"Popular accounts of the California condor often state or imply that condors were found prehistorically throughout much of North America. Except for one discovery of three bones in New York State, there is no reason to think that the species was ever regularly found east of Nevada and Oregon, or north of Arizona, New Mexico, Texas, and Florida. There is also no reason to think that California condor populations survived past the late Pleistocene or middle Holocene in any location more than about 200 miles from the Pacific Ocean. Every sight record beyond that area is suspect in some way; no condor relics have been found in any archaeological sites east of California; and I have not located any information to suggest that condors were known to aboriginal populations beyond the West Coast."
[The following was originally published as a chapter in: "Nine Feet from Tip to Tip: the California Condor through History." (Gresham, Oregon: Symbios Books, 2012). If you would like a free copy (PDF) of the entire book, send me an e-mail.]
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Whether considered species or subspecies, all prehistoric “California” condors date from longer than 9,000 years ago. Most bones have been radiocarbon-dated at 11,000 to 13,000 years before present (B.P.), and a number of samples exceed 30,000 years in age [1]. At about 9,000 years B.P., the condor record fails and remains empty for 5,000 years. Almost certainly, the aboriginal people of the Pacific Coast knew condors during some of that time (see Chapter 2), but so far the earliest radiocarbon dates for archaeological sites where condor remains have been found are around 4,000 years B.P. [2]. The first specific date of the condors’ return to the record is at about 2,900 years B.P., the radiocarbon date applied to a condor metatarsus found on Pender Island, British Columbia, Canada [3].
What was happening with the condors in those intervening 5,000 years? Perhaps that will never be known any more clearly than it is today, but some speculation may be worthwhile.
Popular accounts of the California condor often state or imply that condors were found prehistorically throughout much of North America. Except for one discovery of three bones in New York State [4], there is no reason to think that the species was ever regularly found east of Nevada and Oregon, or north of Arizona, New Mexico, Texas, and Florida. There is also no reason to think that California condor populations survived past the late Pleistocene or middle Holocene in any location more than about 200 miles from the Pacific Ocean. Every sight record beyond that area is suspect in some way [5]; no condor relics have been found in any archaeological sites east of California; and I have not located any information to suggest that condors were known to aboriginal populations beyond the West Coast [6].
As long ago as 1912, Loye Miller suggested that Pleistocene scavengers decreased in numbers, and in some cases vanished, because of food supply shortages following extinction of large mammals [7]. Sixty-seven years later, I made a similar observation, adding to megafauna extinctions the additional loss of food resulting from the effects on the remaining mammals of increasing aridity in the Southwest [8]. In 1990, Steven Emslie restated the case, now armed with radiocarbon dating of condor bones that showed condor presence in the West at the same time as the Pleistocene megafauna [9]. Such observations are intuitive – less food, lower carrying capacity for scavengers – but clearly it was not that simple. First, megafaunal extinctions in North America may have happened over a long time period, and at different times geographically, as they did in Europe [10]. Scavenger populations likely had considerable time to adjust to the changing food supply [11]. Second, although the “megafauna” (the very large mammals) died out in the late Pleistocene or early Holocene, a wide variety of large and small mammals survived to the present time [12]. Populations of condors and other scavengers would have had to adapt to a diminished food base, but it’s unlikely they were left entirely without food anywhere in their known prehistoric range. Perhaps a more interesting question is why did California condors ultimately disappear from all former habitat except along the Pacific Coast? The answer may rest in the climate of the middle Holocene.
There is general agreement among climatologists, botanists, zoologists, and archaeologists that most of western North America was exceptionally warm and dry during the middle Holocene. There is not complete accord on the timing or duration of the drought – in fact, it appears that timing did vary geographically, and that there were intervals of greater or lesser drought – but the period of greatest aridity is usually identified as between approximately 8,000 to 3,000 years B.P. The magnitude and intensity has been described as “the greatest aridity the Great Basin has seen in the last 10,000 years, and perhaps for the last 100,000 years or more” [13]. “A variety of analyses show that this period was in general far warmer and drier than what came before or what followed, at least in part a response to the fact that summer precipitation decreased at the same time as temperatures increased” [14]. Middle Holocene aridity was not confined to the Great Basin, although it may not have been as severe in other areas. Evidence for such aridity has been identified in (among other locations) the Pacific Northwest [15], California [16], Wyoming [17], Arizona [18], New Mexico and Texas [19], Oklahoma [20], Missouri [21], and even Florida [22]. (Not all of these locations had condors; I note them to show that the drought event was so widespread that condors anywhere in the interior United States would likely have felt its impacts.) Manifestations of the drought included dried up lakes, springs and streams; retreat of temperate climate vegetation to higher elevations; decreased rates of sedimentation in marshlands; deposits of blowing sand following loss of vegetative ground cover; and reduced rates of stalagmite growth in southwestern caverns [23].
The length and intensity of the middle Holocene drought was such that human populations were disrupted. Apparently, large areas of the Great Basin were depopulated as people moved closer to the few remaining locations with dependable water [24]. On the plains of west Texas, Oklahoma, and eastern New Mexico, people dug water wells to help cope with the drought, and even then may have had to eventually vacate the most severely affected areas [25]. In Arizona “the Santa Cruz Valley and the rest of the desert lowlands of the Southwest were largely abandoned by people” [26].
Humans were not the only mammals affected. At Homestead Cave in north-central Utah, Donald Grayson found that “the Middle Holocene small mammal faunas of this area underwent a decrease in species richness and evenness, driven largely by a series of local extinctions and near-extinctions coupled with a dramatic increase in the abundance of taxa well-adapted to xeric conditions” [27]. Of greater significance to condors were the effects on the artiodactyls (“big game” – deer, elk, pronghorn, bison, sheep – of the mammalian Order Artiodactyla). This group of mammals has been shown to be strongly sensitive to variations in temperature and moisture. “The primary links between artiodactyl population growth and climate patterns stem from the effects of temperature and precipitation on forage quality and the availability of drinking water. In arid regions, environmental productivity and forage quality correlate positively with effective precipitation and soil moisture... The availability of high-quality forage, in turn, influences maternal condition, initial offspring survival, birth weight, growth rate, survival through the first winter, resistance to disease, overall recruitment rates and, ultimately, herd size… The availability of high-quality forage also affects the extent that animals require free drinking water. In times of drought, low-quality forage containing little water can tether herds to scarce free water sources and eventually restrict herd size… Several studies document the positive effects of cool and moist weather and the negative effects of hot and dry conditions on the reproductive success of artiodactyl species in a variety of contexts across the arid West” [28].
In support of those findings on the effects of heat and dryness on artiodactyls, the archaeological record of the middle Holocene suggests major decreases in those species in such diverse locations as eastern Washington [29], southwest Wyoming [30], western Texas and eastern New Mexico [31], Utah [32], southern Arizona [33], and northern California [34]. With the return of more moderate climatic conditions in the late Holocene, some artiodactyl populations rebounded. Probably the return of more dependable food conditions came several centuries too late for Southwest condor populations.
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If it is true that California condors disappeared from much of their former habitat because of lack of food, then why were they able to survive through the arid middle Holocene along the Pacific fringe of the continent? The answer seems to be that, even though areas west of the Sierra Nevada and Cascade Range felt the effects of the middle Holocene drought, the effects were moderated by proximity to the coast. “Climatically influenced changes in terrestrial environments along the coast during the Middle Holocene appear to have been less drastic than in the interior, particularly in central and northern California” [35]. The California coast, San Francisco Bay, and the Sacramento-San Joaquin delta have been considered “climatically complacent,” implying they were likely to have been less affected by changing climatic conditions than more interior locations [36]. It is probably not coincidental that much of the evidence of human occupation of California between 8,500 and 5,500 B.P. has been found in coastal and near-coastal locations [37].
Artiodactyls appear to have become considerably less common in interior western California during the middle Holocene. However, their rapid increase following the establishment of a more temperate climate regime suggests that a significant population survived through the drought [38]. Along the central California coast, there may have been little or no reduction in abundance of black-tailed deer [39]. Even in the Pacific Northwest, both coastal and inland archaeological sites show evidence of local populations of deer, elk, pronghorn, sheep and bison throughout the Holocene [40]. Condors living within regular foraging distance of the seacoast would have had access to marine mammal carcasses throughout the Holocene, as well [41]. Avian scavengers on the Pacific Coast might not have had the quantity or variety of foods they had during the late Pleistocene, but every indication is that they had much more than did the condors of the interior Southwest.
The earliest European explorers to reach the Pacific Coast in the late 1500s and early 1600s reported seeing large numbers of big game; many similar reports followed in the 1700s. Declines in artiodactyl populations may have occurred in the middle Holocene due to climate, and later from aboriginal hunting [42], but they were clearly back in abundance by the 17th century. It seems likely that condors increased along with the increase in large mammals, but that is intuitive. By the time Lewis and Clark reached the Pacific in 1806, condors were probably found from Canada to Mexico. Whether they were there all the time, or whether condors expanded their range following the Holocene hard times, are unanswerable questions at this time.
CHAPTER NOTES
1. Emslie, S. D. 1987. Age and diet of fossil California condors in Grand Canyon, Arizona. Science, New series 237(4816):768-770.
Emslie, S. D. 1990. Additional Carbon 14 dates on fossil California condors. National Geographic Research 6(2):134-135.
Syverson, V. J., and D. R. Prothero. 2010. Evolutionary patterns in late Quaternary California condors. Palarch’s Journal of Vertebrate Palaeontology 7(1):1-18.
2. Simons, D. D. 1983. Interactions between California condors and humans in prehistoric far western North America. Pages 470-494 in: Wilbur, S. R., and J. A. Jackson. Vulture biology and management. Berkeley, California: University of California Press.
3. Specimen at the Royal British Columbia Museum, Victoria, British Columbia, Canada.
4. Steadman, D. W., and N. G. Miller. 1987. California condor associated with spruce-jack pine in late Pleistocene of New York. Quaternary Research 28(3):415-426. The bones were identified by competent paleontologists, and there is no reason to doubt that these were bones of a Gymnogyps condor. Still, bones have been initially attributed to condors that were later assigned to other species. This would be an extreme range extension for Gymnogyps – one that seems highly unlikely geographically, ecologically and climatologically - and I will feel much more comfortable when some linkage is found to close the 1,000 mile gap between these bones and others from the species.
5. There are nine sight records of California condors east of California, Oregon, or Washington that are regularly cited in books and articles.
Idaho: In 1879, General T. E. Wilson saw two birds at a sheep carcass near Boise, which were “much larger than turkey buzzards,” and which “hissed at me and ran along the ground for some distance before they were able to rise in flight.” [Lyon, M. W. Jr. 1918. Report of the Secretary, Biological Society of Washington, 20 October 1917. Journal of the Washington Academy of Sciences 8(1):25-28.] Although this was reported almost 40 years after the fact, it was a first-hand record and moderately detailed. Probably, there were still condors in western Oregon at that time, and non-breeding condors could possibly have foraged that distance on occasion. There is no support for the added hearsay report that condors were previously “not uncommon” in the area.
Alberta, Canada: John Fannin reported seeing two condors west of Calgary in 1896. [Fannin, J. 1897. The California vulture in Alberta. Auk 14(1):89.] In a letter to Harry Harris 6 March 1931, Major Allan Brooks claimed that Fannin had later recanted the sighting, on the basis that at the time he had not known that immature golden eagles had white under their wings. [I examined the letter at the Bancroft Library (Berkeley, California) in 1971, but have been unable to relocate it recently.]
Utah: Henry Henshaw reported a bird "believed to be this species" in Utah in 1872 [page 428 in Condor Henshaw, H. W. 1875. Report upon the ornithological collections made in portions of Nevada, Utah, California, Colorado and New Mexico during the years 1871, 1872, 1873 and 1874. Volume 5, U. S. Geographical Survey west of the 100th Meridian. Washington, D. C.: U. S. Government Printing Office.] However, he later claimed not to have seen a living California condor until 1884 in California [Henshaw, H. W. 1920. Autobiographical notes (continued). 22(1):7-10].
Arizona: (A) “Resident in Southern Arizona. Individuals observed at Fort Yuma, in September 1865” [Coues, E. 1866. List of the birds of Fort Whipple, Arizona. Proceedings of the Academy of Natural Sciences of Philadelphia 18:39-100]. Fort Yuma is actually on the California side of the Colorado River, not in Arizona. Although an unlikely desert location for condors, it is less than 100 air miles from condor habitat in the Cuyamaca Mountains of San Diego County, California, and the Sierra Juarez in Baja California Norte, Mexico. Samuel Rhoads claimed to have seen one condor in the Sierra Cocopah, in Baja California Norte not far south of Fort Yuma, in 1905 [Stone, W. 1905. On a collection of birds and mammals from the Colorado Delta, Lower California. Proceedings of the Academy of Natural Sciences of Philadelphia 57:676-690]. Interestingly, the Sierra Cocopah was the location of a much-repeated story of a “condor” observed by Edgar A. Mearns’ International Boundary Commission surveyors in 1895 [For example: Anonymous. 1895. Some rare western birds. Interesting discoveries of Dr. Mearns of the United States Army. New York Times 26 May 1895]. The bird in question was fighting a rattlesnake: “The big bird had seized the snake behind the head, and was struggling upward with its writhing, deadly burden. The snake's captor appeared aware that its victim was dangerous. The burden was heavy, as the reptile was nearly five feet long. The great pinions of the vulture waved rapidly as it slowly ascended from the mountain mesa. Although large in size, these vultures are not as strong as they appear to be. Up and up and up went the bird and the rattlesnake. The grip of the bird on the snake's body was not of the best. The snake seemed to be squirming from its captors talons at least sufficiently to enable it to strike at the great bird. The triangular head of the snake was seen to recoil and dart at the mass of feathers. It did this once or twice, and then, with a shriek, the vulture dropped its prey. The bird was then probably 500 feet or so above the observers. The astonished men below were then treated to a spectacle seldom seen anywhere. Few birds but the vulture could accomplish such a feat. The instant the snake escaped from the bird's clutches it dropped earthward like a shot. And like a shot the bird dropped after it, catching the astonished snake in midair ere it touched the ground, with a grip that caused death. At any rate the snake ceased to wriggle and the vulture soared away to a mountain peak to devour its hard-earned meal.”
The Mearns story proves that presumably “reliable sources” can be wrong. On the other hand, the Fort Yuma and Cocopah records considered together may lend some support to there being condors along the lower Colorado River.
(B) “A large Vulture seen at Cave Creek [Chiricahua Mountains, far southeastern Arizona] March 7 [1881], was thought by Mr. [Frank] Stephens to be Pseudogryphus californianus” [Brewster, W. 1883. On a collection of birds lately made by F. Stephens in Arizona. Bulletin of the Nuttall Ornithological Club 8(1):21-36]. In his field notes and autobiography, the first certain mention I find of Stephens observing condors was in 1886 in California.
(C) “In March 1881, three men, Bill Johnson, Joe Henderson and Miles Noyes [at Pierce’s Ferry, northwestern Arizona, observed] a pair of Vultures… Noyes fired a shot from a model 76 Winchester and struck one breaking its wing near the body… It was described as being ‘of a dark brown color with purplish warts on the neck.’ The men had no rule, so measured it with a gun. It was over a gun length in height and more than three gun lengths in the spread of its wings.” [Brown, H. 1899. The California vulture in Arizona. Auk 16(3):272.] This second-hand report, recorded almost twenty years after the fact, is too vague to evaluate. The “purplish warts on the neck” suggest a bare head, but not a condor’s head.
(D) Jack Alwinkle, “an excellent hunter and reliable observer” who reportedly had seen condors in California, shot one at “Mt. Lemon” [Lemmon] “several years ago” before 1891 [Rhoads, S. N. 1892. The birds of southeastern Texas and southern Arizona observed during May, June and July 1891. Proceedings of the Academy of Natural Sciences of Philadelphia 44:98-126]. No description was offered other than that it was “twice as large as a buzzard.”
(E) One condor reported feeding on a dead horse, 26 March 1885, “between Ash Creek and Bumblebee, Arizona [near Payson?] [Edgar A. Mearns, manuscript cited in: Phillips, J. Marshall and G. Monson. 1964. The birds of Arizona. Tucson, Arizona: University of Arizona Press.] No other details available.
(F) One condor seen ca 1924 near Williams, Arizona [E. C. Jacot, manuscript cited in: Phillips, J. Marshall and G. Monson op. cit.] No other details.
6. Claude E. Schaeffer [Was the California condor known to the Blackfoot Indians? Journal of the Washington Academy of Science (1951), 41(6):181-191] compiled a number of stories from early Montana and Alberta about “big eagles” that occasionally visited the region. All but one of the stories described the birds as eagle-like, not vulturine. One mentioned a neck ruff and bald head, but others described features such as brown stripes or dark spots on the tail feathers, “elongated” tail, and brownish head “feathers – none of which are condor characteristics. The big birds were considered by some to be aggressive and predatory, not vulture-like, and their arrival in the region was sometimes tied to portentous events (a subsequent earthquake, and warriors dying in battle shortly after the big bird appeared). Taken individually or as a group, there is nothing in this record that suggests the sightings and stories were about condors.
7. Miller, L. H. 1912. Contributions to avian paleontology from the Pacific coast of North America. University of California Bulletin of the Department of Geology 7(5):61-115.
8. Page 13 in: Wilbur, S. R. 1978. The California condor, 1966-76: a look at its past and future. North American Fauna Number 72. Washington, D. C.: U. S. Fish and Wildlife Service.
9. Emslie 1990 op. cit.
10. “The loss of some 35 genera of North American mammals toward the end of the Pleistocene continues to be hotly debated… Although the timing of the losses is unclear, there is no reason to think that any lasted significantly after ≈10,500 14C years ago, whereas 16 of the mammals are known to have existed beyond 12,000 14C years ago. Some, however, cannot be shown to have survived the last glacial maximum, some 22,000 to 18,000 14C years ago.” [Grayson, D. K. 2008. Holocene underkill. Proceedings of the National Academy of Sciences of the U.S.A. 105(11):4077-4078.] Note: As an update to the above, Donald Grayson (personal communication, October 2011) informed me that the official figure for lost genera of North American mammals is now 36.
For a longer, more detailed review, see: Grayson, D. K. 2007. Deciphering North American Pleistocene extinctions. Journal of Anthropological Research 63(2):185-213. Grayson shows that in Europe, extinctions of various species sometimes had occurred over thousands of years, disappearing completely from some regions while remaining in others.
11. Samples of California condor bones from Arizona and New Mexico were carbon dated at around 9,600 yr B.P. [Emslie 1987, op. cit.]. If most of the megafaunal loss had occurred by 10,500 yr B.P., this suggests that condor populations in at least some areas had already survived 1,000 years on reduced food resources.
12. A few references to the presence of mammals following the megafaunal extinctions, both in and out of the known condor range:
Minor, R., and A. F. Pecor. 1977. Cultural resource overview of the Willamette National Forest, western Oregon. Anthropological Papers No. 12, University of Oregon. Eugene, Oregon. Pages 106-107, deer and elk bones in western Oregon radiocarbon dated to 7910 yrs B.P.
Wolverton, S. 2005. The effects of the hypsithermal on prehistoric foraging efficiency in Missouri. American Antiquity 70(1):91-106. White-tailed deer bones in Missouri with radiocarbon dates as early as 8678+/-74 yrs B.P.
Lyman, R. L., and S. Wolverton. 2002. The late Pleistocene-early historic game sink in the northwestern United States. Conservation Biology 16(1):73-85. “Along the Lower Snake River between its mouth and the Washington-Idaho border, ungulate remains outnumbered those of small mammals during each 2,000-year period between 10,000 and 100 B.P.”
Walker, D. N. 2000. Pleistocene and Holocene records of Antilocapra Americana: a review of the FAUNMAP data. The Plains Anthropologist 45(174):13-28. Review of all palaeontological and archaeological sites showed that pronghorn have been well distributed in North America since the Pleistocene.
Meltzer, D. J., and M. B. Collins. 1987. Prehistoric water wells on the Southern High Plains: clues to altithermal climate. Journal of Field Archaeology 14(1):9-28. “Following megafaunal extinction (ca. 10,500 b.p.), bison emerged as the largest and most abundant mammal on the High Plains [of the Texas-New Mexico border area] not to mention the primary constituent of the human diet in the early Holocene.”
Jones, T. L., J. F. Porcasi, J. W. Gaeta, and B. F. Codding. 2008. The Diablo Canyon fauna: a coarse-grained record of trans-Holocene foraging from the central California mainland coast. American Antiquity 73(2):289-316. “At Diablo Canyon, a reliable population of deer provided a primary target for hunting for nearly 10,000 years.”
Spencer, L. M., B. Van Valkenburgh, and J. M. Harris. 2003. Taphonic analysis of large mammals recovered from the Pleistocene Rancho La Brea tar seeps. Paleobiology 29(4):561-575. Ten specimens of modern pronghorn and 21 of black-tailed deer were found in Pit 91.[The bones themselves were not carbon-dated, but Pit 91 has two depositional layers, one at 45,000 to 35,000 yr B.P., and another at 26,500 to 23,000 B.P.]
Codding, B. F., J. F. Porcasi, and T. L. Jones. 2010. Explaining prehistoric variation in the abundance of large prey: a zooarchaeological analysis of deer and rabbit hunting along the Pecho Coast of central California. Journal of Anthropological Archaeology 29(1):47-61. Black-tailed deer remains were found in all 11 time periods investigated (9,000 to 500 yrs B.P.). “The overall trend throughout the Holocene (was) a general increase in the abundance of deer in the Early-Middle Holocene with relative stability through the Middle-Late Holocene.”
13. Louderback, L. A., D. K. Grayson, and M. Llobera. 2010. Middle-Holocene climates and human population densities in the Great Basin, western USA. The Holocene 21(1):366-373.
14. Grayson, D. K. 2000. Mammalian responses to Middle Holocene climatic change in the Great Basin of the western United States. Journal of Biogeography 27(1):181-182.
15. Butler, V. L., and S. K. Campbell. 2004. Resource intensification and resource depression in the Pacific Northwest of North America: a zooarchaeological review. Journal of World Prehistory 18(4):327-405.
Lyman, R. L., and S. Wolverton. 2002. The late Pleistocene-early historic game sink in the northwestern United States. Conservation Biology 16(1):73-85.
16. Benson, L., M. Kashgarian, R. Rye, S. Lund, F. Paillet, J. Smoot, C. Kester, S. Mensing, D. Meko, and S. Lindstrom. 2002. Holocene multidecadal and multicentennial droughts affecting northern California and Nevada. Quaternary Science Reviews 21(4-6):659-682.
Kennett, D. J., J. P. Kennett, J. M. Erlander, and K.G. Cannariato. 2007. Human responses to Middle Holocene climate change on California’s Channel Islands. Quaternary Science Reviews 26 (3-4):351-367.
17. Byers, D. A., C. S. Smith, and J. M. Broughton. 2005. Holocene artiodactyl population histories and large game hunting in the Wyoming Basin, USA. Journal of Archaeological Science 32(1):125-142.
18. Hasbargen, J. 1994. A Holocene paleoclimatic and environmental record from Stoneman Lake, Arizona. Quaternary Research 42(2):188-196.
Grimm, E. C., S. Lozano-Garcia, H. Behling, and V. Markgraf. 2001. Holocene vegetation and climate variability in the Americas. Pages 325-370 in: Markgraf, V. (editor), Interhemispheric climate linkages. Academic Press.
19. Holliday, V. T. 1989. Middle Holocene drought on the Southern High Plains. Quaternary Research 31(1):74-82.
Meltzer, D. J., and M. B. Collins. 1987. Prehistoric water wells on the Southern High Plains: clues to altithermal climate. Journal of Field Archaeology 14(1):9-28.
20. Hall, S. A. 1988. Environment and archaeology of the central Osage Plains. Plains Anthropologist 33(120):203-218.
21. Wolverton, S. 2005. The effects of the hypsithermal on prehistoric foraging efficiency in Missouri. American Antiquity 70(1):91-106.
22. Watts, W. A., B. C. S. Hansen, and E. C. Grimm. 1992. Camel Lake: a 40,000-yr record of vegetational and forest history from northwest Florida. Ecology 73(3):1056-1066.
23. A summary of some of the principal evidences of middle Holocene drought is given in Louderback, Grayson and Llobera 2010 op. cit., and in: K Kennett, D. J., B. J. Culleton, J. P. Kennett, J. M. Erlandson, and K. G. Cannariato. 2007. Middle Holocene climate change and human population dispersal in western North America. Pages 531-557 in: D. G. Anderson, K. A. Maasch, and D. H. Sandweiss (editors), Climate change and cultural dynamics: a global perspective on mid-Holocene transitions. Academic Press.
Lack of stalagmite growth: Polyak, V. J., and Y. Asmerom. 2001. Late Holocene climate and cultural changes in the southwestern United States. Science, new series, 294(5540):148-151.
24. Benson, L., et al., 2002, op. cit; also, Louderback, Grayson and Llobera 2010, op. cit.
25. Holliday 1989, op. cit; Meltzer and Collins 1987, op. cit.
26. Pages 97-100 in: Mabry, J. (editor). 2005. Feasibility study for the Santa Cruz Valley National Heritage Area. Tucson, Arizona: Center for Desert Archaeology.
27. Grayson 2000, op. cit.
28. Byers, Smith and Broughton 2005, op. cit.
29. Lyman and Wolverton 2002, op. cit.
30. Byers, Smith and Broughton 2005, op. cit.
31. Holliday 1989, op. cit; Meltzer and Collins 1987, op. cit.
32. Byers, Smith and Broughton 2005, op. cit.
33. Mabry 2005, op. cit.
34. Broughton, J. V. 1994. Declines in mammalian foraging efficiency during the late Holocene, San Francisco Bay, California. Journal of Anthropological Archaeology 13(4):371-401.
Broughton, J. M., and F. E. Bayham. 2003. Showing off, foraging models, and the ascendance of large-game hunting in the California middle archaic. American Antiquity 68(4):783-789.
Broughton, J. M., M. D. Cannon, and E. J. Bartelink. 2010. Evolutionary ecology, resource depression, and niche construction theory: applications to central California hunter-gatherers and Mimbres-Mogollon agriculturalists. Journal of Archaeological Method Theory 17:371-421.
35. Kennett et al., 2007, op. cit.
36. Moratto, M. J., T. F. King, and W. B. Woolfenden. 1978. Archaeology and California’s climate. Journal of California Anthropology 5(2):147-161.
37. Glassow, M. A. 1992. Archaic cultural development in California. Revista de Arqueología Americana 5:201-229.
38. Broughton, J. M., D. A. Byers, R. A. Bryson, W. Eckerle, and D. B. Madsen. 2008. Did climatic seasonality control late Quaternary artiodactyl densities in western North America? Quaternary Science Reviews 27(19-20):1916-1937.
39. Jones, T. L., J. F. Porcasi, J. W. Gaeta, and B. F. Codding. 2008. The Diablo Canyon fauna: a coarse-grained record of trans-Holocene foraging from the central California mainland coast. American Antiquity 73(2):289-316.
Codding, B. F., J. F. Porcasi, and T. L. Jones. 2010. Explaining prehistoric variation in the abundance of large prey: a zooarchaeological analysis of deer and rabbit hunting along the Pecho Coast of central California. Journal of Anthropological Archaeology 29(1):47-61.
40. Butler, V. L., and S. K. Campbell. 2004. Resource intensification and resource depression in the Pacific Northwest of North America: a zooarchaeological review. Journal of World Prehistory 18(4):327-405.
41. It has been suggested "that the restriction of the range of condors to the Pacific coast after the Pleistocene megafaunal extinction was largely controlled by the presence of a 'fall-back' food source, marine mammals" [Chamberlain, C. P., J. R. Waldbauer, K. Fox-Dobbs, S. D. Newsome, P. L. Koch, D. R. Smith, M. E. Church, K. L. Sorenson, and R. Risebrough. 2005. Pleistocene to recent dietary shifts in California condors. Proceedings of the National Academy of Sciences 102(46):16707-16711]. Condors have undoubtedly always fed on dead seals, sea lions, whales, porpoises, dolphins, and sea otters whenever they were available. Just as clearly, marine mammals were not the only food available to post-Pleistocene condors in the Far West. In any event, such food would have only been available on a regular basis to condors that lived within effective foraging distance of the coast, say less than 50 miles. Sea mammals may have been important to some condors, but they were not vital to the survival of the condor population.
42. For compiled references to early wildlife observations, see Broughton 1994 op. cit., and especially pages 95-98 in: Burcham, L. T. 1981. California range land. Center for Archaeological Research at Davis, Publication Number 7. Davis, California: University of California.
43. Broughton, J. V. 1994. Declines in mammalian foraging efficiency during the late Holocene, San Francisco Bay, California. Journal of Anthropological Archaeology 13(4):371-401.
Broughton, J. V. 1994. Late Holocene resource intensification in the Sacramento Valley, California: the vertebrate evidence. Journal of Archaeological Science 21(4):501-514.
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