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At least 37 records · Page 2Linked to original sources
USGS2011

Big Spring spinedace and associated fish populations and habitat conditions in Condor Canyon, Meadow Valley Wash, Nevada

Executive Summary: This project was designed to document habitat conditions and populations of native and non-native fish within the 8-kilometer Condor Canyon section of Meadow Valley Wash, Nevada, with an emphasis on Big Spring spinedace (Lepidomeda mollispinis pratensis). Other native fish present were speckled dace (Rhinichthys osculus) and desert sucker (Catostomus clarki). Big Spring spinedace were known to exist only within this drainage and were known to have been extirpated from a portion of their former habitat located downstream of Condor Canyon. Because of this extirpation and the limited distribution of Big Spring spinedace, the U.S. Fish and Wildlife Service listed this species as threatened under the Endangered Species Act in 1985. Prior to our effort, little was known about Big Spring spinedace populations or life histories and habitat associations. In 2008, personnel from the U.S. Geological Survey's Columbia River Research Laboratory began surveys of Meadow Valley Wash in Condor Canyon. Habitat surveys characterized numerous variables within 13 reaches, thermologgers were deployed at 9 locations to record water temperatures, and fish populations were surveyed at 22 individual sites. Additionally, fish were tagged with Passive Integrated Transponder (PIT) tags, which allowed movement and growth information to be collected on individual fish. The movements of tagged fish were monitored with a combination of recapture events and stationary in-stream antennas, which detected tagged fish. Meadow Valley Wash within Condor Canyon was divided by a 12-meter (m) waterfall known as Delmue Falls. About 6,100 m of stream were surveyed downstream of the falls and about 2,200 m of stream were surveyed upstream of the falls. Although about three-quarters of the surveyed stream length was downstream of Delmue Falls, the highest densities and abundance of native fish were upstream of the falls. Big Spring spinedace and desert sucker populations were highest near the upper end of Condor Canyon, where a tributary known as Kill Wash, and several springs, contribute flow and moderate high and low water temperature. Kill Wash and the area around its confluence with Meadow Valley Wash appeared important for spawning of all three native species. Detections of PIT-tagged fish indicated that there were substantial movements to this area during the spring. Our surveys included about 700 m of Meadow Valley Wash upstream of Kill Wash. A small falls about 2 m high was about 560 m upstream of Kill Wash. This falls is likely a barrier to upstream fish movement at most flows. Populations of all three native species were found upstream of this small falls. Age-0 fish of all three species were present, indicating successful spawning. The maximum upstream extent of native fish within Meadow Valley Wash was not determined. Our surveys included about 700 m of Meadow Valley Wash upstream of Kill Wash. A small falls about 2 m high was about 560 m upstream of Kill Wash. This falls is likely a barrier to upstream fish movement at most flows. Populations of all three native species were found upstream of this small falls. Age-0 fish of all three species were present, indicating successful spawning. The maximum upstream extent of native fish within Meadow Valley Wash was not determined. A population of non-native rainbow trout (Oncorhynchus mykiss) was found within the 2,000 m of stream immediately downstream of Delmue Falls. Non-native crayfish were very common both upstream and downstream of Delmue Falls. We were not able to quantify crayfish populations, but they compose a significant portion of the biomass of aquatic species in Condor Canyon. There were some distinctive habitat features that may have favored native fish upstream of Delmue Falls. Upstream of the falls, water temperatures were moderated by inputs from springs, turbidity was lower, pool habitat was more prevalent, substrate heterogeneity was higher, and there was less fine sediment than

Open-File Report↗
USGS1978

The California condor, 1966-1976: A Look at its Past and Future

The California condor (Gymnogyps californianus) was studied on about 900 field days between 1966 and 1976. In addition, some 1,000 items of literature, specimen records from 56 museums, and 3,500 reports of condor sitings by cooperators were analyzed. Distribution does not appear to have changed significantly since the 1930's, although there are some areas within the. species' range that have become unusable. Two subpopulations of condors exist, one occupying the Coast Range Mountains, and the other found in the Transverse Ranges, Tehachapi Mountains, and Sierra Nevadas. There are well-defined seasonal movements within each subpopulation area. The surviving, wild population was estimated to be 45 condors in 1976, a decline of about 20% since 1965 and probably over 50% since 1940. No reliable population estimates are available before the 1940's, but it appears that a major decline occurred between 1880 and 1920. Shooting and specimen collecting were the primary causes of the early decline, and shooting continued as a major problem into the 1960's. Recent declines are a result of inadequate production; annual surveys indicate that only 16 young have been produced since 1968. Causes of low production are unknown but inadequate food supply, environmental contaminants, and disturbance from air traffic and petroleum extraction are implicated. A recovery plan for the condor is in operation; steps have been taken to supplement food supplies, preserve nesting and roosting habitat, and protect surviving birds from man-caused mortality or disturbance. The condor's prospects of recovery in its natural habitat seem bleak; a captive propagation program is proposed to supplement wild production.

North American Fauna↗
USGS1983

Environmental contaminants in tissues, foods, and feces of California condors

Two wild California Condors contained moderate to high levels of DDE in their tissues. The levels found could be high enough to cause reproductive problems in adult condors, if the assumption is made that condors are as susceptible to DDE as many other species of birds of prey. Other organochlorines occurred at low levels and probably were not high enough to cause deleterious effects. Metal residues in tissues of one bird were generally low except for copper in liver and lead in bone. Normal background levels of these metals in cathartids are unknown, making interpretation of the results difficult. Organochlorine residues in biopsy samples from a captive condor were low and probably would not have an adverse effect on reproduction if the bird were used for captive breeding. Organochlorines were not detected in food items used in the supplemental feeding program, and mercury and lead residues in these items were generally low. Information is needed on current contaminant levels in natural condor prey throughout the condor range.

Book chapter↗
USGS1973

The California condor in the Pacific Northwest

The California Condor ( Gymnogyps californianus ), once found along the Pacific Coast from Baja California to British Columbia, had become very rare north of California by 1850. Koford (1953), summarizing information available on the species in the Pacific Northwest, tentatively concluded that birds seen in that area were wanderers from California, perhaps forced north in some years by food shortages. As support for his theory he noted that there were no records of fossil condors in this northern region, known occurrences there were all in winter, and only a few individuals seemed to be present at any one time. Recently information has come to light that suggests the Pacific Northwest condors were permanent residents with a long history there. An Indian midden on the Columbia River near The Dalles, Oregon, has yielded a considerable number of California Condor bones, dating back thousands of years (Miller, 1957). A more recent, but still precaucasian condor bone was found in another midden in southwestern Oregon (Miller, 1942). These finds indicate the condors are not recent invaders from California.

The Auk↗
USGS2023

Policy comparison of lead hunting ammunition bans and voluntary nonlead programs for California condors

The endangered California condor ( Gymnogyps californianus ) is negatively affected by lead poisoning from spent lead-based hunting ammunition. Because lead poisoning is the primary mortality factor affecting condors, the California Fish and Game Commission banned lead hunting ammunition during 2008 in the southern California condor range followed by a statewide ban implemented in 2019. In contrast, the Arizona Game and Fish Department instituted an outreach and awareness program encouraging voluntary use of nonlead hunting ammunition in the northern portion of the state during 2005 and a similar program was launched in Utah during 2012. The juxtaposition of policy tools provided a unique opportunity to evaluate the intended efforts to mitigate lead exposure in condors and their respective positive and negative effects. Herein we reflect upon the effectiveness of lead policy actions in the 3-state region on the basis of condor blood-lead levels, population status, and hunter awareness of the issue and use of nonlead hunting ammunition.

California↗
USGS2015

Activity-specific ecological niche models for planning reintroductions of California condors (Gymnogyps californianus)

Ecological niche models can be a useful tool to identify candidate reintroduction sites for endangered species but have been infrequently used for this purpose. In this paper, we (1) develop activity-specific ecological niche models (nesting, roosting, and feeding) for the critically endangered California condor ( Gymnogyps californianus ) to aid in reintroduction planning in California, Oregon, and Washington, USA, (2) test the accuracy of these models using empirical data withheld from model development, and (3) integrate model results with information on condor movement ecology and biology to produce predictive maps of reintroduction site suitability. Our approach, which disentangles niche models into activity-specific components, has applications for other species where it is routinely assumed (often incorrectly) that individuals fulfill all requirements for life within a single environmental space. Ecological niche models conformed to our understanding of California condor ecology, had good predictive performance when tested with data withheld from model development, and aided in the identification of several candidate reintroduction areas outside of the current distribution of the species. Our results suggest there are large unoccupied regions of the California condor’s historical range that have retained ecological features similar to currently occupied habitats, and thus could be considered for future reintroduction efforts. Combining our activity-specific ENMs with ground reconnaissance and information on other threat factors that could not be directly incorporated into empirical ENMs will ultimately improve our ability to select successful reintroduction sites for the California condor.

California, Oregon, Washington↗
USGS2010

Status of the California condor (Gymnogyps californianus) and efforts to achieve its recovery

The California Condor ( Gymnogyps californianus ; hereafter "condor"; Fig. 1) has long been symbolic of avian conservation in the United States. Its large size, inquisitiveness, and association with remote places make it highly charismatic, and its decline to the brink of extinction aroused a continuing public interest in its plight. By 1982, only 22 individuals remained of this species whose range once encompassed much of North America. The last wild bird was trapped and brought into captivity in 1987, which rendered the species extinct in the wild (Snyder and Snyder 1989). In the 1980s, some questioned whether viable populations could ever again exist in the natural environment, and whether limited conservation funds should be expended on what they viewed as a hopeless cause (Pitelka 1981). Nevertheless, since that low point, a captive-breeding and release program has increased the total population by an order of magnitude, and condors fly free again in California, Arizona, Utah, and Baja California, Mexico (Fig. 2). At this writing (summer 2009), more than 350 condors exist, 180 of which are in the wild (J. Grantham pers. comm.). The free-living birds face severe challenges, however, and receive constant human assistance. The intensive management applied to the free-living populations, as well as the ongoing monitoring and captive-breeding programs, are tremendously expensive and become more so as the population grows. Thus, the program has reached a crossroads, caught between the financial and logistical pressures required to maintain an increasing number of condors in the wild and the environmental problems that preclude establishment of naturally sustainable, free-ranging populations.

The Auk↗
USGS2016

Ancient DNA reveals substantial genetic diversity in the California Condor ( Gymnogyps californianus ) prior to a population bottleneck

Critically endangered species that have undergone severe population bottlenecks often have little remaining genetic variation, making it difficult to reconstruct population histories to apply in reintroduction and recovery strategies. By using ancient DNA techniques, it is possible to combine genetic evidence from the historical population with contemporary samples to provide a more complete picture of a species' genetic variation across its historical range and through time. Applying this approach, we examined changes in the mitochondrial DNA (mtDNA) control region (526 base pairs) of the endangered California Condor ( Gymnogyps californianus ). Results showed a >80% reduction in unique haplotypes over the past 2 centuries. We found no spatial sorting of haplotypes in the historical population; the periphery of the range contained haplotypes that were common throughout the historical range. Direct examination of mtDNA from California Condor museum specimens provided a new window into historical population connectivity and genetic diversity showing: (1) a substantial loss of haplotypes, which is consistent with the hypothesis that condors were relatively abundant in the nineteenth century, but declined rapidly as a result of human-caused mortality; and (2) no evidence of historical population segregation, meaning that the available genetic data offer no cause to avoid releasing condors in unoccupied portions of their historical range.

The Condor↗
USGS2018

Flight response to spatial and temporal correlates informs risk from wind turbines to the California Condor

Wind power is a fast-growing energy resource, but wind turbines can kill volant wildlife, and the flight behavior of obligate soaring birds can place them at risk of collision with these structures. We analyzed altitudinal data from GPS telemetry of critically endangered California Condors ( Gymnogyps californianus ) to assess the circumstances under which their flight behavior may place them at risk from collision with wind turbines. Condor flight behavior was strongly influenced by topography and land cover, and birds flew at lower altitudes and closer to the rotor-swept zone of wind turbines when over ridgelines and steep slopes and over forested and grassland cover types. Condor flight behavior was temporally predictable, and birds flew lower and closer to the rotor-swept zone during early morning and evening hours and during the winter months, when thermal updrafts were weakest. Although condors only occasionally flew at altitudes that placed them in the rotor-swept zone of turbines, they regularly flew near or within wind resource areas preferred by energy developers. Practitioners aiming to mitigate collision risk to this and other soaring bird species of conservation concern can consider the manner in which flight behavior varies temporally and in response to areas of high topographic relief and proximity to nocturnal roosting sites. By contrast, collision risk to large soaring birds from turbines should be relatively lower over flatter and less rugged areas and in habitat used during daytime soaring.

California↗
USGS1985

Photographic censusing of the 1982-1983 California condor population

An intensive census of the remnant California condor (G. californianus) population based on photographic identification of individuals revealed a minimum of 21 and a probable maximum of .apprx. 24 condors in late summer 1982. Corresponding figures for 1983 were 19 and 22 condors. Two condors are known to have died in the wild since the 1983 census. These data, when compared with earlier population estimates, indicate a continuing catastrophic decline of the species. In the absence of intensive conservation measures, extinction of the wild population can be expected within 10-20 yr.

Condor↗
USGS1987

Primary molt of California condors

Primary molt of the California Condor (Gymnogyps californianus) was studied intensively from 1982 through 1985, using repeated flight photographs of the remaining individuals in the wild population as a basis for most analyses. On the average, wild condors replaced 4.4 of the 8 emarginated primaries on each wing each year. The sepcific primaries molted were generally the ones missed in the previous year and were usually well-distributed among the eight possibilities, with a tendency for low-numbered primaries to molt earlier than high-numbered primaries. Within individuals, molt of one wing was commonly very different from that of the other wing. Primarily molt of captive juveniles was similar to that of wild juveniles. The interval from loss to full replacement of individual primary feathers was normally 3 1/2 to 4 months, with the primaries closest to the leading edge of the wing growing most slowly. Most primarities were shed between 1 February and 1 September. Primaries lost in late fall and early winter were not replaced until the following summer, indicating interrupted molt over the winter. In general, primary molt of the condor differs from that of smaller cathartids in being highly seasonal, highly variable in sequence, highly asymmetric between wings, and in following a roughly 2-year cycle. Molt of the condor shows many similarities to that of the White Stork (Ciconia ciconia) and to that of large accipitrid vultures.

Condor↗
USGS1992

Range use and movements of California condors

Between 1982 and 1987, photographic and telemetric tracking of California Condors (Gymnogyps californianus) yielded information on use of the last known range of the species by 23 individual birds. Except for yearlings, most and possibly all individuals in the population used all major foraging zones. Use of the foraging zones was not uniform among individuals, however. Breeding pairs tended to forage most frequently in zones close to their nests (usually within 70 km, occasionally as far away as 180 km). Immatures (at least older immatures), unpaired birds, and paired birds that were not breeding foraged more widely. Male and female adults used the foraging range in a similar manner. Although most portions of the foraging range received some condor use throughout the year, use varied seasonally in accord with recent and historical patterns of food availability. Nesting areas were separated from foraging zones and were visited much less freely than foraging zones. Paired birds tended strongly to visit only their own and immediately adjacent nesting areas. Their nesting areas remained stable over the years. Unpaired adults and immatures ranged more widely among nesting areas. Condors were sometimes documented flying more than 200 km and traversing the entire range of the species during a day. Birds were variably social in movements. Pair members tended to stay together during long-distance travels. Immatures and unpaired birds sometimes traveled with other condors but often moved singly. In years when the population still included many breeders, the largest observed aggregations included one-half to two-thirds of the total population. The comparative strengths and weaknesses of photographic and telemetric methods are described for tracking and other research endeavors.

Condor↗
USGS2014

An analysis of monthly home range size in the critically endangered California Condor Gymnogyps californianus

Condors and vultures comprise the only group of terrestrial vertebrates in the world that are obligate scavengers, and these species move widely to locate ephemeral, unpredictable, and patchily-distributed food resources. In this study, we used high-resolution GPS location data to quantify monthly home range size of the critically endangered California Condor Gymnogyps californianus throughout the annual cycle in California. We assessed whether individual-level characteristics (age, sex and breeding status) and factors related to endangered species recovery program efforts (rearing method, release site) were linked to variation in monthly home range size. We found that monthly home range size varied across the annual cycle, with the largest monthly home ranges observed during late summer and early fall (July–October), a pattern that may be linked to seasonal changes in thermals that facilitate movement. Monthly home ranges of adults were significantly larger than those of immatures, but males and females used monthly home ranges of similar size throughout the year and breeding adults did not differ from non-breeding adults in their average monthly home range size. Individuals from each of three release sites differed significantly in the size of their monthly home ranges, and no differences in monthly home range size were detected between condors reared under captive conditions relative to those reared in the wild. Our study provides an important foundation for understanding the movement ecology of the California Condor and it highlights the importance of seasonal variation in space use for effective conservation planning for this critically endangered species.

Bird Conservation International↗
USGS2010

Feather lead concentrations and 207Pb/206Pb ratios reveal lead exposure history of California Condors (Gymnogyps californianus)

Lead poisoning is a primary factor impeding the survival and recovery of the critically endangered California Condor ( Gymnogyps californianus ). However, the frequency and magnitude of lead exposure in condors is not well-known in part because most blood lead monitoring occurs biannually, and biannual blood samples capture only ∼10% of a bird’s annual exposure history. We investigated the use of growing feathers from free-flying condors in California to establish a bird’s lead exposure history. We show that lead concentration and stable lead isotopic composition analyses of sequential feather sections and concurrently collected blood samples provided a comprehensive history of lead exposure over the 2−4 month period of feather growth. Feather analyses identified exposure events not evident from blood monitoring efforts, and by fitting an empirically derived timeline to actively growing feathers, we were able to estimate the time frame for specific lead exposure events. Our results demonstrate the utility of using sequentially sampled feathers to reconstruct lead exposure history. Since exposure risk in individuals is one determinant of population health, our findings should increase the understanding of population-level effects from lead poisoning in condors; this information may also be helpful for other avian species potentially impacted by lead poisoning.

California↗
USGS2026

The rising threat of lead: Trends in fatalities of California condors

Endangered species face threats that change over time, and understanding variation in the importance of threats is valuable for guiding species recovery. The reintroduced population of critically endangered California condors has faced a number of threats over the three decades since the species was first released back to the wild. We modeled interannual and interseasonal trends in the leading causes of death for wild condors. Our analysis showed strong evidence ( P = 0.971) that the estimated annual probability of death from lead toxicosis has increased since reintroduction started. This increase was most pronounced in the central California subpopulation. Adults were disproportionately affected by lead toxicosis, a trend that may be explained by increased exposure associated with age-related changes in foraging behavior that lead to decreased reliance on clean proffered food sources. Population-level mortality from trauma showed a temporary increase in 2012, and fire-related mortality was higher during the summer months. Pattens also varied across subpopulations, with the southern California subpopulation of condors showing distinct temporal peaks in deaths from trauma (in 2012) and predation (in 2010). Our analysis suggests that threats to condors have not been static over space and time. Managers can therefore use this information to adaptively manage and target mitigation efforts when and where they are the most effective.

California↗
USGS2017

Meteorological and environmental variables affect flight behaviour and decision-making of an obligate soaring bird, the California Condor Gymnogyps californianus

The movements of animals are limited by evolutionary constraints and ecological processes and are strongly influenced by the medium through which they travel. For flying animals, variation in atmospheric conditions is critically influential in movement. Obligate soaring birds depend on external sources of updraft more than do other flying species, as without that updraft they are unable to sustain flight for extended periods. These species are therefore good models for understanding how the environment can influence decisions about movement. We used meteorological and topographic variables to understand the environmental influences on the decision to engage in flight by obligate soaring and critically endangered California Condors Gymnogyps californianus . Condors were more likely to fly, soared at higher altitudes and flew over smoother terrain when weather conditions promoted either thermal or orographic updrafts, for example when turbulence and solar radiation were higher and when winds from the east and north were stronger. However, increased atmospheric stability, which is inconsistent with thermal development but may be associated with orographic updrafts, was correlated with a somewhat higher probability of being in flight at lower altitudes and over rougher terrain. The close and previously undescribed linkages between Condor flight and conditions that support development of thermal and orographic updrafts provide important insight into the behaviour of obligate soaring birds and into the environmental parameters that may define the currently expanding distribution of Condors within and outside the state of California.

California↗
USGS1989

Turkey vulture and California condor

Populations of turkey vultures in the western states appear stable, with no evidence of recent significant changes in distribution. Turkey vultures occupy a variety of habitats, nest in diverse situations and utilize a wide variety of carrion. Consequently, no particular limiting factor is likely to have a major effect on the total population. California condor numbers, in contrast, have continued to decline. With the capture of the last wild bird in 1987, the species has been extirpated from the wild. Reestablishment will depend on production and introduction of captive-reared birds, hopefully within the next 10 years. In the 18th century, condors inhabited areas along the Pacific coast from British Columbia to Baja California. Since 1950, the range has been restricted to a six county area adjacent to the southern San Joaquin Valley of California. Within this area, there appears to be no shortage of suitable nest sites; all recently used nest sites are within federally-controlled lands. Suitable foraging grounds have continued to diminish and are now largely limited to private rangelands and some Bureau of Land Management rangelands within the foothills of the San Joaquin Valley. Only these areas continue to supply the large mammal carcasses that the California condor needs for survival. The habitat of the condor is subject to a variety of land use practices and development pressures. Excessive mortality, coupled with low reproductive potential, continues to threaten the recovery of the species. Development of management practices to reduce mortality, particularly those that are contaminant-related, and of a preserve design to insure adequate habitat for the reintroduced population are still necessary for eventual recovery of the species.

Book chapter↗
USGS1985

Effect of ACTH on plasma corticosterone and cortisol in eagles and condors

The effect of ACTH on plasma corticosterone and cortisol was determined in 12 eagles (Haliaeetus leucocephalus) and in 6 Andean condors (Vultur gryphus). In all raptors, the concentration of plasma corticosterone was substantially greater than that of cortisol. After ACTH administration, the eagles had a marked increase (P less than 0.001) in plasma corticosterone concentrations, but not in plasma cortisol. Administration of saline solution did not induce increased plasma corticosterone concentrations in the eagles. The condors had a smaller increase (P less than 0.002) in plasma corticosterone concentrations after ACTH administration, as compared with that of the eagles. However, administration of saline solution in 2 condors resulted in an increase in corticosterone similar to the increase after ACTH administration. In the condor, a stress-related release of endogenous ACTH may have an effect similar to that induced by exogenously administered ACTH. Plasma cortisol concentrations did not increase significantly after administration of ACTH or saline solution in either raptor species.

Journal of the American Veterinary Medical Associa↗