Quantitative assessment of pair formation behavior in captive whooping cranes (Grus americana)

Instantaneous scan sampling for mean distance and synchronous action patterns and all-occurrence sampling for unison call, dance, strut, and hoover-up behaviors were conducted for five potential whooping crane pairs at Patuxent Environmental Science Center, Laurel, Maryland. Dance, strut, and hoover-up differed among pairs, as did total frequency of social behaviors. It was unclear whether or not total frequency of social behaviors during pair formation can be used as an index for potential breeding success. The relative importance of different action patterns should be used as indices of pair compatibility in captive whooping cranes. © 1995 Wiley-Liss, Inc.     

Decision analysis for conservation breeding: Maximizing production for reintroduction of whooping cranes

Captive breeding is key to management of severely endangered species, but maximizing captive production can be challenging because of poor knowledge of species breeding biology and the complexity of evaluating different management options. In the face of uncertainty and complexity, decision-analytic approaches can be used to identify optimal management options for maximizing captive production. Building decision-analytic models requires iterations of model conception, data analysis, model building and evaluation, identification of remaining uncertainty, further research and monitoring to reduce uncertainty, and integration of new data into the model. We initiated such a process to maximize captive production of the whooping crane (Grus americana), the world's most endangered crane, which is managed through captive breeding and reintroduction. We collected 15 years of captive breeding data from 3 institutions and used Bayesian analysis and model selection to identify predictors of whooping crane hatching success. The strongest predictor, and that with clear management relevance, was incubation environment. The incubation period of whooping crane eggs is split across two environments: crane nests and artificial incubators. Although artificial incubators are useful for allowing breeding pairs to produce multiple clutches, our results indicate that crane incubation is most effective at promoting hatching success. Hatching probability increased the longer an egg spent in a crane nest, from 40% hatching probability for eggs receiving 1 day of crane incubation to 95% for those receiving 30 days (time incubated in each environment varied independently of total incubation period). Because birds will lay fewer eggs when they are incubating longer, a tradeoff exists between the number of clutches produced and egg hatching probability. We developed a decision-analytic model that estimated 16 to be the optimal number of days of crane incubation needed to maximize the number of offspring produced. These results show that using decision-analytic tools to account for uncertainty in captive breeding can improve the rate at which such programs contribute to wildlife reintroductions. © 2011 The Wildlife Society.     

Behavioral profiles of the captive juvenile whooping crane as an indicator of post‐release survival

Predation by bobcats (Lynx rufus) is the major cause of mortality in captive‐reared whooping cranes (Grus americana) released into the wild to establish a nonmigratory flock in Florida. This study investigated whether rearing methods (parent‐rearing, hand‐rearing, or hand‐rearing with exercise) of cranes, and behaviors observed in birds either before or shortly after release in the wild, are associated with survival after release. Rearing methods did not affect survival first year post‐release, which was 55 ±8% in 2 yr (1999 and 2000). Logistic regression revealed, however, that foraging bouts (+), walking bouts (?), and body weight (?) before release, and nonvigilant bouts (?) after release were significantly associated with survival. These results suggest that post‐release survival of whooping cranes might be increased by rearing techniques that promote foraging. Zoo Biol 0:1–14, 2005. © 2005 Wiley‐Liss, Inc.     

Factors affecting wounding aggression in a colony of captive chimpanzees (Pan troglodytes)

Previous research has suggested that chimpanzees (Pan troglodytes) display higher levels of aggression in captivity than in the wild. One of the challenges of captive management, therefore, is to balance the chimpanzees' need for social interaction with managements' desire to minimize wounding and aggression. Various captive studies have examined the effects of individual and social variables on the frequency of wounding aggression, but none have examined these variables simultaneously. We collected retrospective wounding data for severe wounds from 83 captive chimpanzees (36 males, 47 females) from January 1993 to December 2003. The context of the wounding event, including individual age and sex, group age and sex composition, group duration, and portion of the week (weekday vs. weekend) were collected. Logistic regression analysis was performed to determine which variables had a significant effect on the probability of a severe wounding event. The sex and age composition of the group, group duration, and portion of the week had a statistically significant association with wounding. All‐male groups (Odds Ratio (OR)=6.738) had the highest risk of wounding aggression, with uni‐male groups (OR=3.311) having the next largest. Compared to individuals in all sub‐adult groups, individuals in either all‐adult (OR=4.516) or mixed‐age (OR=3.587) groups had a higher risk of wounding. There was an inverse association between group duration and wounding (OR=0.821). Finally, there was an increased risk of wounding during the work week (OR=1.653). These results suggest that captive management should pay close attention to group composition, as well as levels of human activity, when devising strategies to reduce captive chimpanzee aggression. Zoo Biol 29:351–364, 2010. © 2009 Wiley‐Liss, Inc.     

Development and evaluation of methods to assess populations of black flies (Diptera: Simuliidae) at nests of the endangered whooping crane (Grus americana)

Hematophagous insects can negatively affect the reproductive success of their vertebrate hosts. To determine the influence of hematophagous insects on endangered vertebrates requires specially designed programs that minimize disturbance to the hosts and address problems associated with their small populations. We developed and evaluated a surveillance program for black flies potentially affecting a population of whooping cranes (Grus americana) introduced to central Wisconsin, U.S.A. In one of the few studies to survey host‐seeking female black flies and their immature stages concurrently, we processed nearly 346,000 specimens and documented 26 species, of which only two, Simulium annulus and Simulium johannseni, were attracted to nesting whooping cranes. Attempts to assess black fly populations with artificial nests and real crane eggs were unsuccessful. Carbon‐dioxide traps performed well in describing black fly taxa on the landscape. However, the number of black flies at whooping crane nests was consistently higher than the number captured in carbon‐dioxide traps. The carbon‐dioxide traps poorly described the presence/absence, population fluctuations, and periodicity of black flies at whooping crane nests. The weak performance of the carbon‐dioxide traps might have resulted from microhabitat differences between trap locations and nests or from Simulium annulus and Simulium johannseni using sensory cues in addition to carbon dioxide to find hosts. Choice of trapping techniques, therefore, depends on the information required for the particular study objectives.     

Introducing mother's curse: low male fertility associated with an imported mtDNA haplotype in a captive colony of brown hares

Mitochondrial DNA mutations create variation in the efficiency of the oxidative phosphorylation pathway and therefore cellular energy production. Mildly deleterious mutations may reduce the performance of sperm cells in particular, due to their high energy requirements and low number of mitochondria, yet have little or no effect on the viability of somatic cells or ova. Mutations will be maintained in the population, despite the fitness cost for males, because mtDNA is passed down the female line. We looked for this so-called mother's curse effect in our captive colony of European brown hares. Significantly reduced male reproductive success was detected for a divergent haplotype that could be traced back to hares imported from a remote population. Median reproductive success for these hares was 0.17 compared to 0.49 for the indigenous haplotypes (Wilcoxon rank-sum, P  = 0.002). No difference was detected for female reproductive success, nor were we able to find a nuclear DNA component to variation in male fertility. Our data are strong evidence for a mother's curse effect persisting despite multiple crossings over seven generations. These data raise important issues relating to the reproductive fitness of small or intermixing populations and have particular implications for the management of populations for conservation.     

Optimal conditions for breeding of captive humboldt penguins (Spheniscus humboldti): A survey of British zoos

We surveyed 16 British zoos and bird gardens to assess the optimal conditions for breeding of captive Humboldt penguins (Spheniscus humboldti). We obtained information on population, enclosure, and husbandry characteristics and related these variables to three measures of per capita breeding success, namely, per capita egg productivity, chick productivity, and hatching success (measured as the proportion of eggs laid that hatched). All three fitness measures increased with an increasing number of breeding pairs and total population size but were not related to population density. Once the effect of number of breeding pairs was removed statistically, chick productivity was found to be highest when nesting boxes were lined with sand and gravel instead of alternative substrata such as twigs or vegetation. Hatching success increased with increasing pool size and was highest in enclosures with concrete floors. Adult mortality in zoos was generally low and appeared related to the use of chlorine in freshwater pools and to the presence of other penguin species in Humboldt penguin displays. Several enclosure and husbandry parameters were not variable enough to assess their impact on reproduction of captive Humboldt penguins. Recommendations for optimising conditions for captive breeding of Humboldt penguins include keeping as large a population as possible in a concrete enclosure with a large pool area, while providing sand and gravel as nesting material. Bird density may be important but we did not detect detrimental effects on breeding for densities up to 0.25 birds m^–2. Adult mortality can be minimised by exhibiting Humboldt penguins in single‐species display and avoiding chlorination of pool water. An experimental approach is recommended to confirm the results of this correlational study. Zoo Biol 20:545–555, 2001. © 2002 Wiley‐Liss, Inc.     

Genetic diversity analysis of captive populations: The Vietnamese sika deer (Cervus nippon pseudaxis) in zoological parks

The Vietnamese sika deer (Cervus nippon pseudaxis) is an endangered subspecies; it has disappeared in the wild, but is being bred in zoological parks. We studied the neutral genetic diversity and population structure of herds kept in different European zoos, using nine microsatellite loci. The goal was to evaluate the consequences of founding effects and breeding practices on the level and structure of genetic variability. The level of genetic diversity within the European zoos is not lower than that of the populations kept in Vietnamese farms. Strong differences among zoological parks and between the European group and the Vietnamese population were detected. This is probably due to founding effects, genetic drift, and possibly hybridization in both Europe and Vietnam. We expected to find a much lower level of genetic diversity in Europe. The current overall level of genetic diversity is probably due to the recent introduction of Cuc Phuong individuals, and to important differences among the populations of different zoological parks, which increase the total genetic variability. Although the current level of genetic variability is not particularly low, future levels are probably threatened by the current herd sizes and structure. Based on these results, management guidelines are proposed. Zoo Biol 22:465–475, 2003. © 2003 Wiley‐Liss, Inc.     

Factors determining persistent asymmetry and egg shape in birds: A hypothesis

The shape of birds' eggs has fascinated scientists for many years. It is now possible mathematically to describe shape accurately, allowing exploration of the physical and ecological factors driving the evolution of egg shape. However, there has been relatively little consideration of how egg shape is established in the oviduct or, given that even without an external calcitic layer eggs retain their shape, how shape is fixed in the isthmus. This paper proposes a hypothesis that attempts to explain how egg shape is established and fixed in the oviduct. The hypothesis suggests that as the egg mass (i.e. yolk and albumen) moves from the magnum into the isthmus, it is squeezed by the physical restriction imposed by the isthmus lumen and cannot easily move into the isthmus. As the leading edge of the egg mass enters the isthmus, the egg mass in the distal magnum is forced to bulge outwards, resulting in an asymmetrical shape. The various egg shapes observed in birds are, hence, produced by the interaction between the size of the egg mass relative to female body mass, and the degree of the restriction of the isthmus. Thus, a large egg mass, i.e. relative to female body mass, entering a narrow isthmus will produce a pointed egg shape. If the egg mass is relatively small, and the isthmus lumen wide, more of the egg mass could enter the isthmus and the degree of asymmetry would be reduced. It is further proposed that egg shape is fixed during the formation of the shell membranes in the isthmus because the constituent protein fibres permanently stick together as they are deposited. For the first time this hypothesis helps explain the pattern of deposition and characteristics of the calcitic egg in relation to the diversity of egg shapes in birds and reptiles.     

Dilauroylphosphatidylcholine liposome effects on the acrosome reaction and in vitro penetration of zona-free hamster eggs by bull sperm: II. A fertility assay for frozen-thawed semen

Frozen-thawed sperm from five bulls with fertility rates ranging from 48% to 77% were treated with seven concentrations of dilauroylphosphatidylcholine (PC12) liposomes to induce an acrosome reaction (AR) that enabled sperm to penetrate eggs. Treated sperm were incubated with liposomes for 7 min prior to insemination of zona-free hamster eggs in vitro. Sperm and eggs were incubated 3 hr at 39°C prior to fixation, staining, and examination for sperm penetration and nuclear decondensation. The percentage of motile sperm immediately after thawing as well as after treatment with liposomes had a low correlation with sire fertility (r = .39 and ?.63, respectively). The percentage of sperm exhibiting an AR was more highly correlated with fertility (r ? ?.85). Similar correlations were found between fertility and the penetration rates of zona-free hamster eggs or the total number of penetrating sperm. When data for two high and for two lower fertility buils were each grouped to increase information per data point the correlation between the PC12 concentration giving the maximum proportion of eggs penetrated and fertility was r = .92 (P ≤ .05). The correlation between the PC12 concentration producing the most total sperm penetrating the eggs and fertility r = .97 (P ≤ .05). It was concluded that PC12 liposomes induced an AR in bull sperm frozen-thawed in egg yolk extender. Frozen-thawed sperm from low fertility bulls require less PC12 to induce the AR and to penetrate zona-free hamster eggs than do sperm from higher fertility bulls. These differences in lipid requirements may help to provide a quick, direct laboratory assay method to estimate the fertility of frozen bull semen.     

Deslorelin acetate implant induces transient sterility and behavior changes in male olive baboon (Papio anubis): A case study

This case study evaluates the effects of a 4.7 mg deslorelin acetate implant on one male olive baboon (Papio anubis). Implantation induces transient azoospermia after which the subject was able to conceive again. Behavior was also impacted with a decrease in our proxies of aggressiveness and sexual arousal.     

Dilauroylphosphatidylcholine liposome effects on the acrosome reaction and in vitro penetration of zona-free hamster eggs by bull sperm: I. A fertility assay for fresh semen

Fresh sperm from five bulls having nonreturn rates ranging from 48% to 77% were treated with 15.7, 21.0, 26.2, 31.5, 36.7, and 42.0 μM dilauroylphosphatidylcholine (PC12) to induce the sperm acrosome reaction (AR). Treated sperm were incubated 3 hr with zona-free hamster eggs at 39°C prior to fixation. The eggs were then stained and examined for sperm penetration. Differences in the percentages of motile sperm and of sperm exhibiting an AR among bulls were small when compared on a within-liposome-concentration basis. Increasing the PC12 concentration from 15.7 μM to 42.0 μM increased the percentage of sperm exhibiting an AR for all bulls. At the lowest lipid concentration (15.7 μM), the percentage of eggs penetrated by sperm from the five bulls was 6% to 36%, with 0% in controls. When sperm were incubated with increasing lipid concentrations, the egg penetration rate increased to over 80%, and the total number of sperm increased to over 100 per 36 eggs in each treatment for every bull. These penetration rates decreased at the highest lipid concentration. A correlation between the PC12 concentration maximizing egg penetration and the nonreturn rate of ?.63 was found. The correlation between the PC12 concentration maximizing the total number of penetrated sperm per treatment and the bull nonreturn rate was ?.96. It was concluded that PC 12 liposomes induce the AR in bull spermatozoa, which enables them to penetrate zona-free hamster eggs. High fertility bulls required less lipid to induce the AR than did lower fertility bulls. Consequently, this assay of fresh semen could provide a laboratory method to estimate the fertility of a bull.     

A captive feeding study with the Pacific harbor seal (Phoca vitulina richardii): Implications for scat analysis

Seven prey species ( n _total > 2,700) were fed to seven captive male Pacific harbor seals ( Phoca vitulina richardii ) in 177 experimental meals to quantify biases associated with scat analysis and current consumption models. Hard parts from an individual meal were recovered in an average of 3.8 ± 1.8 scats (range 1–10; mean ± SD). Overall, 57.7 ± 33.2% of otoliths and 89.5 ± 15.5% of squid beaks were recovered. Recovery rates varied, and prey with smaller, fragile otoliths were recovered in lesser quantities than prey with larger, robust otoliths. Recovery rates of all prey except pink salmon were improved by a mean of 31.7% when all diagnostic structures were included in estimates. Estimated recovery of pink salmon was 9.5 times that fed seals based on the all-structure technique. Mean length reduction of recovered otoliths was 20.4 ± 10.1%. Correction factors calculated from average length reduction improved length estimates for all fish species. Grade-specific length correction factors (gLCFs) reduced variability in all of the estimates and significantly improved estimates of prey with highly eroded otoliths including Pacific hake and shortbelly rockfish. The Biomass Reconstruction (BR) model accurately predicted biomass consumption within 4% of known consumption, whereas estimates based on frequency of occurrence were inaccurate.     

Factors influencing reproductive success in small captive exotic felids (Felis spp.): A multiple regression analysis

Environmental, genetic, and social factors associated with captive maintenance of small felids (Felis spp.) were systematically examined at eight different zoos to determine which of these factors most closely correlated with successful reproduction. Almost half of all the pairings examined failed to produce offspring. However, at least some representatives of the 20 species examined successfully reproduced, suggesting that failure to breed could not be solely attributed to species specific requirements. Multiple regression techniques revealed an association between number of litters produced and number of medical treatments, latitude range of wild counterparts, group size (all negatively correlated), and a positive correlation with husbandry style. These findings have direct relevance to how small cats are managed in captivity. Specifically, when small felids are maintained in groups larger than a pair (1.1), they are not likely to reproduce. Furthermore, a husbandry style in which keepers spent considerable time talking to, and interacting with, the cats under their care was more likely to result in offspring than one in which these interactions did not occur. These and other results generated suggestions for management techniques necessary to assure the continued survival of small cats in captivity.