Tejon Ranch Conservancy staff
and 26 guests spread out across Tejon Ranch on Monday, December 15th
for our annual 7th Annual Christmas Bird Count. We were able to
field five teams to bird the San Joaquin Valley and Antelope Valley sides of
the Ranch. Teams counted a combined
total of 103 species. It was a quiet
year, in terms of number of birds tallied, we were well below the number of
species counted last year and we were not able to add any new species to the
Tejon Ranch Bird List, but it was still a wonderful day filled with birds, the
beauty of the landscape and quiet companionship. One couldn’t ask for more in a day spent in
the great outdoors.
Storm systems had come
through the area the week before the count, pouring rain on the lower
elevations and depositing snow on the mountaintops, with another system predicted
to move into the area the day of the count.
It was with trepidation that people gathered at their respective meeting
places, unsure of road conditions and what the day may bring. These dedicated supporters of our
organization had woken in the dark hours of the night to drive to Tejon from
their far off homes in Ridgecrest, the greater Los Angeles area, Ojai, Santa Barbara,
San Luis Obispo, and the Kern River Valley to help us conduct our CBC. Acquaintances that have bonded through our
birding events greeted each other fondly as the sky began to lighten, telling
tales of their adventures since the last time they had met and the birds they had
already tallied since arriving at the gate.
Soon teams headed off in opposite directions to see what they could see
(Photos 1, 2, 3). I led a team on the
San Joaquin Valley side of the Ranch.
Away from the canyons, where the wind whipped over the crest of the
Tehachapis, the day was calm and the sky provided a revolving show of cloud
formations throughout the day. The
recent precipitation had spurred on germination and the landscape was coated in
a carpet of green that had not been seen in over a year. Across the hillsides the skeletons of the bare
California Buckeye (Aesculus californica)
trees showed silver in contrast to the dark green of the live oaks (Quercus wislizenii and Q. chrysolepis) (Photos
4 and 5). Worries about road conditions
and storms disappeared as the sky continued to brighten and the birds began to
sing.
Results from all CBCs are
posted on our website.
Photo 1. Great-horned owl (Bubo
virginianus) hunkered
down in a tree cavity in a cottonwood (Populus
fremontii) in El Paso Canyon. Photo
by Devon Pryor.
Photo 2. California condor (Gymnogyps
californianus)
perched on a tree on Winters Ridge.
Photo by Devon Pryor.
Photo 3. Volunteer birder scanning the ridges. Photo by Devon Pryor.
Photo 4. A hillside in Tejon Canyon scattered with the
silver skeletons of leafless California Buckeyes (Aesculus
californica). Photo by Phoebe Prather.
Photo 5. A flock of wild turkeys (Meleagris gallopavo) in Tejon
Canyon. A large flock of 60-70 is seen
in Tejon Canyon every year during the Christmas Bird Count. Photo by Phoebe Prather.
The Beginning
The Christmas Bird Count
(CBC) is a long-standing program of the National Audubon Society. It is the longest running Citizen Science
survey in the world with over 100 years of citizen involvement. Prior to the creation of the CBC, there was a
holiday tradition known as the Christmas “Side Hunt.” (1) Gatherings of people divided into teams and
went out and shot as many birds as they could.
The team that returned with the largest number of dead birds was the
winner of the event. Frank Chapman, a
famed ornithologist at the American Museum of Natural History, the editor of
Bird-Lore and an early officer in the budding Audubon Society, recognized that
bird populations could not withstand this over-hunting. He proposed that people should count birds on
Christmas Day instead of shooting them, leading him to the idea of a “Christmas
Bird Census.” The first Christmas Bird Census, later renamed the Christmas Bird
Count, was held on December 25, 1900.
Twenty-seven volunteer birders participated in 25 count locations that spanned
from Toronto, Ontario to Pacific Grove, California with most counts occurring
near population centers in northeastern North America. The 25 counts totaled a combined 89 species.
Stories
Amazing stories of
dedicated citizen scientists have come from the CBC experience since the
creation of the count.
- Only one of the inaugural CBCs occurred in the southern United States. A single volunteer, Mrs. L. G. Baldwin, considered the founding mother of the CBC, counted 8 species in Baldwin, Louisiana: killdeer, blue jay, Carolina chickadee, Carolina wren, red-winged blackbird, grackle species, northern mocking bird, and turkey vulture (2). She conducted her count again in 1901 and added four more species, the red-headed woodpecker, crow species, tufted titmouse, and ruby-crowned kinglet. In 1903, Mrs. Baldwin continued her citizen science activities when she had an article published in American Ornithology about her concern over the Cardinal Grosbeak, later renamed the Northern Cardinal, and its decline due to hunting and trapping: “The brilliant plumage of the cardinals makes its end a tragedy. In Louisiana they are hunted and trapped for sale, as cage birds, until they are nearly exterminated. Their pathetic fate appeals to bird lovers, and unless something can be done for their protection the Cardinal Grosbeak will be gone from the wild bird life of this state." With the shifting of philosophies on wildlife brought on by the creation of programs such as the CBC and the building of a citizen scientist base, it is species such as the Northern Cardinal that are now once again considered to be common birds.
- In 1916, two young girls, with the help of their aunt, participated in a CBC in Georgia (3). Their story, published in the magazine Bird-Lore, illustrates the importance of raising children in nature and exposing them to citizen science projects early in their lives: "We are two little girl-sisters who are living in Georgia now with our papa and mama. We were born in Knoxville, Tenn., on Chestnut Hill, where there are a great many birds, and Aunt M who loves birds, taught us their names. When I was two and a half years old I could name twelve birds. Aunt M came from Tennessee to spend Christmas with us. This morning we took little sister B and walked through Inman Park where there are a great many evergreen trees called water oaks. We were looking for birds for our Christmas Census. We saw: 12 Blue Jays, 6 Towhees, 5 Cardinals, 2 Mockingbirds, 25 in all. We heard a Flicker and a Carolina Wren and thought we heard a Bewick’s Wren. The weather is so warm that we have the windows open."
- Many other stories are reported each year, ranging from tales of counting ravens at Prudhoe Bay, Alaska, birding in Belize, and the CBCs along the Gulf Coast after the BP oil disaster. These stories and others are posted on the National Audubon Society’s website for all those interested in the wide-range of CBCs occurring each year.
Survey Methods and Count
Circles
Each Christmas Bird Count
occurs within a designated 15-mile (25-km) diameter circle (4). Volunteers follow specified routes through
the circle and count every bird they see or hear. The individual CBCs are conducted between
December 14 to January 5 of that count year and each count is conducted in one
calendar day. Thousands of volunteers
participate across the United States, Canada and many countries in the Western
Hemisphere. Participation has continued
to increase every year since 1900. By 2008
there were 2,113 CBCs and 59,918 volunteers (Figures 1 and 2) (5).
Figure 1. Locations of Christmas
Bird Count circles in the Western Hemisphere (8).
Figure 2. Number of
Christmas Bird Counts and participants over the years (5).
Data and Analysis
Over a century of data has
been collected as a result of the CBC.
This data allows researchers, conservation biologists, and other
interested individuals to study the long-term health and status of bird populations
across North America. The data has been
used to build strategies to protect birds and their habitat. It shows local trends in bird populations
that can indicate habitat fragmentation or an immediate threat. An example is the American black duck. In the 1980’s, CBC data documented the
decline in the wintering population of the species (8). Conservation measures were put into place to
reduce hunting pressure and the species has rebounded.
In 2007, CBC data was
instrumental in the development of two Audubon Society State of the Birds
Reports (6). Common Birds in Decline analyzed 40 years of CBC data and revealed
an alarming decline in some of America’s most beloved and familiar bird species. There are 20 bird species on the list, all of
which have lost at least half of their populations since 1965. The average population of these common
species has fallen by 68 percent, with some species having declined by 80
percent. WatchList 2007 identified 176 species in the
continental United States and 38 species in Hawaii that need immediate
conservation action. The report lays the
groundwork for a standard to guide conservation priorities among conservation
organizations and government agencies.
It helps focus attention on “red” species, species of greatest concern,
while highlighting other sensitive “yellow” species so action can be taken to
keep them off of the “red” list.
In 2009, CBC data was
essential in two more reports (8). The
Audubon’s Birds and Climate Change analysis documented how climate
change could affect the ranges of 588 bird species. Three decades of citizen science observations
were used to define the range of temperatures, precipitation, and seasonal
changes each species needs to survive. Climatic
models based off these data indicate that 314 species will lose more than 50
percent of their current range by 2080.
126 of these species were classified as climate endangered and are
projected to lose more than 50 percent of their current range by 2050. A collaborative report by the North American
Bird Conservation Initiative, 2009 State of the Birds Report, also used CBC data. This was the first ever comprehensive report
on bird populations in the United States.
It showed that nearly a third of the 800 bird species in the United
States are endangered, threatened or in significant decline due to habitat loss,
invasive species, and other threats. But the report also highlights examples where
habitat restoration and other conservation measures have reversed previous
declines.
The U.S. Environmental
Protection Agency included Audubon’s climate change work described above as one
of the agency’s 26 indicators of climate change in their 2012 report. The report shows
that among 305 widespread North American bird species, the average mid-December
to early-January center of abundance has moved northward by more than 40 miles
between 1966 and 2013 (Figure 3). Of
these species, 48 have moved northward by more than 200 miles. These northward moving trends can be closely
related to increasing winter temperatures.
Analysis of the CBC data has also indicated that bird species have moved
their wintering grounds further inland from the coast since the 1960s. Inland areas tend to experience more extreme
cold than coastal areas, but these extremes are becoming less severe as the
climate changes, allowing inland areas to become suitable habitat.
Figure 3. The annual change in northward
movement of bird species centers of abundance for 305 widespread bird species
in North America from 1966 to 2013. The
shaded band shows the range of values, based on the number of measurements
collected and the precision of the methods used (6,7).
The online CBC database can be a useful tool to guide
further, more in-depth research on bird distributions across North America and
is available to the public. Case study reports of specific species such as the
American black duck, hooded merganser, and evening grosbeak, as well as
communities of birds such as waterbirds and land birds of the boreal forest
have been analyzed using CBC data. Over
200 peer-reviewed articles have resulted from an analysis of CBC
data. It is an incredible source.
In the beginning, it was
hunting that ignited bird conservation efforts.
Today, the challenges we face are much
more difficult to address than just changing hunting regulations. Continuing to track populations as habitat disappears and the climate changes will be essential for the conservation of our bird species and natural communities. There is more work to be done than organizations and agencies can do by themselves. It is essential to continue to build a strong citizen scientist base and to promote projects in which they can help and take ownership in our natural resources. With a staff of 7, many of the efforts of the Tejon Ranch Conservancy are reliant on volunteer citizen scientists.
Tejon CBC
The
Tejon Ranch Conservancy has been conducting a Christmas Bird Count on Tejon
Ranch since 2008. The 15-mile diameter
circle fit perfectly into the body of the Ranch (Figure 4). The circle is divided into 5 areas. We typically are only able to cover the low
elevation portions of the Ranch and using four or five teams we are able to
cover portions of areas 1, 2, 3, and 4. We
usually have a turnout of 20-25 volunteers to help us. We have designated locations within each area
that teams visit which allows us to collect consistent data in specific
places every year. We now have a data
set encompassing seven years. With this data we are able to track our wintering bird populations over time. We have seen that we get an influx of raptors
occupying the Ranch during the winter.
Several bald eagles spend time here and are then gone by spring. Our red-tailed hawk and golden eagle numbers
also increase during the winter. Reservoir
Number 2 on the San Joaquin side of the Ranch fills with waterfowl species such
as ruddy ducks, eared grebes, American wigeon, ring-necked ducks, American
coots and canvasbacks. Combined with our
spring Breeding Bird Blitz, which uses the same methodology as the CBC, we will
be able to piece together long-term trends of the resident, wintering, and breeding bird species that occur on
the Ranch. Stay
tuned for results from that future venture into data analysis!
Figure 4. Tejon Ranch
Christmas Bird Count circle.
Citations
(5)
National
Audubon Society. http://birds.audubon.org/sites/default/files/documents/Number_of_Christmas_Bird_Count_circles_and_participants_over_time.pdf.
(6) Environmental Protection Agency. www.epa.gov/climatechange/indicators
(6) Environmental Protection Agency. www.epa.gov/climatechange/indicators
