Transoceanic migration by a 12 g songbird
Many fundamental aspects of migration remain a mystery, largely due to our inability to follow small animals over vast spatial areas. For more than 50 years, it has been hypothesized that, during autumn migration, blackpoll warblers (Setophaga striata) depart northeastern North America and undertake a non-stop flight over the Atlantic Ocean to either the Greater Antilles or the northeastern coast of South America. Using miniaturized light-level geolocators, we provide the first irrefutable evidence that the blackpoll warbler, a 12 g boreal forest songbird, completes an autumn transoceanic migration ranging from 2270 to 2770 km (mean ± s.d.: 2540 ± 257) and requiring up to 3 days (62 h ± 10) of non-stop flight. This is one of the longest non-stop overwater flights recorded for a songbird and confirms what has long been believed to be one of the most extraordinary migratory feats on the planet.
Magnetoreceptor systems in animals can be extremely complicated. For instance, a 2008 article in the Journal of Comparative Physiology A reported, “light is indeed required for magnetic compass orientation in birds and salamanders.”2 The researchers noted that when young homing pigeons were placed in total darkness, they seemed to be disoriented. Although light is electromagnetic, there is no magnetism associated with a beam of light; so it has no obvious relationship to magnetoreception except perhaps as a trigger. Furthermore, “a wavelength-dependency of magnetic compass orientation was reported for salamanders, passerine birds, and homing pigeons.”3 In other words, only certain frequencies of light trigger magnetoreception!
Presumably, if animal brains can evolve complex “computer” systems to determine location based on the Earth’s magnetic field, there isn’t any reason why these systems couldn’t evolve so that they would turn on and off due to light and/or different wavelengths of light. That these two features would evolve together seems increasingly improbable, but for the sake of argument, let’s concede these evolutionary steps.
The internal navigation map seems the most difficult feature to explain by gradual neo-Darwinian evolution. How could it evolve by trial-and-error? How many pied flycatchers perished crossing the Alps, the Mediterranean Sea, or the central Sahara over how many millennia before a lucky pair emerged with an internal map that allowed them to migrate safely around these obstacles—and passed this trait on to their offspring? How did the species even survive this process? And how many swallows died—unable to fly south for the winter and return north for the summer—until, finally, one fortunate pair evolved an internal magnetic map that returned them to Capistrano every March 19? Building such a map seems an incredibly complex process with an incalculable number of variables and a vanishingly low probability verging on the impossible.
Yet one additional feature must be added to the internal magnetic map: a trigger, perhaps unrelated to magnetism, that tells the animals when to migrate. Migratory birds are well dispersed in the summer, but they migrate together in huge flocks in the fall. Either there is a bird hierarchy that communicates the need to migrate, or the birds have an internal inborn alarm that tells them when to go—and such an alarm adds another trait which increases the difficulty of justifying the gradual evolution explanation.
Moreover, why did such evolution only occur in lower animals? Why didn’t humans evolve a brain function to utilize our internal magnetoreceptors? A PNAS article reports that cattle and deer are affected by the Earth’s magnetic field.4 Wouldn’t this have benefitted early human hunter-gatherers? Those who evolved magnetoreception would surely be among the “fittest,” able to return to the best food-producing areas in season. If magnetoreception is due to natural selection, why did it pass us by?
All this illustrates the problem with the evolutionary model. The first step is spontaneous evolution of a magnetoreception system, but that alone is not sufficient. Migratory animals must also evolve a magnetic “map” to and from the correct destinations, preprogrammed into the brain, apparently from birth. And as a final step, they must also evolve some kind of a seasonal trigger to tell them when to migrate. All this seems totally improbable—impossible even—within any reasonable evolutionary timeframe. To the contrary, well-designed, preprogrammed magnetoreception systems seem much more probable within a creation model.
The riddle of migratory birds: Another evidence of God’s design
Navigation is the part of migration that has puzzled scientists the most. How birds can find their way with apparent ease over vast distances remains the unsolved riddle of migration. So precisely can they follow their invisible paths that scientists have from time to time suspected that birds possess a special sense unknown to us. At one time they were thought to have a kinesthetic sense, by which they could form patterns of their route through pressures on the inner ear. Another idea was that birds navigate through responses to the Earth’s magnetic field, perhaps even to its rotational effects. None of these hypotheses has, however, stood the test of experiment.
The Bible, however, invites us to study the wonders of nature and to see in them evidences of the handywork of a wise Creator: “’Ask the animals, and they will teach you, or the birds of the air, and they will tell you.’” “‘Look at the birds of the air,…your heavenly Father feeds them’” (Job 12:7, 8; Matthew 6:26, NIV).
So, what we can learn by observing or studying bird migration? First, not all birds migrate. Therefore, migration is not the law of all flying birds. Secondly, birds take more or less the same migratory routes. This selection cannot be by chance. Third, before sin, there would have been no migration, for in the pre-Fall world, there would have been no harsh climate necessitating bird migration.
Consider migration itself and its relation to the Earth’s magnetic field and gravity. The magnetic field changes according to the latitude of the Earth and height. The strength of gravity also changes according to latitudes, though we usually say, “gravity is constant”. God created the Earth, populated it with all kinds of creatures, and designed each of them to be adapted to its circumstances. Also, the Sun radiates the light and electromagnetic energies to all the creatures. These might be affected by quantum energy even though they may not feel it. God designed the birds to make good use of their tiny variation in energy and also gave them abilities to detect even the smallest amount of gravity and variations in the magnetic field in ways that are unknown to us, and to orient themselves toward this direction. To the extent this happens, migration reveals God’s intelligent design and benevolent providence.
Photoreceptor-based magnetoreception: optimal design of receptor molecules, cells, and neuronal processing