Note: Click here for a brochure for So CA now available on this subject!
I wasn’t sure how to title this article — as it’s about best tree and shrub trimming practices. But it also stems from disturbing reports of commercial tree trimmers deliberately harming nests. I’ll go with the more positive heading; although when a local rehabber told me that employees of local tree trimmer companies have put nests with nestlings through woodchippers to get rid of the evidence, that sure caught my attention — as I’m sure it does yours.
So enough said, let’s stop that illegal practice by learning about nesting times and proper tree/shrub trimming practices. This article focuses on Southern California, where the heat has arrived and most nests are waning, although in other parts of the country nesting is just picking up.
Fall through Winter Pruning Best
Generally, in our hotter drier West, the best time to trim and prune is during fall and early winter when trees are dormant. In addition to avoiding nesting times, it’s also generally better for the tree. Cutting, trimming and pruning during spring and early summer can lead to diseased trees and pest intrusions that harms trees.
A recent nest disturbance example occurred in our city of Redlands CA several weeks ago. After the previous owners hired tree trimmers at Mike Cohee’s new house, he discovered an owlet in a shallow portion of his swimming pool, which had apparently fallen from a trimmed palm. State certified wildlife rehabber Kandie Cansler was contacted, who retrieved it. The exposed nest with a second owlet, and nest material on the ground was below. It was obvious the tree trimmers knew there was an active nest there (Photos by Redlands resident Emily Bendemire below).
Birds and Nests are Protected
Most nesting birds are pretty smart: the majority of nests are camouflaged, and some like hummingbirds are tiny. Some photos to illustrate:
Tree trimmers may not see nests until too late. And as mentioned some ignore them and continue with the job. Here in California, the California Department of Fish and Wildlife biologists define the nesting season as February 1st through August 15th. If this is impossible, the area must be surveyed and active nests avoided. Brush removal, tree trimming, building demolition, or grading activities should occur outside of the nesting season.
Birds and active nests are protected from harm or harassment by the Migratory Bird Treaty Act and in California by the recently passed California Migratory Bird Protection Act of 2019. The CA Department of Fish and Wildlife and the U.S. Fish and Wildlife service will issue citations and levy fines to those who blatantly disregard the regulations.
In states outside California, look up your regulations. In 2018 the Trump Administration issued an opinion to federal wildlife police that “the take [killing] of birds resulting from an activity is not prohibited by the Migratory Bird Treaty Act when the underlying purpose of that activity is not to take birds.” In other words, even if you don’t mean to kill the owls or the seabirds, you can kill the owls incidentally. Oil companies are the greatest beneficiaries of this change. (Click here for a critical view of the reversal of this 100 year old policy)
Additionally for us in California, our California State Code 3503 states it is “unlawful to take, possess or needlessly destroy the nest or eggs of any birds.”
Regardless of your state regulations, please observe the nesting times below, and make sure commercial trimmers are aware of nesting birds.
Palm trees trimmed during nesting season are especially prone to harming nestlings not visible from the ground.
Nesting Times for Local Birds
Raptor rehabber Kandie Cansler and two other area bird rehabbers provided the following nesting times for our local birds in Southern California – starting with the earliest Great Horned Owl. On the other spectrum, woodpeckers can have clutches into September. For other areas, find someone in your local Audubon to learn nesting times.
|January – March||Great Horned Owls||Tops of large trees, pines|
|January – May||Ravens – January but 2nd clutch sometimes
Crows – April
|High in large trees|
|February – May (or later)||Hummingbirds||2 -30 ft high in shrub/tree|
|February – August||Songbirds (passerines): Jay, Swallows and Chickadees are earliest, Robins & goldfinch – May-June. Mockingbirds into summer||Mostly trees (occas. shrub)|
|March – August||Orioles||Palms (occas. eucalyptus, ash)|
|March– April (occas July)||Barn Owls||Mostly palm trees, cavity nesters|
|March – June||Screech Owls||Tree cavities, dead hollow trees, old woodpecker holes|
|April||Red-tailed Hawks||Tops of large trees, pines|
|April – July||Red-shouldered Hawks||Large trees, pines, eucalyptus|
|June||Cooper’s Hawks||Mostly large trees (occas. smaller tree like maples, mulberries, oaks|
Call Cal-TIP for Violations – 888-334-2258
If you see tree trimmers disturbing an active nest in California, take photos – of the nest, any destruction that has occurred and the company’s truck with name/phone number. If willing, tell the company they are violating the law and to stop. Immediately call Cal-TIP – 888-334-2258 This is the Law Enforcement Office of the U.S. Fish and Wildlife Service – and they will have a game warden respond asap. And they can even call the number of the tree trimmer as they’re coming.
If you find an injured or fallen bird as a result, they can also help you contact the appropriate bird rehabber. Or you can call your local animal control number.
Both homeowners and tree trimmers are breaking the law. As a state game warden told me, “While homeowners may not be aware, most companies and their employees know this but ‘play dumb’. Tree timmers can’t use the excuse that the ‘homeowner told me to do it.”
Also, here is a good handout (done by an Audubon group in Orange County) that can be given to homeowners and tree trimmers
For more info:
Brochure on Bird Nesting and Tree Trimming – for Southern CA residents and tree trimmers
Great local (SoCA) birding book with nesting times and other useful info – Backyard Birds of the Inland Empire by Sheila N. Kee
Previous article if you find a wildlife rescue – what to do, who to call (locally)
Again — an excellent handout for homeowners, neighbors and tree trimmers. Education is key.