California Condors in the Pacific Northwest

Chapter 4: Timing and Causes of the Condor's Range Collapse

77 Chapter 4 Timing and Causes of the Condor’s Range Collapse col•lapse (kə-lǎps') vi. [Lat. collabi, collaps-] 1. To fall inward suddenly: cave in. 2. To break down suddenly in strength or health and cease to function. Population Decline The extinction problem has little to do with the death rattle of its final actor. The curtain in the last act is but a punctuation mark—it is not interesting in itself. What biologists want to know about is the process of decline in range and numbers. (Soulé 1983, 112) The California Condor has sometimes been portrayed as a Pleistocene relict or a senescent species that has been in a state of population decline for thousands of years (e.g., L. Miller 1942; Pitelka 1981). Despite a significant range contraction and the concurrent extinction of several large avian scavengers (including several condor species) at the end of the Pleistocene, the ethnographic, paleontological, and early observational record of California Condor populations along the West Coast of North America suggests that they were not rare at the time of Euro-American contact. While the exact population size of condors at Euro-American contact is unknown, a number of early explorers and settlers considered them common or numerous, especially in California. Bryant (1891, 52) noted that [the California Vulture] is better known in California than elsewhere, where, previous to the civilization of that country, it was very abundant , approaching in large flocks the near vicinity of the Missions, where it contended with the coyote for the offal and carcasses of cattle slaughtered for their hides and tallow. 78 CHAPTER 4 In the fall of 1826, David Douglas observed condors in “great numbers” along the lower Columbia River (1914). Townsend said he would not consider them numerous along the Columbia in the 1830s (Audubon 1840) but also stated, “during the spring, I constantly saw the [California] Vultures at all points where the Salmon was cast upon the shores” (J. Townsend 1848, 266). Clyman (1926) described them as being in “greate abundance” in Napa Valley, California, in 1845. John Strong Newberry (1857, 73) saw them “every day” on his travels in the Sacramento Valley in 1855. Joseph Lamson observed “upwards of fifty” condors flying over the mountains east of San Francisco in the 1850s (Monteagle 1976). Snyder and Snyder (2005) calculated that if the 5 percent annual population decline estimated for 1950 to 1968 was extrapolated backward in time, there could have been one thousand condors alive at the beginning of the 1900s, although they recognize the possibility of differential mortality rates through time and do not consider this to be a reliable estimate of the population at the turn of the century. While we may never know the true historical population size, the abundance of ungulates and marine mammals prior to Euro-American expansion into the region would likely have once supported several thousand condors in the western United States. A. Taylor (1859) reported that in July 1859, his friend had observed as many as three hundred condors feeding on dead sea lions in Monterey, California, but Taylor’s facts were sometimes inaccurate and the identity and reliability of his source are unknown. Nevertheless, it is not beyond the realm of possibility, as flocks of several hundred vultures are not uncommon when food is abundant (e.g., Prather et al. 1976; Mundy et al. 1992; Bildstein et al. 2009). Andean Condors—which also have high wing loading, are long lived, have slow rates of maturation, and are restricted to more mountainous regions of South America—were estimated to number roughly 6,200 individuals in 2000 (Díaz et al. 2000). Using mark-recapture techniques, Lambertucci (2010) estimated that there were 260–332 Andean Condors in just one area of northwestern Patagonia measuring 6,300 km2 (smaller than the Olympic Peninsula). This estimate may represent a reduced number of birds from the historical population size due to ongoing threats such as persecution, poisoning, and electrocution (Lambertucci 2010). Given the similarities in body size, diet, reproductive output, and mobility between California and Andean Condors, it seems plausible that TIMING AND CAUSES OF THE CONDOR’S RANGE COLLAPSE 79 California Condors, which once occupied an area from Baja California to British Columbia, may also have historically numbered several thousand individuals rangewide. However, without additional information, this remains a tentative, untested hypothesis. Analysis of genetic data in museum specimens may provide one avenue...