Night wings and water: Discovering the aquatic habits of Western Screech-Owls
By Megan A. Buers
It was a warm summer night and the air smelled smoky sweet. There was a soft breeze from the north that offered a bit of respite from the heat, still baking in the ground from earlier in the day. As it started to get dark, we pulled up to our spot, hopped out, and set up the antennae. A few months earlier, I had deployed a VHF tag on the unsuspecting back of a Western Screech-owl, a male. The owls had tried to nest in a birch tree but had abandoned early in the season after the eggs failed to hatch. Now, all the owls had was each other, and the bounty of this little riparian stream tucked away from the Okanagan Valley along a derelict service road.
The service road, connecting to Summerland, ran right next to the stream. Often, outdoor enthusiasts would kick up dust, continuously driving past far faster than the roads would have safely allowed. The thick vegetation of the riparian buffered this dust but coated the leaves of the birch and dogwood that ran up to the road's edge. The tight topography of the little valley made it often feel later in the day than it was, with most of the spaces often shadowed regardless of the time of day. But there was one buffet that secretly moved through the little greenery, and one the owls would sit and wait for.
We turned on the receiver and heard the reliable bursts as the tag on the owl registered. Close by, as usual. Often the owls were quite reliably found depending on the time of day, but you never knew what you were in for when you turned on the receiver. A quick check-in could easily turn into a whole night adventure, leaving you craving your bed at the end of the night.
He was close. Super close, in fact. I looked at Avery, who was holding the receiver.
“Is he right here? That sounds super loud,” I said.
“He must be,” she pointed the receiver around, and the bursts intensified.
In the dusk light, I could just make out a round mass, perched daintily on a small branch overlooking a shallow part of the stream. We stopped for a second and just took in the scene. The owl was staring down at the water intently, not noticing us standing a few meters away. He looked transfixed by the water. A car approached, and the veil was lifted. He flew off into the forests, taking the strong bursts from the radio transmitter with him.
“What was he doing?” Avery asked.
“I don’t know,” but I had a sneaking suspicion he was fishing.
Western Screech-owls are typically considered generalists, with accounts of diet coming primarily from regurgitated prey remains in the form of pellets. Like the ones you would dissect in grade school, wrapped in foil. Previous work had suggested that these owls were more insectivorous in the more southern parts of their range like Arizona and California. Whereas the more northern owls were typically more reliant on small mammals to get their fill. I would like to challenge those perceptions.
I had started my master's in the winter of 2022, eager to set out to ask questions around Western Screech-owl ecology within the heart of the Okanagan Valley. Based out of Kelowna, many of my sites landed right in the backyards of lucky homeowners. It took me a mere 10-minute walk from my house to find a reliable and local legend nestled comfortably in the cedar boughs of Mission Park Greenway.
I had set out with two main research questions: 1) were owls using certain features within the riparian habitats to shield themselves from scorching temperatures, 2) were we able to detect any changes in behavior if temperatures rose above a certain threshold? What I got in turn was a lot more than I had anticipated.
We started out by locating nests, a far more difficult task than I had originally planned. I managed to find some nests and set up some ill-mounted camera traps facing the cavities of these nesting owls, accompanied by acoustic recorders to be able to spy unbeknownst to the owls. Later I would look through all the camera trap data and acoustic data to determine how many times the chicks were being fed and compare that to temperature fluctuations. But one nest came with an extra surprise gift.
Nestled further up Mission Creek, away from the hustle and bustle of town, there was a nest in a dead cottonwood, encircled in cedars. This nest was one of the only nests where a camera trap could be placed in any kind of reliable way. The male here also had a tag. My technicians had come up with various naming schemes over the course of the two-year project, and the adults of this spring had all been named after popular cereal brands. This male’s name was Corn Pop.
Corn Pop was, and remains, the most reliable owl. Only ever using a single cedar tree to perch in for the majority of the breeding season. Only ever traveling within 400-m of his, arguably rotting and likely to fall over, chalet.
When we finally retrieved the equipment after the young had left the nest, we were shocked. Roughly 15 photos into the SD card, there was the female at the nest with a long, and rather slippery looking, fish. To be exact it was likely a Rainbow Trout (scientific name), which were in full spawn at the time the chicks were most hungry. Not only that, we were treated with 11 other fish, varying in size. This was not a one-off! Both the tag adorned male and the female were fishing. I immediately thought back to the owl we saw perched over the stream a few weeks earlier and thought I have to go put some cameras up.
We put two cameras up on the little fishing spot, located further south in the valley. Unfortunately, on top of being a speedy and agile predator in the night, screech-owls were bathed in well-insulating feathers. Our cameras worked off temperature sensors, and therefore we likely only saw a small portion of the action going on at the fishing hole, but it was enough for me to be happy. Over the next 10 months, I watched as both the male and female from that other territory stare and attempt to catch fish within the stream. I thought to myself what a happy coincidence that these owls have spawning fish right here just as their chicks are most in need of fat and protein.
For thousands to millions of years, the Pacific Northwest boasted a bounty of spawning fish in rivers leading inland. It wasn’t until later in the 1900s that we started to notice concerning declines in spawning fish. This was echoed throughout much of the world as rivers, lakes, and oceans depleted of their once vibrant and tasty occupants. It only makes sense, that an owl that nests near rivers, spends all its waking and sleeping moments in riparian forests, would fish.
I maintain that Western Screech-owls are still generalists. But I do wonder whether in our study of owls in North America, we looked to other species such as Northern Saw-whet Owls, Great Greys, and Long-eared Owls and thought ‘small mammals are the way to go’. Or maybe we were deceived by the neatly packaged clues they left under their roosts that suggested they were furry mammal specialists? I am not the first one to have this idea either. In 1892, Bendire remarked on the prevalence of frogs and fish in their diet, and later accounts by Monroe in 1929 suggested an overwhelming complexity and richness in their diets, from caterpillars to sculpins.
Perhaps future work will examine exactly how closely tied these species are to rivers or bogs. Unlike the interior macfarlanei subspecies, the coastal subspecies has a smorgasbord of complex ecosystems rife with amphibians, fish, and intertidal invertebrates. Expanding our knowledge on the intricacies of their diet could allow us to better understand what habitats are important for their conservation. For example, if the owls that are situated close to streams or bogs do better, and fishing owls produce more offspring, maybe this is cause for more targeted and, in a way, broader conservation measures. Instead of focusing only on terrestrial or forested habitats, we should look in the water and see how we can improve the numbers of our waterbody tied friends.
In classrooms, we often are taught one thing as truth or fact, but the reality with wildlife is always more complicated. One owl might make a fantastic fisherman, whereas another might be better suited for hawking moths in the open air. Our conservation and research priorities should be set around relearning what we think we know. Instead of coming up with preconceived ideas, we should broaden our minds and think of the individual in the context of where it is situated. An owl in downtown Kelowna is a separate and unique entity from an owl in the heart of old-growth forest. My hope is that this re-discovered discovery will lead to more research around the importance of aquatic habitats in screech-owl ecology, and therefore, a better understanding of what these owls need from us. We just need to listen.
I would like to thank my collaborators and funders for supporting my work. I would like to thank my technicians Avery Stashko, Reese Embree, and Tasha Schweb for their bravery and dedication in the field. My supervisors, committee members, and friends for their support.
