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The thrills of a saw-whet owl banding station

A bird bander at the Rocky Point Bird Observatory gently extends a wing of a Northern Saw-whet Owl. Photo by Sheri Rypstra

Early in 2017, my family discovered that the amazing Rocky Point Bird Observatory (RPBO) is located less than an hour’s drive from our house. We live in Sidney, British Columbia, on Vancouver Island, and RPBO has a bird-banding site at Pedder Bay, which is near the southernmost tip of the island. The site has been operating since 1994 and has been a member of the Canadian Migration Monitoring Network (CMMN) since 2000. As the only CMMN station on the West Coast, RPBO has the unique ability to provide difficult-to-obtain information on bird populations and add it to data collected across Canada.

Like other bird-banding stations across Canada and the United States, it offers a thrilling, unparalleled opportunity to people of all ages to see wild birds up close.

One of the species RPBO studies and bands at Pedder Bay is Northern Saw-whet Owl. When my family found out that owl banding is open to the public for observation, we were excited and eagerly waited in anticipation for the autumn banding session. We had witnessed their volunteers banding songbirds and hummingbirds during Migratory Bird Day at a local park several years earlier and had become fascinated with the work they do. The fact we had never seen saw-whets was another draw. We weren’t disappointed.

On October 1, we arrived before 8 p.m. at the booth where data is collected. We were in time to see the volunteers’ headlamps bobbing along the trail from the net area with the first three catches of the night. Three white jiggling cloth bags were carefully hung on hooks within the open-air booth. We were warned ahead of time to remain quiet during the banding because an owl’s hearing is 10 times more sensitive than a human’s. But we were nonetheless hard-pressed to contain our enthusiasm when the first owl was carefully brought out of the bag after being weighed.

Owls are very animated: They turn their heads to take in the surroundings, blinking and even winking, while the bander-in-charge deftly measures wing length and checks eye color, age, and other characteristics of the bird. Males tend to be feistier and will kick and bite. If distress is noted, the bird is released immediately. This only happened once while we were there. In all, we witnessed seven owls that night from the time we arrived till 9 p.m. The volunteers remained until 1:30 a.m.

Three-pronged approach

Bird monitoring undertaken at RPBO includes information gathered by three methods: a standardized daily census taken along an established transect, observations by experienced birders, and banding. This approach to gathering data offers a fuller picture of fluctuations in bird populations than if only one method were used.

Two main bird-banding projects (of saw-whet owls and passerines and hummingbirds) take place during the summer and fall at two locations: Rocky Point Ammunition Depot and Pedder Bay. The Rocky Point site is on restricted Department of National Defence property. Pedder Bay, however, is open to the public for observation and for educational purposes, such as school programs and training new volunteers.

Bird banding is an important means for gathering data for several reasons. In many cases, the age and sex of a bird can only be determined during handling. A combination of wing measurement and weight for example, will indicate if a saw-whet is a male or female. As with all raptors, females are larger than males. Banders can usually determine a bird’s sex, except for smaller-than-normal females or large-than-normal males. The health of the bird can also be surmised, which may reflect the availability of food and the quality of the breeding or wintering grounds.

A bander measures the wing of a saw-whet owl. Photo by Sheri Rypstra

Age can be deduced by shining UV light on wing feathers, which highlights the presence of the protein porphyrin. This protein is high in new feathers and shows up clearly in young birds. As the bird ages, the patterns shift in predictable patterns. There are exceptions, of course. It was speculated that one young owl grew up in a nest or roosted in a spot that had partial sun exposure. One wing indicated it was a fledgling from the current year, but the sun broke down the protein in the other wing, making the substance almost non-existent. Seeming genetic anomalies have also been noted.

A record-breaking year

Elusive species such as the Northern Saw-whet Owl can be under-represented by visual counts alone. Although it has been monitored extensively in the East since 1950, little is known about western populations. Rarely seen on the coast, it was once thought their numbers were low. Banding during the 2017 fall migration, however, showed the population may be on the rise. With 3,543 net hours put in by volunteers, a record-breaking 1,848 owls were banded. This was a 622 percent increase over 2016 and a significant increase over 2014-15. The percentage could be misleading, however, as 2016 was an exceptionally slow year.

The saw-whet population follows a cyclical pattern, which is believed to mimic the fluctuation of prey — deer mice. Approximately every four years a significant decrease occurs in mouse numbers, possibly due to low reproduction. The following year will usually have a huge increase. Since 2017 was predicted to be a slump year for mice and owls, experts have speculated that the increase in the owl population happened due to a combination of an unexpected early crash year in 2016 and extensive wildfires in interior British Columbia that flushed owls west.

Southern Vancouver Island is important in the saw-whet’s migratory route. Although wintering and breeding grounds are known, the banded owls’ range is unclear. In 2014, an owl banded at Pedder Bay was captured and released 18 days later in Boise, Idaho, an astounding 633 miles to the southeast. (That distance is a straight-line measurement, but owls don’t fly in a straight line.)

When crossing large bodies of water, the owls travel together in loose associations along flyways. Although it has been speculated owls island-hop to decrease flying time over water, the flight between Vancouver Island and mainland America is around a 17 km-distance (11 miles) with few islands along a direct transect. Recoveries have been made on Race Rocks (barren islands not far off shore) as well as areas to the southeast, such as Bainbridge Island, near Seattle (66 miles from Pedder Bay). What route they take once they reach the mainland is unknown.

Alarming trends

RPBO’s passerine bird banding has shown the start of an alarming trend for some species. As has been noticed in the rest of Canada, and indeed the world, bird populations as a whole are decreasing. Forty years of data show that many species have declined by about 12 percent. Some species show a drastic decrease of 95 percent. The Pacific-slope Flycatcher is down by 78 percent. The Pacific Wren, Golden-crowned Kinglet, and warblers are also affected. A study in 2013 by Avian Conservation and Ecology, suggested habitat loss, cats, and collisions with human structures were the greatest killers.

Conversely, the Anna’s Hummingbird is increasing its range and numbers. The fact that many people keep their feeders up year-round is probably a contributing factor. A pair may have 2-3 broods of 2-3 eggs each, per year. Females will start building the next nest before the young have fledged from the active nest, and they may even use material from the first nest to build the second. In one documented case, four consecutive broods were raised.

Public viewing of the banding at Pedder Bay starts in mid-July for the passerines, and it runs daily until mid-October, from 8:30-10:30 a.m., weather permitting.

The Northern Saw-whet Owl banding runs from mid-September until the end of October, from 8 p.m. to midnight. Visitors are asked to remain quiet during banding. Please gauge the suitability of young children for this opportunity. Wearing winter gear is highly recommended.

For more information, check the RPBO’s website at http://rpbo.org

Sheri Rypstra is a writer, photographer, and artist and holds a BSc in biology. She has written for Seaside Times and other magazines. She previously wrote for us about a young hawk that was raised by eagles. View her photographs on Flickr.

Originally Published

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