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Reflections on Summer
by Steve Frye
My kids are returning to school this week, marking the end of another summer break. They are much sadder about this event than I. For Genevieve and Charlie, this marks the end of "summer". For many birds this is also the end of summer because some are gathering in flocks in preparation of southward migration, some are just quietly leaving us to return to their wintering grounds. Hummingbirds mark the end of their "summer" sometimes as early as the Fourth of July. We always tell our customers that 'the fireworks start on the Fourth of July', because that is typically about when we start to see rufous hummingbirds travelling south and stopping briefly along the Front Range. We say that the fireworks start because rufous are feisty (and colorful).
The Fourth of July is the quintessential summer day with hot weather, riding bikes, cookouts, and long evenings. I love the other elements of the Fourth like parades, fireworks, and putting out the red, white, and blue. This Fourth of July one of our customers had a special decoration to display: a male northern cardinal. How's that for celebration! A flashy red bird would have made a great addition to my backyard, if only it would show up there. Over the years, we have received many questions about cardinals.
norhern cardinal
So why don't we have cardinals in Colorado? We do, just not many and not near Boulder County. In 1991 I helped search for birds in Beecher Island, CO near the Kansas state line for the Colorado Breeding Bird Atlas. We searched a beautiful ranch for many hours one morning. Along the creek that ran through the property we found a cardinal pair building a nest. I was thrilled to watch the construction (and have a new state bird on my list). Later that morning we sat down with the rancher, she told us all about the birds that visited her property and she mentioned that the cardinals usually nested right near the house. They had been nesting there for 19 years. According to the Colorado Breeding Bird Atlas, the "stronghold" for cardinals in Colorado is right there near Beecher Island and Wray, and not anywhere else. Others are reported along the Arkansas and Platte Rivers in eastern Colorado and a pair has made the Wheatridge Greenbelt their home for a few years now.
This little niche on a ranch near Beecher Island seems to be alright with the cardinals, but why don't we see more cardinals elsewhere? The question has at least two answers. One is that cardinals must not do well here. Biologists would call the cardinals in eastern Colorado a sink population; meaning that young produced are not faring well or that the birds only exist there because of a constant importation of birds from other parts of their range. The local population never grows.
In part, eastern Colorado is devoid of cardinals because of habitat. When you're a screaming red bird, you won't last long in a shortgrass prairie. Cardinals need cover to hide from predators and that means understory with a tangle of bushes, trees, and other plants. Their nest locations are often in a bush or tree with thorns like rosebushes or in pine trees. Cardinals are also found in the desert southwest in places like Tucson. The Sonoran Desert habitat there is vastly different from their eastern deciduous habitat, but it still has a dense and thorny understory. My thirty five year old neighborhood seemingly has plenty of good habitat with trees of varying sizes including fruit trees, lots of bushes, vines, and other plantings. So why wouldn't a cardinal do well in my neighborhood?
I'm not sure, but maybe food has something to do with it. True, there are plenty of feeders with many things that cardinals like in my yard, but that is not enough. Birds only eat a little of their daily diet from a feeder, the rest has to come from the surroundings. Cardinals eat quite a variety of things including many kinds of beetles, many insects like caterpillars and crickets, various fruits, weed seeds, waste grains, and, of course, seeds from bird feeders. We have plenty of those choices here. So I don't think food is the limiting factor for cardinals in the Front Range, at least not in the more established urban and suburban habitats.
One other part of the equation is their mobility. Cardinals tend to hatch, grow up, live, and die in the same place. They are not stricken with wanderlust. Cardinals have expanded their range to the west in much the same way that blue jays did several decades ago by means of the river courses. The rivers across the plains are highways of woodland habitat that are travelled by many animals. Blue jays came to the Boulder area in the late 60's and early 70's by travelling these paths and have now established themselves as regulars along the Front Range. The cardinals are coming too, but they're just plodding along. One thing I haven't figured out is what happens to these few cardinals that do show up here because they don't stay long. The customers with the Fourth of July bird only had it stay for a day. Others have been spotted in the county over the years, but the same thing happens, they are here for only a few hours before disappearing. A male cardinal was banded on Mount Evans near treeline a few years ago. What happened to that bird?
One thing that I am confident about is cardinals will get here and become established. Just don't hold your breath about it; I think it will be a long time before that happens. For all of you who can't wait, you can always prepare your yard for their coming much in the same way that Linus prepared for the visit of the Great Pumpkin. You can produce the most sincere cardinal habitat including thorn bushes, vines, large and small trees, and a water feature in hopes that cardinals will find your yard worthy. At least you can enjoy all the other creatures who find your new habitat worthy, even if the cardinals never show up.
Cornell Lab of Ornithology, All About Birds: Northern Cardinal
Colorado Birding Society: Northern Cardinal
Peterson Field Guides (Youtube): Northern Cardinal 2008
Cornell Lab of Ornithology, Birding By Ear (Youtube): Northern Cardinal Song
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