December | 2018 | Birds and Buds

Many species of birds, including raptors, warblers, waterfowl, shorebirds and sparrows migrate twice each year, south in fall, north in spring. Not all birds migrate to the same places each year though. Some birds that breed in the boreal forests of the north come as far south as the Mid-Atlantic states only occasionally, after an absence of several winters. These irregular southward migrations are known as irruptions. Unusually large numbers of several of these “irruptive” species have reached Virginia this winter, including such beautiful birds as purple finches, red-breasted nuthatches, and evening grosbeaks.

Purple Finch

Other irruptive species include boreal finches, like pine siskin, red and white-winged crossbills, common and hoary redpolls, and pine grosbeaks, as well as certain species of owls and raptors, such as rough-legged hawk, northern goshawk, and snowy owl. Black-capped chickadees also irrupt. These northern species rarely all come south in the same years, but it is not uncommon to have years when multiple species have large coordinated movements.

Irruptive birds move south when there is not enough food to support their populations in the north. The finches, red-breasted nuthatches and black-capped chickadees fly south because of bad conifer cone crops in the boreal forest. Snowy owls, on the other hand, seem to irrupt in years when their prey, lemmings, are particularly abundant. While these irruption triggers appear contradictory, they really are not. In both cases, relative scarcity of prey to predators causes a food shortage. The snowy owl population explodes from the plentiful food to the extent that the lemming population can no longer support them all come winter, so they come south in search of food.

Pine Siskin. Photo by Drew Chaney.

Irruption is closely tied to a cyclical fluctuation in the seed crops of trees the birds depend on as winter food sources. Birches, alders and conifers in the boreal forests— all important food sources for irruptive songbirds — do not bear equal seed crops every year. “Mast” years when lots of seeds are produced are followed by several years of poor seed production. This appears to be an evolutionary strategy to limit the populations of creatures that eat the trees’ seeds to ensure the maximum possible number of seeds survive. In good seed crop years, seed eaters do well, and their population expands. When the next year’s crop is poor, there’s even less food for each animal than there would have been if the population hadn’t grown the year before, and the population falls. Then, when the next good year comes, there are not enough animals to fully capitalize on the seed crop, and some seeds escape. Oaks, hickories, and beeches in the deciduous forests of the East have similar cyclical fluctuations in seed production.

The winter of 2018-2019 is an irruption year for many species of boreal birds. Red-breasted nuthatches started moving south into Virginia as early as August. I saw my first of the season on August 19^thin Sussex County. By September they were abundant throughout the state, with several migrating individuals being observed each day at the Rockfish Gap Hawk-watch in Augusta County. Starting in September and October, the nuthatches were joined by large numbers of purple finches and pine siskins. Numbers of these three species dropped significantly by December, but they remained present throughout the state. Many evening grosbeaks and even a couple of common redpolls have also been found in Virginia this year.

Few of the irruptive finches are as beautifully colored or as interesting as the evening grosbeak. Evening grosbeaks were fairly rare in eastern Canada over 100 years ago. Their population exploded about 60 years ago, which corresponded to a major outbreak of their preferred summer food — the spruce budworm. During the mid to late 20^thcentury, they irrupted in huge numbers, sometimes with hundreds in Virginia at once. Since then, their population in the East has crashed, possibly due to habitat reduction from logging in the boreal forest, increased diseases, or decreased spruce budworm populations. As the evening grosbeak population has declined, they’ve irrupted in smaller numbers. So far, this winter has been relatively great for them though, with many having been seen at feeders around the state.

Evening Grosbeak

Bird feeders are a particularly good way to see some of the beautiful finches that will be visiting our region this winter. Almost all of them like black-oil sunflower seeds. Pine siskins and redpolls — if we should be lucky enough to have more of them this winter in Virginia — particularly like nyjer or thistle seed. My brother and I recently put up a large platform feeder full of black-oil sunflower seeds in hopes of attracting an evening grosbeak, as they apparently prefer platform feeders to tube feeders. In all probability, we won’t see one on our feeder this winter, but you never know!

Sources

Pittaway R. (2014, September 20). Winter Finch Basics. Retrieved from http://www.jeaniron.ca/2012/winterfinches.htm

Pittaway R. (2018, September 20). Winter Finch Forecast 2018 – 2019. Retrieved from http://jeaniron.ca/2018/wff18.htm

Ehrlich P. R., Dobkin D. S., & Wheye D. (1988). Irruptions. Retrieved from https://web.stanford.edu/group/stanfordbirds/text/essays/Irruptions.html

Shaw D. W. Bird Irruption: A Sudden Surge of Birds. Retrieved from http://www.birdsandblooms.com/birding/birding-basics/bird-irruption-surge/

Cornell Lab of Ornithology. Evening Grosbeak Life History. Retrieved from https://www.allaboutbirds.org/guide/Evening_Grosbeak/lifehistory

Mortensen R. (2012, November 7). Birders Can Contribute to Evening Grosbeak Science Right Now! Retrieved from http://blog.aba.org/2012/11/birders-can-contribute-to-evening-grosbeak-science-right-now.html

Devokaitis M. (2018, November 6). This Could be the Winter You Get Evening Grosbeaks at Your Feeder. Retrieved from https://www.allaboutbirds.org/this-could-be-the-winter-you-get-evening-grosbeaks-at-your-feeder/

I don’t remember the first time I heard about the Virginia rarity roundup, but I know I had wanted to participate last year. I couldn’t, because it coincided with the Rio Grande Valley Birding Festival in South Texas, which I was fortunate enough to attend. This November, though, I was excited to bird in this annual birding event on Virginia’s coast.

Rarity roundups are events dedicated to finding rare birds. The first ever rarity roundup was held in coastal Maryland on November 11, 2000. Since then, many other East Coast states have held rarity roundups in early November, including North Carolina, Maine, and Virginia.

Todd Day organized the first Virginia rarity roundup in Northampton County in 2002, and continued to do so on and off until 2016, when James Fox and Matt Anthony took over. The rarity roundup encourages birders to thoroughly survey Northampton County, arguably the best county for birding in the state, during November, which is prime time for vagrant birds. This sort of organized hunt is unique in that it encourages birders to cover all areas equally, including random roads, fields, and woodlands, which visiting birders usually wouldn’t give much attention to. Matt Anthony thinks it’s important to emphasize this approach to rarity finding. As he says, “obviously a rarity can turn up anywhere.” Matt also particularly appreciates the community aspect of the roundup, trying to involve teams from all over the state and organizing a “tally rally” dinner at the end of the day. This year, birders traveled from all over Virginia to participate, including teams from Northern Virginia, Charlottesville, Williamsburg, and as far away as Montgomery County.

Many great rarities have been found over the years during the Virginia rarity roundup, including white-winged dove, western tanager, western kingbird, sandhill crane, ash-throated flycatcher and Harris’s sparrow. Sparse but regular migrants such as cave swallow, golden eagle, clay-colored sparrow, snow bunting and lark sparrow are also sometimes found.

For the rarity roundup, Northampton County is split up into small territories, each of which is assigned to a team. My team, Andrew Rapp, Theo Staengl and myself, got the Eastern Shore of Virginia National Wildlife Refuge territory, which makes up the southeast corner of Northampton County.

We started at dawn at the end of the furthest south road in our territory — Ramp Road. To the south and east we looked out through the half light on expanses of salt marsh and scattered islands. A clapper rail called loudly from a nearby clump of marsh grasses. Wood ducks and mallards flew overhead. A northern harrier hunted over the marsh.

By the time it was light enough to see well, Andrew arrived, and we waded out into the salt marsh in search of sparrows and wrens. Several species of sparrows inhabit Virginia’s coastal marshes during the winter, primarily Nelson’s, saltmarsh and seaside. All three of these sparrows have an extremely annoying habit of hiding deep in the marsh grasses where they can’t be seen, then suddenly taking flight only to plop back down under cover. The difficulty in seeing them combined with the fact that Nelson’s and saltmarsh look rather similar, can make them challenging to identify. We flushed a couple of sparrows, including a Nelson’s. We also heard a marsh wren chipping. When we got back to the parking lot, we saw the first two of the many, many sharp-shinned hawks we would see that day fly overhead. Further down the road, we plunged back into the marsh, this time with more success. We managed to herd a little flock of sparrows between the three of us, and get good enough view to confirm that we had two Nelson’s and a saltmarsh. We even got photos, although they were pretty terrible.

Nelson’s Sparrow (Ammodramus nelsoni)

We birded the rest of Ramp Road, slowly making our way up to the main body of the Eastern Shore of Virginia National Wildlife Refuge. We had hooded mergansers and lesser scaup on a pond, and flocks of willets and greater yellowlegs flying over the marsh. Once we got up into a more forested area, we heard red-breasted and brown-headed nuthatches, as well as a house wren and several gray catbirds.

We drove slowly along Hallett Circle, the main road of the Refuge, listening for bird activity. The vegetation around us was dense and scrubby, perfect habitat for all manner of songbirds, including — we hoped — rare flycatchers like western kingbird or ash-throated flycatcher. We stopped and got out of the car when we encountered a large flock of yellow-rumped warblers. A gray catbird, brown thrasher, winter wren and palm warbler were all we could find mixed in. Sharp-shinned and Cooper’s hawks continued to migrate overhead in large numbers. One was almost always visible in the sky. We also saw several migrant red-tailed and red-shouldered hawks. On the butterfly trail, we had our first unusual birds of the day, a blackpoll warbler and a white-eyed vireo. Both of these are just late migrants, not the really rare birds that the roundup was targeting, but still very interesting finds. We watched them forage with palm and yellow-rumped warblers in fennel stalks for some time before continuing on.

Ash-throated Flycatcher (Myiarchus cinerascens)

We slowly birded our way up to the visitor center without anything else particularly notable. Near the visitor center we encountered a small flock of field sparrows, chipping sparrows and dark-eyed juncos, but we couldn’t find anything else mixed in. We were working our way through a song sparrow flock in front of the visitor center when Andrew said with excitement in his voice that he had an ash-throated flycatcher. Sure enough, just 30 feet away in the bottom of a tree sat the ash-throated. Andrew sent out a text alerting other birders participating in the rarity roundup to its presence, and we set about trying to keep the bird in sight until some of them arrived. Many of the birders that soon arrived did get to see the bird, although some did not, as it disappeared into a thicket of dense brush. I don’t think it was seen again after that. A migrating peregrine falcon and merlin added a few more species to our day list before we decided to leave for the next part of our territory.

We drove down the dirt road to Magothy Bay Natural Area Preserve through fields of corn stubble. We heard an American pipit calling as it flew over us, and we flushed some savannah sparrows from beside the road. We saw gadwall and a large flock of green-winged teal on Bull’s pond, as well as greater yellowlegs and a pectoral sandpiper. Then we started down a mowed path through a pine forest. Eventually, the path opened up with lots of brush and trees on one side and marsh on the other. At the end of the trail we had a good view of the bay, and we set to scanning with our scopes. We could see hundreds of birds huddled on the beach of a distant barrier island, but they were too far to make out anything but a group of oystercatchers among them. Two horned grebes dove in a channel in the marsh closer to us. Common loons, buffleheads and a surf scoter could be seen bobbing on the water in the distance. Flocks of dunlin flew by.

Palm Warbler (Setophaga palmarum)

Our final stop in our territory was Mockhorn Island Wildlife Management Area. We followed Jones Cove Drive almost to its end, where there is a little parking lot for the WMA. When we got out of the car we were immediately aware of sparrows everywhere, hopping and flying around in the dense brush on either side of the road. We scanned them thoroughly, but unfortunately, we didn’t find anything unusual. They were mostly white-throated, with some chipping, savannah and song sparrows as well as dark-eyed juncos and eastern towhees. We found a group of hermit thrushes, and were extremely surprised to see an extremely late Swainson’s mixed in with them. We began to walk down the trail away from the parking lot, where we had red-breasted nuthatch, winter wren and brown creeper. We also heard but did not see a flock of tundra swans flying overhead. We were several minutes down the trail when Andrew got a text that a Sandhill Crane had been seen flying north from the preserve immediately to our south — Magothy Bay. We rushed to an area where we could see the sky, but we could not spot the crane. Andrew received another text saying that the bird was flying low and would likely land in a field somewhere nearby. As we were driving away from Mockhorn we got another text saying someone had seen two American white pelicans flying north from south of us. We got out of the car next to a field and set up our scopes to look for them flying overhead. After several minutes and another text saying they’d been seen to the north of us, we realized we’d somehow missed them, and were getting ready to leave when my dad called that he saw the crane. This seemed a little too coincidental to be true, but he pointed out the big gray lump that was the cranes back. The field that we had chosen completely randomly for looking for the white pelicans turned out to be the same one that the crane decided to spend the night in!

Sunset by Theo Staengl

All the participating birders met at a local brewery for dinner and a “tally rally,” where we tallied all the birds that everyone had seen during the day. I don’t remember exactly what the total number was, but it was over 150 species. While I would always enjoy birding on the Eastern Shore of Virginia, it was particularly satisfying to know that every bit of Northampton County was covered by capable birders. At the end of the day, I may not have gotten to see every single rare bird that was found, but someone did, and I doubt very much that many got away unobserved. This group effort and thorough coverage is important to making Virginia’s rarity roundup a special birding event.

Special thanks to Matt Anthony for providing me with information about the history and organization of the rarity roundup.