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On Common Ground: Beware of nests before tree trimming

CWC recommends checking trees for signs of bird nests if residents need to trim their trees. Most birds nest between March and September. Photo Submitted
Jenn Guess, Senior Wildlife Technician California Wildlife Center
8:26 am PDT March 29, 2017

Spring, summer and fall are active times for people and wildlife alike.  

It may seem like a good time of year to complete landscaping projects, but if your plans include tree trimming you will want to reconsider the time frame. The best time to trim trees is from early December through late January.

More than 350 species of birds live, nest or migrate through the Los Angeles area in any given year. Many of these species use trees, shrubs, and brush to build nests and safely raise their young. Most birds nest between March and September, although a few species like pigeons and hummingbirds have an extended nesting season. Birds aren’t the only animals getting use out of those trees. Squirrels also build high nests out of twigs, leaves, and fiber to keep their young safe. Squirrels nest from February to April and again from September to November.

California Wildlife Center does not recommend moving forward with any tree trimming projects from March through September. 

If you must proceed with tree trimming projects, be sure to carefully inspect the tree for collections of twigs or debris at the Y intersection of all branches. Some nests are only 1 inch in diameter, so make sure to be diligent. Squirrel nests are active during the fall, so you will want to look for larger bundles of leaves and twigs, too. If a collection of debris looks conspicuous, use binoculars to get a better look. 

The Audubon Society suggests looking on the ground all around the tree for a collection of bird droppings. If droppings are consolidated in a single area, carefully inspect the branches above as there might be a hidden nest. 

While inspecting your landscape project, take note if a bird flies close to you and calls aggressively; it might be protecting a nest nearby. Try sitting quietly for a period of time observing and see if there is frequent activity to and from one place. If so, a bird or squirrel might be building a nest or bringing food to its offspring.

Most birds conceal their nests very well so it will be difficult to spot for the average person. Consider bringing in a trained biologist to conduct the inspection.

If an active nest is found, all activity that might potentially disturb the nest must stop immediately. The Audubon Society suggests that all potentially harmful activity must stop within a 50 foot perimeter of songbird nests and a 500 foot perimeter of raptor nests. The nest will need to be left alone until all young have gone and the nest is abandoned. There are many laws on the federal, state, and county level protecting native wildlife. It is illegal to remove, destroy, or tamper with an active nest.

Unfortunately, not everyone is aware of the importance of protecting wildlife. If you come across a wild nest being disturbed, ask the person to stop the harmful activity and make them aware that it is against the law. If the activity continues, document the situation with photographs (if possible) and write down the exact location of the activity. If tree trimming is being performed by a company, write down any license plate numbers and the company name. Contact the Department of Fish and Wildlife to report the activity by calling (888) 334-2258. This toll-free phone number is operated 24 hours a day, seven days a week.

Protecting active nests is one of the many ways everyone can assist in preserving our fragile ecosystem. If you want to do even more to help wildlife, visit our website ( for tips on coexisting with the wildlife, or for information on how to become a volunteer.

On Common Ground is a monthly column written by various California Wildlife Center employees. CWC, a nonprofit located in Calabasas, cares for injured wildlife in Malibu and beyond.