The Wallace Line

Alfred Russel Wallace noted a dramatic difference between species east of the indicated line and those to the west.

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While bullets and cannonballs were flying back and forth across the Mason Dixon line in 1862, Alfred Russel Wallace was wrapping up eight years of adventure studying and collecting biological specimens in Southeast Asia. During that time, he gathered over 125,000 specimens, becoming very familiar with an area he called Malay Archipelago — a chain of more than 25,000 islands between Southeast Asia and Australia, which includes modern-day countries such as the Philippines, Indonesia, Malaysia, Papua New Guinea, and Singapore.

Wallace was an incredible scientist and explorer during a time when interest in the natural world was extremely high. On one occasion, while heading back to England from South America, the sailing ship caught fire, forcing all into life boats. He lost all his notes and specimens collected over the previous four years and spent 10 days adrift before he and some of the crew were rescued. He later returned to South America and repeated his earlier trip without the shipwreck.

Wallace was a contemporary of Charles Darwin and shocked Darwin in 1858 by sending him a letter (called the Ternate Letter) in which he outlined a process for the evolution of species nearly identical to Darwin’s natural selection. They finally submitted a joint paper outlining the theory instead of either one trying to be first.

Wallace was highly regarded in the scientific world and when he said something, people usually took careful note. Such was the case in 1859 when he described a phenomenon he had witnessed during his travels in the Malay Archipelago (which he presented in 1863 at the Proceedings of The Royal Geographical Society of London). Wallace noted that the species he encountered were split quite distinctly along specific lines. Of note, Asian species seemed to be able to move south and east, but Australian species could not move north and west. Animals abundant on one side of the line were absent on the other side. This difference was so distinct that Wallace was able to draw a line delineating where he felt the change occurred. This line became the Wallace Line or, Wallace’s Line (although it should be noted that in 1521, Venetian explorer, Antonio Pigafetta, of Magellan’s fleet noted similar dramatic differences between animals and birds of the Philippines and the Maluku Islands which were on opposite sides of Wallace’s Line).

For 160 years, scientists have drawn and redrawn the Wallace Line and added other lines as well (Huxley, Weber, and Lydekker lines for instance), trying to understand the reason for the dramatic differences over such relatively short distances. For a long time it was thought that the deep oceans in the area prevented travel between the two continents, even during periods when ocean levels were much lower.

However, a study out of Australia seems to have finally found the how and the why of this biogeography dilemma. Yes, there are deep oceans, but what really changed the environment was the creation of a new ocean current, the Antarctic Circumpolar Current (ACC). This occurred when Australia drifted away from Antarctica, opening up an area of deep ocean surrounding Antarctica. This had a global impact, cooling the planet and it still is a major player in climate today. Southeast Asia and the newly formed Malay region remained warm and wet, but Australia became cooler and drier. The species from Southeast Asia adapted well to life on the more tropical Malay islands, but those from Australia, adapted to cooler and drier weather, could not. So, the Asian side of the line is strictly for Asian species, but on the Australian side of the line, the animals are a mix of Asian and Australian species.

The Wallace Line, at once imaginary or theoretical and quite real and has prompted biogeographers to look carefully at the complex systems of nature—in this case, geological history, plate tectonics, climate, ecological adaptation and more. Better understanding them may help in predicting how species alive today are going to respond to our warming planet.

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Help Idaho Wildlife

When we traveled across the state in October 2017, we visited most of the Idaho Department of Fish and Game wildlife management areas. Most of the vehicles we saw using the wildlife management areas did not have wildlife plates. Buying wildlife plates is a great way for non-hunters and hunters alike to support wildlife-based recreation like birding.

C'mon folks, let's help Idaho's wildlife by proudly buying and displaying a wildlife license plate on each of our vehicles! 

See below for information on Idaho plates. Most states have wildlife plates so if you live outside Idaho, check with your state's wildlife department or vehicle licensing division for availability of state wildlife plates where you live. 

And tell them that you heard about it from Nature-track.com!

Wildlife License Plates

Great news! as of 2024, there are three NEW designs for license plates. They still are bluebird, cutthroat trout and elk, but they are beautiful.

Idaho Wildlife license plates provide essential funding that benefits the great diversity of native plants and wildlife that are not hunted, fished or trapped—over 10,000 species or 98% of Idaho’s species diversity. Game species that share the same habitats (such as elk, deer, antelope, sage-grouse, salmon, trout) also benefit from these specialty plates.

No state tax dollars are provided for wildlife diversity, conservation education and recreation programs. Neither are any revenues from the sale of hunting or fishing licenses spent on nongame species. Instead, these species depend on direct donations, federal grants, fundraising initiatives—and the Idaho Wildlife license plates.

Both my vehicles have Bluebird Plates. I prefer the bluebird because the nongame program gets 70 percent of the money from bluebird plates, but only 60 percent of the money from elk and trout plates - 10 percent of the money from elk plates supports wildlife disease monitoring and testing programs (to benefit the livestock industry) and 10 percent from cutthroat plates supports non-motorized boat access.

Incidentally, in 2014, the Idaho Legislature denied the Department of Fish and Game the ability to add new plates or even to change the name of the elk and cutthroat plates (very specific) to wildlife and fish plates, a move that would have allowed for changing images occasionally and generating more revenue. It would seem that they believe that we Idahoans don't want a well funded wildlife program.

I think it is time we let the Legislature know that Idahoan support wildlife funding and that we would like to see these generic plates come to fruition.