All around a symphony, a cacophony, of birds. I woke up to those sounds every day for a week, even before the dim light of the sunrise could creep through my curtains. It was the soundtrack that accompanied me down the wooden-planked walkway, or as I biked past the citrus grove. The birds that didn’t join in the daylight festivities carried the party into the dark of the night. On an island with barely enough residents to organize a soccer match, this veritable rave of noise and dance heralded what would be another successful breeding season for the seabirds of Midway Atoll.
This memory was what immediately came to mind when thinking about a post for today (May 9, 2020): World Migratory Bird Day—“Birds Connect Our World”. I was lucky enough to visit this birder’s paradise in 2011 and to see the millions (yes, actually millions) of birds that called a tiny island in the middle of the Pacific ocean home for a few months every winter. There were albatross (Laysan, Black-footed, Short-tailed), petrels, frigate birds, boobies, ducks, terns…each having traveled hundreds of miles to arrive, raise a chick and breed before heading back out to sea for another 8-9 months.
World Migratory Bird day began in 2006, and since then, this annual, global event celebrates learning about migratory birds and the threats they face. Our education team will be sharing more information on our YouTube Channel, but here on 60° North Science, we wanted to focus on how is it exactly we know so much about migratory birds?
Long before the world of cell-phone apps and pocket-sized GPS, ancient Greeks noted the arrival of Swallows in the spring and their departure in the fall (they didn’t say if the birds were unladen or laden). These types of observations, or phenological records, can provide information on the timing of migration. Tracking the timing of migration, and how this changes gives us an idea of how the overall system is functioning.
More recently, a study looking at over 50 years of arrival data, scientists found that the spring migration of the Black-throated Blue Warblers—a small bird common on the east coast of the US and Canada—has been getting progressively earlier over time. While in some cases this shift isn’t an issue, it could be problematic for the population if arriving too early means they arrive before there is enough food available to raise their young.
Did you know, you can help contribute to this type of data by observing species in your own garden or around your home? Data can be shared through apps like eBird from Cornell Lab of Ornithology; or as part of national events like the Christmas Bird Count).
While observing birds at one location along the path is helpful, we can’t get a good sense of how long it takes birds to migrate, and what those migration paths look like from this data alone. Here, scientists turn to “Banding” — the term for attaching a small plastic, or metal band to the leg of a bird that carries a unique color/number pattern. This enables scientists to monitor the status and trends for both resident and migratory birds from year to year. Many programs using banding have been maintaining these databases for decades.
Banding also helps re-construct migration routes. For example, we might sight or capture a bird with a specific band in Seward on Monday. That information can provide details on timing of arrival if compared to other sightings in Seward each year. However, if a week later the same bird is sighted in Anchorage, we can ALSO get a better idea of the pathway, and the timing of migration for this species. This is actually how the migration flight of the Arctic Tern was first determined. Now with additional data, we know Arctic terns win the “Longest Migration” award of any species, clocking in at 25,000 miles round trip from the Arctic to Antarctic!
Which brings us to our last research approach: with the increasing miniaturization of technology, it is now possible to put a GPS or satellite tracking device on even some of the smallest birds!
This innovation has truly revolutionized our understanding of migration as we now get the whole picture of their route, speed, and behaviors along the way. Satellite transmitters attached to bar-headed geese (Anser indicus) revealed that they actually migrate OVER the Himalayas, flying at altitudes of 6,540-7,290m! If you’re interested in following birds in real time on their migrations, check out these apps (*This is a great Teacher Resource!*).
ASLC scientists actively participate in efforts to track migration patterns of birds in Alaska using a combination of these methods. Additionally, with the rapidly changing Arctic, they are interested in better understanding how habitat and environmental changes might be impacting some migratory birds during their breeding, or wintering seasons.
“So why do migratory birds get a whole day for themselves?”
Migratory birds are truly amazing! You’ve now learned that some fly hundreds of thousands of miles to find the right habitat for feeding, breeding or raising their chicks. While biologically, this is an amazing feat of navigation and endurance, it does come with some challenges. In the sky, birds aren’t bothered by (or aware of) the international, cultural, or legislative boundaries they are crossing on their journey, or how this makes coordinating conservation actions for these species challenging. Similarly, the threats they face might span borders too.
Our actions, even hundreds of thousands of miles, away may impact these animals. So let’s celebrate World Migratory Bird Day by committing to making those impacts positive! Share something you learned with a friend, and help join the effort to bring people from around the world together in appreciation and learning, to be aware of these challenges, and to find solutions!
Other Bird Migration Fun Facts:
- Of the 470+ bird species found regularly in Alaska, over 300 are migratory and arrive from 6 continents across the globe, and every state in the US (including Hawaii!).
- The Ruby-throated Hummingbird weighs less than a nickel (0.12 ounces, or 3.5 grams) and flies across the Gulf of Mexico twice a year. They fly for up to 22 hours straight to cover the 500 mile distance.
- The Sooty Grouse is considered by some to have the shortest migration of any bird species – less than 30 miles, largely traveled on foot. Instead of migrating between hemispheres, the Sooty Grouse migrates between altitudes, traveling up and down the slopes of the Cascade Mountains in search of open breeding areas in the summer and sheltering coniferous forests in the winter.
- At 66 years old, Wisdom, a Laysan Albatross, is the oldest known migratory bird in the world. As of 2019, she has probably flown over 3 millions miles in her lifetime (120 times the circumference of the earth!) and laid 30-40.
Written by: Amy Bishop, PhD with Fun Facts from the ASLC Avian Team!