In the Field with a Spotted Owl Biologist

Below is an unpublished story I wrote in 2010.

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A Northern Spotted Owl roosts during the day.  While Spotted Owls are generally more sedentary during the day, they may be awake for  extended periods. Photo: Gretchen N. Newberry

The owls know his truck.  Tom opens the driver’s side door, strides to the back, grabs a cylinder of live mice, pulls on a pair of gaiters, slings a backpack over his shoulder, and points upward. They’re usually waiting, he says.

The owl peers down at him from a branch 10 feet above his head.

Tom supervises a team of field technicians who scout for Northern Spotted Owl nests in the Oregon Coastal Range, and the data is analyzed by a team of researchers led by U.S. Forest Service ecologists at Oregon State University (OSU).

This is an effort matched by other teams in other regions across the Pacific Northwest.  The object is to estimate population trends and assess the effects of different Spotted Owl management strategies.

Various faculty at OSU have been studying the issue of the Spotted Owl for decades in an effort to find working solutions in those management strategies.  Building study protocols is essential to that effort. And it’s people like Tom who take those protocols into the field.

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An old-growth temperate coniferous forest typical of the Oregon Coast Range.  This dense vegetation is the typical habitat for the Northern Spotted Owls’ nests, and increasingly this vegetation is losing out to logging practices. Photo: Gretchen N. Newberry

It’s a relief to find a bird.  Not only because of their decreasing numbers, but because it’s exhausting work finding a nest.  Usually nests are found far off the road in old growth forests and require climbing over fallen trees, through

heavy brush, knee-deep in rich soil, splashing through streams, and climbing up and down steep hills, grabbing ferns for handholds.  It’s steep terrain, and even the birds get winded flying uphill, Tom says.

At night, Tom and his team drive through the woods calling for the birds, and noting where they hear the distinctive “Cooo-wheep” of the females and other calls of the Spotted Owl.  By day, they search the woods around the calls they heard looking for a nest.  Often, they spot the ravens and scrub jays that bother the owls before they see the actual owls.

Once they spot an owl, they look for a nearby nest.  Typically, the field technician gives a mouse to the owl and takes note of what happens next.  If the owl takes it back to the nest, they usually have young chicks to feed.  If the male and female squabble over the mouse, or if the female stuffs in a nearby tree branch for later, it’s unlikely they have any young chicks to feed.  And if it’s the right time of year, and if there are no nestlings, this might be a year the pair are skipping the arduous task of reproduction altogether.

This pair knows Tom because he scouted their nest before and they know he has mice. Today, Tom places the mouse on the ground within view of the pair of owls, backs away 10 feet, and sits down within the dense ferns.  Within a minute, one of the owls scoops up the mouse. And after a brief squabble with the male, the female stuffs the dead mouse in a nearby tree branch for later and Tom takes note.

What Tom has been doing for the past six years has fed into a larger project that spans decades.  Teams of researchers have been tracking population trends in the Spotted Owl south of Oregon and up into the Pacific Northwest, where its subspecies, the Northern Spotted Owl, prevails.  And since its 1990 listing on the endangered species list, the public has become more aware of the species’ progress.

Overall, the trend indicates that populations numbers have decreased with the loss of old growth forests. According to the Wildlife Ecology Team’s annual report, last published in January 2010, the survey found 220 individuals in 1990 and 125 individuals in 2009 in the Oregon Coast Range study area.

The decreasing population numbers have also been due to the expanding range of the Barred Owl, and changes in climate [Note: This is a hyperlink to another OSU press release talking about these two factors].  Even accounting for fluctuations year-to-year due to normal food availability fluctuations, the overall trend indicates overall decline.

So, what’s new about the owls this year? “Every year is interesting,” Tom says.  But this year was an especially difficult year for the Spotted Owl, he adds.  Due to a warm month of March, a higher than usual percentage of pairs nested.  But because of the unusually cold and wet months following March, many of the owls failed to produce young.

The type of nests they build make them unusually vulnerable to weather, he says.  The Northern Spotted Owl assembles its nests atop trees in the broken top of a trunk, leaving it exposed to the elements.  This is typical of the Northern Spotted Owl in Oregon.  But as you travel northward or southward the Spotted Owl constructs different types of nests along a gradient of tree-trunk-cavity types of nests.  In California, he says, the nests are more exposed but experience warmer temperatures.  North of Oregon, the nests are in more sheltered cavities lower on the tree and covered by more branches that shield it from the colder temperatures.

In Oregon, the middle range of its habitat, the owl’s exposed nests atop the trees are within the dense old-growth forests and are fairly exposed to the elements.  And in a colder year, such as 2010, that can have an impact on the success of producing viable eggs.

So, what’s ahead for the Northern Spotted Owl survey project? Tom expects the same field techniques and project strategies will remain in the coming years to match the past 20 years of strategy for  consistency in data analysis.

Future challenges include a change in the guard as the projects’ principle investigators , its key scientists, reach retirement age, the ever-present budget crises, the deterioration of roads which hampers technicians’ ability to access the birds, and the loss of the Spotted Owl  populations.  For, as some areas, like in the Olympic Peninsula, lose their bird populations, researchers cannot find birds to survey.

And, what’s ahead for Tom?  It’s another change in the guard as Tom takes a new job this fall.

As stimulus moneys pours into the development of alternative energy, many wildlife biologists are finding work and research in risk assessment for birds and mammals whose migration takes them through the growing fields of wind turbines in the Columbia Gorge and other areas.

Tom will be working for a private consulting firm.  It’s a sign of things to come that field biologists like Tom will be scouting planned constructions sites for wind farms for risk to wildlife.

For the Spotted Owl survey in the Oregon Coast Ranges Study Area, it’s unknown who will lead the team of field technicians.  But the project will continue, says Tom.  “It’s a key part of monitoring the species.”

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