Lancaster CBC Analysis Over the Last 45 Years and Beyond
by Nick Freeman
Lancaster CBC Analysis Over Last 45 Years and Beyond . . .
For 2023, we tallied a total of 16,177 (16.2K) birds. Sounds like a lot! It isn’t especially in light of Count history. After excluding one anomalous** year, the adjusted Overall Count Avg is (33.0K/yr); that’s right, we’ve lost more than half (50.9%) of our birds in the Antelope Valley over the last 45 years, compared to our adjusted Count Average! Maybe 2023 was an aberration. The Avg of the last 10 yrs. was (18.5K/yr), and the Avg for the previous 35 yrs. was (37.2K/yr). Not any better; still down (50.2%). If we check another metric – Averages for first 10 yrs. (’79-’88) vs. last 10 yrs. (’14-’23) - we get (49.5K/yr) vs. (18.5K/yr). Recent numbers are down 62.6% from earlier numbers. The CBC data show that over the last 45 years, we have lost at least 62% of the wintering birds in the Lancaster area. If you like your data in tabular form, here it is:
Periods Compared Period Averages ** Decrease in Bird Numbers
2023 vs. Entire 45 Yrs. 16.2K vs. 33.0K 50.9%
Last 10 Yrs. vs. First 35 Yrs. 18.5K vs. 37.2K 50.2%
Last 10 Yrs. vs. First 10 Yrs. 18.5K vs. 49.5K 62.6%
This plummeting trend seems consistent with an earth-shattering article by Elizabeth Pennisi, published in 2019 in Science (*1), revealing “North America has lost nearly 2.9 billion birds since 1970 – more than 25% of the total population of North America’s birds, including both rare and common species. Grassland species” (prominently represented on the Lancaster CBC) “were down more than 50% in the study.” And that was as of four or more yrs. ago, before 2019.
** 2005 may have been an aberration because of (250K) blackbird spp. Reported in a single flock. The Max count of any blackbird in Count history was previously (16K). Even if correct, this number skews the Count data horribly! This flock has been omitted from the Count statistics here.
Historical Facts and Solid Speculation:
Before the 1950’s, water was so shallow in the ground that in many places, wells could be dug with a shovel, with likely riparian stretches (cottonwood, willow?) along seasonal drainages. As recently as a century ago, there were artesian springs feeding Rosamond (Dry) Lake from groundwater recharged by alluvial fans coming out of the north side of the San Gabriel Mountains [per T.Battey, pers. comm.(*2)].
The wintering Kitanemuk people that populated the early Antelope Valley expanded into the Tejon and Tehachepi ranges in the summer and traded with the Chumash of the Santa Barbara coast. Other peoples likely also resided in the AV over the millennia, but the Kitanemuk were physically well documented. Villages of 50-80 people built communal winter shelters of tule rushes [R. Thomas, 1776 (*3)], which may have required marshes akin to Piute (sic) Ponds. With a much higher water table and a healthy Joshua tree/atriplex high desert habitat, numbers of LeConte’s Thrasher, some sparrows, Cactus Wren and Burrowing Owl must have been off the charts.
In these early days before agriculture played a major role in the flora and avifauna of the AV, the area lacked some of its present avian diversity - no Rock Pigeons or Starlings - and probably lower quantities of a few others - blackbirds and Horned Larks, to name a few. But before the appearance of steer-, axe-, and plow-wielding Europeans, an Antelope Valley with an elevated water table, and consequently some seasonal natural drainages, may have boasted many of the shorebirds, waterfowl, owls, raptors and passerines presently found at Piute Ponds, and at “pseudo-riparian” areas like golf courses and parks.
However, diversity of species may have been higher than we see in stretches of healthy J-tree/atriplex countryside with an occasional pond. Fire management in hills and forests by indigenous peoples elsewhere in California is well established and referred to by O. Kaufmann (*5) and others. Documentation of land management with fire in desert habitats is harder to find, although J. Sizek (*4) describes historical customs of fire use in the East Mojave by the Nuwuvi (or Southern Paiute) in the 1930s. Nuwuvi people told anthropologists that they used ground fires in sagebrush plant communities, cutting off lower branches of trees to keep fires small and manageable, to capture rabbits during the summer. If somewhat similar land management practices were in effect in the AV before European ranchers and settlers appeared, this would have opened swaths of grassland for the multitude of pronghorn antelope documented to have saturated the Valley, as well as even more ground squirrels, rabbits, Golden Eagle, Rough-legged Hawk, Swainson’s Hawk, Long-billed Curlew, Mountain Plover, Short-eared Owls, Sandhill Cranes, Longspurs – basically, all of the non-introduced grassland specialists. Again, evidence is scant because indigenous peoples through much of SoCal were forced to give up such customs when ranchers and miners appeared, and before historians could study their ways; but the possibility is real.
These grassland species would later adapt to alfalfa fields, hay and sod fields, and dairies when native people and grasslands disappeared. Some of these birds and animals like pronghorn, Swainson’s Hawk, and Golden Eagle, which are all but gone in the Valley, can still be found in the grassy, wild foothills of adjacent Tejon Ranch.
After the 1950’s, shallow wells dug for agriculture and eventually domestic use, became deep wells, and eventually drew down the ground water until springs dried up, and the water table sunk to hundreds of feet below the surface, in some cases. This made agricultural practices that sustained many bird species, very difficult to maintain. It has also made life difficult for established native plants like Joshua trees, atriplex and sagebrush; and even for exotic windbreaks. And it seems likely that seedlings of native plants can only take hold if they get their start at the beginning of a (less and less common) series of wet years.
In Summary:
Over the last 45 years, the Lancaster CBC has documented the loss of a huge number of birds in the Antelope Valley. Species that may have frequented a possible historic mosaic of healthy desert scrub/grassland maintained by the native peoples; may have later frequented the Ag fields that temporarily replaced them, only to suck the water table dry in the process. Presently, we have a large number of fallow, desiccated fields in the region, as well as many areas just to the west that have been paved over with solar panels. Nearby desert scrub is hanging on by a thread. We are building up wintering avian diversity, some of which might have prehistorically (pre-1769 AD) visited / lived in large cottonwoods and willows around ponds and seasonal streambeds. They are now reappearing in tamarisks, non-native pines and sycamores in irrigated parks and suburbs, as Lancaster grows and expands. This is quite possibly the regional history that relates to our birds.
Nationally and locally, many other forces are at work, from hunting, to quantity and quality of breeding habitat, to migration stop-over habitat, to documented effects of climate change, to migration window strikes and cats, to pollution. All of these have been shown to have significant and measurable effects on various groups of birds, amounting to a loss of over 25% of all birds nationwide since 1970 [(E. Pennisi, see above (*1)]. According to CBC numbers, birds in Lancaster are down at least 62% since 1979, and even more since 1970, if Lancaster has been following national trends! Truly a sobering account.
Cautionary Note and Request: The preceding is an educated guess, sprinkled with solid facts, at reasons for apparent trends, after pouring through 45 years of raw data and stringing together commonalities between the species that presently occur - or have occurred - in the count circle. Sadly, I cannot even claim residence near the count circle, and I do not have the necessary tools or training to undertake a rigorous scientific analysis of what is only a snapshot of avian life in a portion of the Antelope Valley, but I still feel strongly that certain trends are clearly displayed in our CBC data set. If you have managed to plow through this document, I would welcome any dialogue or criticism, whether it stems from your personal observations, familiarity with the region, sources of information that I may not have consulted, or errors in my deductive reasoning - which I find each time I proof the document! If you wish to have a copy of the 8-page Excel spreadsheet of all Count sightings over the 45 years, please contact me.
I hope that this assessment has at least deepened your interest in the unique Antelope Valley portion of Los Angeles County, and increased the likelihood that I will see you out in the field once again on next year’s Lancaster CBC! Next year, the 2024 Lancaster CBC will be on Saturday, December 14, so mark your calendars now!
Bibliography:
*1 Pennisi, Elizabeth; “Three billion North American birds have vanished since 1970, surveys show”, Science Sep 19, 2019. Science.org.
*2 Battey, Todd. Hydrogeologist, High Desert Natural Historian, lay Herpetologist, and Modern Renaissance Man. Contact author for contact information.
*3 Thomas, Roberta; J. Smallwood; T. Clark, “Phase 1 Cultural Resources Assessment for the Palmdale Regional Groundwater Recharge and Recovery Project, Appendix F,” Ethnogeographic Setting / Kitanemuk 2.3.2, pg. 35. City of Palmdale, Los Angeles County, California. Applied Earthworks, Inc., Oct 2015.
*4 Sizek, Julia, “Seeing Beyond the Joshua Trees in the East Mojave”, Edge Effects, May 11, 2021. edgeeffects.net.
*5 Kaufmann, Obi, “The forests of California: a California field atlas”. pg. 51. Berkely California; Heyday Publishers; 2020.
Nick Freeman
Lancaster CBC Co-compiler, with Mary Freeman for LA Audubon, CBC Sponsor
Glendale, CA (818) 640-3421 text or call, mnfreeman@earthlink.net