By Jonathan C. Slaght
May 11, 2016
[This is the fourth post in an ongoing series, “East of Siberia,” reprinted from Scientific American, in which Dr. Jonathan C. Slaght of WCS writes about owls, tigers, and fieldwork in the Russian Far East. Previous installments can be seen here and here.]
Why do tigers always seem to turn up when I’m looking for owls?
My Russian colleagues and I spent about a month surveying for Blakiston’s fish owls in the Sikhote-Alin Reserve this winter, but mostly what we found was snow, cold, and tiger tracks. In fact, if we had been searching for tigers instead of fish owls, our expedition would have been a resounding success.
Fish owls are remarkable birds. Disheveled and determined, they hunt for salmon in even the coldest of Russian winters. We were expecting to find four or five breeding pairs in the reserve, a 4,000 km2area of pine- and oak-covered mountains interspersed with clear, cold rivers. On paper the wide river valleys peppered with behemoth old-growth trees looked like perfect fish owl habitat, with good nesting opportunities and rivers roiling with fish. There are three species of salmon here: cherry, keta, and pink — some of the fish owl’s favorite prey.
To survey for fish owls, we spent our days walking along the frozen rivers searching for signs of them — feathers clinging to branches or tracks in the snow near patches of unfrozen water where they may have fished — and we spent our nights listening for their calls.
But in the end, after more than a month of skiing or snowmobiling nearly 150 km of river and pushing through tangles of riverside forest, we only found two nesting pairs. That’s a lot of time in the cold for such a paltry result. The problem was unfrozen water: we found very little. And where there is no flowing water, fish owls cannot fish.
We were accompanied not just by silence and the crunch of snow underfoot in these weeks without owls; we had the shadows of tigers to keep us company.
Tigers use frozen rivers for some of the same reasons we do: these are flat, open expanses and much easier to walk along than the deep snows of the adjacent forest. We often found ourselves walking directly on tiger tracks; following these experienced predators that knew the most efficient routes through their territories. We would defer to their instincts while avoiding patches of ice that seemed too thin, or weaving among the labyrinths of logjams left from terrible floods of the past.
At one site, we found hours-old tiger tracks every day for three days in a row: an adult female walking west along the river as we worked our way through the forest east.
This big cat sauntered for kilometers down the center of the river where it was a straight, wide channel, then dipped into the floodplain forest to scout for deer and boar where the river meandered and broke into multiple streams. These were the same places we’d look for side channels where the fish owls might be hunting.
I’m convinced this tiger watched us from the cover of fallen log and concealing branch as we walked obliviously past. One morning, in fact, we found her tracks within ten meters of our camp’s snowy latrine. She approached sometime during the night, stood there, then turned back into the forest before we woke.
In the end, we discovered tiger tracks at every single one of the five river basins we were hoping to find owls. Tracks of adult males, adult females, and cubs.
The 2016 field season showed me two things. First, that the amount of unfrozen water in winter is a seriously limiting resource for fish owls. We investigated extensive patches of old-growth forest populated with enormous, cavity-filled trees ideal for the owls to nest in, but these forests were fish owl ghost towns without flowing river water nearby.
Second, I learned that fish owl conservation and tiger conservation are intertwined: the rich riverside forests provide natural resources for both of these endangered species. Moreover, both species have large populations outside of protected areas. While we only found two fish owl pairs within Sikhote-Alin Reserve, we know of four or five additional pairs that live on its fringe; and an estimated 80 percent of tiger habitat in Russia is unprotected.
Conservation of these rare and magnificent animals cannot rely on reserves alone — there must be comprehensive protection and management of forests and rivers adjacent to reserves as well.
So yes: in one sense the winter field season was frustrating with its paucity of fish owls. But in another, more important sense, it’s given me direction for the future.
This is the fourth post in an ongoing series, “East of Siberia,” in which Dr. Jonathan C. Slaght of WCS writes about owls, tigers, and fieldwork in the Russian Far East. Previous installments can be seen here, here and here.
A Russian translation of this post is available
Originally published at blogs.scientificamerican.com on May 11, 2016.