Reproductive behavior in captive California condors (Gymnogyps californianus)

From the fall of 1987 to the spring of 1994, data on reproductive behavior were collected on seven different pairs of California condors (Gymnogyps californianus) housed at the San Diego Wild Animal Park. Behavioral data were collected from videotaped activities in their flight pens. Behaviors for this report include male and female displays and incomplete and complete copulations. Data on the time it took for females to recycle and lay another egg after egg removal were acquired from the California Condor Studbook. Male display rates were significantly higher than female rates throughout the breeding season. Males began displaying 52–132 days before the start of copulations. Copulations slowly increased from Day -51 and peaked ∼ Day -8, prior to egg laying. Female display rates were significantly more frequent at the end of the season after the last egg was laid. An average of 26.8 (±3.1 SEM) copulations occurred prior to egg laying. Copulations occurred throughout the day, with the higher mean percentages occurring between 0700 and 0900 hours. After egg removal, the interval between laying of the first and second eggs and between the second and third eggs had a mean of 34.1 (±10.1 SD) days. © 1996 Wiley-Liss, Inc.     

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.     

Changes in incubation sharing in one pair of captive California condors (Gymnogyps californianus)

Three years of behavioral data were collected on incubation behavior in one pair of captive condors (Gymnogyps californianus) at the San Diego Wild Animal Park. Data were collected from daily video tape reviews of the nest box. The amount of time each bird was in the nest box, and whether it was on or off the egg were recorded, along with any aggressive interactions observed in the nest. For the first 2 years, the female incubated the egg(s) significantly more than the male. During the third year, the male increased his incubation time on the egg, resulting in no difference between the two sexes in incubation time. Changes in male incubation behavior may be a result of several factors: increased compatibility between the pair, social maturation, and/or increased dominance on the part of the male. © 1994 Wiley-Liss, Inc.     

Artificial incubation of California condor Gymnogyps californianus eggs removed from the wild

The currrent California condor (Gymnogyps californianus) recovery plan entails increasing the reproductive rate via replacement-clutch manipulation of eggs. During the period from 1983 to 1985, 15 eggs were removed from wild nesting pairs for artificial incubation. The eggs were incubated at a dry bulb temperature of 36.4°C in modified forced-air Lyon Electric incubators. The incubation humidity was adjusted for individual eggs based on weight loss data (water = weight), 25.6–30.0°C wet bulb (41.0–63.0% Relative Humidity (RH)). The chicks were hatched initially under forced-air conditions of 36.1°C dry bulb, 31.1–01.7°C wet bulb (70.0–73.0% RH). In 1984, hatching parameters were changed to still-air conditions, 36.1°C dry bulb (top of the egg), 35.0°C dry bulb (bottom of the egg), 31.1–31.7°C wet bulb (70.0-73.0% RH). Tactile and auditory stimulation was utilized during the pip-to-hatch interval. From among 15 eggs collected, 13 hatched, and 12 condor chicks were raised successfully (hatchability: 86.7%; survivability: 92.3%).     

Patterns of mortality in free-ranging California Condors (Gymnogyps californianus)

We document causes of death in free-ranging California Condors (Gymnogyps californianus) from the inception of the reintroduction program in 1992 through December 2009 to identify current and historic mortality factors that might interfere with establishment of self-sustaining populations in the wild. A total of 135 deaths occurred from October 1992 (the first post-release death) through December 2009, from a maximum population-at-risk of 352 birds, for a cumulative crude mortality rate of 38%. A definitive cause of death was determined for 76 of the 98 submitted cases, 70% (53/76) of which were attributed to anthropogenic causes. Trash ingestion was the most important mortality factor in nestlings (proportional mortality rate [PMR] 73%; 8/11), while lead toxicosis was the most important factor in juveniles (PMR 26%; 13/50) and adults (PMR 67%; 10/15). These results demonstrate that the leading causes of death at all California Condor release sites are anthropogenic. The mortality factors thought to be important in the decline of the historic California Condor population, particularly lead poisoning, remain the most important documented mortality factors today. Without effective mitigation, these factors can be expected to have the same effects on the sustainability of the wild populations as they have in the past.     

Cytogenetic analysis of California condor (Gymnogyps californianus) chromosomes: comparison with chicken (Gallus gallus) macrochromosomes

The California condor is the largest flying bird in North America and belongs to a group of New World vultures. Recovering from a near fatal population decline, and currently with only 197 extant individuals, the species remains listed as endangered. Very little genetic information exists for this species, although sexing methods employing chromosome analysis or W-chromosome specific amplification is routinely applied for the management of this monomorphic species. Keeping in mind that genetic conditions like chondrodystrophy have been identified, preliminary steps were undertaken in this study to understand the genome organization of the condor. This included an extensive cytogenetic analysis that provided (i) a chromosome number of 80 (with a likelihood of an extra pair of microchromosomes), and (ii) information on the centromeres, telomeres and nucleolus organizer regions. Further, a comparison between condor and chicken macrochromosomes was obtained by using individual chicken chromosome specific paints 1-9 and Z and W on condor metaphase spreads. Except for chromosomes 4 and Z, each of the chicken (GGA) macrochromosomes painted a single condor (GCA) macrochromosome. GGA4 paint detected complete homology with two condor chromosomes, viz., GCA4 and GCA9 providing additional proof that the latter are ancestral chromosomes in the birds. The chicken Z chromosome showed correspondence with both Z and W in the condor. The homology suggests that the condor sex chromosomes have not completely differentiated during evolution, which is unlike the majority of the non-ratites studied up till now. Overall, the study provides detailed cytogenetic and basic comparative information on condor chromosomes. These findings significantly advance the effort to study the chondrodystrophy that is responsible for over ten percent mortality in the condor.     

Incorporating uncertainty in spatial structure for viability predictions: a case study of California sea lions (Zalophus californianus californianus)

In recent years, population viability analysis has become a popular tool to assess the relative risk of extinction among populations. Viability estimates for spatially structured populations require movement data that are often unavailable. In this paper, a diffusion approximation model was used to explore the effects of different spatial scenarios resulting from assumptions about movement rates. Census data for 13 breeding islands occupied by California sea lions Zalophus californianus californianus in the Gulf of California were used to explore three potential scenarios: unlimited movement between sites (panmictic population), limited movement (several clusters of populations) and no movement between islands (isolated islands). Predicted viability estimates were different for each scenario, but contrary to expectations, the mean extinction risk estimates were generally lowest when movement was unlimited (panmictic scenario). However, despite an extensive dataset, the confidence of the viability predictions for each scenario was low. In some cases, uncertainty in predictions within a scenario was greater than differences between scenarios. Therefore, it is recommended that in situations where movement rates and spatial structure are unknown, extinction risk estimates should reflect both the confidence intervals for each risk estimate and the uncertainty resulting from different spatial scenarios. This study also provides the first estimate of population viability (considering spatial structure) for California sea lions in the Gulf of California and an evaluation of population status based on the IUCN criteria for species listing.     

The influence of processing and temperature conditions on hatching of resting eggs of Streptocephalus proboscideus (Crustacea: Branchiopoda: Anostraca)

In large freshwater branchiopods, erratic hatching success of resting eggs is a major obstacle to various applications. Lack of knowledge of the diapause-regulating processes makes control of hatching difficult. In the Sudanese fairy shrimp Streptocephalus proboscideus cysts are considered to include a diapausing and a quiescent fraction. To effect hatching, diapausing cysts have to be activated, while the quiescent portion has to be triggered by suitable environmental conditions. Of several attempts to control hatching with varying production, processing, and incubation conditions, only a few treatments proved consistently successful. Cysts were produced in an indoor culture system under controlled conditions and were harvested, washed, and dried according to defined procedures before processing (if any) and incubation. Hatchability (first-day and cumulative) was consistently higher in chemically decapsulated than in untreated (non-decapsulated) cysts at 25 °C. At a temperature of 28 °C, hatching was comparable in untreated and in decapsulated cysts and was significantly higher than at 25 °C. Pre-treatment with 7.5% NaOCl for 5–10 minutes, resulted in higher hatching than other decapsulation procedures and durations. It is believed that the decapsulation and temperature treatments were only effective in triggering quiescent cysts but did not activate the diapausing fraction.     

Demography of Amboseli baboons, 1963–1983

Repeated censuses of a population of yellow baboons (Papio cynocephalus) in Amboseli National Park, Kenya, revealed a decrease from over 2,500 animals in 1963–1964 to 123 individuals in 1979, or from a density of about 73 to 1.8 baboons per km² over a 15-year period. Median group size decreased from 43 in 1964 to 27 in 1979. The largest and smallest groups declined the most; groups near the median have maintained fairly stable size and age distributions. The population seemed to have stabilized by 1983 at approximately 150 animals in six groups (median group size 28; density 2.2/km²). Although baboon population and group size appeared to be stable during 1963–1964, the age distribution and demographic parameters (age-specific mortality and natality for one social group) during that year indicate that the population decline had already started. The rate of population decline was greatest in the 1964–1969 period and remained appreciable during the next 5 years. The decline of the baboon population was paralleled by that of other Amboseli savannah woodland mammalian species and took place during a period of very high mortality of fever trees (Acacia xanthophloea) and extensive invasion of the area by halophytes, a transition brought on by rising ground water and consequent elevation of the soil salinity zone. In this and several other primate populations, mortality of infants and juveniles appears to be the demographic variable most sensitive to environmental change.     

Changes in elemental composition of fertilized and unfertilized northern pike (Esox lucius) eggs incubated in buffer with and without dimethyl sulfoxide: An X-ray microanalysis study

Fertilized and unfertilized eggs from the northern pike (Esox lucius) were incubated 2 hr in buffer with 0 and 10% (v/v) dimethyl sulfoxide and then quickly frozen in the wells of aluminum blocks submerged in liquid nitrogen. Control eggs and ovarian fluid were similarly frozen immediately after collection. The frozen eggs were sectioned, freeze dried, mounted on stubs, and carbon coated. X-ray microanalysis was used to determine changes in element levels and dimethyl sulfoxide (Me₂SO) penetration in the zona radiata, cytoplasm, cortical alveoli, and egg yolk. Unfertilized eggs incubated without Me₂SO showed decreased levels of Na, Cl, and K in the zona radiata; fertilized eggs, incubated without Me₂SO showed decreased levels of Na, P, and Cl in the zona radiata and increased levels of K in the cytoplasm; unfertilized eggs, incubated with 10% Me₂SO showed decreased Na and Cl in the zona radiata, decreased K in the cytoplasm and increased K in the cortical alveoli; fertilized eggs incubated in buffer with 10% Me₂SO showed decreased levels of Na, P, Cl, and K (zona radiata), P, Cl, and K (cytoplasm), Na (yolk), and increased Cl in the yolk (all P<.01). Me₂SO (v/v) levels reached 1.5-3.1% in the zona radiata, 0-3.2% in cytoplasm, 2.3-8.7% in cortical alveoli, and 0-1.6% in the yolk. Unfertilized eggs showed more Me₂SO penetration than fertilized eggs.     

The β association of (DLLys)10–(LVal)20–(DLLys)10: An nmr study

(DL Lys)₁₀–(L Val)₂₀–(DL Lys)₁₀, a copolymer of a valine block in the β conformation with randomly coiled flanking blocks of lysine [Kubota, S. & Fasman, G. D. (1975) Biopolymers 14 , 605–631], was studied by nuclear magnetic resonance. The peak areas of the N? H and C? H resonances of valine and lysine are concentration-dependent with little chemical shift change. A model is presented describing the aggregation of the copolymer. Additional evidence, obtained by monitoring the spin-lattice relaxation times of amino, amide, γ-methyl-valine, and ?-methylene-lysine, is consistent with the aggregation model. Hydrodynamic studies are presented which show monomer → oligomer aggregation of four or five subunits.