Black Squirrels

“Mom, there’s a black squirrel in the flat area.”

A black gray squirrel

A black gray squirrel (Photo by Robert Taylor on Flickr, Creative Commons license)

It was 5:30 p.m. on a balmy day in early March and my son Dave and I were fixing dinner in the kitchen.

I rushed to the window, grabbed my binoculars, and called my husband Bruce to come and see the unusual eastern gray squirrel.

In the meantime, the squirrel had climbed up the back slope and we thought it would come to our bird feeder area below our porch steps. Instead, it veered over to the far edge of my backyard herb garden beside the feeders and ran off. A few minutes later Bruce spotted it below the slope near our old springhouse before it disappeared.

During our 46 years on our mountain we had never seen a black gray squirrel, although I knew there was a population on the Penn State Altoona campus at the base of the Allegheny Front. And later, our caretaker Troy told us he had never seen any black squirrels on our Brush Mountain, the westernmost ridge in the Ridge-and-Valley Province, but he added that there was a population in a small village at the base of our mountain on the Logan Valley side.

The next time I saw the black squirrel, spring had officially arrived even though it was 17 degrees and the ground had frozen hard again. I stepped outside in the early morning and glimpsed the squirrel at the bottom of a backyard black walnut tree. Spotting me, it ran downslope to the flat area and up into the woods on Laurel Ridge.

On April 3, I again glimpsed the black squirrel in the flat area at 7:30 a.m. A gray squirrel, one of the army of 10 raiding our feeders every day, chased it back up into the woods.

Two days later, after returning from my morning walk, I stopped to admire the blooming hyacinths and daffodils in our backyard. That’s when I noticed the black squirrel crossing the flat area. I watched it through my binoculars while it searched for food beneath the leaf cover at the edge of the woods, and paused a couple times to scratch itself.

A gray squirrel approached a black squirrel

A gray squirrel approached a black squirrel (Photo by Eyesplash on Flickr, Creative Commons license)

Once a gray squirrel approached but did not chase it. Nevertheless, the black squirrel retreated but continued foraging. Next it climbed on to fallen trees, using them as runways. Once it sat up on its hindquarters and I saw that it had an orange underbelly. Then it continued slowly on its trek over to the springhouse and wetland where I lost sight of it among the cattails.

Although I continued looking for it throughout the following months, I never saw it again. I figured that a predator had caught it or that it had been visiting and had moved on. But last November one of our archery hunters saw it still living nearby.

Our black squirrel is one of three possible color phases of the eastern gray squirrel.  In Pennsylvania most eastern gray squirrels are gray, but there are also brown-black gray squirrels (our “black” squirrel) and jet black gray squirrels. Canadian researchers, writing in the Journal of Heredity in 2009, studied the color variations in the coat of the eastern gray squirrel by inspecting the hair from all three types under the microscope and found that the eastern gray squirrel “had 6 distinct hair types, compared with 4 from the brown-black and only 1 from the jet black.”

An example of a squirrel with a grizzled coat

An example of a squirrel with a grizzled coat (Photo by Eugenia Vlasova on Flickr, Creative Commons license)

“These different hair types,” they wrote, “give the gray an overall grizzled appearance with a white underbelly, the brown-black an overall dark brown appearance with an orange underbelly, and the jet black a uniform black appearance.”

Or, in the words of Dr. Carolyn Mahan, professor of biology at Penn State Altoona, “The genetic basis of this color phase was researched and determined to be a simple dominant/recessive interaction. Black color is dominant, gray is homozygous recessive, and it sounds like you have a heterozygous individual.”

A brown-black squirrel on the Penn State Altoona campus

A brown-black squirrel on the Penn State Altoona campus (Photo by Dr. Laura Palmer, used with permission)

Mahan adds that the brown/black squirrels have been on the campus at least since 1999 when she began teaching there. She says that, “It is not that they ‘arrived’ there. It is just that the allele [one of a group of genes that occur alternately at a place] for the black color is present in that population. It seems that most of the ‘black’ squirrels are heterozygous for the trait so, if you look at them in bright sunlight, they appear dark dark brown. It seems on our campus there are an equal number of gray and black squirrels.”

Scientific descriptions aside, black gray squirrels are more common farther north while gray squirrels dominate southern areas in the eastern United States and Canada.

Some researchers believe that before Europeans arrived in North America, black gray squirrels were predominant throughout eastern North America because forests were old and thick and provided better cover for that color phase. But once the forests were cut, they hypothesize, gray squirrels became the dominant type throughout their range.

A black gray squirrel in Canada

A black gray squirrel in Canada (Photo by DaPuglet on Flickr, Creative Commons license)

Another, earlier study in Canada in 1978, where black gray squirrels dominate, found that they had “significantly lower heat loss” than gray squirrels during the winter which they thought explained why black gray squirrels were common where winters were colder and there was a constant snow cover despite the fact that a black coat would not provide camouflage for them in a white world.

Native black gray squirrels live in Ontario and Quebec and northern Michigan, Wisconsin, Minnesota and Pennsylvania. But there have been so many releases of these squirrels both in the United States and England, usually courtesy of Ontario, that it is difficult to sort the naturally occurring from the released ones.

In Britain they were released at the end of the 19th century and 18 from Canada arrived at the National Zoo during Teddy Roosevelt’s presidency. Canada also sent 10 to Kent, Ohio in 1961.

The home of the black squirrels, Marysville, Kansas

The home of the black squirrels, Marysville, Kansas (Photo by Jimmy Emerson, DVM, on Flickr, Creative Commons license)

Strangest of all is the so-called “Home of the Black Squirrels” out in the plains in Marysville, Kansas. Supposedly the squirrels escaped from a traveling circus or maybe a gypsy encampment in the late 1920s. Marysville even holds an annual Black Squirrel Celebration.

The black squirrels in Washington, D.C. have spread over the city, and they’ve done the same in other towns and cities where they were released. Apparently, they are safer from their predators, which are primarily birds of prey. And squirrel hunters, eager to bag a black gray squirrel, cannot shoot them in such places.

I checked a couple online sources regarding black gray squirrels in Pennsylvania and compiled a list of cities and towns where black squirrels live such as Fairmont Park in Philadelphia, the Haverford College campus, which has so many that they’ve adopted Black Squirrels as their sports mascot, and the eastern suburbs of Pittsburgh.

A.D. Plummer, who says he hunts and fishes every day in central Pennsylvania, according to the Answers section of the Field and Stream website, claimed he had never seen a black squirrel there until 2009 when he saw two in two places 30 miles apart.

A brown-black squirrel photographed in Goddard Park, Chester County, PA

A brown-black squirrel photographed in Goddard Park, Chester County, PA (Photo by Brian Henderson on Flickr, Creative Commons license)

This provoked several more comments over the next few years. S. Testy, who lives in Enola, Cumberland County, also in central Pennsylvania, wrote in 2009, “There’s a pak of black squirrels that live on Valley Road and North Enola Drive…I’ve seen several out at one time.”

M.J. Frazier in 2012 reported from western Pennsylvania that a small colony nested in their neighborhood and liked bird seeds but stayed away from the gray squirrels.

“The squirrels are solid black and look very kinetic as they move about,” Frazier reported. “They will not come to the feeder close to the house [which probably explains why ‘our’ black squirrel ignored our feeders], but [to] one in the yard about 30 yards away which is stocked with black oil sunflower seeds.”

Rudy Glove, writing in 2015, added “Black squirrels everywhere now.’

Well, not quite everywhere. On the website in answer to a hunter’s question about where he can find black squirrels, it looks as if the largest numbers still live in the wild across the northern tier of the commonwealth.

One hunter found black squirrels scattered in five different locations over four counties—Lycoming, Clinton, Potter and Tioga.

Another reported three blacks to one gray in Cook Forest, Clarion County, adding that one day he counted five different black squirrels.

Several were seen near Dubois in Clearfield County and a couple hunters claimed they were common near Kinzua Dam in the Allegheny National Forest. Two hunters mentioned Pike County in northeastern Pennsylvania, and another Brookville in Jefferson County near Treasure Lake.

Whether all these squirrels were coal black, brown-black, or both is not clear except for those reported by M.J. Frazier, but S. Testy does question articles that say only one gray squirrel in 10,000 is black and suspects, at least here in Pennsylvania, that that is a low estimate.


Weird Winter

The weird winter of 2017 had thaws longer and warmer than freezes. Our white nights of bright moonlight shining on snow were scarce. It was an old person’s winter lacking the usual ice and snow that often makes for hazardous walking. Since I am an old person, I should have been grateful but I wasn’t because rain and above average temperatures most of January brought out the ticks.

An eastern towhee taken in winter in southeastern Pennsylvania

An eastern towhee taken in winter in southeastern Pennsylvania (Photo by Kelly Colgan Azar on Flickr, Creative Commons license)

Near the end of January, when the thermometer fell below freezing for a few days, a male eastern towhee appeared in our bird feeding area and stayed for a short while. Never before had I seen a towhee at our feeders in winter.

Our feeder visitor used our old Christmas tree, which we had laid out below our back porch, as cover and he called “toe-hee” several times. His robust reddish-brown, black and white body was a striking contrast to the smaller, brown and gray birds feeding on the ground around him.

On the third day of his visit he sang his “drink your tea,” undoubtedly his swan song since that was the last time we saw him. Maybe he sensed the imminent six-inch snowstorm, but he should have waited until February because on the first of the month it warmed up to 48 degrees and most of the snow melted.

Once again we were back to a snow-less, beige, black, and brown forest with touches of evergreen. On Groundhog Day Punxsutawney Phil saw his shadow and predicted six more weeks of winter. I was dubious of his claim. By February 6 it smelled, looked and sounded like spring as pileated woodpeckers drummed and northern cardinals, black-capped chickadees and tufted titmice sang.

Two chipmunks in Pennsylvania

Two chipmunks in Pennsylvania (Photo by Jim, the Photographer on Flickr, Creative Commons license)

Two chipmunks joined the feeder birds in the morning and two more chased below the guesthouse porch, clearly in courtship mode, as the temperature rose to 56 degrees. I predicted an increase in chipmunk numbers for the year, not only because of the huge acorn crop the previous fall, but because the mild February would give them plenty of time to breed.

“Nature’s pruners” worked overtime as “March” winds ripped through a week of February days and nights, and fallen limbs and dead trees littered the trails. The winds were followed one night by an almost unprecedented February thunderstorm that began with claps of thunder and streaks of lightning and ended with pings of sleet on our bow window as the temperature dropped below freezing.

During the Great Backyard Bird Count (GBBC), scheduled as a mid-winter count February 17 through 20, we had the best weather ever for that time of year. Unlike other years, when the trails were icy or deep in snow, the ground was open, and I was able to wander much farther than during previous GBBCs.

The first day of the GBBC, full of expectation, I hiked up a path-less section of Sapsucker Ridge, but except for distant woodpecker drumming, I neither saw nor heard any birds. Even the spruce grove was quiet.

A white-throated sparrow photographed during a Great Backyard Bird Count

A white-throated sparrow photographed during a Great Backyard Bird Count (Photo by Stephen Little on Flickr, Creative Commons license)

However, when I reached the Far Field, six dark-eyed juncos flushed from the side of Pennyroyal Trail. I listened to a pair of chickadees counter singing, heard a downy woodpecker drumming, and saw a couple white-throated sparrows lurking in the barberry shrubs at the far end of the Far Field.

From there I walked to the Second Thicket and heard a pileated woodpecker drumming. It seemed to be woodpecker-drumming weather, and the pileateds sounded like the drum roll of a marching band. I wondered how far pileated drumming carried, because beyond the Second Thicket halfway down another ridge, I heard another pileated, and on Coyote Bench still another. It was as if the whole mountain was a pileated band, drumming in an early spring.

By mid-afternoon it was 57 degrees, yet my bird species’ list was sparse despite the miles I had walked. Near our feeders and on them were more bird species than I’d seen on my entire hike.

The next day was even warmer, reaching 67 degrees, yet it felt strange. Even though it was as warm as late March, no spring birds had returned. All I heard or saw were pileateds on another long walk in another part of the mountain, an area full of brush that usually held small birds.

Two Canada geese flying overhead

Two Canada geese flying overhead (Photo by Craig Bennett on Flickr, Creative Commons license)

On the third day of the GBBC, it was warm, overcast and breezy and two Canada geese croaked past over Sapsucker Ridge at 7:15 in the morning. They could have been part of the local flock way ahead of their usual 10:00 a.m. flyover or possibly early migrants lost from a larger flock.

As I started on my walk for the day, I paused to watch a pair of white-breasted nuthatches chase a downy woodpecker from a yard black walnut tree.

Then on I walked in Sunday’s silence and, at the entrance to Bird Count Trail, a tufted titmouse scolded, throwing its voice in every direction, starting quietly and getting progressively louder as a male downy woodpecker foraged quietly on a nearby tree.

A red-bellied woodpecker called from Greenbrier Trail followed by a pileated. Slowly I climbed up Dogwood Knoll to Sapsucker Ridge as the wind picked up. A pair of turkey vultures floated overhead—the first migrants of the season and three weeks earlier than usual.

A turkey vulture flying over Plummer’s Hollow

A turkey vulture flying over Plummer’s Hollow (Photo by Dave Bonta on Flickr, Creative Commons license)

A red-tailed hawk flashed past, but it was probably our resident red-tail enjoying the wind. Then a third turkey vulture appeared, reminding me that the Winter Raptor Survey statewide recorded the highest number of turkey vultures ever, although we didn’t see any on our count in nearby Sinking Valley.

By afternoon, it was 62 degrees on the veranda, and Bruce and I sat there, soaking up the sun for a winter that might or might not return. Our resident chipmunk, which has its den hole at the far end of our veranda, approached my feet and then Bruce’s, sniffing his fur-lined slippers before running off. Maybe it was trying to figure out what kind of creature the fake fur was.

The weather was still beautiful, clear and warm the last day of the GBBC. I was hoping to see or hear birds, but I walked a totally silent, bird-less Ten Springs Trail and up a bird-less road. But chipmunks mate-chased throughout the forest.

Even our feeder birds had dwindled—six juncos instead of the usual 40 and no cardinals, goldfinches or blue jays, all of which had been there the previous days. Were they as flummoxed as I was over the “winter” weather or was the open ground providing more natural food for them?

A winter wren taken in February in Delaware

A winter wren taken in February in Delaware (Photo by Kelly Colgan Azar on Flickr, Creative Commons license)

All in all I counted 22 species, the lowest number ever despite the turkey vultures. Winter bird diversity continues to dwindle from GBBC to GBBC. Last winter I found no brown creepers, winter wrens, or golden-crowned kinglets, usually dependable GBBC species here.

Still the warm weather continued. The next day as I walked up First Field Trail, I noticed fresh turkey scat. When I started along the Far Field Road, the leader of a flock of wild turkeys saw me before I saw it. They rushed across the road and out of sight so quickly that I didn’t count them thoroughly, although there were at least 30, giving me species number 23 for the mountain but too late for the GBBC.

I sat on Alan’s Bench and watched as a chickadee extracted cone scales from a low-hanging Norway spruce bough with a cluster of cones at its tip. Then the chickadee landed on a nearby branch to extract the paired seeds from the scale. Silently it did this three times before calling “dee-dee-dee” and flying away. Observing bird behavior is always more rewarding to me than counting species.

Off and on I thought I heard tundra swans, but they must have been above the thin cloud cover. Still, I was eager to see those flying angels and early harbingers of spring. As I descended First Field, near the powerline right-of-way, I stood in the wind and counted 160 tundra swans heading northwest.

A mourning cloak in Plummer’s Hollow

A mourning cloak in Plummer’s Hollow (Photo by Dave Bonta on Flickr, Creative Commons license)

The unseasonable weather continued. On the 24th our son Dave reported the first mourning cloak butterfly on Sapsucker Ridge, a full month ahead of our earliest date. It was 78 degrees by mid-afternoon, and later we learned that 4000 temperature records had been broken for this date throughout northern North America.

The first fox sparrows arrived from the south on the 26th, en route to the north, and a pair of mourning doves billed and cooed for 20 minutes on the ground below the feeder.  The following day I watched them copulating on an ash tree limb.

Spring was definitely in the air. Punxsutawney Phil had called it very wrong, at least for February, and, as it turned out, for March as well.

It was indeed an old person’s winter, but whether it was an anomaly or a portent of winters to come remains to be seen.


Our Noisy World

I used to fear the wind, especially when it roared on top of Sapsucker Ridge. But ever since Interstate 99 was opened, directly beneath the ridge, the wind has been my friend because it masks the traffic noise.

Heavy traffic on an interstate near Pittsburgh

Heavy traffic on an interstate near Pittsburgh (Photo by Doug Kerr on Flickr, Creative Commons license)

During the winter, without the leaves on the trees to absorb some of the clamor, the interstate traffic is louder than ever. Researchers have found that at least six-tenths of a mile on each side of a road is affected by traffic noise, and a portion of our property is much closer than that.

Many humans are badly affected by continual anthropogenic noise, especially that made by roads, airplanes, and extractive industries such as fracking and mining.

In the last couple decades some researchers worldwide have been studying the effects such noise also has on wildlife, particularly birds. They’ve found that sounds made by vehicles, oil and gas fields, and urban sprawl can change the way animals communicate, mate, and prey on one another.

A white-crowned sparrow in California

A white-crowned sparrow in California (Photo by Mike Baird in Flickr, Creative Commons license)

Back in the 1960s, ornithologist Luis Baptista recorded white-crowned sparrow songs in San Francisco and discovered that they sang in three distinct dialects in different areas of the city. David Luther, a George Mason University biologist, studied the same areas in San Francisco in 2008. The traffic noise was much louder in 2008 than it was when Baptista made his recordings. As a result, the white-crowns had raised the pitch and length of their songs to be heard above the urban din and sang in only one dialect.

Another study, of both chipping sparrows and white-crowned sparrows in 2017, also found that white-crowned sparrows as well as chipping sparrows changed their songs in a noisy environment. Two other studies revealed that song sparrows and red-winged blackbirds did the same.

Luther hypothesizes that, “With our loud noise we might be influencing the very evolution of these birds.”

An eastern bluebird on a birdhouse in North Carolina

An eastern bluebird on a birdhouse in North Carolina (Photo by Ken Thomas in Wikimedia, in the public domain)

Eastern North America has little or no areas that are not affected by roads, and Pennsylvania has more than its share of them. Even a bird species seemingly unperturbed by roads—the eastern bluebird—appears to have problems with anthropogenic noise, according to a study of breeding eastern bluebirds in Williamsburg, Virginia.

The scientists concluded that their “study does provide evidence that bluebird fitness is being compromised at stages between egg hatching and chick fledging,” producing smaller brood sizes and less productivity, and thus “the birds will be particularly sensitive to noise during this (approximately) two-week time period.”

Furthermore, they suggest that managers try to keep favored songbird breeding habitats free from human-caused noise pollution.

Other studies report such effects of noise on wildlife as hearing loss from noise levels 85 decibels or greater, masking so that wildlife can’t hear animal signals, predators, or other environmental cues, increased heart rates and stress levels, and even the abandonment of noisy territories.

Probably the most interesting study of road noise in the United States was conducted by Boise State University ecologist Jesse Barber and his graduate students in a roadless southern Idaho forest which had plentiful food for migrating birds. They created a “phantom” road by blasting national park road noise through speakers during fall migration. Thirty-one per cent of the songbird community avoided the area. Those that remained to feed couldn’t gain weight, probably because they were too busy looking for predators.

Barber also cited a study in 49 places worldwide where bird populations declined within six-tenths of a mile of traffic noise. Birds with low frequency songs, such as mourning doves, avoided roads altogether, since they couldn’t be heard above the hum of traffic.

Compressor stations, such as this one in Milford, PA, bombard surrounding forests with noise

Compressor stations, such as this one in Milford, PA, bombard surrounding forests with noise (Photo by cool revolution in Flickr, Creative Commons license)

But roads aren’t the only noise problem that birds face. Studies in natural gas extraction fields found that compressor noise running 24 hours a day changes both breeding areas for songbirds as well as species’ numbers. Those birds that remain despite the noise may have trouble hearing songs or evaluating possible mates, parents may not hear chick noises or have less chance to forage.

In a study Barber and students did of 31 northern saw-whet owls subjected to recordings of a natural-gas compressor station, he reported that every time he raised the sound level by a decibel, the owls’ hunting success declined by eight per cent. Apparently, this owl species can hear sounds as low as negative 20 decibels while hunting for rodents, and when the researchers raised the volume to 60 decibels, the owls couldn’t catch any prey at all. Since all owl species depend on their ears and their eyes to hunt at night, we can only wonder how many other owl species might be impacted by noise.

A three-year study in the woodlands of northern New Mexico surveyed sites next to natural gas wells with compressors, which they compared to sites next to natural gas wells without compressors. Although they found no difference in the number of birds’ nests in both areas, they did observe 21 species nesting at compressor sites and 32 species nesting at those without compressors. However, nests of 14 species were found only at sites without compressors, yet nests of just three species were located only at compressor sites.

In addition, a common species, the house finch, produced 14% of the nests near compressors whereas more uncommon bird species preferred the gas wells without compressors. A whopping 22 of 23 mourning dove nests were built in the vicinity of gas wells without compressors. Even those species that nested near the compressor sites placed their nests farther away from well pads with compressors than they did on those without.

A western scrub jay found in Santa Fe, New Mexico; as of 2016, known as a Woodhouse’s scrub jay

A western scrub jay found in Santa Fe, New Mexico; as of 2016, known as a Woodhouse’s scrub jay (Photo by Peter Wallack in Wikimedia, Creative Commons license)

Another interesting finding was that predators, such as western scrub-jays, avoided the noisy sites and preyed more heavily on nests in the quiet sites. Possibly they preferred the quiet sites because they couldn’t communicate over the noise of compressors.

The researchers concluded that “species intolerant of noise may suffer from not only exclusion from noisy habitats that might be otherwise suitable but also higher rates of nest predation relative to species inhabiting noisy areas.”

They go on to hypothesize that perhaps anthropogenic noise “may help explain the high degree of success among urban-adapted species [such as house sparrows, European starlings, and American crows, for instance] and the homogenization of avian communities in and around human-altered habitats.”

Still another study compared the nesting success of ovenbirds at compressor sites with those without. Although this study was done in boreal Canada, ovenbirds commonly nest in the forests of Pennsylvania and have always and continue to nest in our Laurel Ridge forest, which, unlike Sapsucker Ridge, overlooks a quiet, farming valley. If they still nest on Sapsucker Ridge, I can’t hear them above interstate noise.

An ovenbird on the ground

An ovenbird on the ground (Photo by Trish Gussler on Flickr, Creative Commons license)

The ovenbird researchers discovered that the birds paired at a rate of 92% in the quiet sites and 77% in the noisy sites, probably because the females could not hear the males’ low-frequency “tea-cher, tea-cher” song as readily in the compressor sites. They add that most bird species in forests have low-frequency songs because they “provide optimal long-distance song transmission range in complex forest structures.”

Because of the steepness of Sapsucker Ridge on the interstate side, I have not been able to record bird species and numbers there during the several bird surveys I do here every year, most notably the Christmas Bird Count in December and the International Migratory Bird Count in May. I know that my own hearing is age-impaired, and I can’t hear birdsongs in the distance as I used to.

Since everyone who engages in various bird surveys depends on hearing bird calls and songs to identify them, ecologists in North Carolina wondered if declines in some breeding birds were due to background noise that interfered with the bird counters’ hearing.

The ecologists targeted a few of those experts who participate in the annual North American Breeding Bird Survey, the primary source for population and range information for over 400 species since 1966, and other experienced birders and played singing bird songs against varying levels of anthropogenic noise. Even a small amount of noise led to a 40% decrease in their ability to identify birds.

I can only imagine how many birds I miss every year.


Every winter my feeder birds are mostly the same, both in species and numbers. But usually there is at least one surprise, even in winters when no northern finch irruptions occur.

A blue jay on a feeder in Montgomery County, PA

A blue jay on a feeder in Montgomery County, PA (Photo by Brian Henderson on Flickr, Creative Commons license)

Last winter was the year of blue jays, often nicknamed “jaybirds” because of their calls.

We live tucked away by ourselves atop a mountain so we’ve never had more than a couple blue jays at our feeders over the 46 years we’ve lived here, and many winters none at all. But beginning in early December last year, blue jays started appearing in greater numbers, just as the cold and snow set in.

On December 16, with the thermometer at three degrees Fahrenheit, I counted 10 blue jays at our feeder area. From then until late January, numbers varied from seven to a high of 11 on January 16 when they blanketed the ground with their electric blue color.

Usually they stayed on the ground to feed, sparring with each other and the gray squirrels while the mourning doves and the smaller songbirds hung out in the periphery or visited the feeders, which, in turn were dominated by a pair of red-bellied woodpeckers.

A blue jay feeding with a red-bellied woodpecker in Danville, PA

A blue jay feeding with a red-bellied woodpecker in Danville, PA (Photo by fishhawk on Flickr, Creative Commons license)

At least some of the blue jays roosted in our Norway spruce grove and sounded their clarion “jay-jay” calls whenever I neared it on my daily walks. In mid-February, when blue jay numbers at the feeders had diminished, I found a trail of plucked blue jay feathers in the grove as well as plenty of “white wash” on the tree branches. I suspected a barred owl had been feasting on the blue jays, but whether it was death, the unseasonable warm weather, or some other reason, I last recorded five blue jays at the feeders on February 20 and then no more.

Despite being common birds that almost anyone can identify, these clever members of the Corvid family are not as easy to study as other corvids, such as American crows, because they are secretive and quiet during the spring and summer when they are courting, mating and raising their families.

But as acorns ripen on oak trees, these forest denizens announce their presence here, picking and eating acorns and beechnuts before they fall to the ground. Last autumn both the red and white oak complexes produced a huge crop of acorns, and no matter where I walked I could hear blue jays.

A blue jay with an acorn

A blue jay with an acorn (Photo by Tom Shockey on Flickr, Creative Commons license)

They also cache acorns to eat in the winter and spring, tucking two to three acorns in their expandable throat and upper esophagus, a fourth one in their mouth and a fifth in their bill and carrying them as far as a mile to cache in more open areas. They do the same with beechnuts.

Writing in The Second Atlas of Breeding Birds in Pennsylvania, Douglas Gross (Game Commission Endangered and Nongame Birds Section supervisor) calls the blue jay the “keystone bird of eastern deciduous and mixed forest of North America because of its habit of caching tree seeds, inadvertently planting deciduous trees, especially oaks and beeches…”

Like most caching birds, blue jays have excellent memories for where they hid their nuts, but a few are always missed. In Blacksburg, Virginia, researcher Susan Darley-Hill found that in 28 days approximately 50 blue jays carried and cached 150,000 acorns, which was 58% of the total nut crop from a mere 11 pin oak trees. Furthermore, they were capable of choosing sound acorns that had not been affected by weevil larvae.

Blue jay close-up with an acorn

Blue jay close-up with an acorn (Photo by Kenneth Cole Schneider on Flickr, Creative Commons license)

With those numbers, I can only imagine how many acorns blue jays transported from our forest last autumn. Still, I wondered if the huge crop of acorns was harvested by our resident blue jays or by those that had migrated from other areas.

Like most aspects of blue jays’ lives, their migration patterns are also puzzling. The northernmost subspecies of blue jays (Cyanocitta cristata bromia, our northern blue jay) lives as far north as Canada in the southern half of Ontario, Quebec, and New Brunswick. Sometimes northern blue jays may migrate south since thousands, moving in flocks from five to 250 birds, have been observed over the Great Lakes, including Lake Erie.

In Pennsylvania hawk watchers on our mountain ridges east of the Allegheny Front have reported migrating blue jays from the third week in August to the second week in November, although the greatest numbers migrate in mid-September to mid-October.

While blue jays winter in every Pennsylvania county, the jays are a mixture of resident and migrant birds. Researchers used to think that young jays were the migrants, but more recent studies show that jays of any age may migrate. Furthermore, it looks as if individual jays decide on a year to year basis whether to stay put or move south. Most likely it relates to either food sources, weather conditions or both.

A blue jay on a nest in Codorus State Park, Hanover, PA

A blue jay on a nest in Codorus State Park, Hanover, PA (Photo by Henry T. McLin on Flickr, Creative Commons license)

During spring in Pennsylvania blue jays migrate north from late April until mid-May. By the fourth of May, our resident blue jay males have already engaged in courtship displays with their monogamous partners, which continue as they select their nest sites and construct their nests. Usually they settle on a tree or bush as high as 25 feet from the ground, preferring an evergreen, but settling for whatever is available. They may even use rural mailboxes or occupy the nests of American robins.

Both sexes build their cup-shaped nest of twigs, small roots, moss, lichens and bark as well as human detritus such as light-colored tissue, cloth, paper, string, and wool. The male feeds the female as she sits on the three to seven bluish or light brown, spotted eggs for 17 to 18 days, beginning in late May in Pennsylvania. Then she broods her young for half their 17 to 21 days in the nest before she joins her mate in finding food for their offspring, although the male continues to provide most of the food.

A juvenile blue jay

A juvenile blue jay (Photo by Carolyn Lehrke on Flickr, Creative Commons license)

After their nestlings fledge, usually by July, the family remains together for another month or two. Then the young are on their own, while their parents sustain their bond for their lifetime.

Blue jays eat a wide variety of material including 22% insects during the breeding season. They are known for “anting,” rubbing ants against their feathers to remove the formic acid, not, as previously believed, to rid themselves of parasites, but so they can eat the ants, according to a recent study which found that 10 ants equals one egg in nutritional value.

Blue jays also consume human-based food—cultivated grains (especially corn) and fruit, bread, and dogfood—in addition to hard mast (43%) except in July and August. Their reputation for eating birds’ eggs and nestlings is highly overrated, and most studies put such food at one to two per cent of their diet if that.

Blue jays have their own predators to guard against. As adults they are the victims of Cooper’s, broad-winged and red-tailed hawks, great horned and barred owls and eastern screech-owls. Gray and fox squirrels kill and eat young fledglings, and nest predators include American and fish crows, squirrels, black rat and northern black racer snakes, raccoons and opossums.

Blue jays are known for their wide variety of calls and use them to mob hawks, large snakes, raccoons, domestic cats, and large owls. The video embedded below illustrates the variety of calls made by blue jays. These “songbirds without a song,” as Donald Kroodsma labeled them in his The Singing Life of Birds, use many sounds. After observing a pair on their nest near his home in Amherst, Massachusetts late in April, he noted that “the jays seem infinitely expressive, capable of transforming the simplest of jay sounds into a diverse array. At one extreme, the harsh ‘jay’ becomes a single, fine pure whistle, often with harmonics. Sometimes only one voice box will be engaged, sometimes two, creating special tonal effects.”

Altogether, in three and a half hours, he heard from those jays and others that visited them, five different ‘jay’ variations, two ‘squeaky-gate’ calls, melodious ‘bell calls’ and from the female on the nest ‘rattle’ calls.

“How little we know about these jays—that’s what my brief experience with them has taught me,” he concluded.

In Pennsylvania, blue jays increased from the first to the second atlasing periods with their highest numbers in Montgomery, Lehigh and Bucks counties in scattered woodlots. Because blue jays are able to adjust to changing land practices and airlift tree seeds to open areas, they will remain valuable “ecosystem engineers,” in the eastern United States by “increasing their caching effort after fires and selecting canopy gaps as cache sites,” according to a Cornell Lab press release of a study entitled “Jays and Crows Act as Ecosystem Engineers.”

Even renowned Philadelphia naturalist William Bartram, back in the early nineteenth century, recognized that blue jays “alone are capable, in a few years’ time, to replant all the cleared land.”