Sirens of change.
Birds that depend on the unique ecosystems in Rocky Mountain National Park don’t have long to adapt.
By: Jenna Sampson
Call to action
“One brown-capped rosy finch,” Scott Rashid called to me through the branches of a juniper as I fumbled with my winter gloves and pressed record on my phone to dictate the number. It was my job as a bird count novice to document each sighting.
Rashid is a self-educated bird researcher who organizes the yearly Christmas Bird Count in Estes Park. The local count, which covers ground in the country’s highest national park, Rocky Mountain, has been a yearly volunteer-run endeavor for over 70 years.
On the first Saturday morning of 2020, camo-clad and fur hat donning Rashid discussed details of the day to a group of over 20 volunteers huddled in the entryway of Estes Park Visitor Center. When the volunteers set off to their respective routes, I walked with Rashid to his Jeep, anxious to see what my first birding experience would be like tagging along with an expert. Standing aside, awaiting his invitation to get in, I watched as he cleared a space, tossing books aside and grabbing the paw of a limp carcass, flinging it into the trunk.
“Rabbits are good for my bird boxes because their skin just falls apart,” he said of the foraged roadkill he’d collected that morning.
Rashid has been banding birds for decades, clocking in over 56,000 of them, one traveling as far as the Canadian Rockies and another landing right back in his yard for its final breath. He uses the rabbits and other carcasses he finds around town to lure birds into his boxes. Banding allows him to track the individuals and learn where they end up.
The bird count and banding work point to why birds are such good indicators of ecological disturbance. They are easily observable over time and are sensitive to change, making their shift in whereabouts something of a call to action for researchers.
Over 119 years of bird count observations from thousands of locations combine to create a staggering number of data points that have been used in over 200 peer-reviewed studies. One recent study by the Audubon Society (which organizes the count) in partnership with the National Park Service, found that birds will likely go through a major shift in the coming decades. By 2050, they predict that a quarter of all birds in any given national park could be replaced by new species. This means that some will be pushed out to new homes, but others will have nowhere else to go and are at risk of extinction.
The Audubon study integrated official climate models with observations from the Christmas Bird Count, the longest-running citizen science project in the country. It found that at least ten species of birds may no longer be able to survive in RMNP. Colorado’s state bird, the Lark Bunting, is one of the more ominous examples in that cohort.
Among the species likely to be found at (RMNP) today, climate suitability in summer under the high-emissions pathway is projected to improve for 68, remain stable for 34, and worsen for 20 species. Suitable climate ceases to occur for 9 species in summer, potentially resulting in extirpation of those species from the Park
Figure and text taken from the Birds and Climate Change: Rocky Mountain National Park study published by the National Audubon Society in March 2018.
The good news, however, is that 30 or more species being pushed out of their homes elsewhere are expected to find a new one in the park, particularly in winter as conditions become less extreme. As the researchers are quick to point out, none of their models incorporate the complex dynamics happening aside from climate change, like species interactions that add uncertainty to the equation.
Average annual mean temperature, 5-year rolling average, and trend in Rocky Mountain National Park, 1895-2013. (PRISM Climate Group, Oregon State University, http://prism.oregonstate.edu, created Oct. 2014 by NPS)
Birds will survive through adaptation, as they have through the ups and downs of the last 80 million years of their evidenced life on Earth, but this time is different. Continuing their ever-expanding poleward journeys, as they have since deglaciation, birds are now racing against not only a much more rapidly warming planet, but other human-caused stressors that make the ecosystems they depend on much less resilient.
Humans are cutting off corridors, trampling fragile tundra, polluting the air and so on. All of this together makes ornithologists wonder which species will be able to adapt fast enough to survive the onslaught of changes.
Many species benefit from warming, which allows them to gain new ground as their habitats expand into areas that are becoming more hospitable. During the last glacial maximum bird ranges contracted and then expanded again as a warming climate peeled back the ice to reveal new habitats for exploration. Their northern expansion continues today, with species being tracked farther and farther north than their ancestors.
Like the hundreds of thousands of Canadian geese that descend on Colorado in the winter. They love the urban heat pockets generated by big buildings and lots of paved land that absorb sunlight. But as the climate warms in the north, some of the geese, which many Denver locals consider to be overcrowding city parks, may not need to migrate so far south to enjoy those warmer conditions.
Others, particularly species that reside in high altitude areas like Rocky Mountain National Park, are being closed in on as the tundra ecosystem they depend on is threatened.
Alpine tundra defines the character of RMNP for many visitors, covering one third of the 265,761 acre park. Visitors can even drive along one of the highest paved roads in the country, Trail Ridge Road, up to over 12,000 feet in elevation, to see this habitat in all its glory from the comfort of their car - at least for now. Ecologists predict grasses and shrubs will take over that landscape as the climate continues warming, and the lower elevation (montane) habitats expand.
“Montane habitats are creeping up into the mountains and there’s only so far they can go before they disappear,” said Garth Spellman, Curator of Ornithology at the Denver Museum of Nature and Science.
Two birds, two futures.
The Brown-Capped Rosy Finch is an endangered species. As the highest-breeding bird in the country, the finch is restricted to areas above treeline. This alpine ecosystem is getting squished by the lower-elevation ones that are expanding upward. Because this species is so restricted geographically, scientists worry they aren’t genetically diverse enough to adapt by breeding with a similar species.
Here, a Clark’s Nutcracker feeds on a Limber pine seed. These birds are accidental architects of the forest by caching tens of thousands of seeds each year, more than they are able to return to. Those left behind have a chance of germinating and growing. However, changing climate conditions are proliferating a fungus that kills this tree, which in turn would reduce the food security of the nutcracker. Researchers expect a 40 percent loss in Limber pine coverage over the next ten years.
The Brown-capped Rosy Finch is expected to lose most of its wintering range even in the least aggressive emissions scenario, according to the Audubon. https://www.audubon.org/field-guide/bird/brown-capped-rosy-finch
The Clark's Nutcracker is expected to lose 52% of its wintering range by 2050, according to the Audubon. Since more northern states will get warmer, this will open up new range for expansion as well. https://www.audubon.org/field-guide/bird/clarks-nutcracker
Specimens being tagged and registered into the Museum archive, which is publicly searchable. Photo by Jenna Sampson
Genetic diversity is key to survival
With over 50,000 specimens in the ornithology collection, Spellman has direct access to the DNA of birds from the early 1800’s to present and can pop downstairs to the brisk white halls of the collection to get any data he needs, including from birds like the passenger pigeon that went extinct from over hunting in 1914.
Sitting in the museum’s lounge admiring flocks of Canadian geese grazing a large meadow, grey air revealing our proximity to the noxious I-70, we discussed Spellman’s work looking at the genetic profile of birds as they have evolved since the last glacial maximum.
When you look at the entire range a bird species might travel, which for the geese might be from central Mexico all the way up to Prudhoe Bay, Alaska, Spellman points out individual birds aren’t necessarily migrating the entire distance. There are subgroups within a species with genetic differences that lend their unique traits to slightly different habitats. This genetic diversity across the species is highly valuable for survival.
Genes, Spellman said, can tell him about minor differences between subgroups to help him understand how adaptable the overall species may be to a changing climate. The more subgroups, the more genetic diversity. The more genetic diversity, the more resilient a species may be.
“It looks like their history of mixing with other species is an important facet of their evolutionary history,” said Spellman. “That sort of injection of variation is very important in generating diversity.”
Spellman emphasized that while many birds on the planet interbreed with other bird species, those in the northern latitudes have had much less time to do so because that area has only more recently (as in since the last ice age) opened up for them to explore. This lack of genetic diversity can be seen in their DNA when compared to subgroups of the same species near the Equator. This is called the leading edge effect, where the subgroup that is pushing the range boundary, like many birds are doing now, will be less diverse than those in the rest of the range.
Similarly, high-elevation species that live in small isolated zones, like the brown-capped rosy finch we spotted in the bird count that breeds above 11,000 feet, or the white-tailed ptarmigan that resides year-round in high alpine or subalpine regions, are extremely vulnerable to climate change because researchers expect them to lack genetic diversity due to their restricted ranges. RMNP is a refuge for both of those unique species, and climate models show their habitats quickly shrinking.
Spellman is involved in the first gene sequencing project of the rosy finch to see just how diverse the species is, and thus how vulnerable it may be in the years to come. He suspects there could be subgroups we don’t yet know about.
“We can get DNA out of 100 year old samples and see whether there’s a loss of genetic diversity over time.” —Garth Spellman, curator of ornithology at the Denver Science Museum
The challenges of species protection
Managers at national parks across the country are barely treading water in dealing with the subtle changes that have been taking place in our ecological sanctuaries over the last few decades. According to Koren Nydick, chief of resource stewardship at RMNP, human-caused stressors like air pollution and increasing visitor sprawl are chronic issues already.
“One of the things to remember when we think about climate change is that there are a host of other stressors already affecting the park,” she said.
Because national park service lands are so well protected, they remain refuges for birds and other species vulnerable to changing conditions. The big question is, will park managers be able to do enough to protect them?
According to the Audubon study, even in the most conservative scenario of warming that takes us to +1.5 degrees, the rosy finch will lose the entirety of its summer habitat and most of its wintering habitat from the cascade of consequences that come from early spring heatwaves. The White-tailed ptarmigan is riding a similar headwind, and a 2006 study highlighted the unimaginably impossible job conservation stewards have when it comes to their protection.
That study says that managing the ptarmigan population will require protecting their alpine ecosystem from overuse, recreation, mining and development, and “general environmental perturbations that contribute to global change” like pollution and depletion of the ozone layer.
In essence, erase the human footprint and the species will survive.
In her earlier days as a scientist for the Mountain Studies Institute, Nydick researched the effect of toxic air wafting into high elevation lakes from activities like dairy farming, which emits ammonia. Since her research decades ago, she says the impact has become so severe that you no longer need a microscope to see it. Algae has taken over these lakes, which if left unattended will choke out sensitive aquatic species, further reducing the resources birds rely on for survival.
No ecosystem goes untouched or unmonitored. Forests are changing too.
Blister rust is an issue scientists have been confronting as the damage it causes recently spread farther in the park, likely due to a warming climate. Warming conditions are making trees more susceptible to disease because there’s a longer timeframe for fungus and other killers like pine beetle, which has wreaked havoc on Colorado forests, to proliferate. The tree-killing blister-rust, which surrounds bark with a bright-orange bumpy fungus, surged in 2015, killing 50 precious limber pine trees up from just one or two previously. These slow growth contortionists are a keystone species that, while not very abundant in the park, have an overwhelming impact on biodiversity through their highly nutritious seed. Ounce for ounce, a limber pine seed has more calories than chocolate.
After 50 years of growth, one limber pine will finally produce one pine cone, and after a century it will be fully productive. This pine species defines the Rocky Mountain treeline because of its ability to withstand the extreme conditions.
An old growth limber pine tree (Pinus Flexilis) on a rocky outcropping, where the species is able hold strong against extreme winds. photo by NPS
The limber pine tree is dependent on one bird in particular, the clark’s nutcracker. The nutcracker is a small songbird that some consider an architect of Rocky Mountain forest. A single one of these birds can stash over 30,000 pine seeds in a single season, leaving many of them untouched to germinate. Grabbing a seed with its beak, the nutcracker will gage the seed’s weight to decide whether it bears a tasty endosperm - the meaty inside of a pine cone. It digs little storehouses with its beak in areas that won’t be covered by snow (where limber pines happen to be able to grow) so it can find them come winter, and has evolved a memory to match the immensely of its sprawling pantry.
Other animals feed on the seeds as well, but only the nutcracker can spread such a vast number of them so widely. This symbiotic relationship is in peril if park managers can’t contain the deadly expansion of blister rust and protect the limber pine as a food source.
Researchers like Laurel Sindewald, a Phd student at Colorado State University who studies the tree, devote their lives to understanding the problems that are most threatening our national park ecosystems. Sindewald believes that If limber pines are wiped out of the park, that could force the animals it feeds to move elsewhere.
“Clark’s are primary dispersers. If limber pine were to decline, the bird may be able to sustain on other pines, or they may need to track availability of that better food source and seek greater pastures so to speak,” she said.
This is the great unknown when it comes to birds and climate change. How willing and able are they to venture away from their homes in order to adapt?
“Like the resource it seeks to protect, wildlife conservation must be dynamic, changing as conditions change, seeking always to become more effective.”
Science enables conservation
“When I got involved in ornithology I was really interested in evolutionary history. Now I’m really interested in studying it so that the work we do can help guide conservation,” said Spellman, who worked in academia and at the National Science Foundation before being invited to curate the science museum’s ornithology collection and taking on a more public-facing role.
If you speak to enough scientists, that is one overarching sentiment you’ll see connecting their work.
“I’m motivated by the conservation of natural resources,” said Sindewald, who studies the impact of climate change on high elevation forests. Her mentor was Diana Tomback, a lifelong researcher of whitebark pine trees, which have been heavily impacted by blister rust in the northern Rockies and are now listed as endangered. Tomback founded the whitebark pine ecosystem foundation that lobbies for funds to protect and restore the species.
As the environment changes, scientists are the first to see what lies ahead. Some of them have seen it in the melting ice caps, some have witnessed it in the bleaching of coral, and others see it in the subtle changes in movement of feathered visitors at places like RMNP.
Park managers know that the lands they protect are refuges for biodiversity. And with the help of many hoards of scientists searching for evidence of change, they are in a position to play god. Determining what to protect and how to fan out resources is an act of cherry picking. Which species matter most, to us and to the ecosystem? Which are protected by federal law? With increasingly limited resources (including big dips from government shutdowns and global pandemics that force closures and thus slash visitor dollars), managers need to work smart.
In the past, conservationists have used the weapon of human emotion to bring more resources to a problem.
While trudging into the deeper snow off trail looking for woodpeckers during the bird count, Rashid pointed to a distant cliff where a bald eagle nest was managed by researchers after their massive decline during the Silent Spring.
During the Silent Spring, which was coined by Rachel Carson’s namesake book that brought to light the issue of DDT destroying swaths of the avian population, one powerful and mighty bird was cleverly selected as the icon: the bald eagle. The bird’s majesty is what energized society to take action, and thankfully the rest of the birds benefited from that cultural momentum to regulate DDT, the deadly pesticide that caused avian numbers to plummet.
Unfortunately, even an Arctic icon like the polar bear can’t solve the problems of today that are just not as easy to work out. Scientists, land managers and environmentalists have tried to point to climate change as a way to pin-down cultural remedies that lower our carbon footprint, but the sheer amount of stress on the ecosystems is beyond that which can be fixed by driving less and turning off our lights. Even without climate change, which is playing out uniquely in every nook and cranny of the ecosystem, the parfait of stressors already in place leaves the system in a precarious position.
“Part of our approach to climate change is reducing other stressors to the extent possible,” said Nydick. “We don’t have control over changing climate - it’s one of the things we have the least control over. So we’re trying to reduce other stressors and looking at what processes are important to help buffer climate change.”
With 265 bird species making use of the RMNP for some amount of time during the year, the avian community has a lot to lose. The web of connection between each bird and any given element of the ecosystem shows how tough a job it will be for park managers to determine what remedies will have the biggest impact. As animal ranges shift and ecosystems evolve, the answer may be a moving target.
At a science conference in Estes Park in March, researchers who study issues in the park filled two days with talks about current initiatives, with a small but interested group of citizens there to see how their most beloved public land is holding up.
They heard about elk-proof fences to restore willows, blister rust mitigation to save limber pine, beaver reintroduction to preserve wetlands, nitrogen management to reduce air pollution, citizen science efforts, interagency coordination efforts, and leave no trace reminders. All strategies that help one species or ecosystem brace for the impact of climate change, and hopefully helping them brace for impact.
“If I were a gambling man, I’d bet on more change in the future,” said Scott Esser, Director of the Continental Divide Research and Learning Center, which organized the conference.
And as Nydick pointed out, there’s only so much to be done on the ground to buffer the intensity of climate change. Even in the least dire scenarios, animals will continue to go extinct because their habitats are evolving too fast. It’s only a matter of time before the squishy tundra goes the way of the telegraph and the skies fill with pioneering species.
“If we were to come back ten thousand years after we change the climate, the diversity we see is going to be surprisingly different,” said Spellman. “We’re in the midst of the sixth mass extinction, and when species blink out that quickly, you’re losing important variation.”
“Last year I documented the first boreal owl in the history of the park.” — Scott Rashid, an avid birder and owl researcher who organizes the Estes Park Christmas Bird Count.
Counting on the present
Our bird count route began at the Bridalveil Falls trailhead and we would cover just two miles in two hours, counting roughly 320 birds. It’s not an exact science. There’s a lot of, “We’ll call that five finches...make it 10.”
The work of a single bird counter seems endearing, yet when you add up the number of circles around the world (a circle is a region where one leader like Rashid organizes a count) and then sum it up over 119 years, you get to track migration patterns and relative abundance in places like RMNP over time. For instance, there was only one nutcracker on the books in 1953 and only nine counted in 2009, the year before it spiked to 170. Because of this yearly variation, understanding long-terms trends through observation is an incredible contribution to avian science.
At the end of the day, our circle spotted 55 different species, a bit less than the 79 species that should be able to find suitable habitat in the park over winter. And if the Audubon study predicts right, that number will be closer to 100 by mid-century.
Birders will have their work cut out for them.