An annual fall ritual: the migration of raptors | Local News | Fold | The Weekly Source

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EEach fall, birds of prey head south through Oregon during their annual migration or winter movement. Some come as far as the Arctic and one, the Swainson’s Falcon, leaves its breeding grounds across North America and heads to the highlands of Argentina, although some small populations winter in Florida, Texas and California. Migratory raptors spend the breeding season in northern areas, but as prey availability decreases in the fall and winter, birds fly to areas further south to overwinter before returning north to the spring.

The term “raptor” comes from the Latin rape, meaning loot or grab – an apt description for this group of predatory birds with features such as excellent eyesight to locate prey, sharp talons to grab prey, and hooked upper beaks to tear prey apart. Although the term “raptor” includes owls, these mostly nocturnal predators differ from diurnal hawks, eagles, and hawks.

  • Courtesy of Hawkwatch International
  • Bonney Butte’s sight keeps hawk watchers engaged even on slow days.

Across the west are various falcon viewing sites where biologists congregate to record the species and numbers of birds passing through sites in Washington, Oregon, Utah, California, Montana and Alberta, Canada. Locally, the East Cascades Audubon Society is monitoring a spot on Green Ridge above the Metolius River while Salt Lake City-based Hawkwatch International employs Bonney Butte on the southeast side of Mount Hood to record the passage of these predators. at the top during the fall. .

So why watch these birds to begin with? Collectively, these birds are at the top of the food chain, and disruptions in this chain due to forest fires, pesticides, low prey density, etc., are a long-term indication that something is wrong with it. nature.

“Long-term data from these efforts can be used to assess whether the number of migrants for different species is stable, increasing or decreasing,” said Dave Oleyar, Ph.D., director of long-term monitoring and community science from HWI. “Trends in a network of sites can paint a larger picture: are the declines local to one or two sites, widespread in a certain area or continent-wide? This knowledge can help guide targeted research to understand declines. ”

David Vick, East Cascades Audubon Society’s Green Ridge Project Coordinator, provided a history of the group’s falcon sighting location on Green Ridge, a long promontory above the Metolius River.

Spurred on by HawkWatch International’s 1994 trail count on Green Ridge, members of what was then the East Cascades Bird Conservancy walked the 15-mile-long ridge in 2004 in search of a study site. . ” HWI moved its falcon-watching activities to the Bonney Butte site for various reasons, so birders in central Oregon began their research.

Several ECBC members scoured Green Ridge in search of a suitable location and in 20004 member Kim Boddie discovered a location with excellent views to the north, east and west.

“The first official Green Ridge fall raptor survey was conducted in 2005 and this volunteer citizen science project is now in its 15th year of data collection,” said Vick. The group did not count in 2014 because of the fire at Bridge 99 and in 2020 because of the COVID-19 pandemic.

The majority of counting days for the Green Ridge site are in September and October on weekends with a few weekdays depending on volunteers. At the observation site, members and participants set up spotting scopes and focus their binoculars on distant and close areas to spot raptors.

Click to enlarge
A red-tailed hawk stops atop a sign during its fall migration.  -DAMIAN FAGAN

  • Damien fagan
  • A red-tailed hawk stops atop a sign during its fall migration.

“While the falcon sighting might last two hours just of scenery followed by 20 seconds of adrenaline, we still hope to be there on a big day, which keeps us coming back time and time again,” said Vick. “In addition to acting as the project coordinator and counter, Peter Low is our unparalleled official observer and has been the driving force behind this project for many years.”

During this year’s first ECAS weekend, September 11-12, the group recorded 199 birds of prey migrating south. A day of over 200 birds is not uncommon, and the group’s daily maximum was 420 birds. Daily totals are published online through Central Oregon Birders Online and Oregon Birders Online, as well as in a database maintained at Hawkwatch.org. Data from falcon viewing sites across North America is compiled into a Raptor Population Index, which is updated every three years.

“The Raptor Population Index uses count data from across North America to assess the status of raptor populations using migration data,” Oleyar said. “Migration counts are a common and effective way to effectively take the ‘pulse’ of regional populations for a group of species that are generally dispersed and / or secretive at other times of the year.” The data is also available. available to land management agencies and conservation organizations. At the Bonney Butte and Green Ridge falcon viewing sites, 22 and 18 species, respectively, of eagles, hawks, hawks, vultures, ospreys and harriers were recorded.

So what is the status of birds of prey these days?

“Twenty-six years of migration monitoring at the Bonney Butte HawkWatch shows a stable overall number of total migratory raptors with fluctuations from year to year. Northern Harriers, Red-tailed Hawks and Rough-legged Hawks, ”Oleyar added. “We have seen an increase in the number of bald eagles, peregrine falcons and turkey vultures at the Bonney Butte HawkWatch.” The increase in the numbers of bald eagles and peregrine falcons can be attributed to the success of the reintroduction programs that were initiated for these two species when they were listed under the Endangered Species Act.

Volunteers scan the skies for migrating raptors at the Green Ridge Falcon Viewing Site.  - CHUCK DOORS

  • Chuck gates
  • Volunteers scan the skies for migrating raptors at the Green Ridge Falcon Viewing Site.

Declining species trigger local reviews or conservation efforts, which can target various impacts on populations, including forest fires, prey abundance, pesticides, habitat loss, collisions with vehicles or buildings, disease, electric shock to power lines, and entrapment or shooting. Although protected by law, indiscriminate raptor killing occurs in areas where birds such as Cooper’s hawks or Northern Goshawks feed on backyard or farm poultry.

One difference between the two sites, other than the location, is that HWI captures live raptors at its Bonney Butte site, taking body measurements and affixing a unique numbered USFWS ring to the bird’s leg. “Most of the time we trap and bandage migrating raptors as well, so it is possible that you can see one up close before our crew releases it,” said Oleyar. “Mount Hood provides a stunning backdrop for observing migrating raptors, which is worth it even on the slowest of days.”

The final count weekend for Green Ridge is scheduled for October 23-24, but if the weather is good, volunteers can count the last weekend in October. Bonney Butte’s count will continue until October; check the website for updated access conditions and opening hours. Vaccinated bird watchers are encouraged to visit the site and are advised to adhere to state masking guidelines for outdoor activities.

Don’t worry if you miss visiting Green Ridge or Bonney Butte, as many birds of prey winter across Oregon, providing plenty of opportunities to view these magnificent birds of prey.

ECAS: ecaudubon.org

HMI: hawkwatch.org

Bonney Butte Seasonal Report: dunkadoo.org/explore/hawkwatch-international/bonney-butte-hawkwatch-fall-2021


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