Autumn Migration

Common yellowthroats are small warblers of the marshes. They may have already begun their autumn migrations to places south.

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On a recent drive over to Red Rock Lakes National Wildlife Refuge, Montana, west of Island Park, we were stunned by the numerous mountain bluebirds we saw. There were multiple flocks of up to 20 birds. I assumed at first that these were the broods from the summer as this area is a bluebird hotspot, and they may have been, but I got to wondering if they could be migrating flocks.

Autumn migration is a much different animal than spring migration. In the spring, there is an urgency to get to the breeding ground, establish a territory, find a mate and get with the business of procreation. Timing is critical and routes are direct. Birds still have to stop to refuel, but they move at a relentless pace once they get started.

In the fall, migration may stretch over a much longer time as birds swoop into new habitats to take advantage of resources there. It is interesting that the same environmental triggers that initiate spring migration also help to trigger fall migration, just in reverse. For instance, increasing daylight helps to trigger spring migration, decreasing day length helps to trigger fall migration. Warming temperatures promote spring migration, cooling temperatures promote autumn migration. Food increases along a south to north gradient and spring migrants follow it. Fall migrants follow food sources as well, finding increasingly more food as they fly south.

There is one thing that spring migrants do not have to concern themselves with that is top of mind for fall migrants. Are the nestlings ready for their first big journey south? Parents generally won’t leave until their nestlings are ready for the trip or at least able to care for themselves.

Location is yet another factor. For both spring and fall migrations, those that travel the furthest typically leave the earliest.

The timing of fall migration depends a lot upon the species or guild of species. For instance, shorebirds may start migrating as early as July 1st and may be mostly gone by the end of September. Many hawks are on the move by late August. Warblers are highly variable. For instance, one of our favorites, the common yellowthroat, may have already left our area. Another favorite, the yellow-rumped warbler, may stick around until mid-October. Sparrows of most sorts hang out in summer areas until late October and early November. Hummingbirds have already begun their migration. We haven’t seen ours in over a week.

Waterfowl are the most visible of the autumn migrants. They migrate late in the fall. However, migration for a number of duck species may still be precipitated by a cold front. Apparently, they can sense when the water is about to freeze up and they migrate ahead of that event. When major cold fronts pass, migrants are so numerous that they can be seen on radar, moving away from the storm.

Here are a few things we can do to help migrating birds. Begin by planning your landscape to include late-summer blooming flowers. A well-planned yard can be a great help to migrants.

It is especially important to practice untidy gardening. Leave fruits, dried up seed-bearing flowers and berries to provide a refueling stop for birds. Winter birds will appreciate them too. Avoid pruning trees and shrubs in the fall. Leave the extra cover for the birds. In fact, build a brush pile from earlier trimming efforts as easy escape cover. Leave the leaves on the gardens until spring, or better yet, don’t pick it up at all. Leaf litter is a great place for birds to forage for invertebrates.

You can also provide roosting boxes (I will cover these in detail in a future article). Roosting boxes can help migrants as well as year-round birds survive cold temperatures at night.

Fall migration may not be as spectacular as spring migration, but it is just as important. Help these birds out if you can. They will appreciate 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.