Nelson County Rarity Roundup – Volunteers Wanted!

The first rarity roundup I participated in was the Virginia Rarity Roundup in the fall of 2018.  Held every year in Northampton County, one of the state’s best for birding, this event emphasizes finding state rarities and building the local birding community.  It was great birding — my team found an ash-throated flycatcher! — and lots of fun, and it got me thinking about the ways in which the format of the event could be applied to my home county.  Obviously Nelson is not Northampton.  There are no — or very few — Western, European, or Caribbean birds in the county each fall.  However, I believe Nelson is actually one of the better Central VA Piedmont counties for rare and uncommon but regularly occurring migrants, from species like Connecticut warblers and Philadelphia vireos to northern goshawks and golden eagles.  There are several eBird lists from Rockfish Valley trail with multiple rare species.  Some of the most mouth watering lists are below:

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Mourning Warbler.  This photo was taken in Highland County.

https://ebird.org/view/checklist/S48719356

https://ebird.org/view/checklist/S11684470

https://ebird.org/view/checklist/S49182860

https://ebird.org/atlasva/view/checklist/S38795337

Rockfish Valley Trail is one of the only places in Nelson that gets regular coverage in migration.  Just across the border in Augusta County, State Route 610 also used to get regular coverage, by Edward Brinkley.  He reported massive fallouts of migrating songbirds, including some rare species, like golden-winged, blue-winged, and Connecticut warblers, and olive-sided flycatcher.  More recently, I’ve had good numbers of birds on foggy days in fall, although nothing yet approaching what he reported.  The number and variety of birds that can be observed when an area is thoroughly covered by birders is amazing.  Here’s one of Edward Brinkley’s best lists:  https://ebird.org/view/checklist/S12891616

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State Route 610 during the summer.

I wonder how many more rare migrants are out there along the Blue Ridge that we don’t detect?  How many more fantastic migrant trap locations like Rockfish Valley Trail and State Route 610 are waiting to be discovered?  If birders birded all of Nelson County in one day, how many species and how many individual birds would we find?  I think the format of a rarity roundup provides a good way to encourage people to explore and begin to answer these questions.

I’ve divided Nelson County into 18 territories of unequal size and shape.  They’re drawn somewhat randomly, but I’ve tried to make the boundaries logical and to make it clear what territories the already well established birding spots lie in.  My hope is that I can get as many people or teams as possible to commit to bird a territory as thoroughly as possible for the day of Sunday October 6.  The territories are humongous compared to the one’s used for the VA Rarity Roundup in Northampton, and have much more private land, so I recognize that thorough coverage will be impossible.  The idea is more to use the territories as a broad organizational tool, so birders can split their effort across the county.  Some territories don’t have an eBird hotspot in them.  Some may not even have public land, which is OK.  There’s a lot of barely traveled backroads in Nelson, many of which could prove to be good birding.  How many new eBird hotspots can we add?

If you’re a birder, and interested in helping discover birds and birding hotspots in Nelson County and are available on October 6th, please consider covering a territory!  Here’s a link to a map of the territories.  Covering any of them would be a huge help, although I’m personally most curious about the territories along the Blue Ridge that don’t get birded, like 12 and 13.  I also think the territories along the James River, including the one with James River State Wildlife Management Area, could be interesting and productive.  Don’t worry if you don’t get your first choice territory, because I’ll be making a text group so we can alert each other to any rarities we find.  Once you know which territory you would like, or if you have any questions, contact me at ezraperegrine@gmail.com.

Winter Bird Irruption

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.

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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.

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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 19th in 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 20th century, 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.

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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/