American Crow (Corvus brachyrhynchos)
   
 
Narrative and Science Lens
 

Audubon places the crow among nutritious but well-defended walnuts. Walnut seed kernels are rich in proteins and essential fatty acids, wrapped in a seed coat containing antioxidants that guard against rancidity from atmospheric oxygen, and encased within a hard shell covered by a tough husk.

A crow that can get past the husk will then drop the walnut onto a hard surface from a height great enough to crack the shell. Daniel Cristol and Paul Switzer found that crows adjusted the height from which they dropped the husked nuts, and their adjustments decreased the likelihood of other birds stealing the walnuts (See kleptoparasitism, below ). In the video listed below, crows in Japan have added a tool to the process of harvesting walnuts.

There's a large California Black Walnut (Juglans californica) a few blocks from here, and a multi-trunked walnut on Lomita Drive near Harmony House and Kingscote Gardens.

 
  Campus Locations
Formerly uncommon resident throughout campus, foraging on a wide variety of food items (fruits, small animals, and human refuse), but populations have increased over the past few decades.
  Campus sustainability
  American crows are notorious nest predators, and have been recorded feeding on the eggs and young of a wide variety of birds and posing a conservation problem for scarcer species. They readily exploit anthropogenic food sources at dumpsters and picnic areas, etc. This helps to maintain their populations, which adversely affect more sensitive species.
       What you can do
  1. Share sightings—especially of nesting—on campus, and consider keeping a journal.
  2. See if they're exploiting refuse where people eat outside and send in suggestions for improving food waste disposal.
  3. Record which birds mob them. (See Mobbing, below.)
  4. Locate roosting sites and try to determine if other species are scarce where they are plentiful.
  Science
       Essays from The Birder’s Handbook:
             Decline of Eastern Songbirds; Eye Color; Cooperative Breeding; Pellets; Communal Roosting; Mobbing
       References:
          Gifts of the Crow: How Perception, Emotion, and Thought Allow Smart Birds to Behave Like Humans (John Marzluff and Tony Angell)
          Cristol, Daniel A. and Paul V. Switzer, Avian prey-dropping behavior. II. American crows and walnuts. Behavioral Ecology (1999) 10 (3): 220-226.
       Videos:
          "Wild crows inhabiting the city use it to their advantage"- David Attenborough--BBCWorldwide
  Art
       Photos:
            Johanna van de Woestijne's photo of American Crows mobbing a Red-tailed HawkShoreline Mountain View, CA, See more of Johanna's photographs.

       Drawings and Paintings:
            Darryl Wheye: American Crow, after Audubon, with Walnut
 
  To add to the Science or Art links, submit bird sightings, comment on the exhibit or the web presentation, or ask questions, please use the web forms on the Art at Exits home page.