The Birds: Symbols of the Great Plains
You may consider it an unfortunate fact that many grassland birds are brown. Birders call them LBJs, for Little Brown Jobs. Open grasslands enforce unique evolutionary pressures on birds—there are fewer places to hide than, for example, in a forest. Being brown is a wonderful camouflage strategy for a bird, and Great Plains birds have explored the available hues of the brown color palette thoroughly.
Grassland birds are also lonely. Rather we should say that grassland birds have to fight the problem of potential loneliness. How can they find a mate in such a large, open landscape? Some species, like the western meadowlark, solve this problem through song. My research teams have documented hearing meadowlarks’ musical invitations at a distance of almost one-third of a mile during our surveys. Males of other species, like the McCown’s longspur and Sprague’s pipit, use aerial displays high above the sea of grass to attract their mates. Species like lesser and greater prairie-chickens and sharp-tailed grouse are more sparsely distributed than meadowlarks, longspurs, and pipits, which makes it very problematic to find a mate. Grouse could easily go all day without seeing a familiar face. To solve that dilemma, these prairie grouse species have developed unique “lekking” mating systems, in which the males gather at the same dancing or booming ground year after year to compete with other males by strutting, fighting, and vocalizing. The females come to the lek sites to find the males, and all is solved. Breeding and comparison shopping for a mate can happen in wide open spaces, and it is amazing to see the variety of techniques that different species have developed to make reproduction happen.
Mating and Breeding Behaviors
Bird watching can be viewed as a multilevel sport. The entry level involves noticing birds from time to time, especially strange or unusual birds that we encounter. The second level is defined by a bird watcher who runs about and finds as many species as possible: list- making. However, once a bird has been found, there is an opportunity to learn more about the bird—an opportunity to let the bird talk to you and tell you about its life. Thus, the third level of bird watching involves prolonged observation.
What little quirks does the bird have? Maybe it twerks its tail every few seconds—why does it do that? Maybe it crawls head- down along a tree trunk—what is it doing? Perhaps it flits out away from a tree and flits quickly back—what is the purpose of these little flights? This is the realm of bird behavior.
As we discuss behaviors of birds, I am going to break a golden rule held by many ornithologists: thou shalt not ascribe human qualities and thoughts to birds. Strictly, it is true that without experimentation it is impossible to know the real function for the behaviors we see in birds. However, I want to encourage you to think about why birds do what they do. Make a guess. The father of wildlife management, Aldo Leopold, enjoyed watching wildlife on walks near his cabin in Wisconsin, and he wrote descriptive passages in which he used humanlike actions to describe the animals around him. Regarding the death of a rabbit on a warm January day, Leopold wrote in A Sand County Almanac: “To this rabbit the thaw brought freedom from want, but also a reckless abandonment of fear. The owl has reminded him that thoughts of spring are no substitute for caution.”
As we watch animal behavior, we do need to keep in mind that our conclusions about the events unfolding before us may be quite false. It is hard to get inside the brain of a bird. Consider an alien life-form landing its invisible spacecraft in the grassy space of a very large city park in which a group of yoga enthusiasts have gathered for their Yoga-i n- the- Park exercise session. The yoga session begins, and the class follows the leader in a series of poses, extending their arms toward the rising sun, raising their arms to the sky, and then squatting. Clearly, the alien surmises, the group is training for combat, and their commander is forcing them through odd rituals to suppress all individualistic tendencies. Of course, they are simply exercising. Our understanding of bird behavior may be as poor as an alien’s understanding of yoga, but if we try to think like a bird and imagine a list of possible explanations for what we observe, we cannot help but close the gap that often exists between humans and the world around us.
To pique your interest in bird behavior, in the next section I have chosen five species to describe that are common targets of bird watchers and tourists on the Great Plains. Focus your attention on their behaviors shown in the sketches by Allison Johnson, a research ornithologist; her insights from hours in the field with birds guide her artwork.
Sandhill Crane Stick Throwing
Sandhill cranes mate for multiple breeding seasons, which some people interpret with the phrase “mate for life.” If you could avoid adopting that terminology, it would be best. Many interpret the mating behaviors of species such as swans and cranes to mean that when a mate dies, the other individual dons a black outfit and mourns for the rest of their days, like the English Queen Victoria when her beloved Albert passed away. In fact, swans and cranes do form a pair bond that lasts longer than a single breeding season. However, there are always exceptions to the rule. Birds go astray with infidelities, and if a mate dies, the other individual usually finds a new mate. Reproducing is the major goal of life, you see. All mating behaviors—including mate attraction, copulation with a nonmate, pair bonds, and parental behavior—are for one purpose: reproducing as much as possible.
You will most likely encounter cranes in the Great Plains on their way north. At any given time during spring migration, there are some young cranes finding their first mate and older cranes seeking to confirm their pair bond. Because of this, spring migration is filled with a lot of fun-to-watch dancing and shaking among the cranes. Crane dancing may involve bowing, wing stretching, and jumping or running. If you find a flock of cranes in a field or wetland during migration, spend some time looking for these behaviors. At first, the flock may look like they are all feeding, but soon you will see the hanky-panky happening. And it is important hanky-panky.
Cranes and other birds use mating displays to reduce physical fighting. As you heard from your third-grade teacher when you punched the bully who pushed you down the hill and covered your face with mud, fighting doesn’t solve any problems—you just end up bruised and you still hate the other person. Fighting between animals is risky: they could win or they could be injured or die. Much better to hop around and make funny faces and point to the treetops and then your shoelaces to show your prowess. Male birds hope that a fancy and fitful display will tell the other males that a fight is not worth the effort—they would be beaten. In this manner, many fights are averted, but not all. There is still sometimes a need for third-grade teachers to pull them apart.
You will also see male and female birds performing courtship rituals in addition to the actual act of mating. As an example, mated pairs of sandhill cranes often do “unison calling”—throwing back their heads at the same time and cackling to the clouds above. It is simply their manner, we ornithologists believe, of telling each other that they are still there and still interested in the other. “I love you so much that I will do this ridiculous display,” they are saying, we think. By this behavior, their bond is further strengthened.
And then there is stick throwing—another way to confirm the pair bond. Either the male or female will pinch a stick, a corncob, a corn stalk, or other sticklike object with their bill and toss it into the air (figure 10). Some biologists believe that the birds are so excited about nest building that they simulate picking up sticks to build a nest as they migrate toward their nesting grounds. Whatever the reason, stick throwing is one of my favorite bird behaviors to watch.
The Dance of the Western Grebe
We all have an amazing person in our life who we think can walk on water, and western grebes insist on this trait in their mates. In contrast to the longer pair bonds of cranes, grebes find new mates each year. Thus, the journey north to the breeding grounds is a time to display, impress the opposite sex, and form pairs. During migration, you can observe grebes and their mating behaviors on larger, deeper lakes.
The mating dance of the western grebe is called “rushing.” Individuals begin by facing each other with bellies on the water. Then they point their bills at each other, with heads up or straight out along the water, while making loud, staccato “tic” vocalizations. Suddenly, one individual will twist sideways, hold their wings stiffly to the back, rise up, and scamper across the surface of the water (figure 11). The second individual will quickly follow and catch up. The synchronized scampering that ensues is a display that is almost unbelievable. The rushers may be two males, a male and a female, or more than one male and a female. The dance is over in about four to five seconds and only lasts for about fifty to sixty feet. I have tried to do this, and it is quite difficult. In fact, I do not even have a personal record for distance yet, but it is fun to try and good exercise.
We know that grebes’ feet hit the water up to twenty times per second during these rushes, because biologists have used high-speed filming of the dance to get a better view. The slap of the webbed foot on the surface, along with a quick push with each foot into the water, keeps the birds on the surface of the lake. As with other displays in the world of birds, it is likely that the display serves to provide potential mates with an idea of which male is best built and thus a more acceptable mate. Coordinated dancing between males and females may serve to strengthen the forming pair bond.
Greater and Lesser Prairie-Chicken Dance
The competition between males that occurs at prairie-chicken lek sites can be furious. The prime location is the middle of the lek, and the males here typically end up participating in at least 80 percent of the copulations at the lek. Those males pass on their genes to the next generation, and research from Kansas reveals that the males who obtain the more central locations are really the prime individuals from the standpoint of genetic quality. Just as cattle breeders use the best bull to fertilize their cows, prairie- chickens have a system that almost guarantees that females who pay attention to location will get the best product available that year. As my wife likes to joke, “If you do not have real estate, you do not mate.” I am pretty sure she is talking about prairie-chickens.
Lek-based mating systems are used by some species of ante-lope, bats, frogs, and moths, and the behaviors at leks of any species are always quite dramatic. All of the males have gathered in one spot, it is breeding season, and everything is on the line. Think of a dance club for college students and remember back to the crazy dancing you did at that age. I apologize for bringing that up, but now you understand the dynamic. Females get the information they need, and we enjoy it when we have the opportunity to peek into their world for a moment. I may be biased because I have studied prairie-chickens in Nebraska for over a decade, but I feel that the mating displays of grouse on the Great Plains are some of the most visually appealing behaviors to watch.
Lesser prairie-chickens are a bit smaller than greater prairie-chickens and lessers are found in the southern plains, while greaters are found in the north. However, their dances are similar, and males start to gather at lek sites each morning in mid-January. In February, they really get serious about demarcating the lek site into display territories, and in March the females start to arrive at the lek. Females will land near the lek, which sends all of the males into a complete frenzy. If you are watching a lek site in the spring, a sudden increase in volume and activity in the males is a sure sign that a female has landed nearby. The female prairie-chicken has lessons to share regarding self-confidence and dignity in the face of peer pressure. Gracefully, she will walk through the lek, looking over the males, turning her back on them, one by one. Most days, all will be shunned, and the males will go back to squabbling over borders again. Eventually, the day comes for the female to make a decision, and she chooses. More often than not, a nearby male may come in to try to force his opinion onto the situation, which may throw all plans askew for a moment. Eventually, a copulation occurs.
Males have a variety of behaviors at the lek. When females are present, males will make short jumps into the air, called flutter jumping, associated with shorter high-pitched whoop vocalizations. They rarely flutter-jump without a female on the lek. “Over here, over here,” they seem to be saying with their leaps. “You should walk over here to check me out.”
The main booming display involves foot stomping (watch their feet and listen for the repetitive thump sounds), raised feathers on the neck (called pinnae feathers because they appear like large ears) that expose orange air sacs, stiffened tail feathers (figure 12), and booming vocalizations that use the air sacs to produce a low frequency sound. From a distance, the booms sound like someone blowing on a pop bottle. Through your binoculars, the male prairie- chickens will appear like a wide U with their pinnae feathers and their tail raised vertically. In landscapes where prairie-chickens overlap with sharp-tailed grouse, you can distinguish the sharp-tailed grouse as an L shape from their vertical tail and outstretched head that is lacking the long pinnae feathers of the prairie-chicken.
The boom sound echoes over the landscape, and on a still morning, it is possible to hear a prairie-chicken lek at a distance of one mile or a bit more. On the lek, the birds are alternating between scuffling, stare-downs with neighbors, or just standing or sitting while they wait for the next action to start. Small leks of two or three birds occur in some places, and there are reports of single males dancing by themselves; the largest lek in our study site in southeast Nebraska had almost seventy males. That was a busy place.