The Sacramento Valley population of the common raven has ridden a roller-coaster over the years, owing entirely to its interaction with people. Three characteristics of the species have been involved. First, ravens are highly social, and more experienced birds teach the less experienced how to make a living, including what constitutes danger and how to keep safe. Second, they are long-lived, sometimes to age thirteen and occasionally much longer, as captive birds can live between forty and eighty years. Third, they have extraordinary long-term memory to match their longevity.
Early ornithologists noted that the species was widespread here around the time of the Gold Rush. But by the early twentieth century they had abandoned settled areas entirely, because people “persecuted” them, that is, shot them on sight. Ravens had learned to associate humans with danger, and the mutual intolerance continued into the 1970’s and even the 1980’s. By then much of the valley had become urban and suburban, and with that change came both a softening of human attitudes and bans on firearm use in populated areas. For the first time in over one hundred years, a generation of ravens was not persecuted, and the birds slowly and cautiously edged into a valley now full of the humans they had previously avoided.
Their recent history in Yolo County reflects the shift. Into the 1990’s ravens were rare in winter and mostly absent as breeders here, and occurred only in the hinterlands of the inner Coast Range. By twenty years ago they were rated “uncommon” on our checklist, and their numbers were noticeably increasing on the valley floor. Today they are common birds, with flocks foraging on farmland and patrolling the highways in search of road-kill. Little surprise, then, that one day this fall I saw a flock of two hundred and fifty near County Road 29.
The Putah Creek Christmas Bird Count results illustrate the pattern. Ravens occurred in single-digit numbers until 1982, and consistently surpassed one hundred birds from 1998 on. Each of the last five years has brought a new record high number. Likewise, Cornell University’s huge eBird database shows that observations of ravens have grown almost everywhere in the Sacramento Valley since 2007 (when eBird began), including increases of about 40% around Davis and 60% near Winters.
Ravens still seem to visit our cities cautiously. In my neighborhood, pairs and small groups flew over at altitude in the early years, possibly to avoid attacks by resident crows. Now they sometimes skim over the treetops in passing, and only in the last year a few have been bold enough to perch in tall trees. Maybe their next move will be to touch ground in a city park. Away from cities, I have seen nests in cell phone towers, tall trees, and in a barn on an abandoned dairy farm. Will they ever nest in town? Please watch them and let me know.
For more on these birds and their relatives, see the book “In the company of crows and ravens” by John Marzluff and Tony Angell.
–Michael Perrone, Conservation Chair
