Photo by Sandrine Biziaux Scherson
By Gillian Martin
Palms are nesting and roosting sites for birds and other wildlife. In the western region of the United States, orioles, Cassin's Kingbirds, starlings, egrets, herons and a variety of small mammals use them regularly. Because of their height and crown configuration, and because skirts of dead fronds may surround the stem, it is difficult to spot nesting wildlife from the ground. While the excellent cover provided by palms is advantageous to birds, these conditions can be problematic and dangerous to tree care crews as well as to wildlife. To prevent harm to active nests, the safest option is to avoid pruning in spring and summer when most birds nest, however property managers and tree care providers must balance additional considerations apart from birds.
Bird advocates often ask, ‘Why can’t palms be trimmed or removed in fall and winter?’ In theory they can, of course, and doing so is ideal for wildlife. Unfortunately cities often lack the resources to inspect all trees annually. Some municipal tree inventories can be less than 25,000 and others may exceed 100,000. The Canary Island Palm when infested by a deadly palm weevil can die rapidly. This means that declining or dead palms may remain ‘untagged’ for months or until a complaint is received. If residents are aware that birds regularly nest in certain palms and/or those palms appear unhealthy or dangerous, a timely call or letter to their city or property manager could be helpful.
Trimming palms outside of the nesting season does not resolve an annual problem faced by cities. It is this: Palms usually produce fruit in spring and early summer. When fruit ripens it falls to sidewalks, on parked cars and roadways. The mess, as well as the risk to pedestrian safety trigger numerous complaints from residents. For a city or other property manager, these calls translate into concerns about liability, and are time consuming to manage. Pruning palms in fall and winter does not address this problem.
Another consideration is wildfire. When it occurs, dead fronds can become ignited. When carried by wind they become a torch in a new location or can brush up against high-voltage power lines. The need to remove dead fronds in high risk fire zones before the fire season is therefore an additional priority. Another measure of prevention is to select palms wisely and plant them where they are least likely to pose a problem.
Looking for birds nesting in palms before work starts is important but not fully effective because nests are often well-concealed. Since numerous species may nest in a palm simultaneously, a good assumption is that more than one nest is present during spring and summer. This includes nests affixed to the back of fronds, suspended like tiny hammocks under them or in cavities.
When a palm is dead it is especially attractive to cavity-nesting birds. Woodpeckers easily excavate holes in areas of decay or in spaces where previously removed fronds create suitable space. Where entire decayed sections exist, other cavity nesting birds such as Barn Owls, the American Kestrel, and non-native parrots and House Sparrows find many holes in which to nest. Tree workers cannot see all cavities from the ground, nor can they see birds concealed within holes. ‘Slow as you go’ is a good motto. Workers should pause frequently to listen and look. If an active nest is discovered, the best rule of thumb is to stop work and return when young birds have matured and left. Outside of nesting season, some birds use palms to roost or shelter. When disturbed, they are likely to bolt. For worker safety and to avoid injuring wildlife, remain watchful in all seasons.
A wildlife biologist, the nearest licensed wildlife rehabilitation center and your regional Department of Fish and Wildlife should be consulted when a dead palm (or any tree) with the active nest of a native bird must be removed immediately for safety reasons. A permit from the latter is required to capture or relocate native birds. This is especially important when birds and nests with additional legal protections are present (e.g. herons and egrets and eagles).
When non-native birds (which are not protected by the Migratory Bird Treaty Act) nest in dead trees, saving them is a challenging issue. Some (not all) non-native species adversely impact native birds. (Parrots in California are not yet known to do so.) Animal cruelty laws apply, and measures to avoid harming wildlife should be taken. Wild parrots are of particular concern for several reasons. They are highly intelligent and their self-reliance is contingent on years in the care of their parents and flock. Orange County’s parrot expert, Loretta Erickson of California Parrots explains that parrots cannot successfully thrive in the wild if they have been removed from their cavity and not quickly released back to the care of their parents after being rescued. When held in captivity for a protracted period they do not learn how and where to forage in the wild. Such behavior is not instinctual to parrots but taught by parents.
An unresolved dilemma is what should tree care workers do if they are unable to find a wildlife rehabilitation center that will accept non-native species? Most wildlife rehabilitation centers are understaffed and overburdened. With rare exception, rescuing non-native birds is not a priority, especially if they are uninjured.
The fate of birds during tree care hinges on many factors not included in this article. Where municipalities are concerned, factors include: lack of interdepartmental coordination and urban forest planning, insufficient funds, high risk of litigation, conflicting priorities, vagueness of wildlife protection regulations, absence of wildlife protection policies, changing tree care needs, and diverse cultural values. Meanwhile, communities can reduce harm to nesting birds by adopting as policy the best management practices (BMP) provided by Tree Care for Birds and other Wildlife. Bird and tree advocates can be instrumental in promoting these BMPs to their city and homeowners’ association.