This year is not a particularly white Christmas. Across the United States, families are gathering to enjoy a walk on a warm, sunny day. The fingerprints of climate change are all over the 2025 holiday season, and we at CNN thought it would be a great time to find out how the animals that shape our stories and traditions are weathering the warmth.
From Santa's reindeer and the Hanukkah armadillo to some very festive sea worms, our changing world is changing life for creatures great and small. And while some of these animals are struggling, a few may be key to helping us adapt to the future.
Reindeer can't handle this warming
You'd think a species that already survived some of history's most intense and rapid Arctic warming events would have the wherewithal to weather modern, human-driven climate change. Unfortunately, things are not looking good for reindeer, who soon could be as mythological as Santa's elves.
Reindeer survived through the rapid warming that melted the last big Ice Age about 20,000 years ago. In Greenland, temperatures shot up by as much as 18 degrees Fahrenheit in a matter of decades, pushing other Arctic megafauna to extinction. But in the last 30 years, about 40% of the global reindeer population has been lost. It appears the adaptations that served the species well last time aren't as effective today, according toa study published in Augustby researchers at the University of Adelaide, in Australia, and the University of Copenhagen.
Those scientists found that reindeer survived previous changes in the climate because they had spread into lots of different ecological niches. They could thrive in a small, cooler refuge and repopulate broader areas when things got cold again.
Today, however, the warming is global; the reindeers' range isn't as large; and it's harder to find a cool place to hunker down. Incorporating these findings about the past into models of the future, the researchers found that global populations of reindeer could shrink by as much as 58% between now and 2100 — with places like North America losing even more.
Unfortunately,new research shows that fewer reindeer could actually make climate change worse. Researchers from Finland and Alaska found that, in far northern forests where snow isn't falling like it used to, soils release more carbon dioxide to the atmosphere rather than storing it. But reindeer can counteract that effect. If reindeer are grazing under the trees, the soil still traps carbon — even when there's no snow.
Christmas tree worms might help us protect coral
The Christmas tree worm looks like a Christmas tree — but the kind you'd find in a Kodachrome photo from a 1950s magazine. Conical, feathery and brilliantly colored in blues, pinks, plum and orange, these tiny worms attach to coral reefs as larvae and then hang out, immobile, for the rest of their lives.
While they aren't particularly active, they're far from lazy. Christmas tree worms have a symbiotic relationship with the coral they live on.
Tendril-waving adult worms circulate water around the coral, which helps the coral eat. And baby coral polyps find shelter under the Christmas tree's branches, where they can hide from predators like the sea star. Because of this, scientists think we might be able to use Christmas tree worms as a way of learning about the health of coral.
For example,a 2022 study by students at the University of California Berkeleyfound a correlation between healthy coral and higher numbers of Christmas tree worms. It's possible that, in the future, these worms could become an early warning signal — showing scientists where corals are under stress from warming seas before the situation becomes dire.
Hanukkah armadillos are coming to your town
Back in 2000, when Ross from "Friends" dressed up as an armadillo to teach his son about the true meaning of Hanukkah, the real-life animal was still thought of as a creature of the Southwest. But that's changed.
First identified in Texas in 1849, the nine-banded armadillo expanded its range significantly, its steps tracing a pattern of warming weather toward the north and east of its historic homeland.A survey in 2014found that the animals were able to establish a footing anywhere the average low in January remained above about 18 degrees Fahrenheit.
Turns out, that describes a lot of the United States. Take Iowa, for example. That state didn't even have a verified report of a live armadillo until 2017. But in 2025, researchers from the US Geological Survey used public wildlife reporting apps, live tracker cams and other data sources to documentmore than 250 recent armadillo sightings in Iowa.
Their data found hundreds of armadillos happily digging up gardens as far north as Indiana and as far east as North Carolina. The data is teaching us about what makes good armadillo country — warm, but not too dry, and forested seems to be best — and where they're most likely to expand next — Ohio, Virginia and Michigan are all good candidates.
Narwhals are surviving in surprising ways
In 2007, a young researcherreached out to the curator of the Rosenborg Castle museumin Denmark with a weird request. She wanted to drill into the king's throne.
The museum houses the Coronation Chair of Denmark, used by real Danish kings from 1671 to 1840. But what made it special to Eva Garde were the spiraling narwhal tusks that decorate the sides of the throne. Garde's research focuses on the history and future sustainability of narwhals, a species of Arctic toothed whale famously beloved by both small children and Buddy the Elf.
But narwhals, as a group, aren't very genetically diverse — a fact that could prove dangerous for them as it will likely limit their ability to adapt to a warming Arctic. Garde wanted to know what the narwhals' ancestors were like. And DNA samples drilled out of a 350-year-old throne was the perfect place to start. Maybe, if Mr. Narwhal could find his dad like Buddy did, then humans could better understand how to keep that species healthy into the future.
The museum allowed Garde to remove samples from the throne, and the whole thing was reassembled. Since then, her team has learned a lot about these creatures. In fact,her researchhas helped establish that narwhals have been living comfortably with a low genetic diversity for thousands of years — something that is a bit of a surprise.
That doesn't mean climate change isn't a risk to narwhals, however.The genetic datasuggests that this species might be stable with the lowest amount of diversity possible right now. If a hotter Arctic reduces that further, the narwhal could be in trouble.
The partridge is dying by a thousand cuts
Sending your true love a partridge in a pear tree might have been an invitation to do a little easy target hunting. Red-legged partridges have been a favorite game bird in Europe for millennia; its bones even show up in Paleolithic settlements.
But its long association with humans has put the red-legged partridge in the path of several different negative impacts. It has been over-hunted; squashed by tractors and other modern farming equipment; sickened and killed as a side-effect of agricultural pesticides; cut off from care by former farmers abandoning the countryside for city jobs; and outcompeted by other species of partridge bred specifically for hunting.
Between 2010 and 2020, red-legged partridgepopulations have likely declined by as much as 40-45%, according to the International Union for Conservation of Nature and Natural Resources, the organization that determines whether a species is endangered.
None of that has to do with climate change, specifically. But all of it makes the partridge more vulnerable to climate change in the long run.
In 2021, a team led by scientists from Sweden and Italysequenced the red-legged partridge genomeand learned a few key things. First, this bird didn't do well during a warming event 140,000 years ago. In fact, its population declined so significantly back then that its genetic diversity has never recovered. And unlike the narwhal, which grew in population and remained stable with a low genetic diversity, partridges have had no such luck.
The result is a bird that isn't well-equipped to adapt to climate change and whose numbers are already plummeting, reducing its ability to adapt even more.
Donkeys bring blessings on their backs
Las Posadas is a Central and South American Christmas tradition where people recreate the story of Mary and Joseph searching for an inn. Given their prominent role in Biblical transportation, donkeys are a big part of the festivities.
And research shows donkeys have a role to play in helping humans adapt to climate change, as well. In northern Kenya and southern Somalia, for example, they're used to carry water and food over long distances during droughts. Other animals could do that job in good times, but donkeys are particularly adept at helping people survive climate disasters, wrote a team of researchers from University College London ina recent book on animal human interactions under climate change. Donkeys' digestive systems function like internal saddle bags — absorbing extra water when it's available and holding onto that moisture when water is scarce. Because of that, they're able to keep carrying water and food to humans even in situations where other animals can't.
Donkeys also help support healthy ecosystems. Other grazing animals easily strip sensitive soils bare, leaving them prone erosion. But donkeys eat a wider variety of plants, so they're less likely to over-indulge on grasses. And onerecent report from researchers in Tunisiafound that donkeys in the Mediterranean preferred to eat the invasive plants, which helps diverse species thrive.
There's even a possibility that donkeys could help protect us against insects and the diseases they carry. Ticks and tick-borne illness are increasing their range thanks to warming weather. Buta new studyfrom the University of Massachusetts at Amherst found that donkeys' skin secretes a chemical that ticks avoid. When the chemical was applied to horses, the ticks stopped biting them, too.
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