• Field Notes
• Magic of Migration
The Magic of Migration
Spring 2007 Newsletter
With the lengthening of the days, we can look forward to the arrival
of migratory birds. It won’t be too long before we will awaken
to the persistent songs and calls of the males seeking nesting territories
What we are witnessing is a rite of spring that is “as old
as time,” even older than the glaciers. The arrival of the birds
in spring is always welcome, and a little mysterious. The more we
learn about migration, the more we are amazed by nature, evolution
and the risks that these beautiful creatures undertake.
The birds we see in the Midwest are either migrants or “temperate
residents,” birds that do not migrate. Some species have members
that fall in both camps, like bluebirds. Since bird behavior has evolved
to improve reproductive success, migration facilitates the chances
for bearing and rearing healthy young, primarily due to more available
food sources and nesting sites.
Migration is dangerous and costly for adult birds. The annual survival
rate for adult migrants is only 50 percent. Migrating birds may be
shot, eaten by predators, or die from hunger or exhaustion. It is
estimated that more than 100 million disoriented migrants die from
collisions with high rise windows! The trade off is that their reproductive
success is improved by seasonally abundant food supplies and greater
day length. While a lot is yet to be known about migration, it is
known that birds that migrate raise more young (4-6) annually compared
to their resident tropical relatives (2-3). Temperate residents raise
the most young (greater than 6) but have the lowest annual survival
rate (20-50%) due to the harshness of winter.
So our migratory birds have evolved to undertake the risks of migration
to produce more viable offspring and pass on their genes.
Many aspects of migration are little understood. For example, most
birds migrate at night, beginning 30-45 minutes after sunset and peaking
around midnight. We are not sure why this is, as most of these birds
spend their non-migratory periods out and about during the day. We
do know that migrants fly higher over water than they do over land.
Songbirds may fly above 12,000 feet over water, apparently to take
advantage of favorable winds, and 2100 feet over land.
There are also several theories about what triggers migration. The
most commonly held theory is that it is the length of daylight. According
to Miyoko Chu in Songbird Journeys songbirds, even captive ones, become
restless in the fall: “Ornithologists know this migratory restlessness
by the German name, Zugunruhe. Like molt and weight gain in fall,
Zugunruhe is triggered by changing day length, ensuring that the birds
are ready to leave at the same time every year.” Other influences
can be environmental conditions such as temperature.
Where do they come from?
A tiny blackpoll warbler flies over the Atlantic from South America
non-stop for four days and nights. The bobolink we see in the hayfield
may have arrived from Argentina, and the turkey vultures soaring high
over the Palisades were only recently in Central America. The fact
that birds can travel this far to arrive at their breeding grounds
truly is amazing.
Where can we see the migrants?
We are fortunate that we are located so close to the Mississippi
Flyway, a major North American migration route (the others are the
Central, Pacific and Atlantic Flyways). From local sites such as Spring
Lake, Thomson and Blanding Landing, starting in late March and April,
we can watch flocks of hundreds of American white pelicans arriving
from South Florida on their way north. Dozens of other species of
ducks and other waterfowl—northern pintails, American wigeons,
grebes, loons—also pass through.
In May, we can see warblers, some of whom stay here to breed, along
the Mississippi and at Palisades State Park. Scarlet tanagers make
their home at Apple River Canyon State Park and Tapley Woods.
The Guardians explore many of these sites on our Thursday birding
outings during migration season. These walks begin on March 22 and
usually include trips to Lost Mound Refuge, recently declared an Important
Bird Area, and to Green Island in Iowa. Please contact Barb Rutherford
if you are interested in being added to the e-mail notification (see
A little further away, but worth the trip.
In addition to the Mississippi flyway areas, there are other great
birding locations within a short drive of Jo Daviess County:
- The Magic Hedge is on the shores of Lake Michigan at Montrose
Harbor, on the north side of Chicago. We have personally birded
there and have seen 20 warbler species in one day. Information can
be found at www.chicagoparkdistrict.com.
- Illinois Beach State Park is also on the shores of Lake Michigan
in Zion, Illinois. The park has a varied habitat of beach, marsh,
grassland and woods.
Information can be found at dnr.state.il.us/lands/landmgt/parks.
- The Nachusa Grasslands in Franklin Grove, Illinois is a wonderful
birding site and has as many as 180 species, including grasshopper
and Henslow sparrows and dickcissels. Information can be found at
- Wyalusing State Park is in southwestern Wisconsin and boasts
nesting red-shouldered hawks, Kentucky warblers, hooded warblers
and cerulean warblers, among others. Information can be found at
- If you are willing to venture a little further, a great spot
is Magee Marsh Wildlife Area (AKA Crane Creek) in Northwestern Ohio
on the shores of Lake Erie. Around Mother’s Day, you may see
eighty-five species in a day, including golden-winged warblers.
Information can be found at http:www.daf.state.oh.us/parks/cranecrk.htm.
Further information on migration may be found in: