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American Crow (Corvus brachyrhynchos)
   
 
Narrative and Science Lens
      Audubon shows us how these well-defended walnuts seem to pose a challenge for crows. Walnut seed kernals are rich in proteins and essential fatty acids, but wrapped in seed coat containing protective antioxidants guarding against rancidity from atmospheric oxygen, and encased within a hard shell covered by a tough husk. If the birds can get past the husk, it can't just crack the shell with its bill. It needs to drop the walnut onto a hard surface from a height great enough to crack the shell. In a study by Daniel Cristol and Paul Switzer, they found that these birds crows not only adjusted the height from which they dropped husked nuts, the adjustments decreased the likelihood of other birds stealing the walnuts (kleptoparasitism, see below) and increased the energy they obtained.
There's a large California Black Walnut (Juglans californica) a few blocks from here, as the crow flies, and there's a multi-trunked walnut on Lomita Drive near Harmony House and Kingscote Gardens.

In the video listed below, crows in Japan have added a tool to the process harvesting walnuts.
 
  Campus Locations
Uncommon resident throughout campus, foraging on a wide variety of food items (fruits, small animals, and human refuse). Populations have increased in the Stanford area over the past few decades.
  Campus sustainability
  These birds ------
  What you can do
  1. Report any sightings—especially of nesting on campus. Keep a journal of sightings
  2. See if they fly to the Dish area
  3. Record which birds mob Crows
  4. See how large the flocks are and if you can see where their roosting sites are and 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; Kleptoparasitism
       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:
            T (p )
          C (n )
       Drawings and Paintings:
 

          DW drawing after Audubon
 
  To add reports or images please submit them via the Art at Exits home page