Golden Gate Raptor Observatory

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Golden Gate Raptor Observatory

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A program of the Golden Gate National Parks Conservancy in cooperation with the National Park Service, inspiring the preservation of California's birds of prey.

09/03/2024

Welcome back to Diary of a Hawkwatcher - our weekly series giving you a glimpse into the life of a Hawkwatch volunteer! Please enjoy this recap of our beautiful day up on the hill on 9/2/24.

“We couldn’t have asked for better Labor Day weather – the skies were sunny, and a consistent delightful breeze kept things from getting oppressively hot on top of the hill. Lots of human and avian visitors came by Hawk Hill today! We ended up counting 182 raptors; the steady increase in raptors counted per day is giving us a good reminder that peak season is just around the corner. There was a healthy diversity of 8 species counted, including another Merlin and the second Sharp-shinned Hawk of the season! We were treated to some incredible aerial acrobatics when a male American Kestrel and a juvenile Sharp-shinned Hawk got into a bit of a tussle right at eye level with the counting team. Both birds flew off with their feathers and egos intact, and we all marveled at the show. Yet another spectacular day on the hill!”

Photo 1: Monday’s amazing count team - Peter, Conner, Roy, Deborah, Linda, Amy, and Jim! (Photo by Rose Fielding)

Photo 2: Male American Kestrel (Photo by John Davis)

Photo 3: Juvenile Sharp-shinned Hawk (Photo by John Davis)

08/28/2024

Welcome to our new weekly series, Diary of a Hawkwatcher! For those of you who aren’t able to join our teams up on Hawk Hill, we thought we would bring the hill to you by giving you a glimpse into the life of a Hawkwatch volunteer 🙂 Please enjoy this recap of Tuesday, 8/27/24!

“The fog was thick this morning over Rodeo Lagoon and the Golden Gate Bridge, but Hawk Hill was clear and calm with visibility all the way to Mount Diablo. The windless and hot morning might have been tiresome if it wasn’t for the Prairie Falcon spotted perched on a rock on the South side of the hill! Almost as soon as the words “Prairie Falcon” were uttered, the bird took flight and jetted past the hill towards San Francisco. This was the first Prairie Falcon seen from Hawk Hill this season - not a bad start to the day!

The exciting morning was followed by a sporadic flurry of American Kestrels darting past the hill. In total, we counted 16 kestrels today - a record high for the season! Later in the day a west wind picked up a bit, allowing us some reprieve from the heat as a gradual stream of Red-tailed Hawks and Turkey Vultures floated around. We also spotted the resident Peregrine Falcon sitting on the north tower of the bridge and were pleased to see a few Cooper’s Hawks and Northern Harriers fly by the hill.

Thanks for the great day, everyone!”

Image 1: Tuesday’s count team - thanks to Mary, Andy, Chris, Luke, Paula, Carmen, Step, Rose, Lisa, Ren, and Woody! Photo by Mary Kenney

Image 2: Prairie Falcon in flight; photo by Ian Routley

08/19/2024

Fog-gust can present some challenges, particularly with visibility🌁, the start to the GGRO's fall migration season is an exciting time!⁠
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If you're hoping to catch the migration from Hawk Hill, it's good to check the weather forecast in advance. Just keep in mind that one minute the fog is there, and the next the skies are clear for miles and miles away!⁠
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📸: Kelly Sullivan⁠
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08/16/2024

Watch out songbirds, this fierce adult Cooper's Hawk⁠ (Accipiter cooperii) is on the lookout for a snack!⁠

📷️: T. Ely

**All banding, marking, and sampling is conducted with the appropriate training and handling under a federally and state permits.**

08/14/2024

Juvenile Cooper's Hawks can have such beautiful icy blue to lime-yellow eyes! As they get older, the iris changes color to a deep blood red, especially for males. (See this upcoming Friday's post for an adult Coop!) These are some of the details we are able to appreciate when we have a bird in hand while also collecting data.⁠
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**All banding, marking, and handling is conducted with the appropriate state and federal permits.**⁠
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📸: Laura Echávez⁠
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07/23/2024

The Broad-winged Hawk, a species that breeds in Eastern North America, flocks in huge numbers during migration and may be seen in the tens of thousands in some places! Although they breed in the East, some individuals make it all the way to the Marin Headlands during their journey South in the Fall. This juvenile Broad-winged Hawk is distinguished by the broad, dark subterminal band on its relatively short tail and the dark trailing edges of its short, pointed wings.

📷️: John Davis

07/18/2024

What a beauty! The Red-tailed Hawk may be widespread and common, but that doesn't make it any less magnificent!

📷️: John Davis

07/15/2024

Have you ever wondered what Sharp-shinned Hawks (Accipiter striatus) eat during migration? Sharp-shinned Hawks (Sharpies) are small Accipiters that feed on birds and must frequently hunt during migration to keep their energy levels up. ⁠
To figure out what species Sharpies eat during their long journeys, GGRO banders swabbed the beaks and talons of hawks to detect remnants of prey DNA leftover from previous meals. Using a technique known as DNA metabarcoding, researchers were able to determine what they were eating! They detected prey as small as Anna’s Hummingbird, and as large as the Band-tailed pigeon!⁠
This project combined community science data from eBird, the efforts of GGRO volunteers and staff at raptor banding stations, as well as modern techniques in molecular biology to paint a better picture of Sharp-shinned Hawk feeding strategies during migration. Researchers working with GGRO used these data to evaluate trends in Sharp-shinned Hawk prey selection across sexes and over time. They found that female Sharpies tend to select larger prey species than males, and in both sexes, migration diet was correlated with the timing and abundance of preferred prey species! Some of the favorite prey species of Sharpies were Hermit Thrush, Spotted Towhee, Yellow Warbler, and Red-breasted Nuthatch. Yummy!⁠
This awesome collaborative study helps wildlife biologists understand predator-prey dynamics to better inform avian conservation efforts along the Pacific flyway. ⁠
Check out the open-access article by Ryan Bourbour et al., recently published in the Journal of Animal Ecology: https://doi.org/10.1111/1365-2656.14122⁠
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📷️: Ryan Bourbour⁠
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⁠**All banding, marking, and sampling is conducted with the appropriate training and handling under a federally and state permits.**⁠
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07/08/2024

Happy Merlin Monday!

In North America, some Merlin populations practice long distance migration, where they breed in Canada or Alaska, then move south into the United States and Mexico during winter months. Other Merlins live year round in the Midwest, the Pacific-Northwest and along coastal regions extending north into Canada and Alaska. This phenomenon is known as "leapfrog" migration, where one population of a species "leaps" over the other during migration.

📷️: John Davis

07/05/2024

Northern Harriers not only have sexually dimorphic plumage, meaning that adult males and females look different, but juveniles have plumage that is distinct from the adults. The individual in this photo is a juvenile, showing a brown head and an unstreaked tan belly. In the Marin Headlands, peak Harrier migration occurs from the end of October into early November. Looking forward to it!

📷️: John Davis

07/03/2024

The Northern Harrier is the only member of the Circus genus to occur in North America. This unique bird is known for flying low over open areas while it hunts. Harriers have sexually dimorphic plumage, meaning that adult males and females look strikingly different. The individual in this photo is a male, showing beautiful gray and white plumage. In the Marin Headlands, peak Harrier migration occurs from the end of October into early November. Can't wait!

📷: Don Bartling

05/20/2024

Here is our Senior Biologist and Banding Manager, Teresa, taking a look at the underside plumage of this adult Redtail., while teaching a group about feather molt.
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Red-tailed Hawks are one of the most common raptors across North America, and because of that, they are often underrated! Every Redtail we see is a new opportunity to learn something about identification, especially because of the immense variation in plumage across individuals.⁠
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**All banding, marking, and handling is conducted with the appropriate state and federal permits.**⁠
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📸: Kelly Sullivan⁠
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Address

Hawk Hill
San Fransisco, CA

Telephone

+14154265290

Website

http://ggro.org/

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