Photo: Yellow-throated Warbler, Lorraine Minns/Audubon Photography Awards
Greg Butcher
Audubon Society of Northern Virginia sponsors a Birdathon every spring. We send out a bunch of teams whose goal is to see as many species as possible in a 24-hour period and to raise money for our programs.
Here are the 4 main tricks to seeing the maximum number of species in a 24-hour period:
Trick #1 is to get up before dawn and bird all day long (and into the night for owls).
Trick #2 is to visit a wide variety of habitat types.
Trick #3 is to find the best birders with good eyes, good ears and good knowledge of the local birds (especially their songs).
Trick #4, especially in the Washington DC region, is to go at the peak of migration.
More and more information exists to help determine the peak of migration in any given place. There is a ton of information on eBird, the website maintained by Cornell Lab of Ornithology that records all birds encountered by eBirders every day at every birding spot in the world. The data are summarized in a variety of easy-to-understand formats, but I haven’t yet figured out the easiest way to study peak migration for species diversity using eBird.
However, in Northern Virginia, we have a golden gem of a resource that highlights anything you might want to know about spring migration of landbirds – it’s a website called MPNature. MPNature has a limitation that you might think minimizes its usefulness – it is focused on the birds (and plants) of one of the smallest and most suburban parks in Northern Virginia – Monticello Park.
But Monticello Park has three advantages that make it a wonderful barometer of the state of landbird migration in Northern Virginia and Washington DC:
It is an amazing magnet for birds, with 124 species.
Its spring birds have been meticulously documented since 2005 by Tom Albright and a host of other birders.
And, of course, it has an amazing website, beautifully and purposefully created by Bill Young, Ashley Bradford and their friends.
I should probably have written an article about the beauty of the website. Ten different photographers have contributed gorgeous stills and videos of the birds, the plants and views from within the park. But that’s a different article!
Under the “Daily Checklist” tab is a list for each day of April and May of all the birds that have been seen on that date between 2005 and 2018 divided into 4 groups: resident birds, migrants that averaged more than 2 individuals on that date, migrants that averaged between 1 and 2 individuals, and migrants that have been seen in the park on that date, but not every year.
If you are interested in a particular migratory species, there is another section of the website with photos and the earliest, latest and best dates to find that species in the park. The park is a woodland with a stream running through it, so you can’t learn much about waterbirds or grassland birds, but it does have information about 35 species of warblers!
But I had a single goal in mind – I wanted to know THE best date for spring migration in our area, so I reduced all of Tom Albright’s species-specific information to numbers, and here’s what I found out:
The website’s report of expected species begins on April 1, and for the first 24 days in April, you can expect 4 common migrant species that average more than 2 individuals per day. In addition, you have the chance to see about 11 other less predictable migrants on any of those 24 days.
Everything starts to pick up on April 25. All of a sudden, there are 7 common migrants and 14 additional possible species.
The good news is that peak migration lasts for 15 days: May 1 through 15. On any one of those days, you can expect 17-21 common migrants with a possible total of 33-37 migratory species, plus up to 23 of the park’s resident species.
The next week – May 16-22 – isn’t too bad, with 16 common migrants expected on the 16th, dropping to 11 on the 22nd and a possible total of 26-32 migratory species each day.
After May 23, migration drops off sharply, with only 7 or 8 migratory species expected on May 30 or 31.
A few caveats: every day is different! The above numbers are averaged over 14 years, creating great uniformity, but migration depends on the weather. On a beautiful clear night with strong southerly wings, all the migrants might pass us by. Better conditions (for seeing a lot of migrants) are rainy nights with northerly winds that keep migrants from flying too far too fast. But the only way to find out if tomorrow is a great day to see migrants is to get outside and look for yourself.
If you want to see the most landbird migrants in Northern Virginia on a single outing, I suggest you plan to bird between May 1 and May 15, so if you participate in ASNV’s Birdathon, this would be the best time to choose your 24-hour count day. If you just want to see as many spring migrants as possible, you should go out on as many of these days as you can, because some species are early migrants and others are later – and I still have never seen all the expected species on a single day. (Maybe this year!)
Good luck and happy birding!