Predicting Fall Colors

Catching the peak of fall colors requires science, art and lots of luck.

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A few years ago, we were returning from a trip back east and happened to be driving through Grand Teton National Park on September 23rd. A journal entry from that day noted that in my opinion, the fall colors around Moose along the Snake River were at their absolute peak. That is why this year, we planned to be camping at Grand Teton’s Gros Ventre campground starting on the 20th of September. I was sorely disappointed. Colors had just begun to change and the peak was still at least a week away when we left on the 23rd.

As a photographer, precisely predicting when colors will change would be a handy skill. I have noted over the years that there is more or less an order to the change, so that is a start. Underbrush species such as huckleberry, spirea, serviceberry and snowberry, along with herbaceous plants such as fireweed, tend to start the show. In my experience, willows follow. Maples precede aspens and finding a hillside with both maples and aspens in color is a definite balancing act. Cottonwoods seem to be some of the last of the deciduous trees to change while larches, evergreens that drop their needles, don’t peak with their brilliant yellows until November. The degree of variability in all this would give a statistician gastric reflux, but this seems to be a general pattern I can count on.

Predicting exactly when the peak will occur and how vibrant the colors will be is another matter. It isn’t that the science isn’t there. There are just so many different combinations of the factors that determine color change that make me a poor forecaster.

The one single and consistent factor, and thus the most important in my mind, is day length. As days get shorter, or perhaps better stated, as nights grow longer, with the progression of autumn, biochemical changes in the leaf begin the process, irrespective of other factors. Leaf veins begin to seal off and at some point, chlorophyll production is going to stop, the bond between the petiole and the stem will weaken and the leaf will fall. Whether or not it provides a show during that process may be dependent on other factors.

There are several ways nature can stop this show. The first is drought. Leaves stressed by drought may simply wither and die without the blast of color we always hope for. It should be easy enough then, to predict that a dry summer is going to produce a poor color year. However, timely fall rains can reverse drought impacts and restore autumn’s splendor.

Another way that we could miss autumn color altogether is following a hard frost. Frost will kill the leaves and they may go from green and growing to dead and brown overnight.

Whether or not fall colors are going to be average or spectacular seems to be related to temperature. According to the US Forest Service, “A succession of warm, sunny days and cool, crisp but not freezing nights seems to bring about the most spectacular color displays. During these days, lots of sugars are produced in the leaf, but the cool nights and the gradual closing of veins going into the leaf prevent these sugars from moving out. These conditions – lots of sugar and light – spur production of the brilliant anthocyanin pigments, which tint reds, purples, and crimson.”

What should we hope for in order to get the best fall season? It seems that a warm, wet spring, followed by a warm, but not hot, summer and warm fall days with cool nights is the perfect combination.

However, that is a lot to ask for and even more to keep track of. I suppose I’ll just take what nature gives and be grateful for it.

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Help Idaho Wildlife

When we traveled across the state in October 2017, 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.