Effects of Lead Exposure,Flock Behavior,and Management Actions on the Survival of California Condors (<Emphasis Type="Italic">Gymnogyps californianus</Emphasis>)

Translocation is an increasingly important tool for managing endangered species, but factors influencing the survival of translocated individuals are not well understood. Here we examine intrinsic and extrinsic drivers of survival for critically endangered California condors (Gymnogyps californianus) whose wild population recovery is reliant upon releases of captively bred stock. We used known fate models and information-theoretic methods to compare the ability of hypothesized covariates, most of which serve as proxies for lead exposure risk, to predict survival rates of condors in California. Our best supported model included the following predictors of survival: age of the recovery program, precipitation, proportion of days observed feeding on proffered carcasses, maximum blood lead concentration over the preceding 18 months, and time since release. We found that as flocks have increased in size and age, condors are increasingly likely to range more widely and less likely to be observed feeding on proffered food, and these “wilder” behaviors were associated with lower survival. After accounting for these behaviors, we found a positive survival trend, which we attribute to ongoing improvements in management. Our findings illustrate that the survival of translocated animals, such as highly social California condors, is influenced by behaviors that change through time.     

Lead in Ammunition: A Persistent Threat to Health and Conservation

Many scavenging bird populations have experienced abrupt declines across the globe, and intensive recovery activities have been necessary to sustain several species, including the critically endangered California condor (Gymnogyps californianus). Exposure to lead from lead-based ammunition is widespread in condors and lead toxicosis presents an immediate threat to condor recovery, accounting for the highest proportion of adult mortality. Lead contamination of carcasses across the landscape remains a serious threat to the health and sustainability of scavenging birds, and here we summarize recent evidence for exposure to lead-based ammunition and health implications across many species. California condors and other scavenging species are sensitive indicators of the occurrence of lead contaminated carcasses in the environment. Transdisciplinary science-based approaches have been critical to managing lead exposure in California condors and paving the way for use of non-lead ammunition in California. Similar transdisciplinary approaches are now needed to translate the science informing on this issue and establish education and outreach efforts that focus on concerns brought forth by key stakeholders.     

Lead poisoning in captive Andean condors (Vultur gryphus)

Elevated lead in the tissues of raptors, especially those that scavenge, is a common occurrence, and lead poisoning appears to be a significant problem in the ongoing recovery effort for California condors (Gymnogyps californianus). Elevated blood lead levels have been found in released birds, and a number of birds have died of lead poisoning. In earlier work, we dosed turkey vultures (Cathartes aura) with lead shot but found them to be a poor model for lead poisoning. In this study, we dosed four Andean condors (Vultur gryphus) with lead shot and found them to be quite sensitive, as two of the birds died and the other two exhibit signs of lead poisoning within 50 days. All lead-responsive parameters were affected, and regurgitation of dosed shot occurred only once. The response of the Andean condors appeared to mimic California condors, suggesting that once exposed to lead, the possibility of survival is poor. This is consistent with observations in the wild, where otherwise healthy birds exposed to metallic lead quickly succumb. At the very least, the release program has to maintain constant surveillance and an active lead monitoring program.     

Exposure of California Condors to Lead From Spent Ammunition

ABSTRACT The scientific evidence that California condors (Gymnogyps californianus) are frequently sickened and killed by lead poisoning from spent ammunition supports the conclusion that current levels of lead exposure are too high to allow reintroduced condors to develop self-sustaining populations in the wild in Arizona and, by inference, in California. The evidence for lead poisoning and its source comes from the following sorts of data: 1) 18 clinical necropsies revealing high levels of lead in body tissues and (or) presence of lead shotgun pellets and bullet fragments in digestive tracts; 2) moribund condors showing crop paralysis and impending starvation with toxic levels of lead in their blood; 3) widespread lead exposure among free-flying condors, many with clinically exposed or acute levels; 4) temporal and spatial correlations between big game hunting seasons and elevated lead levels in condors; and 5) lead isotope ratios from exposed condors showing close similarity to isotope ratios of ammunition lead but isotope ratios in less exposed condors being similar to environmental background sources, which are different from ammunition lead. Simple population models reveal harmful demographic impacts of unnatural mortality from lead on population trajectories of reintroduced condors. Recent innovations in the manufacture of nonlead shotgun pellets and bullets with superior ballistics now provide for a simple solution to the problem of lead ingestion by condors, many other species of wildlife, and human beings: substitute nontoxic forms of ammunition for traditional lead-based ammunition. The substitution of nontoxic ammunition would be highly efficacious for hunting, economically feasible, and the right thing to do.     

Seroepidemiologic Survey of Potential Pathogens in Obligate and Facultative Scavenging Avian Species in California

Throughout the world, populations of scavenger birds are declining rapidly with some populations already on the brink of extinction. Much of the current research into the factors contributing to these declines has focused on exposure to drug residues, lead, and other toxins. Despite increased monitoring of these declining populations, little is known about infectious diseases affecting scavenger bird species. To assess potential infectious disease risks to both obligate and facultative scavenger bird species, we performed a serosurvey for eleven potential pathogens in three species of scavenging birds in California: the California condor (Gymnogyps californianus), turkey vulture (Cathartes aura) and golden eagle (Aquila chrysaetos). California condors were seropositive for avian adenovirus, infectious bronchitis virus, Mycoplasma gallisepticum, avian paramyxovirus-2, West Nile virus (WNV) and Toxoplasma gondii. Golden eagles were seropositive for avian adenovirus, Chlamydophila psittaci and Toxoplasma gondii, and turkey vultures were seropositive for avian adenovirus, Chlamydophila psittaci, avian paramyxovirus-1, Toxoplasma gondii and WNV. Risk factor analyses indicated that rearing site and original release location were significantly associated with a positive serologic titer to WNV among free-flying condors. This study provides preliminary baseline data on infectious disease exposure in these populations for aiding in early disease detection and provides potentially critical information for conservation of the endangered California condor as it continues to expand its range and encounter new infectious disease threats.     

The effects of rearing method on social behaviors of mentored,captive‐reared juvenile California condors

Puppet‐reared and parent‐reared captive‐bred California condor (Gymnogyps californianus) juveniles were studied before their release into the wild. Behavioral data were collected during social interactions within two cohorts of juveniles (N = 11) and their adult mentors (N = 5). The purposes of this study were to (1) document the social behaviors of mentored juvenile California condors, and (2) compare social behaviors for two different rearing methods (puppet‐reared versus parent‐reared) during two phases of the mentoring process (San Diego Wild Animal Park versus release sites). Of the 17 behaviors examined by 2 × 2 analyses of variance (ANOVAs), two significant interactions between the rearing method and mentoring phase were found: pulls feathers and feeds alone. For both behaviors, parent‐reared condors engaged in these activities more often at the zoo and less often at the release pens than did the puppet‐reared condors. The main effect of rearing was also significant for two behaviors: near others, and receives contact aggression from other. Parent‐reared birds were more likely to be near another bird and receive contact aggression, regardless of mentoring phase, than puppet‐reared birds. The effect size for 16 of the 17 behaviors was greater for the rearing method than for mentoring phase. Rearing method differences may persist long‐term, as parent‐reared adult mentors were significantly more aggressive than puppet‐reared adult mentors. Dominance relations were examined for both cohorts, with the first cohort exhibiting a strong linear relationship (h′ = 0.86, P = 0.018), whereas the second cohort exhibited a moderate but non‐significant linear hierarchy (h′ = 0.63, P = 0.21). The rearing method had no effect on dominance among the juveniles, but adults were probably dominant to juveniles (P = 0.052; the difference was nearly significant). Although social behaviors between the two rearing groups were similar in most respects, this study is the first to document measurable differences between puppet‐ and parent‐reared captive‐bred California condor juveniles. Zoo Biol 27:1–18, 2008. © 2007 Wiley‐Liss, Inc.     

Nuisance Ecology: Do Scavenging Condors Exact Foraging Costs on Pumas in Patagonia?

Predation risk describes the energetic cost an animal suffers when making a trade off between maximizing energy intake and minimizing threats to its survival. We tested whether Andean condors (Vultur gryphus) influenced the foraging behaviors of a top predator in Patagonia, the puma (Puma concolor), in ways comparable to direct risks of predation for prey to address three questions: 1) Do condors exact a foraging cost on pumas?; 2) If so, do pumas exhibit behaviors indicative of these risks?; and 3) Do pumas display predictable behaviors associated with prey species foraging in risky environments? Using GPS location data, we located 433 kill sites of 9 pumas and quantified their kill rates. Based upon time pumas spent at a carcass, we quantified handling time. Pumas abandoned >10% of edible meat at 133 of 266 large carcasses after a single night, and did so most often in open grasslands where their carcasses were easily detected by condors. Our data suggested that condors exacted foraging costs on pumas by significantly decreasing puma handling times at carcasses, and that pumas increased their kill rates by 50% relative to those reported for North America to compensate for these losses. Finally, we determined that the relative risks of detection and associated harassment by condors, rather than prey densities, explained puma “giving up times” (GUTs) across structurally variable risk classes in the study area, and that, like many prey species, pumas disproportionately hunted in high-risk, high-resource reward areas.     

Breeding condors in captivity for release into the wild

Recognizing the decline of the South American Condor in some parts of its range and the highly endangered status of the California condor, the New York Zoological Society developed a captive-breeding program for South American condors. This program was designed to produce techniques applicable to hand-rearing of either species of condor. Once condors were successfully reared in captivity, it became imperative to develop techniques to ensure that captive-reared condor chicks could be released into the wild, could survive there, and could interact naturally with other wild condors. Captive-bred hand-reared condor chicks were taken to Northwestern Peru and successfully released into the wild.     

Effects of age at pairing on reproduction in captive California condors (Gymnogyps californianus)

The lack of breeding behavior seen in some pairs of adult California condors, Gymnogyps californianus, is of great concern for the captive breeding program. One possible cause for absent or delayed breeding in what are otherwise seemingly compatible animals is inbreeding avoidance behavior. To examine this possibility, housing and reproduction records were examined for all adult California condors. The influence of housing on reproduction of birds that had been exclusively paired for at least one full breeding season was examined with linear regression, and the age of females at the age of exclusive pairing was shown to have a significant influence on fertility, which increased with increased age at pairing. Behavioral data from adult pairs at the San Diego Wild Animal Park corroborated these findings, as mounts and copulations were observed at significantly lower frequencies in pairs that had been formed when the female was less than two years old. © 1994 Wiley-Liss, Inc.     

Pair Formation in California Condors

SYNOPSIS. Pair formation is a prerequisite for reproductionin California condors and exploring the process has been centralto the captive breeding program for this endangered species.Observations show that once birds reach sexual maturity theycan form pairs within a matter of months; even birds who havelost or been separated from their mates will successfully bondwith others. However, some adults who are housed together showlittle indication of pairing. When such birds are placed withother potential mates they frequently successfully pair andproduce young, suggesting that individual differences play arole in pair formation. We recommend that adults who have notbonded within two years be housed with different potential mates. Condors raised together may or may not form pair bonds uponreaching sexual maturity; unfamiliar condors introduced at fouryears of age or older will form pair bonds. In the four caseswhere pairings have been successful the male initiates moreintrapair interactions with aggressive behavior than does thefemale. Unpaired condors housed in groups do show courtshipand the most dominant birds, usually males, are the most activein giving wings-out/head-down displays. Displays may be directedto males or females and may signal dominance and/or interest.Displays may be followed by mounts and one female may crowdin front of the bird to whom a male is displaying, increasingthe chances that she will receive the display and be mounted.Displaying and the response to displaying birds may be mechanismswhich influence mate selection.     

The Incidence of a Generalist Thrips Herbivore Among Natural and Translocated Patches of an Endangered Vernal Pool Plant, Blennosperma bakeri

As a restoration strategy, translocation of endangered plant populations may be a risky procedure with uncertain outcomes. Often, very little ecological information is known about these populations before, as well as after, translocation. The endangered vernal pool plant, Blennosperma bakeri, is a case in point. As a consequence of vernal pool habitat destruction, many populations of B. bakeri have been transplanted or translocated to various receptor sites. In this study, we examine the incidence of a thrips herbivore, Frankliniella minuta, in natural and translocated populations of B. bakeri in relation to floral patch size and degree of isolation and present implications for B. bakeri restoration and management. At a vernal pool mitigation site in California, U.S.A., thrips were present in both kinds of B. bakeri populations, and the range of thrips densities in both kinds of populations was similar for adults and immatures. Significant negative relationships between patch size, patch isolation, and numbers of flower heads infested with adult or immature thrips were found only among natural patches. Natural patches tended to be smaller in size than translocated patches, but patch isolation distances were similar. Some evidence suggests that B. bakeri is a F. minuta host plant, but the impact of these herbivores on B. bakeri remains unclear. Our findings, although preliminary, suggest that the distribution and abundance of F. minuta varied with floral patchiness, thrips stage, and the natural or translocated status of B. bakeri populations. In addition, our results provide a starting point for understanding the spatial context of plant–herbivore interactions in artificially altered vernal pool landscapes.     

Comparing Survival and Movements of Non-Urban and Urban Translocated Mule Deer

In many parts of North America, deer (Odocoileus spp.) have adapted to live in urban areas and are a source of negative human-wildlife interactions. Management strategies such as culling, immunocontraceptives, sterilization, and translocation have been implemented to manage urban deer populations. In the East Kootenay region of southern British Columbia, urban mule deer (Odocoileus hemionus) populations have been increasing, whereas non-urban mule deer populations have decreased. In 2014 a non-urban mule deer research project began in the area and in 2016 an urban deer translocation trial was approved in the same region. We fit 121 non-urban deer with global positioning system (GPS)-collars and translocated 135 urban mule deer to non-urban areas, of which 57 were fit with GPS-collars. We tested if annual survival between urban translocated (i.e., translocated) and non-urban deer differed, and if translocated deer survival increased in subsequent years after translocation. We also determined if age, body condition, release site, capture area and distance between capture and release sites affected translocated deer survival. We evaluated if translocated deer exhibited different movement behaviors than non-urban deer by comparing probability of migration, maximum net displacement, home range size, and probability of crossing a paved road. Finally, during our study we observed some translocated deer return to a municipal area after translocation and assessed if any covariates such as age, release site, or capture city could help predict this behavior. Annual survival of translocated deer was 0.48 and was significantly lower than survival of non-urban deer, which was 0.77. We observed 20 of 57 collared translocated deer return to a town after translocation. Translocated deer had larger net displacements and larger seasonal home range sizes than non-urban deer. Non-urban deer were more likely to migrate than translocated deer and crossed fewer paved roads than translocated deer. The management effectiveness of translocation to reduce urban deer densities is mixed because annual survival of translocated deer may be lower than may be acceptable to some stakeholders. Additionally, some translocated deer returned to an urban area, and the large distances traveled by deer after translocation may unintentionally spread disease. © 2020 The Wildlife Society.     

Survival of adult mountain goats in Washington: effects of season,translocation, snow,and precipitation

Elucidating patterns of adult survival rates is key to understanding population dynamics of large mammals. We used data from 7 separate studies of mountain goats (Oreamnos americanus) conducted from 2002 through 2022 in western Washington, USA, to quantify survival rates in relation to key biotic and abiotic factors using known fate models implemented in program MARK. We monitored 324 (206 females, 118 males) radio-marked mountain goats for 178,339 days. A substantial number of mountain goats in our sample (n = 217) had been translocated from the Olympic Peninsula to the Cascade Mountains on Washington's mainland, providing an added opportunity to examine translocation effects. We adopted a sequential modeling approach, first building a set of models to examine fundamental survival patterns by age, sex, season, study area, and translocated status. We used variables retained from the top model in a second set to investigate relationships between annual survival and local weather covariates hypothesized by previous studies to influence mountain goat behavior, habitat selection, and vital rates. Survival among adult females in spring was slightly lower than other sex and age categories, but seasonal patterns were otherwise not evident. There were significant negative relationships between survival and winter snow depth, an index of the previous year's drought, and mean daily temperature during the previous May, and a positive relationship with previous year's precipitation. Weather effects were similar among resident and translocated animals. By the end of the study period, weather effects had evidently contributed to reductions in mountain goat survival to a level low enough that population stability was unlikely. Because the frequency of droughts and warm spring temperatures are expected to increase with climate change, mountain goat populations in Washington will likely be increasingly challenged as the atmosphere warms.     

Andean and California condors possess dissimilar genetic composition but exhibit similar demographic histories

While genetic diversity of threatened species is a major concern of conservation biologists, historic patterns of genetic variation are often unknown. A powerful approach to assess patterns and processes of genetic erosion is via ancient DNA techniques. Herein, we analyzed mtDNA from historical samples (1800s to present) of Andean Condors (Vultur gryphus) to investigate whether contemporary low genetic variability is the result of recent human expansion and persecution, and compared this genetic history to that of California condors (Gymnogyps californianus).We then explored historic demographies for both species via coalescent simulations. We found that Andean condors have lost at least 17% of their genetic variation in the early 20th century. Unlike California condors, however, low mtDNA diversity in the Andean condor was mostly ancient, before European arrival. However, we found that both condor species shared similar demographies in that population bottlenecks were recent and co‐occurred with the introduction of livestock to the Americas and the global collapse of marine mammals. Given the combined information on genetic and demographic processes, we suggest that the protection of key habitats should be targeted for conserving extant genetic diversity and facilitate the natural recolonization of lost territories, while nuclear genomic data should be used to inform translocation plans.     

Evaluation of the Efficacy of Florida Key Deer Translocations

Abstract: The endangered Florida Key deer (Odocoileus virginianus clavium) is endemic to the Lower Florida Keys. In recent years, habitat fragmentation and restricted dispersal have resulted in small, isolated herds on some islands. Recovery biologists proposed translocations to increase the island herds that had declined or remained low; however, efficacy of Key deer translocations had yet to be evaluated. Our objective was to evaluate survival, ranges, reproduction, and dispersal of translocated deer. During 2003–2005, we translocated 39 adult or yearling deer to Sugarloaf (approx. 19 km from trap site; 10 M, 14 F) and Cudjoe (approx. 15 km from trap site; 6 M, 9 F) keys. We kept deer in large, high-fenced holding pens (Sugarloaf = 7.7 ha, Cudjoe = 10.7 ha) on the destination islands for 3–6 months (i.e., soft release). We observed low mortality (n = 6 mortalities) of translocated deer with average annual survival (S) of 0.796 for both sexes. We found translocated deer had larger seasonal ranges than did resident deer (i.e., those located on Big Pine and No Name keys). In evaluating effects of acclimation period on ranges and dispersal, we found no difference in 95% ranges or 50% core areas ≤4 month postrelease versus 4–8 months postrelease. We found, however, postrelease dispersal distances were dependent on time kept in pen. Only 2 of 39 (5%) translocated deer left the destination islands by the end of the study. With high survival and low dispersal indicating success, we credit soft release translocation in establishing deer herds on Sugarloaf and Cudjoe keys. Our data support translocations as an effective strategy for creating sustainable outer-island Key deer herds.     

Impact of the California lead ammunition ban on reducing lead exposure in golden eagles and turkey vultures

Predatory and scavenging birds may be exposed to high levels of lead when they ingest shot or bullet fragments embedded in the tissues of animals injured or killed with lead ammunition. Lead poisoning was a contributing factor in the decline of the endangered California condor population in the 1980s, and remains one of the primary factors threatening species recovery. In response to this threat, a ban on the use of lead ammunition for most hunting activities in the range of the condor in California was implemented in 2008. Monitoring of lead exposure in predatory and scavenging birds is essential for assessing the effectiveness of the lead ammunition ban in reducing lead exposure in these species. In this study, we assessed the effectiveness of the regulation in decreasing blood lead concentration in two avian sentinels, golden eagles and turkey vultures, within the condor range in California. We compared blood lead concentration in golden eagles and turkey vultures prior to the lead ammunition ban and one year following implementation of the ban. Lead exposure in both golden eagles and turkey vultures declined significantly post-ban. Our findings provide evidence that hunter compliance with lead ammunition regulations was sufficient to reduce lead exposure in predatory and scavenging birds at our study sites.     

Age‐ and sex‐specific survival of California sea lions (Zalophus californianus) at San Miguel Island,California

We conducted a mark‐recapture study of California sea lions (Zalophus californianus) using pups branded on San Miguel Island, California, from 1987 to 2014, and annual resightings from 1990 to 2015. We used the Burnham model (Burnham 1993), an extension of the Cormack‐Jolly‐Seber mark‐recapture model, which includes recoveries of dead animals, to analyze age, sex, and annual patterns in survival. Generally, females had higher survival than males. For female pups, the average annual survival was 0.600 and for male pups it was 0.574. Yearling survival was 0.758 and 0.757 for females and males, respectively. Peak annual survival was at age 5 and was 0.952 for females and 0.931 for males. Pups with larger mass at branding had higher survival as pups and yearlings, but the effect was relative within each cohort because of large between‐cohort variability in survival. Annual variability in sea surface temperature (SST) affected survival. For each 1°C increase in SST, the odds of survival decreased by nearly 50% for pups and yearlings; negative SST anomalies yielded higher survival. Annual variation in male survival was partly explained by leptospirosis outbreaks. Our study provides a unique view of one demographic parameter that contributed to the successful recovery of the California sea lion population.     

Long-term genetic monitoring of a translocated population of collared brown lemurs

Post-release monitoring is important to improve translocation success because it provides an opportunity to identify factors relevant to the survival of local populations. We studied a population of the endangered collared brown lemur (Eulemur collaris) translocated from a degraded forest fragment to a nearby littoral forest within the Mandena Conservation Area in southeast Madagascar from 2000–2011. We compared genetic surveys of mitochondrial and nuclear markers with the genetic profile of nearby populations to examine the dispersal capacity of the collared brown lemur. We also performed a landscape analysis to assess changes in connectivity between forest fragments. There was a fluctuating trend characterized by a phase of demographic and genetic stability shortly after translocation, followed by an increase in genetic diversity coinciding with a population decrease and a gradual recovery of initial conditions. These results demonstrated the ability of the collared brown lemur to disperse through unfavorable landscapes and to recover after translocation. Our study revealed the importance of monitoring translocated populations over time using a multidisciplinary approach.     

The Osprey reintroduction in Central Italy: dispersal,survival and first breeding data

Capsule Sex-biased dispersal and an age-dependent effect in survival rate accounted for the pattern of first settlement and reproduction in a newly reintroduced Osprey population.

Aims We estimate the survival of translocated individuals, describe juvenile movements and evaluate the success of first breeding events to document the re-establishment of an Osprey breeding population.

Methods Between 2006 and 2010, 32 fledgling Ospreys were reintroduced via hacking techniques in Maremma Regional Park, Italy. We evaluated the effects of age on survival through multistate capture-mark-recapture analyses. Movements were investigated by radiotracking and using records of resightings.

Results Survival was high for juveniles after the release (0.87), markedly decreased during the first winter (0.26), and improved again in subsequent years (annual apparent survival of 0.69 for immatures and 0.93 for adults). Mean distance covered in initial dispersal was greater for females (246.2?km) than for males (38.7?km).

Conclusion Our results provided information on dispersal and survival rate of reintroduced Ospreys in a Mediterranean area. Despite low apparent survival in the first year, the high survival rates found in immatures and adults suggested favourable conditions for this new population. The study of demographic parameters is important for calibrating management actions aimed at the establishment of a self-sustaining Osprey population.     

Landscape genetics of an endangered salt marsh endemic: Identifying population continuity and barriers to dispersal

Preserving the genetic diversity of endangered species is fundamental to their conservation and requires an understanding of genetic structure. In turn, identification of landscape features that impede gene flow can facilitate management to mitigate such obstacles and help with identifying isolated populations. We conducted a landscape genetic study of the endangered salt marsh harvest mouse (Reithrodontomys raviventris), a species endemic to the coastal marshes of the San Francisco Estuary of California. We collected and genotyped?>?500 samples from across the marshes of Suisun Bay which contain the largest remaining tracts of habitat for the species. Cluster analyses and a population tree identified three geographically discrete populations. Next, we conducted landscape genetic analyses at two scales (the entire study area and across the Northern Marshes) where we tested 65 univariate models of landscape features and used the best supported to test multivariable analyses. Our analysis of the entire study area indicated that open water and elevation (>?2 m) constrained gene flow. Analysis of the Northern Marshes, where low elevation marsh habitat is more continuous, indicated that geographic distance was the only significant predictor of genetic distance at this scale. The identification of a large, connected population across Northern Marshes achieves a number of recovery targets for this stronghold of the species. The identification of landscape features that act as barriers to dispersal enables the identification of isolated and vulnerable populations more broadly across the species range, thus aiding conservation prioritization.