Saturday, March 29, 2008

Big Black Birds a.k.a. Nature’s Clean-up Detail

Photo by David Powell

In my mind, they are among the first harbingers of spring. Each year, beginning in mid-March, my eyes are drawn skyward daily, searching for their dark form, soaring aimlessly above. I record this event faithfully each year, and my records show that our Turkey Vulture (Cathartes aura) friends return from their wintering grounds around March 15 each year, just in time for Saint Patrick’s Day celebrations. This year it happened on March 17, only not in the cerulean blue open sky, but on KOAT-TV, on the news! They ran a wonderful story, showing one of the first big black birds to return. My first sighting occurred a few days later, on March 21, at 8:30 a.m. in the Rio Grande bosque during a songbird survey. First one large black shape caught my eye, followed by another. Ultimately, ten birds took flight from their night roost in snag along the river bank. I knew that spring was on the way despite the dreadfully windy days of late.

Often unappreciated, vultures perform a vital role in the Earth’s food chain, that of the scavenger. Their scientific name, Cathartes, means purifier. Until very recently, they were considered to be a raptor even though they almost never kill their food, preferring instead to eat carrion. DNA studies conducted within the last ten years have proven that this species is more closely related to the stork family. Unlike other birds of prey, Turkey Vultures have a highly developed sense of smell, and can locate concealed carcasses beneath the forest canopy. Vultures tend to forage alone, but keep a keen watch on the activities of other vultures nearby. A discovered carcass may attract numerous vultures to the site, along with the other, much smaller western scavenger, the Common Raven. Even Golden Eagles are sometimes found at carcasses, and indeed, nearly all species of raptors scavenge when live food is scarce. Vultures, including the Black Vulture which does not occur in New Mexico, are responsible for the removal of tons of animal carcasses in North America each year.

Generally acknowledged as a beneficial scavenger, Turkey Vultures were accorded protection in many states even before the Migratory Bird Treaty Act was passed in 1918. They are; however, still persecuted in some areas and have been trapped, shot, and poisoned by ill-informed humans who fear that they may spread disease among livestock, or kill newborn calves, although direct kills of young are almost certainly due to another avian predator. Over 100,000 vultures were killed in Texas in the mid-1900's by baiting walk in traps with carrion, and the species is also vulnerable to steel leg-hold traps such as the ones that were responsible for the deaths of two gray foxes in Jemez Springs in February 2006.

The population of Turkey Vultures is generally stable in the U.S., particularly as increased education about the benefits of this species has reduced persecution. The greatest causes of mortality for this species today are collisions with automobiles and aircraft, and electrocution on power poles. Collisions with military aircraft are particularly serious, costing the U.S. Air Force 21.6 million dollars, 3 crashed aircraft, and 2 fatalities between 1989-1992. Records of collisions with power lines are rare, and Turkey Vultures often forage directly beneath power lines on carcasses of other less adept species; however, electrocutions occur when the bird perches on power poles, and two body parts, such as wings, or a wing and a foot, touch separate energized portions of the structures, causing electricity to arc between them. Their winspan (63-71 inches), which is smaller only than that of eagles, makes them particularly susceptible to electrocution when the fleshy wrist tissue spans two energized wires.

One of my first and most memorable close encounters with Turkey Vultures happened in the Jemez Mountains. A friend and I were attempting yet again, to find a way to hike to the top of Virgin Mesa without driving around to the west side. We struggled through the increasing steep terrain of the tent rocks, where each step forward was countered by a half slide back. Then, just as we were about to admit defeat, several vultures took flight right over our heads. Their presence was impressive as they wheeled buoyantly on the wind, above and around us oblivious to the limitations of the land-locked humans below. I wondered then, if they nested on the cliffs above us, and they may have been doing just that. They do not build nests, but utilize caves and crevices in cliffs, like the escarpment on Virgin Mesa, and other mesas in the Jemez Mountains. By the time this reaches you, these remarkable black birds should have returned to their mountain home.

Friday, March 14, 2008

Watching and Feeding Wild Birds

Photo of Pine Siskin by David Powell. Niger seed is a favorite of this small finch.

The stereotypical birder, or birdwatcher, is an elderly, eccentric woman dressed in very odd attire. However, recent birdwatching demographics belie this myth. Today’s birder may easily be a teenager, middle-aged, or senior, male or female, rich or poor. There is no question that birding is big business worldwide, with an estimated 46 million bird watchers in the United States. Of this total, 88% consider themselves backyard birders. In New Mexico, 28% of the state’s residents participated in bird related activities in a study conducted in 2001. How does that add up economically? In 2001 (the last year for which figures are available), birding generated $32 billion in retail sales, $85 billion in overall economic output, $13 billion in state and federal income taxes, and 863,406 jobs were created!

To some, the thrill is traveling to special locations in search of unusual birds. To others, gaining insight into bird behavior is most gratifying. But, to the vast majority of bird lovers, the greatest pleasure is derived from attracting birds to their back yards. Some birds are naturally bolder, and easy to attract, like the ever-present Steller’s Jay and their smaller cousin, the Western scrub-jay. These colorful birds can become regular visitors to your back yard through frequent feedings of raw peanuts, still in the shell, one of their favorites. They also like whole and cracked corn, and will eat black oil sunflower when all the other, more desirable seeds are gone.

Black oil sunflower is without doubt, the all-around favorite for many birds. It has a high meat-to-shell ratio and a high fat content. It is small, and thin shelled, so even small birds can easily crack and eat. This type of seed can be offered in a platform type of feeder, or simply spread along a deck rail. Striped sunflower seeds are larger, and have thicker seed coats. If you are using bird feeders made from hardware cloth, striped sunflower will clog the openings.

Many ground feeding birds, such as mourning dove and dark-eyed junco prefer white millet or red milo. Beware of commercial seed mixes. Often, these are a blend of sunflower, plus a high proportion of less desirable filler seeds. Birds pick through the mix, feasting on the prized sunflower, and leaving the rest. You can make your own birdseed mix to suit the birds in your back yard. Combine 25 pounds of black oil sunflower, 10 lbs. of white proso millet, and 10 lbs. of cracked corn.

Smaller birds, like the pine siskin and lesser goldfinch simply adore niger, or thistle seed. This can be offered in a hanging, tube-type feeder or a cheesecloth bag which holds the seed but is loosely woven to allow the bird to pull the seeds from the bag. These types of feeders permit the smaller birds to avoid competition with jays, black-headed grosbeaks, and woodpeckers which take over platform feeders.

Some people feed only during the winter, which attracts good numbers of birds, and also helps birds survive the rigors of cold, icy, and snowy weather. However, year-round feeding bolsters the wild bird population and provides hours of entertainment to the watcher. Because naturally produced seeds are uncommon in the spring and summer, mixed flocks of birds visit feeders filled with oil-type sunflower seeds in the growing season. Chickadees, jays, nuthatches, and mourning doves will visit daily. Young birds, often with clumps of down still attached, follow their parents, begging. Seeing an adult black-headed grosbeak stuffing food into the incessantly begging, flapping youngster is a thrill to new or experienced birdwatcher alike.

Your neighborhood birds are not completely dependent on you for a food source. They visit several feeding sites daily and waste little time at an empty feeder. Occasional periods of emptiness are unlikely to result in starvation.

Just like the birds that you want to attract to your yard, other less desirable birds, and even avian and mammalian predators will be attracted to your yard. Fortunately, species such as house sparrow, starlings, and rock pigeons are not very numerous in the Jemez Valley. At some point in your bird feeding activities though, a sharp-shinned or Cooper’s Hawk will visit. The primary diet of these two forest dwelling hawks is small birds, and the abundance of songbirds in your back yard provides a food source for the hawk as well, who coincidentally, also needs to eat to survive. If this becomes a big problem, remove your feeders for a few days. The hawk will get hungry, and move on to another area.

Squirrels, although fun to watch, are persistent, and can seem to outsmart every human built squirrel baffle. One way to distract them is to feed them peanuts or dried ears of corn in a location far from the bird feeders. There are a number of commercially available non-lethal squirrel deterrents that can help to reduce damage from this furry, agile mammal.

Bears often become a problem in New Mexico’s mountain communities during the summer and fall, particularly during drought years when little natural food is available. To deter bears: bring all of your feeders in each night; hang all feeders at least 10’ above ground and 6’ away from tree trunks; clean up spilled birdseed; and don’t hang your feeder on your front porch. If you do see a bear, do not approach it.

The family cat is one of the biggest avian predators, killing millions of wild birds each year. Ground feeding, ground nesting, and fledgling birds are at the greatest risk. While kitty may be very well fed, cat’s natural instincts cause them to hunt other animals. If you do own a cat, keep it indoors to reduce the senseless loss of bird lives. For more information about cats and wildlife, visit Cats Indoors, created by the American Bird Conservancy at