Garden Mastery: The truths, and the myths, about ravens in the garden
By Michael Harrelson
For The Union-Tribune
The narrator of Edgar Allen Poe’s poem, The Raven, struggles to deal with the loss of his love, Lenore, and is haunted by her death. The presence of a raven at his window adds a sinister element to the scene and the creature constantly reminds him that she is gone forever by repeatedly responding to his mournful questions with the famous line, “Nevermore.”
For Poe, the raven symbolized darkness, death and the supernatural. Intentionally or not, Poe created for us the perfect metaphor of creepiness for scary movies and Halloween decor.
The common raven (Corvus corax) has always had a historically poor reputation. Maybe the best measure of that is to note that when gathered together in a group, they are known as an “unkindness” or “conspiracy.” Seen by ancient cultures worldwide as tricksters or shape-shifting demons, ravens have the broadest geographic range of all birds, populating areas from the arctic to the desert. Ravens, like all corvids, such as crows, magpies, jays and jackdaws, are included in the order Passeriform (songbirds) and are the largest of this group.
Ravens and their close cousin, the American crow (Corvus brachyrhychos), are ubiquitous in our landscape. For many, they are hard to distinguish one from the other. Generally, ravens are twice the size of crows and are often described as “stocky,” having a broader bill and a prominent tuft of feathers at their neck called a “throat beard.” Probably the easiest way to differentiate the two when they are in flight is by the shape of their tail: Crows have a wide, flat look to their tail when soaring overhead. Ravens’ tails are more pointed toward the center.
A rule of thumb is that crows are more common in urban environs, where ravens tend to congregate in rural areas. There is no particular affinity between the two groups, and when territories overlap, one species will harass the offending bird until it departs for friendlier skies.
Even though we all grew up associating ravens with crop damage and the straw-stuffed scarecrow propped up in the middle of a field, for the backyard gardener, ravens (and crows) are not much of a problem. They are opportunistic feeders and, being omnivores, will dine on the occasional grape, apple, berry or nut, especially if it is already on the ground.
They do greater damage to commercial crops, especially grain fields, but they most often take advantage of what has already fallen from the seed head and, relative to other vertebrate pests, the crop loss numbers for crows and ravens are small.
Some consider ravens scratching for a meal under fruit and nut trees or around gardens to be beneficial, as they eat many insects and dead animals. Because ravens have a habit of feeding on baby birds, poultry farmers have to take extra steps to keep them from feasting on the eggs and hatchlings of their chickens, turkeys and ducks.
Interestingly, most everything is on the raven’s menu, with the notable exception of avocados. They contain a chemical called persin that is toxic to all corvids, so the birds leave them alone.
Ravens’ penchant for feeding on eggs and babies of wild birds, whether in a tree or on the ground, make them a significant problem for maintaining the populations of certain endangered species found in San Diego County. Those responsible for protecting the least tern and Californian least tern — two common visitors to our county’s sandy beach areas — have had to take precautionary steps to keep ravens and crows from predating on vulnerable nestlings. Similarly, conservationists and park staff statewide erect barriers and implement other measures to protect dwindling populations of endangered egg-layers, such as California condors, murrelets, plovers and even the Mojave desert tortoise.
Homeowners can attest that the broad and diverse diet of ravens and crows include whatever they can find in a garbage can. Those who have chronicled human migration have made the observation that whenever large populations move, they are followed by crows and ravens looking to capitalize on the food waste that has been jettisoned. The same behavior has also been documented for hunting parties that have ranged beyond their borders looking for large animals. In this sense, human migration has expanded the range of ravens and crows.
Ravens are an early warning sign of West Nile virus season, late spring to early fall. Ravens and crows are particularly susceptible to this mosquito-borne disease and it is almost always fatal when they contract it. Pre-morbidly, infected ravens and crows have tremors and balance problems. Consequently, a sick bird will suffer on the ground and eventually die there. Humans and pets should not come in contact with a sick raven or crow. If one is found, contact the San Diego County Department of Animal Services for removal and testing at sddac.com or call 619-236-2341.
It is Halloween season. Edgar Allen Poe and Vincent Price (in the 1963 film “The Raven”) have made Corvus corax a fun and spooky part of our All Hallows Eve celebration. In reality, they are a critical part of our ecosystem and far more fascinating than frightening.
Harrelson has been a San Diego Master Gardener since 2012. He practices low-water landscaping at his home in Jamul.
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