On the Trail of the Elusive Red Crossbill

Anant Deshwal is a Ph.D. candidate in Department of Biological Sciences under the guidance of Douglas James. He is studying the ecology of shrubland birds in the Eastern Ghats mountains of India, with the intent of seeing the forest from the perspective of the birds that live there. He also works to understand the socioeconomic structure of communities in and around the shrubland forests in an effort to create effective conservation and wildlife management plans.

 Deshwal trained as a civil engineer, but decided to follow his passion and study wildlife. He has researched tiger prey-predator density, snake-bite mitigation, crocodile behavior, and four-horned antelope and birds. In Arkansas, he has become “obsessed” with red crossbills.

 The following is his story of research that led to surprising findings about these elusive birds. His work is dedicated to the memory and honor of Kimberly Smith, a Distinguished Professor of biological sciences at the University of Arkansas who died in April.

 The eternal words of Theodosius Dobzhansky, “Nothing in biology makes sense except in the light of evolution,” echoed in my thoughts as I stood admiring the beauty of a red crossbill.

One of my favorite lines about red crossbills is, “This is the bird where we can see evolution happen live.” Often, we can separate birds out as species or sub-species, but with red crossbills the bird is a step behind turning in to sub-species or species.

I should back up a step. What is a red crossbill?

Red crossbills are a medium-sized finch with a crossed beak, hence the name. They eat pine cones, and it is this specialization that led the bird to have a strange bill. A crossbill puts its beak between the scales of a pine cone and pries it open. The bird’s thick, fleshy tongue shoots out and scoops up the seed inside.

Red crossbills are a medium-sized finch with a crossed beak which they use to pry open pine cones. They are difficult to find and even more difficult to study. All photos by Joe Neal

Obviously, pine trees do not like their precious seeds being destroyed, so there is something of an evolutionary race between the two. There is a vast variety of pine tree species, and red crossbills adapt to a particular type of pine tree. The bigger the pine cone, the bigger the beak, each beak size defining a different type of red crossbill. There are nine types of red crossbills in the United States.

This is weird, but there is more.

Red crossbills are nomadic migrants. That means they do not observe any fixed migratory route, but will turn up just about anywhere there is food. They are nomads of the avian world.

And it gets weirder!

Most birds have a fixed breeding period that researchers can identify. Red crossbills are the original rebels in this sense. Generally, they will breed if they find a good crop for at least three weeks. They have been known to breed in middle of a snowstorm. Now that’s heavy metal!

I am obsessed with red crossbills. This bird has made me cry and laugh at the same time. This bird is my Everest!

I learned of this enigmatic bird through Ragupathy Kannan, a biology professor at University of Arkansas Fort Smith, the late Kim Smith here at U of A, biology professor emeritus Doug James and wildlife biologist Joe Neal. It is commonly thought that red crossbills are so difficult to study that they are not worth time and effort. That challenge alone was enough to get me interested, as Arkansas has shortleaf and loblolly pine trees.

In 2012-2013, we had a significant influx of red crossbills, a phenomenon known as irruption.  Smith, Neal and Matt Young of Cornell University studied and recorded the irruption. Until then it was thought that only three types of red crossbills visit Arkansas. The birds are identified by recording and analyzing their vocalizations. Each type of red crossbill has a unique call and song.

Is there a resident population of red crossbills in Arkansas? Is there a breeding population? Those are the questions I wanted to answer.

But there is a lack of data on red crossbills. The birds are often easy to miss as they are small and at the canopy of pine trees. They are usually heard before they are seen.

In 2017, Smith, Neal, Kannan, fellow graduate biology student Pooja Panwar and I embarked on an adventure to answer the questions about red crossbills in Arkansas.

Deshwal, left, recording bird calls with fellow biology graduate student Pooja Panwar.

Packed with audio recorders and binoculars, we would head out before the crack of dawn to explore Northwest Arkansas for the elusive, enigmatic bird. Ears on high alert and eyes on the pine tree canopy, we walked for hours, scanning the stands of pine trees, our necks sore from the strain, fingers numb from the freezing cold, legs covered in brier bush thorns. Finally we heard it: “chip chip … chip chip… chip chip chip … .”

Ah, pure joy! Cold, thorns and sore necks were irrelevant! We flipped the buttons on our recorders and captured the calls.

After analyzing the recordings, we couldn’t believe what we were hearing. We asked Young, the ornithologist from Cornell, to verify our findings. He confirmed that we had found two more types of red crossbills, one of which has never been reported anywhere near Arkansas. Now we know that Arkansas has five types of red crossbills that visit!

Excited by this fantastic find, we wanted to know more. We had recorded something else, something interesting enough to get the folks from Cornell very interested. Watch Research Frontiers for the next steps in our research.