Left: Photo provided by Adam Fudickar — A dark-eyed junco, caught in the Appalachians in Virginia, with a tiny GPS logger on its back. For this project, Fudickar is collaborating with the Smithsonian to try to
understand the environmental cues that lead to facultative altitudinal migration and the influence of facultative migration on survival and reproductive success.
Right: Photo provided by Indiana University — Adam Fudickar and Lia Bobay capturing and tagging birds at the Kent Farm Banding Station to collect information on migratory bird patterns in Southern Indiana as part
of a long-term (forty-plus years) data collection project on the effect of weather changes on the proportion of male and female birds (specifically, juncos) over wintering in the region.
Over the past decade, our understanding of the phenomenon of migration has
increased tenfold. Not only has there been a sea change in our understanding of
how birds migrate over long distances but we’ve also seen a wealth of new data
describing these fascinating flights. Among the remarkable individual journeys that
have been observed using new technology are an 18,000-mile round-trip migration
from Alaska to sub-Saharan Africa by a bird that weighs just under one ounce, the
northern wheatear. These tiny birds fly, on average, 180 miles nightly on each leg
of their trip for up to three months to reach their destination. Think about that!
Wheatears spend half of their lives flying. The Arctic tern, a circumpolar migrant,
splits the year between the Arctic and Antarctica, essentially chasing summer year-round. Traveling a total of 44,000 miles a year, the Arctic tern departs Greenland at
the end of the summer in the northern hemisphere and spends the rest of the year in
Antarctica, when summer in the southern hemisphere brings an abundance of food
to the seas.
The reliance of migrants on habitat across large geographic areas makes them
particularly vulnerable to environmental change. For instance, the beautiful
rose-breasted grosbeak that spends the summer in your backyard is impacted by
deforestation in the Yucatan. Conversely, the boreal forests and tundra of Canada
and Alaska are a hatchery for birds that visit the lower 48 after the summer.
Ongoing changes to the timing of spring warming and summer temperatures near
the polar regions have resulted in a geographic shift in suitable breeding habitat
for many birds, which is likely to alter the species that visit our backyards in the
winter. Animals don’t observe political boundaries, and that makes protecting them
a global challenge.
In the late summer, migratory birds on every continent begin to prepare for their
journey. Prior to departure, migratory birds have to store fuel, and lots of it. Fuel for
birds comes in the form of fat. It’s not uncommon for a bird to increase its weight
by 50 percent in preparation for migration. However, the high energetic demand of
long-distance flight means birds quickly burn through that fat. Unlike Alpine swifts
and frigatebirds, most birds have to rest daily, and they use most of their time on
Ongoing changes to the
timing of spring warming
and summer temperatures
near the polar regions have
resulted in a geographic
shift ... which is likely to
alter the species that visit