Sunday, July 10, 2011

The Barred Owl - Spotted Owl cousin and competitor

Although my first great wildlife job was with the lovely, peaceful Spotted Owl (see last post), I also have quite a fondness for the Barred Owl (Strix varia), and why not, they are both interesting and beautiful large owls. I'm sure you will agree as you look at these pictures (this one taken by owl researcher and friend Jamie Acker who lives in Washington)

But here is the thing with the Barred Owl. They have expanded their range from east of the Rockies to the mountain ranges where the Spotted Owl lives - the Cascades and Sierra Nevada.
Being a habitat generalist (as opposed to a specialist like the Spotted Owl), and having much greater prey variety, they have bull-dozed their way through Spotted Owl habitat, first breeding with them (the offspring are called SPARRED Owls), and then displacing them.

When I lived on Bainbridge Island, WA, I met Jamie who was monitoring all the owl species on the island. I introduced color-banding and radio telemetry to his Barred Owl monitoring, and from that we became to know individuals, their habitat preferences and habits, and their offspring's dispersal. Their populations on the island continue to increase and they are very fecund, each pair having 2-3 young per year. This picture of a juvenile Barred Owl was taken this year by owl researcher Dale Herter, who I worked with in WA, conducting Spotted Owl surveys. We had only a handful of Barred Owl detections then, from 2000-2004.

In the Northwest, the Barred Owl populations have increased so greatly that in some forests- they will be managed for (killed) to help the federally threatened Northern Spotted Owl populations recover. I don't think this is a sustainable plan, because Barred Owls are savvy generalists, sort of like crows and coyotes, they are tough survivalists. But the other components of the plan (USFWS 2011) are more sustainable, and include better protection and restoration of Spotted Owl habitat (mature and old growth forests) and introducing fuel reduction and fire management, which opens the understory (important for Spotted Owl prey and hunting).

As with the Spotted Owl, Barred Owl's are quite personable. This is a pair of wild Barred Owls that Jamie is currently observing in his backyard on the island. The female, the larger owl is on the left and the male is on the right. In this picture they have molted all of their tail feathers so they look smaller than they really are. Their tail feathers will grow back in the course of 3 weeks to 1 month. Jamie and I published a paper, exciting for us, about Barred Owl rectrices characteristics and molt.

Jamie has also found that the Barred Owl preys on Western Screech Owls and is likely responsible for their demise on the island. Despite their competitive and invasive nature, it is hard not to have a fondness for the Barred Owls, once you get to them. Go here To see Barred Owls in action!

Friday, July 1, 2011

Spotted Owls

Since the star of my blog- the saw-whet owl, is out of our project area for the summer, I will introduce you to another species- the Spotted Owl (Strix occidentalis). I was fortunate to have my first wildlife job in 1988 when I worked with the US Forest Service gathering baseline data on the Northern Spotted Owl (Strix occidentalis caurina- N. SPOW). Since, then the N. SPOW has been listed as threatened under the Endangered Species Act (1990) in Washington, Oregon and California, primarily due to loss of habitat (late successional forests), and in the last decade and second major threat - competition with the Barred Owl (Strix varia). The Barred Owl expanded its range from the east of the Rockies and is a larger, more aggressive and more opportunistic owl (in habitat and prey preferences) then the Spotted Owl. More on the Barred Owl later.

Working in Washington for a consulting firm for five years, I had the opportunity to help conduct a demographic study, where we located, captured, color-banded, and followed families of spotted owls and their young as seen in the photo above. These owls are amazingly tame and have incredible dark eyes. They are considered a large owl and primarily eat flying squirrels and wood rats.

The California Spotted Owl (Strix occidentalis occidentalis - CA SPOW) is found in our neck of the woods (the southern-most Cascade Range, Coast and Sierra Nevada Ranges) and is not currently listed (it is a CA species of special concern) although the Barred Owl populations are increasing here and becoming a threat to Spotted populations. I have worked with the CA SPOW for a several years for a consulting firm and currently for the US Forest Service. We are also monitoring their populaitons in the Sierra Nevada and documenting their reproductive success. To me, the subspecies are very similar in looks and behavior. The plumage of the CA SPOW is somewhat lighter than the N. SPOW which might you see in the picture below, a handsome male spotted owl - photo by my colleague Mary Muchowski. I do love my work!