Newly discovered crossbill species numbers few

August 1, 2018, American Ornithological Society
Newly discovered crossbill species numbers few
Recently discovered Cassia Crossbills may already be in trouble. Credit: C.W. Benkman

As might be expected for a recently discovered bird species in the continental United States—only the second in nearly 80 years—the Cassia Crossbill (Loxia sinesciuris) is range-restricted. It occurs in just two small mountain ranges on the northeast edge of the Great Basin Desert where it is engaged in a coevolutionary arms race with lodgepole pine. Based on a current paper in The Condor: Ornithological Applications, Cassia Crossbills occupy about 70 km2 of lodgepole pine forest and number only ~5,800 birds.

Not only are there relatively few of these crossbills, but earlier work showed that their population is vulnerable to hot summer days (>32?C or 90?F). Hot days can cause seeds in the fire-adapted lodgepole pine cones—the sole food of Cassia Crossbills—to be shed to the ground and effectively lost to the crossbills. After three summers with four or more hot summer days, Cassia Crossbills declined by over 80% between 2003 and 2011. Fortunately, hot summer days have been few in the last 10 years, allowing the crossbill population to rebound. However, the impact of these hot summer days may help explain why the recent study shows that Cassia Crossbills occur more commonly in larger mature stands of lodgepole pine present on the cooler north-facing slopes where cones are less exposed to such extreme temperatures and large numbers of seeds can accumulate in the cones.

Unfortunately, the outlook for the continued accumulation of seeds in closed cones in the canopy is bleak. More hot summer days are projected, along with increasing fire frequency, preventing pine from reaching the ages most productive for the Cassia Crossbill. "Maintaining mature lodgepole with lots of old, closed cones that the crossbills rely upon will be a challenge," Craig Benkman, a co-author of the study, concedes. "However, a concerted effort is likely worthwhile, as these forests provide more than just great habitat for Cassia Crossbills."

Explore further: New bird species found in Idaho

More information: Nathaniel J. Behl et al, Habitat associations and abundance of a range-restricted specialist, the Cassia Crossbill (Loxia sinesciuris), The Condor (2018). DOI: 10.1650/CONDOR-17-257.1

Related Stories

New bird species found in Idaho

March 19, 2007

One does not expect to discover a bird species new to science while wandering around the continental United States. Nor does one expect that such a species would provide much insight into how coevolutionary arms races promote ...

Storing seeds for a rainy day -- or in this case, a fire

May 31, 2011

As mountain pine beetles march across the forests of western North America, these insects may kill millions of pine trees during a single outbreak. A rise in overall temperatures over the past several years has increased ...

Mountain pine beetle marching east from Alberta

April 4, 2011

A University of Alberta-led research team has determined that the mountain pine beetle has invaded jack pine forests in Alberta, opening up the possibility for an infestation that could stretch across the Prairies and keep ...

Recommended for you

A decade on, smartphone-like software finally heads to space

March 20, 2019

Once a traditional satellite is launched into space, its physical hardware and computer software stay mostly immutable for the rest of its existence as it orbits the Earth, even as the technology it serves on the ground continues ...

Tiny 'water bears' can teach us about survival

March 20, 2019

Earth's ultimate survivors can weather extreme heat, cold, radiation and even the vacuum of space. Now the U.S. military hopes these tiny critters called tardigrades can teach us about true toughness.

Researchers find hidden proteins in bacteria

March 20, 2019

Scientists at the University of Illinois at Chicago have developed a way to identify the beginning of every gene—known as a translation start site or a start codon—in bacterial cell DNA with a single experiment and, through ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.