A few weeks ago, as my friend Forest and I rode our bikes on the vast white sheet of the frozen Yukon River downstream of Galena, the river forced us into a 90-degree hard left. There, the channel suddenly necked down from being almost a mile wide to just a quarter mile.

A 300-foot outcrop known as Bishop Rock sits at this pinch point on the middle Yukon. Its name — bestowed by someone in remembrance of an Oregon missionary who was murdered there in 1885 — comes up at this time every year when people start talking about river breakup and the potential for ice-jam flooding.

Kyle Van Peursem of the Alaska Pacific River Forecast Center mentioned Bishop Rock during a recent presentation on the potential for spring floods in communities along the state’s rivers.

Though the Yukon, Kuskokwim, Koyukuk and other rivers in central and northern Alaska are all very solid and white as of this writing, that will soon change. River breakup happens when the power of the sun melts feet of snow from the landscape and rots the ice of the river that was hard as iron for so dang long.

Predicting when breakup will occur at any of the dozens of villages along river systems is an inexact science. The most important variable is air temperature. Warmer Aprils are good, Van Peursem said, because they allow the snow and ice to melt at a more gradual rate that won’t overwhelm river channels.

The biggest driver of the dynamic breakups that flood villages is a cold April that “compresses the time to get rid of snowmelt,” he said.

Alaska villages on rivers most often flood in springtime due to ice jams. Jams happen when meltwater shoves chunks of recently broken ice sheets together.

“I think of these as like a dam in the river,” Van Peursem said. “The breakup front (a conveyor belt of ice chunks) stops, water has no place to go and piles up behind it.”

Constrictions in rivers like Bishop Rock are common places for ice jams. In 2013, a pileup at Bishop Rock swelled the river upstream like a python and flooded Galena. The same happened in 1945, when U.S. Air Force bomber pilots dropped more than 75 bombs on the ice jam in front of Bishop Rock. They failed to dislodge the mass of ice.

Bishop Rock will soon loom large in windows of a single-engine aircraft in which Van Peursem will fly. He will monitor that portion of the Yukon River on flights from Galena as part of the Riverwatch program.

Van Peursem said the part of the Yukon he is monitoring is trending toward a dynamic breakup due to a cold April — Galena’s low temperature on April 22, 2026, was in the single digits Fahrenheit — but “hopefully we can slowly warm up as we go into May.”

A note to my readers: This, friends, is the second-to-last Alaska Science Forum I will write. After 31 years in the saddle, I am retiring from my science-writer job here at the Geophysical Institute on May 1, 2026. Though I have planned this for a while, the date sure has snuck up. I will sum up the whole adventure in my final column next week.

And — fear not — my boss and other leaders at the Geophysical Institute are committed to continuing the Alaska Science Forum after I leave.

Short-tailed shearwaters used to blacken the skies on the south-west coast of Australia, so abundant were they in their coastal homes each Djilba season – the time in the calendar of the Noongar peoples between August and September, when days shift from blustery cold and wet winds to warmer weather.

In Wudjari Noongar, the language of the traditional owners of this place they call Kepa Kurl, but which since colonisation has been called Esperance, the birds are called yowli. To other cultures they are muttonbirds.

At the other end of the year, on the other side of the globe, flocks of shearwaters would darken the skies in Alaska, ready to feast on the teeming fish and squid from melting ice and snow in the Arctic summer. Like the Wudjari, the Yup’ik would mark their arrival.

But First Nations peoples on both coasts have noticed that something is wrong. They began to see sick and dying shearwaters washing up on beaches: emaciated, their bellies filled with microplastics instead of food. Birds were turning up in places they hadn’t been seen before, veering far away from their fixed migration routes as they searched farther afield for food.

Jennell Reynolds, healthy country program coordinator and senior ranger with Esperance Tjaltjraak Native Title Aboriginal Corporation, grew up hearing stories of the yowli. More than 30 million return each year to breeding colonies off Australia’s southern coastline, mostly concentrating in the eastern states – but large numbers also return to burrows in the craggy archipelagos off Western Australia’s southern coast as well as the sand hills near Esperance, an area known for its pristine waters and white sandy beaches.

“It’s so graceful seeing them skip across the water when they’re feeding and diving,” Reynolds says. “They are such inquisitive birds when they come into the land.”

In April they return north to make the 15,000km journey back to Alaska, with newly fledged chicks in tow.

In an attempt to understand the birds’ perilous journey, Tjaltjraak rangers are working with Yup’ik and other Alaskan traditional owners. The global research project combinesecological, scientific and ancestral knowledge.

“It was one of those things where you know that you’ve got this connection through this one bird,” Reynolds tells Guardian Australia. “It’s a special moment because we are all on the same page in relation to taking care of country. We both have a kinship with the animals and wildlife and we’re making sure that we have that same responsibility for looking after them.”

The collaboration began by building on pre-existing relationships between the Tjaltjraak rangers and their Eyak, Iñupiaq, Yup’ik and Alutiiq community counterparts. Early conversations revealed shared concerns about declining numbers.

David Guilfoyle, a coordinator with the Tjaltjraak rangers, spent many years living and working in Alaska. He says those longstanding community ties helped fast‑track what is now a formal cross‑cultural partnership.

The project aims to form a clearer picture of how the birds live: their migration patterns; how deep they plunge the ocean in their quest for food; and ultimately the risks they are facing in a changing environment.

“It’s very holistic,” Guilfoyle says. “It’s not just looking at the species so much as looking at the whole ecosystem and what role these birds play, and what we can do to protect and manage them. But we can’t do that until we get a lot of data.”

The rangers knew the birds returned each year to colonies off Esperance; Alaskan communities knew when they arrived in their waters. But the exact route, the staging areas and what was happening in between remained largely invisible.

To answer those questions, Tjaltjaak rangers had to catch and tag the yowli. That meant working quietly and quickly in cold, dark and potentially snake-infested sand dunes on an island in the middle of the Southern Ocean, with only red torchlight to see by, says one ranger, Hayleigh Graham.

The team placed tiny, almost weightless sensors and tags on them – which required a little finessing to ensure the technology would adhere to delicate legs and tails.

“We had to sort of sand it back, so we made a bit of glue but the glue didn’t really work as well, so then we tried double-sided tape but, nope, that wasn’t so good,” Graham says.

“We ended up having to get some smaller zip ties to try and trim it off and make sure the ethics of the way we put it on wasn’t hurting or damaging the birds, and then as the sun started to go down, within a few minutes, we got our first yowli.”

By the end of the night, they had tagged 21 birds.

“It’s still really early days,” Guilfoyle says. “We’re really nervous. I can’t sleep since we’ve tagged these birds – every hour I’m checking the map about where they’re going. It’s like being an expectant parent.

“We watch them every day, so now it seems like they’re starting to slowly track towards Tassie, and then eventually they’ll just start missioning north to Alaska.”

Tjaltjraak rangers say the birds are not only culturally significant but vital to the area’s delicate ecosystem. The shearwater’s fixed habits make it a warning sign for the health of their breeding and feeding grounds.

“It’s like an alarm bell,” Guilfoyle says. “If we don’t see them as much now, what have we lost? At the very basic level, that observational data is a call to action: we need to make sure that we’re not just falling for the trap of shifting baselines.”

Climate threats

Estelle Thomson is a Yup’ik leader and president of the Native Village of Paimiut Traditional Council. She lives in Anchorage and works closely with Indigenous rangers and wildlife ecologists as a bird migration advocate and vice-chair for the Yukon River Inter-Tribal Commission, which represents 43 tribes from the Bering Sea to territories bordering Canada.

She says the shearwater were not originally one of the hundreds of birds that flew to the vast Yup’ik lands but were usually found on a cluster of islands in the Bering Sea. But they have been recorded as far south-west as the Kuskokwim River, far from their traditional migration path.

“They typically go to the Aleutian Islands … but because of climate change and because of a whole bunch of extenuating circumstances, they’ve actually been starting to come into my region,” Thomson says.

“We can tell when things are starting to go a little bit awry with the birds. We can tell when they’re not getting enough food, if they’re not coming in at the times that they normally do. We can tell when they’re late. We can tell if their food sources are having difficulty.”

The permafrost tundra is melting, leaving the region vulnerable to typhoons and other extreme weather events. The climate emergency is displacing Indigenous peoples from their lands. Once-abundant traditional food sources are becoming scarcer.

Many of those food sources are migratory birds – some 220 species of which spent part of the year in Alaska. Thomson has partnered with Indigenous peoples around the globe through a collective calledChildren of the Sky, which brings First Nations people together to gain a deeper shared understanding of migratory birds and their place in our ecosystem.

“Our peoples have specific, traditional ecological and Indigenous knowledge about our non-human relatives,” she says. “The people on the other side of flyway that we’re on also carry knowledge. So when we get together, we’re able to share what we know from each of our perspectives …

“The birds are a global citizen. This bird has no allegiance to any specific country. It doesn’t look at the boundaries of borders.”

Reynolds says she hopes the project will open the way to other cross-cultural endeavours.

First, though, rangers will have to catch the birds again next November to remove their tags.

“We’re all custodians now,” Reynolds says. “It’s not just us. It’s everyone’s responsibility to be able to care for country.”