Raven nests in San Francisco

This page attempts to attach a number to the question: how many Common Raven nesting pairs are there in San Francisco? The estimate is built on observational data collected from 2010-2017, and tries to determine a territorial size of a San Francisco Common Raven pair. And from that create estimates of how many ravens nest inside the city of San Franciso.

There seem to be a couple parts of the city that don't see many ravens (Potrero Hill and northern part of the city from downtown to the Marina). Potentially this is because of competition from American Crows (there is a large crow roost in the financial district, and they can often be found in numbers at Fort Mason). This could also just be that I have not visited these areas enough.

Another factor of density could be substrate. Common Ravens can be found nesting on a variety of human structures, but only on a few types of trees (Montery Pine mostly, Eucalyptus and some other odd trees). These types of trees can be found all over the city, but not all may be suitable for a variety of reasons (exposure, tree size, tree shape, and other competitive species).

I've expanded the search from year to year. Each year, I've concentrated on different parts of the city trying to go to new places, but also revisit as many previous nests as possible.

One question I had was do ravens nest near where juvenile flocks congregate: The west end of Golden Gate Park, Fort Funston, Visitacion Valley, Sutro Tower, and Hunter's Point. Nests are found close to all of these spots.

Nest TypeNumberNotes
TreesMostly Monterey Cypress & Monterey Pine, a few Eucalyptus, and a Redwood.
BuildingsCommerical buildings, schools, Catholic churches (so far), etc.
StructuresSome examples: a ship, a crane, large signs, etc
UnknownProbably nesting pair but actual nest not found.

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