owls as much as I do, then the Peterson Reference Guide to Owls of North America and the Caribbean is the book for you.  Filled with gorgeous, glossy photographs of owls, this book also serves as an excellent reference source.

Neither as folksy and readable as the Bent series on birds nor as daunting and dense as the scientifically rigorous Birds of North America accounts, Weidensaul has read the scientific papers and translated them into a reference guide for interested amateur naturalists.

peterson-owls-coverThis book is one of a new series by the renowned Peterson field guide publisher Houghton Mifflin called Peterson Reference Guides and is sponsored by the National Wildlife Federation and the Roger Tory Peterson Institute in Jamestown, New York.  Creator of the field guide series back in the 1930s, Roger Tory Peterson was the most accomplished birder and bird artist of the 20th century.

Weidensaul’s book covers 39 owl species found north of Guatemala, including five endemic Caribbean species.  His extended introduction to owls explains how to use the book, and one illustration labels every possible term describing the parts of an owl such as “upper chest,” “primaries,” and “ear tufts.”

But Weidensaul’s species’ accounts form the heart of the book and cover the natural history, taxonomy, ecology, migration, and conservation status of owls.  Well-executed color range maps illustrate their breeding and wintering ranges.

Weidensaul is especially well-versed in snowy and northern saw-whet owls because of his ongoing studies of these species, as well as those owls that live here in his native state of Pennsylvania—barn, barred, great horned and eastern screech-owls. He has also written fascinating pieces on short-eared and long-eared owls, a few of which winter in Pennsylvania.  Many of the excellent photos of short-eared owls, for instance, were credited to Pennsylvanians Alan Richard and Tom Johnson.

In addition to a bibliography of every species at the end of their account, there is a general bibliography at the end of the book, an index, and a comprehensive glossary of such words as “neoptile,” “polymorphic,” and “zyodactyl.”

Weidensaul pays tribute to the many people who study owls, writing that, “They are diurnal primates studying nocturnal raptors, which calls for even more fortitude and tenacity than is typical in scientific research.”

As readers and owl aficionados, we can take advantage of their dedication and expertise by sitting comfortably in an armchair and browsing through this beautiful and informative book.

White-throated Sparrows

A white-throated sparrow in Quebec

A white-throated sparrow in Quebec (Photo by Cephas in Wikimedia, Creative Commons license)

By November most of our songbirds are gone. But at least a few white-throated sparrows, which nest farther north and have been migrating through here since late September, elect to stay instead of heading to the southeastern United States to spend the winter.

Not only do they stay, but they continue to whistle their plaintive “Poor Sam Peabody, Peabody, Peabody” song throughout the winter, a distinctive song that has led to many nicknames for this sparrow such as “Whistling Sparrow,” “Peabody Bird,” “Poor Kennedy Bird,” and “Sweet, Sweet, Canada bird,” among the literally dozens, in both English and French, that were unearthed by W.L. McAtee back in 1957.

To hear an example of their song, see an excellent video by naturalist and photographer Lang Elliott of some white-throated sparrows.

Our 37-acre First Field is especially popular with white-throated sparrows because of their fondness for grass and weed seeds as well as the fruits of wild grapes, dogwood and sumac during the fall and winter. I’ve also heard and seen them at the smaller, but equally overgrown Far Field as well as along Bird Count, Greenbrier and Ten Springs trails, all of which are in the 26-year-old, poorly logged, brushy area of our property.

Although a couple white-throats come to our feeder area, others are able to sustain themselves on wild foods during most winters. Only when the winter is particularly harsh do more white-throats, eager for oil and shelled sunflower, millet, milo and cracked corn, appear in our feeder area. Using both feet, they scratch up seeds that I throw below our back steps.

A white-throated sparrow in the snow

A white-throated sparrow in the snow (Photo by Dr. Thomas G. Barnes, USFWS, in Pixnio.com, in the public domain)

Here on our mountaintop we don’t have the wintering numbers of white-throats that stay in the valleys and lowlands of Pennsylvania, especially in the warmer southeast Coastal Plain and Piedmont regions. And when I studied my old Project FeederWatch records dating back to the winter of 1988-89, I was surprised to note that there were no white-throats until 1995-96 and then they only averaged 1 to 1.6 per visit to the feeders each winter until 2004-05 when the average shot up to 4.4 and 2005-06 when it was 5.6. After that, the feeder numbers averaged between 2 and 3 until the frigid winter of 2014-15 when there was an average of 6.7, the highest number ever. Last year’s mild winter pushed their average back down to the more normal 2.2.

Checking my journals, I also discovered that we have always had wintering white-throats in brushy, wet areas as well as the drier brush of the Far Field. Furthermore, I rarely see them during my walks, but I know them by their songs and their scolding “clicks” even as they remain hidden from me.

When they feed in flocks during the winter and even in feeder situations, they maintain a discreet distance from others in their flock, probably to avoid aggression with other white-throats. As a species, they give up space and food to blue jays, eastern towhees, northern cardinals, fox, song and most white-crowned sparrows but will dominate swamp and field sparrows and chickadees.

A white-throated sparrow on a bird feeding platform

A white-throated sparrow on a bird feeding platform (Photo by John Flanner on Flickr, Creative Commons license)

In white-throat winter flocks, males, old birds, and those that have returned winter after winter to the same area are dominant. They sing the most, feed close to protective cover, and are not often interrupted in their feeding by other members of their flock. Their winter home ranges are small, and they remain there even through midwinter when food resources dwindle.

My only time to study them is at the feeder area when they are out in the open. And it’s then that I can plainly see the two morphs or forms for which they are famous among researchers. Both do have white throats as well as yellow lores or spots in front of their eyes and grayish bills, but those with white and black stripes on their heads are known as white-striped morphs and those with tan and brown stripes as tan-striped morphs. Because each morph mates with its opposite, these differences remain from generation to generation.

A brown and tan striped morph of a white-throated sparrow

A brown and tan striped morph of a white-throated sparrow (Photo by Cephas in Wikipedia, Creative Commons license)

Not only do they look different, they behave differently. White-striped males sing more, are more aggressive and are more likely to mate with other females in addition to their mates. Tan-striped males and females and white-striped females provide more parental care than white-striped males. White-striped females sing and help defend territory, but tan-striped females do not.

Here in the eastern United States, white-throated sparrows (Zonotrichia albicollis) and their close congeners white-crowned sparrows (Zonotrichia leucophrys) can be mistaken for each other. But white-crowns have brighter white crowns edged with black, pink or orange bills, and no yellow lores. Still, all white-crowns have grayish-white throats and immatures have dark red-brown and light buff head stripes that resemble tan-striped white-throats, but the latter still have those distinctive yellow lores. Both species also have white wing bars on brown-streaked wings, backs and tails.

Except for their unique polymorphism, white-throats are much like other sparrow species. Although they breed mostly in the boreal coniferous and northern hardwood forests of Canada and the northern United States, northern Pennsylvania is the southern edge of white-throat breeding in the East, especially in the forested wetlands and shrub lands of northern Susquehanna and Wayne counties, the juncture of Lackawanna, Luzerne, Carbon and Monroe counties, on North Mountain in eastern Sullivan and southeastern Wyoming counties, along the border between Wyoming and Bradford counties, and in or near the Allegheny National Forest in McKean County according to Nicholas C. Bolgiano in the Second Atlas of Breeding Birds in Pennsylvania.

“The White Throated Sparrow, from Pensiluania, and the Yellow Butterfly, from Carrolina,” plate 304 in Gleanings of Natural History (1758) by George Edwards (In the public domain)

“The White Throated Sparrow, from Pensiluania, and the Yellow Butterfly, from Carrolina,” plate 304 in Gleanings of Natural History (1758) by George Edwards (In the public domain)

White-throated sparrows were first described back in 1760 in G. Edwards’s “Gleanings” and was based on a specimen from “Pensilvania,” so the species has a long association with our state. No doubt there were many more white-throats then when our state had a larger coniferous component in our forests, the climate was colder, and we had many more wetlands. Between our first and second atlasing periods, breeding white-throats had declined and were found in 33% fewer blocks, suggesting, Bolgiano writes, “that the White-Throated Sparrow may be contracting into a few core areas in Pennsylvania,” most notably North Mountain of Sullivan County, which he calls “an important stronghold for this species” in the commonwealth. He mentions our warming climate and the maturing of our forests as possible causes.

Today white-throats begin appearing as spring migrants in Pennsylvania the second or third week in March in the Coastal Plain and Piedmont areas and the third and fourth weeks in March in the rest of the state with peak numbers from the third or fourth week in April to the second week in May. The last date I have for them here is May 15.

Since white-throat females winter farther south than males, males usually arrive on their breeding grounds a week or two ahead of the females and experienced males earlier than novices. Here in Pennsylvania breeding white-throats appear in mid-to-late April. They search for mixed forests with openings that have low, dense vegetation where they can hide their nests on or near the ground. They also establish and defend their 1.9 to 3.2-acre territories from other males.

Once the females return, they pair up and couples forage together, with the males protecting or perhaps guarding the females from other intruders. The females probably choose the nest site. They also construct their open cup nests of bulky materials such as coarse grasses, twigs, pine needles, and roots and line them with finer materials including fine grasses, rootlets, and deer hair.

A white-throated sparrow nest with eggs

A white-throated sparrow nest with eggs (Photo by Kent McFarland in Flickr, Creative Commons license)

When their nests are finished, they lay on average four pale blue or cream-colored boldly brown-spotted eggs and begin incubating on the day the fourth egg is laid. Usually the females incubate the eggs for 12 days.

The young are born mostly naked and their eyes remain closed for the first three days. Their mothers do much of the brooding and shading of the nestlings, and they remain mostly still until they are seven days old. Then they call as their parents approach the nest with a selection of insects and spiders.

Both the eggs and nestlings are especially prey for red squirrels, eastern chipmunks, and eastern garter snakes. Other possible predators are red foxes, short-tailed weasels and short-tailed shrews. Predators on adults include merlins, sharp-shinned hawks, and short-eared owls as well as the mammalian predators.

An immature white-throated sparrow

An immature white-throated sparrow (Photo by Jeremy Meyer on Flickr, Creative Commons license)

The young leave the nest on foot at seven to 12 days of age, but they need another week before then can fly. Their parents continue to feed them and to defend them from predators by distraction displays such as a slow flutter-flight above the vegetation, a wing-drooping run while calling loudly, or a wings-up-walk where the parent seems to fall to one side while holding up one or both fanned wings.

The parents care for their young for at least two weeks after they fledge and sometimes even after the females begin incubating a second brood. But not much is known about how the young disperse.

Still, by September adults of both sexes and immatures have flocked together and begun their long, slow migration south for another winter in warmer climes.