Cerulean Warbler

One of the great evidences of design in the cosmos is the migratory behavior of living things on the earth. There are countless examples, but one of the most amazing are the songbirds that migrate across the Gulf of Mexico to spend their summer in northern latitudes. The staging grounds for these birds as they prepare to migrate north are the area between Honduras and the Yucatan Peninsula of Mexico. The cerulean warbler has come some 2,000 miles to this area from the Andean foothills where it spent the winter. It breeds in Wisconsin or Ontario, so by the time it gets to the edge of the Gulf of Mexico it has a considerable distance yet to go.

The cerulean warbler is a tiny bird which normally weighs about a third of an ounce (nine grams). Before it makes the flight across the Gulf it will add as much as four grams of fat. In the days before its departure the warbler will act restless, flitting up into the sky just after sunset, but then settling back to continue to eat. Finally a night will come when there is a tail wind, and this bird along with millions of other warblers, thrushes, vireos, flycatchers, orioles, and tanagers will take off right after sundown and head across the Gulf of Mexico. The bird will have difficulty climbing to a cruising altitude of several thousand feet due to the extra weight, but as the hours pass the weight burns off. The birds' wings beat at 20 times a second, but its air speed is still only 20 mph. Without the tail wind it would be impossible for the bird to make the crossing.

Southerly winds prevail in the Gulf at this time of year and the birds make the trip in 15-24 hours. If a cold front comes in, the birds will fly higher as the warm winds ride over the cold air mass. If that does not work, the birds may have to force their way through the cold air mass which can add 16 hours to their trip. Once the fat reserves are gone, the bird's metabolism will start to pull energy from its breast muscles. Very rarely does a healthy bird run out of what is necessary to make the trip.

From a chance viewpoint, such a journey is difficult to understand. It would seem that birds that migrate over land routes would be much more likely to survive and would dominate the population. The design features that are built into this beautiful little bird enable it to be able to move quickly between distant habitats and populate ecosystems in the north that would be greatly restricted in life forms without it.

Knowing where to go, when to overeat, how high to fly, what to do in a cold head wind, and when to take off all are processes that are critical to survival and yet cannot be reasoned out by such a small creature. There is an intelligence which has designed this into the birds, and that designer is the same God who tells us we can know that He is "through the things He has made" (Romans 1:19-22).

--Reference: Nature Conservancy, Spring 2004, Volume 54, Number 1, page 41.

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