The holiday season brings many traditions, such as setting up a train under the tree, hanging greens or putting up a nativity set. For birders, another annual holiday tradition is participating in the annual Christmas Bird Count.
Sometimes known by the acronym CBC, the count is held all over the United States. For a few days in a row, bird watchers will venture out in elements, look through the lenses of their binoculars and count whatever avian species they see - such as one blue jay, four crows, a bald eagle and a few chickadees.
The Lycoming Audubon Society will hold its Christmas Bird Count on Monday, but the event officially occurs anytime from mid-December through early January.
As bird watchers move through areas counting and recording their sightings, the data they collect is important and can render some findings useful to scientific, biological and wildlife agencies.
"Bird counts allow us to get sound data about the geographic distributions, population sizes and population trends of many North American and Neotropical bird species," said Keith Russell, Pennsylvania's Audubon's outreach coordinator on-site ornithologist.
He said it is like taking a census, but instead of people, it's for birds.
"And like a human census, the data can be used on a continental, regional or local scale by conservationists, biologists, state and federal agencies and others to better understand and manage North America's bird populations," he said.
Within the region, local Audubon chapters participate and ask for the help of other bird watchers who may not even be club members.
"The annual Christmas Bird Count is like taking a giant snapshot during the winter of bird populations throughout North America and the Neotropics. There's no way to do this without thousands of people counting in thousands of representative locations, just like when when we send thousands of Census takers out to census people. Anyone can participate, but participants need to be skilled in identifying all of the birds that occur in the geographic location they are censusing," Russell said.
Predicting irruptions
Even before the year's annual bird count began, Russell noted major irruptions already have been documented this year
The term "irruption" refers to a sudden, sharp increase in the relative numbers of a population. In this circumstance, irruptions of birds are seen as species travel to follow food sources.
"There are major irruptions occurring this winter of almost every irruptive bird species except for owls and a few others,"?Russell said. "So these species will be found widely throughout the state."
Certain species of birds migrate southward in large numbers each year. However, the distance they travel and the numbers in each flock vary each year.
"During winters when they migrate south (versus not migrating at all), it's called an irruption,"?Russell said. "During winters when large numbers of individuals migrate south (versus small numbers), it's called a 'major irruption.'
"Irruptions occur due to natural cycles in the population, sizes of seed and fruit crops of various plant species, and natural cycles in the population sizes of various prey species (such as) rodents," he added.
In Pennsylvania this winter, irruptions already have been seen in the following species: white-winged crossbill; red crossbill, red-breasted nuthatch, black-capped chickadee, pine grosbeak, evening grosbeak, purple finch, pine siskin and common redpoll.
Those species seek out a variety of food sources, including seeds, berries, dormant insects and seeds from pine cones.
Because the bird count happens in the mid-winter time frame, Russell said irruptions often occur, making for perfect timing.
"Irruptions occur during the fall and winter months in North America. As a result, the Christmas Bird Count season is an ideal time to document irruptions," he said.
Rarity
It can't be predicted which avian species will be spotted, or what numbers will be counted. But, rarities do happen.
"No one can predict what unusual rare species will show up in northcentral Pennsylvania during the winter, in addition to what may have already been found. But there are always rare and unusual species found each year," Russell said. "However the southeastern section of the state usually has more bird species overall than any other section of the state during the winter because it's warmer."
More hummingbirds are being spotted in the fall and winter.
"Dozens of individual hummingbirds from a few of the western species occur in the northeast each fall and winter," Russell said.
About 15 species of hummingbirds breed in North America and north of Mexico.
Eastern North America's main hummingbird is the ruby-throated.
"The rest occur in the west (mainly in the southwest and along the West Coast).
"The species that occur along the West Coast migrate south to winter in the Neotropics, but scattered individuals from some of these western species migrate east each year and wind up in eastern North America for the winter where most survive at hummingbird feeders," Russell said.
He said this fall and winter, individuals from the following hummingbird species have been present in various places throughout Pennsylvania: rufous, Anna's, calliope and Allen's.
"This has been a major winter for western hummingbirds in Pennsylvania," he said.
Technology changing the count
Russell said technology changes the way birders communicate with each other every year.
"Birders are aggressively using all of the above tools in their pursuit of birding," Russell said.
Faster ways to communicate with one another have been made possible by email, cellphones, listserves, Twitter and Facebook.
It's even easier to document sightings, too. Birders can use cellphone or digital cameras to photograph species, then use social medias to share the photos.
"The Christmas Bird Count results, however, will no longer be made available through a printed hard copy. They will now just be available online, saving paper, printing, production and mailing costs," he said.
Counting birds may seem like a hobby, but Christmas Birds Counts render important data on habitats and environments.
"Birds are extremely beneficial because of the important ecological services they perform, such as controlling insect populations and diseases spread by insects, pollinating flowers and distributing plant seeds," Russell said.
