This year, the issue of tree-trimming or cutting during the nesting season was highlighted by the sad destruction of black-crowned night herons’ nests when the Oakland Post Office decided to get its trees trimmed. Five young herons were injured, others may have died. The tree trimmer potentially faced criminal charges, but was so remorseful – and so willing to pay for the care of the baby herons – that everyone was relieved when he didn’t.

Most people just don’t know that it’s a bad idea to trim trees (or worse, remove them) during the nesting season. Even aggressively trimming undergrowth could damage or destroy birds’ nests.  In San Francisco, the season extends approximately from February to September, depending on many factors including the weather.

Each year, Wildcare, a wonderful organization that rehabilitates hurt or orphaned wildlife,  gets a deluge of baby birds during the summer. Most of  them are displaced by tree-trimming or removal.

Birds nests are difficult to spot, even for experts. Herons’ nests are large and noisy, and the Oakland Post Office staff surely knew the birds were there. But most birds hide their nests. Unless they are huge ones like nests of hawks or owls, the parent birds need to conceal their young from predators. Humans, who typically aren’t really looking out for them, would usually miss seeing them altogether. It may take even experienced birders hours of observation to be sure. Nests of hummingbirds, for instance, are around the size of a quarter. They’re common in San Francisco but very difficult to spot.

BROCHURES AND INFORMATION

Here’s Wildcare’s page  “Stop! Don’t Prune Those Trees!”  It explains the problem in a user-friendly way, and also gives references of two bird-friendly arborists who can do emergency work if needed.

 “Spring (and summer!) are busy baby season— procrastinate now!

When is wildlife nesting? There is some variation, but most wild animals have their babies in the spring, between March and June. However, many species will also have a second brood in July or August if food supplies are sufficient. If you can plan to trim your trees in the winter months, you can completely avoid the possibility of damaging a nest. It’s also a healthier time for the trees, when the sap has gone down and trees will be in their dormant phase. Call WildCare at 415-456-7283 if you’re unsure when it is a safe time to trim or remove a tree. “

The Golden Gate Audubon Society has published an excellent brochure:  Healthy Trees, Healthy Birds that is available as a PDF on their website. Here are pictures of the brochure (the download will be clearer and can be printed).

IT’S ILLEGAL TO DISTURB BIRDS’ NESTS

Disturbing – or worse, destroying – a birds nest is illegal. It’s a strict liability offense punishable by up to six months in jail and/or a $1,000 fine per offense.  There are laws at the Federal, State and City level. Here’s what they say:

• Federal Migratory Bird Treaty Act. This applies to over 1,000 bird species, including many that are found in San Francisco. It makes it ” …illegal for anyone to take, possess, import, export, transport, sell, purchase, barter, or offer for sale, purchase, or barter, any migratory bird, or the parts, nests, or eggs of such a bird…” (“Taking” means to harass, harm, or pursue a bird.)
•  California State Code 3503, 3503.5: ” It is unlawful to take, possess, or needlessly destroy the nest or eggs of any bird, except as otherwise provided by this code or any regulation made pursuant thereto.”  California State Code 3503.5 relates to birds of prey: ” It is unlawful to take, possess, or destroy any birds in the orders Falconiformes or Strigiformes (birds-of-prey) or to take, possess, or destroy the nest or eggs of any such bird except as otherwise provided by this code or any regulation adopted pursuant thereto.”
• San Francisco County Municipal Code 5.08: It’s unlawful “to hunt, chase, shoot, trap, discharge or throw missiles at, harass, disturb, taunt, endanger, capture, injure, or destroy any animal in any park...” (with exceptions for small rodents like gophers).

The general rule is to stay 50 feet away from song-bird nests, and 500 feet from raptor nests.

TREES IN “POOR CONDITION” ARE GREAT FOR BIRDS

Sometimes, trees are removed because they’re in poor condition – dead or dying. Those are often the very trees that birds love, especially those that nest in cavities. Like this flicker (a kind of woodpecker) nesting in a half-dead eucalyptus tree. If you weren’t watching very patiently, you would have no idea that a family of young birds (three in this case) were being raised here.

PLAYING SAFE

The only safe way is to NEVER cut trees or thin dense bushes during the nesting season – and even when working in the off-season, typically September to February, to be very observant and watchful before starting work.