In the 1990s the City of Los Altos enacted a number of tree removal prohibitions. Today those grown-up trees have caused an explosion of the high perches that crows love. Add more food from litter, home gardening, and home orchards and that means expanded food sources that let the Los Altos crow population thrive. Livin’ is easy!
I have lived in sunny Los Altos since 1975. I first noticed crows here in 1995 – but not too many. By 2000 they were becoming the most common bird in my yard. I live along a litter-rich collector road, and today my neighborhood has lots of tall fir trees, few of which were here in 1975.
Facts about Crows from a Google Search
Crows like “anthropogenic food subsidies”
A Google search on “crow population increase” shows crow density is way, way up in the U.S. and worldwide. There are photos of unfortunate places in the U.S. where the crow roosting density (sitting in trees) is so high that it’s as creepy as a haunted house flick (or The Birds). There are places where crow guano causes property damage to cars and buildings. Research shows that although bird nest robbing is something crows can do, in practice that usually does not happen. Yet most other songbird species populations are declining because they are less able to adapt to suburban and urban sprawl. Crows don’t need to eat other species’ eggs because of the increased availability of “anthropogenic food subsidies” – mostly human food litter. Crows are much more adaptable than other songbirds, because they can (and will) eat just about anything.
Crows need high perches
Besides availability of anthropogenic food supplies for scavenging, crows need places with high perches that increase visibility for their predator/hunting behavior. That means they like tall trees and buildings, ideally surrounded by shorter trees, bushes, and some clearings. Crows don’t live where there is very limited tree cover. That means they can thrive in most modern suburbs, but probably not the suburbs of Santa Fe (New Mexico) where there are no trees. (High temperature is another turn-off for crows.) Crows are social birds, living in small groups that can form larger groups for self-protection while roosting at night at a high point with good visibility.
What Happened in Los Altos – A Short History
The pioneer semi-desert
The city of Los Altos is naturally a semi-arid environment of grassland and a few oaks — not a favorite of crows. And there were very few crows when the Ohlone Indians lived here along Summerhill Road. Even with early waves of development, the pueblo, the ranch, the wheat farm, the vineyards, the orchards … there was little irrigation. Naturally-occurring tall trees were generally limited in range to the west side of the Santa Cruz mountains and on the east side, along more permanent creeks. European settlers ranched and they farmed. They didn’t landscape. There were no or few tall perches for crows, and there weren’t any crows. Or, if there were, people would shoot at them as with any other vermin. Crows are not stupid. If the environment is hostile they will move elsewhere.
The original suburban low maintenance yard design
Early suburbanization of Los Altos in the 1950’s featured low maintenance yards, which also happened to be low water yards. Small lawns, hardscapes, with slow-growing, hardy, water-miser plants were popular. People preferred to mix martinis in the cute built-in bars of the tract home “mini-estates,” and drink those cocktails with the neighbors, rather than fuss with their yards. In those days middle-class people maintained their own yard. Immigration was highly restricted and household income was relatively low, so gardeners were not yet cheap, abundant, and affordable. Sometimes the suburban developers planted short deciduous street trees such as pepper trees. Full grown, such street trees were rarely taller than 30 feet. Old-timers I have talked to thought trees were “too messy.” Bottom line: There were no tall perches for crows in Los Altos and there weren’t any crows.
The 1980’s suburban high-maintenance yard design
But in the mid-80’s suburban tastes changed. Maybe water got cheaper. There were lots of gardeners for hire because of the wars in southeast Asia and other world troubles. People arriving from the East Coast had started to plant high-maintenance, water-drinking plants and trees. Fir trees became popular in response to the negative media coverage of lumbering practices in Northern California. “Save a tree.” Fir trees can live well in arid Los Altos because of all the lawn irrigation.In the 80’s City of Los Altos developed a goal to increase the tree canopy. Besides education, eventually Los Altos and every other city in the Bay Area passed “tree protection ordinances.” At first, our Los Altos ordinance protected only fir trees (except Monterey pines – why?). Later it was expanded to cover all trees with a diameter greater than 1-½ feet. After 20 years of this policy, there are now tall perches in Los Altos every 500 feet or so. Our collector roads provide tasty litter. A renewed interest in growing our own food attracts little critters that crows may hunt. Now we have a high density of crows.
What Should Be Done?
What should be done by the City?
Nothing. There are lots of reasons for all cities to reexamine tree and landscaping ordinances, but high density of crows is not one of them.
What should be done by you?
Fussy “English” yards are trending down in popularity. Easy-care, water-conserving native-plant and native-tree plantings are trending up. These are the hip, cool, in thing. Reconsider your future landscaping and tree choices.
Resource: Here is the most useful study we found.