Climate change lures 'snowbird' cormorants to Phoenix, upsetting ecosystems and residents
On every other swing, Larry Seckels pauses for a deep breath as his wife, Joan, calls out the number of flyouts. From the branches above, disgruntled caws interrupt the steady beat of his metal baseball bat.
"You got six on that hit, hon," Joan shouts from the patio. "Less on that swing, just two."
From the nests they're being rustled from, the neotropic cormorants have a clear bird’s-eye view of Larry panting below.
The 79-year-old resident of Sun Lakes is taking on what he sees as a bird infestation with blunt force. He spends the last hour of light every day pounding on the trunk of the eucalyptus tree in his backyard, scaring away cormorants that would otherwise roost.
“I shouldn’t have to do this every night. But if I don’t, they’ll eat all the fish, then ruin the tree, then the grass, then the porch,” Larry said. “They used to leave, so you’d only have to put up with them for three or four months, but now they’re here year-round.”
Warmer winters, artificial water bodies, seasonal fish stocking, a selection of nesting trees and federal protection of the species has turned communities across metro Phoenix into an ideal long-term habitat for the cormorants.
Hundreds of these once migratory birds are now wintering in Arizona, setting off an environmental chain of dominoes on ecosystems across the region.
At Sun Lakes, year-round hunting pressure from the birds has led to a dwindling fish population. With fewer fish in the lakes, algae has muddied the water, leading to more insects. An abundance of well-fed birds also means more droppings, which studies have shown can negatively alter soil chemistry.
Residents, like Larry and Joan Seckels, have been asking homeowners associations and state agencies to intervene, but with federal protection, the cormorants are almost untouchable.
Arizona is the only state in the country to have intentionally euthanized neotropic cormorants in more than a decade. Wildlife officials and conservationists continue to debate the legality of killing protected birds, which is made more complex with an impending change in presidential administrations.
One thing led to another
While roughly six different species of cormorants migrate through the U.S., the most common in Arizona are the double-crested and neotropic cormorants.
The greater Phoenix area attracts the highest winter density of both cormorant species in Arizona, according to the most recent Coordinated Bird Monitoring Program Progress Report.
Data from the Arizona Game and Fish Department's annual urban water bird survey has recorded a steady rise in the abundance of neotropic cormorants in the greater Phoenix area since 2007. These cormorants surpassed their double-crested cousins in 2008 and have maintained the lead ever since. In 2020, nearly 4,000 were recorded in Phoenix, compared to just over 980 double-crested cormorants.
Usually, neotropic cormorants have a migratory path spanning North and South America. But these cormorants have recently become the true definition of a snowbird, a local term used to describe out-of-state residents who spend winters in Arizona.
Unlike human snowbirds, who eventually go home, the cormorants are nesting in local communities and extending their summer stay into a year-round visit.
Troy Corman, an avian monitoring coordinator for the game and fish department, says warmer winters are one of the factors causing this phenomenon.
“Warming climates are allowing some bird species, like the neotropic cormorants, to steadily continue northward,” Corman said. “These birds used to just come up here to breed, but with winter months being so much warmer in Arizona, they can now winter here as well.”
In the last three decades, from 1990 to 2020, the average winter temperature has been roughly 57.5 degrees, according to the National Weather Service. That's more than two degrees warmer than the 30 years prior, from 1960 to 1990, which averaged at 55.1 degrees.
These last 60 years follow a century-long trend of warming winters in Phoenix.
“This is all because of the warming climate," Corman said. "Like most places in the region, we’re not getting as much snow or hitting the same freezing temperatures. That means birds can travel farther and stay longer."
A 2020 study on avian migration in the U.S. found that climate change is causing migratory shifts in birds across the country.
“Bird migration has always been in response to long-term climate change patterns. Birds migrate because of seasonality and their patterns are driven by different climates," said Kyle Horton, an assistant professor at Colorado State University, who was one of the lead researchers for the study. "But the pace of climate change is more rapid than the animals we are looking at can actually adapt to."
The study used 24 years of radar data from across the country to quantify the way temperature changes affect migration. Using the data, the study focused on analyzing general bird patterns, rather than the patterns of specific species.
Horton thought the analysis was unlikely to reveal anything with all the data from different birds. But he said the fact the study found a shift in migration among several species is "compelling evidence that there is something real happening with climate change and bird migration."
"Birds can be the keystones of a healthy ecosystem," Horton said. "Start removing enough of them or adding too many of them and that will ripple through the entire system."
That ripple is being felt across greater Phoenix, which has the highest winter density of neotropic cormorants anywhere in the western U.S., according to the same coordinated bird monitoring report.
Along with warmer winters, human modifications are making it easier for the cormorants to stay. Many suburban communities in Phoenix feature artificial lakes and ponds. Sun Lakes is home to 21 of them.
The lakes, which are often surrounded by large trees that could be used for nesting, are seasonally stocked with fish.
Steve Nolan, the general manager of the Sun Lakes Homeowners Association, says constant hunting pressure from the cormorants has made him have to double the amount of fish stocked each season.
On average, a single cormorant can eat up to a pound of fish a day. While double-crested cormorants are more infamous for their ravenous appetite, they are much larger than their neotropic counterparts. The hefty appetite of the smaller neotropic cormorants usually goes unnoticed because they prefer smaller, more common fish, like tilapia.
With fewer fish to maintain the 21 bodies of water at Sun Lakes, Nolan has seen the waters become more muddied with weed and algae. This has caused another domino to fall.
Fewer fish means more flies.
The diet of fish, like tilapia, often consists of algae. Studies have correlated insect abundance with algae availability. Record-breaking heat and less algae-eating fish may have led to a boom in the bug population at Sun Lakes.
“In the summers, you can’t even sit out on your patio because a hundred flies will swarm you,” Joan Seckels said. “This is a totally new issue for all of us living here. Larry and I have been here for 10 years and this is the first time we’ve had this problem.”
The volume of droppings from the well-fed flocks of cormorants has also led to the deterioration of grass patches and trees at Sun Lakes.
A 2016 study found that one of the impacts of cormorant colonies was an altering of soil chemistry. With daily droppings, the soil from these colonies were found to be more acidic and have higher concentrations of phosphorous.
The incessant pooping, on top of the fishless lakes, fluttering flies and chorus of caws, led to the cormorants tipping the final domino: the residents.
Less lethal locals
Luckily for the bird, neotropic cormorants are one of the seven cormorant species protected under the Migratory Bird Treaty Act, which generally means people can’t just shoot them.
“There’s got to be something that can be done because it’s hard to believe that in this age of pandemics a bird has more rights than a human,” Joan Seckels said. “It’s good they’re protected because I don’t want them dead, I just want them gone or at least gone for most of the year. I don’t know how best to do that, but I do have a thing against killing.”
“Well, I don’t,” Larry Seckels interrupted, furtively glancing at the safe where he stores his 12-gauge shotgun. “I could clean that tree in two days. But I’d only do it if it were legal, and if you weren’t looking, hon.”
Finding non-lethal ways to scare away cormorants has become a passionate pastime for the law-abiding couple, who will celebrate their 58th anniversary this June. At first, their tactics were rudimentary, simply relying on vigorous clapping and angry shouting. But as the pair, retired teachers both, used to teach their students, you must be open to learning.
They've fired pressurized water guns, ordered on Amazon for $25 apiece, to splash the birds into the sky. But the branches where the cormorants perch are just out of range.
They've released reflective balloons into the tree canopy to startle the birds from the branches. But the cormorants just look the other way.
They've blasted hunting eagle sounds from a wireless Bluetooth speaker to terrify the birds into flight. But the cormorants know eagles prefer their double-crested cousins.
They've used a high-frequency electric bird chaser to irritate the birds into the air. But while the frequencies are supposedly too high for the human ear, the cormorants don't seem to hear them either.
Now, they've settled on turning their eucalyptus tree into a batting cage. Over text, Joan said, "You can't say us old people aren't up for a good fight!"
All of the Seckels' attempts to scare away the cormorants are legal because none of these tactics are lethal. What the couple is doing is considered harassment. Other legal harassment tactics listed by the U.S. Fish and Wildlife Service, include habitat management, loud noises, pyrotechnics, propane cannons, scarecrows, dogs and trained raptors.
A solution the couple has consistently pitched is cutting down their eucalyptus tree. While the homeowners association has trimmed its branches, which is legal since it would be considered habitat management, they’ve declined to cut it down.
“When you cut down a tree, you’re just chasing the problem down the road to another house," Nolan said. "Destroying trees is not a resolution."
With all these options exhausted, Larry has come full circle back to asking different agencies and organizations to lethally remove the cormorants. But while most have said it's impossible because of the bird's federal protection, that's not completely true.
It takes a federal permit from the U.S. Fish and Wildlife Service to lethally remove native migratory birds, such as neotropic cormorants. According to data from the Animal and Plant Health Inspection Service, Arizona is the only state in the country that has intentionally euthanized neotropic cormorants in more than a decade.
Last year, 25 neotropic cormorants were killed in Arizona. According to Gail Keirn, a public affairs specialist for APHIS, this lethal removal was "done at the request of the Arizona Game and Fish Department as part of a research study."
"One of the objectives of the project was to learn more about fish eaten by cormorants, and inspection of stomach contents was one of the ways that we could collect data on this topic," said Esther Rubin, chief of the department's Research Branch. "A paper describing the results of the project will hopefully be published soon."
This was the first time this species had been intentionally killed since a single neotropic cormorant was euthanized in Mississippi in 2008.
For homeowners to lethally take protected birds, they would have to apply for a Migratory Bird Depredation Permit.
This process begins with the U.S. Department of Agriculture's Wildlife Services reviewing the situation and suggesting nonlethal methods to address the problem. If these methods are ineffective or deemed likely to be, a biologist from the Wildlife Services will then have to complete a separate document — Form 37 — detailing the damage caused by the birds.
Once completed, the homeowners will have to submit the depredation permit application to the fish and wildlife service. The application includes the seven-page permit, Form 37 and an application fee, which for homeowners is $50.
If approved, these permits must be renewed annually. The renewal packet includes a re-submitted application, documentation on any lethal takes, nonlethal efforts being undertaken, a newly completed Form 37 and another permit application fee.
While neotropic cormorants are usually not the subject of these permits, the lethal take of other protected cormorants is not uncommon.
The double-crested cormorant is one of the seven cormorant species protected under the Migratory Bird Treaty Act, but in the U.S. more than 152,000 have been euthanized and another 2.5 million dispersed since 2010.
Unlike the smaller neotropic cormorant, these birds can eat larger fish and are known to feed on wild and stocked fisheries. Conflicts between humans and double-crested cormorants are so widespread there are several published books on the topic.
Earlier this year, the fish and wildlife service asked for public input in regard to a controversial management program that would mitigate conflicts by expanding the ability of states to euthanize double-crested cormorants threatening fisheries.
“Balancing the protection of native wildlife with economic and human health needs is fundamental to effective management practices,” said David Bernhardt, the U.S. interior secretary, in a press release.
Advocacy organizations, like the National Audubon Society, have called the management strategy “unsustainable persecution.”
"This latest proposal ... is absurd. There’s not much of a sense of wise ecosystem management going on with these kinds of plans," said Linda Wires, who has written a book about cormorant management, in the Audubon's press release opposing the strategy.
Bird lovers in Arizona have also stressed caution against any lethal management strategies.
“Caution needs to be taken when we make decisions like these because we can’t start a wholesale reduction of these populations,” said Tice Supplee, the director of bird conservation for Audubon Southwest. “There’s a reason why these species, like the cormorant, are listed as protected in the first place.”
Anton L. Delgado is an environmental reporter for The Arizona Republic/azcentral. Follow his reporting on Twitter at @antonldelgado and tell him about stories at firstname.lastname@example.org.
Environmental coverage on azcentral.com and in The Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow The Republic environmental reporting team at environment.azcentral.com and @azcenvironment on Facebook, Twitter and Instagram.