Bor Mihelič was drifting. Not emotionally—physically. His kayak slowly veered toward a mid-river boulder as he squinted through binoculars, scanning the gravel bar for the distinctive flight pattern of the little ringed plover. A small notebook and sawed-off pencil balanced on the shelf of his opened life jacket pocket. A gentle thud reverberated off the water as his stern clipped a rock, almost sending his notebook into the water. Bor quickly collected himself (and his tools), and brought the binoculars back up to his eyes, unaware that the rest of the four-person crew (who had been watching from downstream) had burst into laughter.

And this is how it went, for almost 300 km on the Sava River.

In June 2021, Balkan River Defence crew embarked on a mellow version of Balkan River Tour 5 (BRT5), descending the Sava River in Slovenia for 258 kilometers. Bor utilized this time out to complete the first continuous bird census of the Sava during nesting season. And he used a unique ‘scientific method’ to do so: a whitewater kayak.

The goal of the BRT5 expedition was to produce a feature-length documentary that shares the magic of the Sava River, advocating for the river which is threatened by 12 new dams. (The film has since been shown to thousands of primary school students throughout Slovenia and is airing on national television and airlines.)

This trip gave Bor—an ornithology expert, active member of DOPPS (BirdLife Slovenia), and student of nature conservation at Biotehniški Center Naklo in central Slovenia—the rare opportunity to observe the river’s avian life uninterrupted, in real time, from the water.

Armed with a childhood of birdwatching—spent searching for elusive species like capercaillie and black grouse in the mountains and forests of Slovenia with his family—Bor’s focus this time was on recording breeding populations of key Natura 2000 bird species like kingfishers, dippers, herons, and storks. For 11 days, while the crew paddled and filmed, he paddled and recorded bird sightings, logging data that would become the foundation of his diploma thesis and a baseline for future conservation efforts.

For his thesis, “A Comprehensive Inventory of Nesting Birds of the Sava River by Kayak,” Bor divides the Slovenian stretch of the Sava into 18 sections based on river flow (free-flowing vs. reservoir). All waterbirds and river-associated bird species were recorded with exact locations, breeding codes, and counts. Breeding codes are standardized indicators of bird breeding activity, meaning he might note a singing male as indicating possible breeding, a pair in suitable habitat indicating probable breeding, and an occupied nest confirming breeding.

In total, Bor recorded 1,972 individual birds from 24 species. The most numerous were mallards (414), goosanders (229), and grey wagtails (223). Notably, a new cormorant colony was identified—a species not previously registered as nesting on the Sava. While overall diversity was comparable between natural and dammed sections, the free-flowing parts of the river supported more species of conservation concern. This supports the argument that intact river ecosystems are critical for protecting biodiversity.

Using a kayak for bird censusing has been proven (by another kayaker-nature conservationist before him, who did his thesis on the effectiveness of surveying birds by kayak) to be more effective than surveying by foot, as it is quicker, quieter, less intrusive and gives a clearer view of birds and habitat, leading to fewer double counts.

What did this look like on the water? Paddling and scanning. Even when we were deep in discussion, or goofing around, Bor was constantly scanning and listening. His eye is trained to identify birds based on their flight patterns and silhouettes, and his ear is honed to specific calls and birdsongs. It’s like he knows a secret language of the river. The whole group helped when the river got wide, broke into multiple channels or opened up on a reservoir. And every few kilometers, he made a tally in his notebook, which was safely tucked into a beaten Pelican case holding his (equally beaten) binoculars.

Bor’s work wasn’t just academic. Conservation groups like the Slovenian Native Fish Society are now using his data to advocate against further hydropower development on the Sava. With 12 new hydroelectric power plants planned along the middle Sava, Bor’s kayak-borne observations offer a snapshot of a river that might soon be fundamentally changed. The Sava is not only a biodiversity hotspot, but a cultural artery—and it’s under attack. But despite efforts from conservation groups, it’s losing.

The proposed developments are part of a national push for renewable energy. The Slovenian government has granted a concession to Holding Slovenske Elektrarne (HSE) to build between nine and 12 dams, and the first projects—Suhadol, Trbovlje, and Renke—are already in the planning phase. Construction is expected to begin following controversial environmental assessments. At the moment, the Middle Sava Hydropower Complex is moving forward.

The push for green energy under the European Green Deal comes at a great cost to the local people, many of which are ironically pro-renewables. But things look different on paper in congress than they do in real life. The devastating floods in Slovenia in 2023 serve as a stark reminder of the consequences of decades-long river containment strategies, such as concrete embankments, dams and straightened channels, which have significantly reduced rivers’ natural capacity to absorb and manage floodwaters.

By confining rivers to narrow corridors and building on floodplains that once served as natural overflow zones, the speed and force of flood surges is increased, making disasters more severe and unpredictable. These floods made it painfully clear that river management must shift from control to coexistence—restoring floodplains, removing barriers, and giving rivers room to spread during high flows. Rebuilding on areas that were historically riverbeds only perpetuates risk.

There are critical lessons that can be learned here: resilience lies in working with rivers, not against them.

Paddling the entire Sava in Slovenia, the group learned, first-hand, many of the Sava’s secrets… one of which is that rivers are resilient. When given half the chance, they recover and rebound, just as the Sava did after years of literally running black from being used to wash coal from coal mines in the 18th, 19th and 20th centuries. The rich insect life, fish darting under our boats and bird presence tells us what scientists have reiterated. The Sava River maintains—for the time being—relatively good ecological conditions.

Despite the dire situation, there are glimmers of resistance. New raft and kayak companies have popped up along the Sava in recent years, helping to reconnect both locals and tourists with the river. A kayak school now operates there, offering courses and guided trips on free-flowing sections. These small-scale, sustainable businesses foster a relationship with the river rooted in respect and appreciation. Still, with the hydropower projects proceeding, Bor’s data may become less a guide to conservation and more a record of what was lost.

In the face of change, Bor’s survey remains a benchmark. It proved the viability and value of using kayaks for bird monitoring on inaccessible river stretches. It documented nesting populations that would otherwise go unseen. And it gave a new lens to what it means to paddle with purpose.

In the end, the Sava Bird Survey wasn’t just about counting birds. It was about seeing the river more clearly—not just as kayakers chasing whitewater, but as observers, documentarians, and stewards. It’s a model for what recreational paddlers can do when we bring a notebook alongside our paddle and choose to look a little closer at the places we love, especially when they might not be the same tomorrow.

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A note from the editor: To get involved in bird watching citizen science efforts, contact your local birding organization or Bird Life chapter. In Europe, the International Waterbird Census (IWC) (a worldwide survey of aquatic birds) takes place every January. In North America, the U.S. The Audubon Christmas Bird Count is an annual citizen science bird survey that takes place from December 14 to January 5. Birds Canada also runs their annual Christmas Bird Count from December 14 to January 5.

Photos courtesy of Bor Mihelič & Rožle Bregar.