The area's annual Christmas bird count will be held on Sunday, Dec. 16. This year's event comes in the wake of the recent declaration: "Southern Arizona Birds in Decline."
That was the attention-grabbing September headline above a column written by Tucson Audubon Society executive director Paul Green for the society's newsletter, Vermilion Flycatcher.
Referencing 40 years of statistics for Arizona obtained from a breeding-bird survey, Green states that five common species of birds have declined between 64 and 83 percent since the 1960s. The five birds are the American kestrel, the northern cardinal, the black-throated sparrow, the verdin (a yellow-faced songbird) and the phainopepla (a long-tailed songbird).
Focusing on these five out of the 28 birds recently listed on statewide data as declining by at least 50 percent over the past four decades, Green says: "I selected species more familiar in the southern part of the state."
Green says he believes the loss of essential natural habitat is the primary reason for the declining numbers. "Once habitat is gone, the birds have no where else to go."
According to Green, two causes of habitat loss are climate change and urban development.
"Birds move higher up as the climate warms," Green says.
Every year, thousands of acres of desert in Pima County are swallowed up to accommodate more residential, commercial and industrial development. To ensure a sufficient supply of natural areas, Green suggests: "Let's retain good functional habitat by preserving what we can during development. The Sonoran Desert Conservation Plan is an excellent way to do this."
Green also supports restoring natural areas that have either been degraded or destroyed. This can be done, he says, by planting vegetation along washes or making sure that parks have the full complement of plant life required by birds.
Even though the figures cited by Green show declines in some statewide bird populations, anecdotal evidence suggests that may not be occurring in all parts of Tucson--at least not yet.
"To say something is declining over a fairly wide range is really difficult to say," observes Will Russell of WINGS, a local company which for 35 years has led birding trips all over the world.
Acknowledging he's accessing only a narrow slice of information, Russell indicates he's been walking regularly in Sabino Canyon for many years, and the birds listed by Green haven't declined in numbers there. On the other hand, Russell believes there is no doubt there have been decreases in large groups of birds nationwide since the 19th century because of the loss of habitat.
"Arizona is lucky that so much of its land is in the public domain," Russell says, and thus is somewhat protected as open space for bird habitat.
A check of two other sources of information on local bird populations also shows variations from the conclusions reached by Green.
Cornell University's Lab of Ornithology is involved with the annual "Great Backyard Bird Count" and lists data for the past decade on its Web site. While certainly not a scientific measure of bird populations, this survey doesn't show much of a change in Tucson for the five species listed by Green.
Tucson's Christmas bird count also doesn't indicate decreases over the past 20 years for either the American kestrel or phainopepla--and a comparison of figures from 1987 and 2007 actually indicates a substantial increase for the verdin. On the other hand, sharp declines in the number of northern cardinals and black-throated sparrows were observed during the same time period.
"The Christmas bird count is not especially reliable," Green says. "The breeding bird data is better."
Larry Liese is the volunteer compiler of this year's Christmas bird count for the Tucson valley area, and he agrees with Green. "It helps show trends," Liese says of the holiday event, "but it's less scientific than other methods."
Begun in 1900, Liese says the Christmas bird count was started by the National Audubon Society to counteract the tradition of seeing how many birds could be shot after the holiday. Today, the count includes not only the United States but other countries as well.
For much of Tucson, the Christmas count will be centered at the intersection of Oracle and River roads and will be defined as a circle 7.5 miles in radius. Approximately 70 people will go out to count birds on Dec. 16 and report their results at the end of the day.
"We have fun," Liese says of the bird count, "and turn in useful data. You never know what you're going to find."
Liese adds that participants pay $5 to help defray costs and that most of the birders who participate in the count select vegetated areas within the circle. "That's where the birds will be," he says.
"Our goal is to reach 150 species," Liese says of this year's count, "since we're usually around 140."
People interested in more information on the Tucson Valley Christmas bird count can contact Liese at 743-3520 or firstname.lastname@example.org.