Captive breeding for reintroduction: influence of management practices and biological factors on survival of captive kaki (black stilt)

An important component of the restoration strategy for the critically endangered kaki or black stilt (Himantopus novaezelandiae) is captive breeding for release. Since 1981 1,879 eggs were collected from wild and captive pairs, with birds laying up to four clutches. Eggs were incubated artificially and most chicks reared by hand until released as juveniles (about 60 days) or sub‐adults (9–10 months). Because survival in captivity is a significant determinant of the number of birds available for release, we wished to identify sources of variation in mortality to assess potential impacts of management on productivity. Hatchability was 78% for captive‐laid eggs and 91% for wild‐laid eggs. Survival of hatched eggs was 82% by 10 months of age for both wild and captive birds. Most egg mortality occurred early in incubation and around hatching: the timing of mortality was unaffected by whether birds were captive or wild, hybrid or pure kaki, or when eggs were laid. Heavier hatchlings showed higher initial survival, as did chicks from wild parents. Hatchlings from fourth‐laid eggs showed lowest survival, even though hatchling mass tended to increase with hatch order. Survival of chicks subjected to major health interventions was 69% after 4 months. No differences in survival were found between different genders, hybrids and pure kaki, hand‐reared or parent‐reared birds, chicks hatching early or late in the season, different seasons, different‐sized groups of chicks, chicks reared in different brooders, juveniles kept in different aviaries, and chicks from subsequent clutches. Birds subjected to minor health interventions were equally likely to survive as healthy chicks (82%). Survival was high despite aggressive management (quadruple clutching and collecting late in the season). Differences between captive and wild birds suggest further improvements could be made to captive diet. Wide variation in hatchability between parent pairs substantiates the practice of breaking up poorly performing pairs. Zoo Biol 0:1–16, 2005. © 2005 Wiley‐Liss, Inc.     

Reproductive assessment of the great hornbill (Buceros bicornis) by fecal hormone analysis

The population of great hornbills (Buceros bicornis) in the United States is rapidly aging, and captive breeding efforts have not met population managers' expectations for a sustainable captive group. Little is known about the reproductive physiology of these birds. This study reports the first data on the re‐productive endocrinology of the great hornbill. The hormone profiles of the only pair of these birds that hatched a chick in the 1999–2000 breeding season are compared to the profiles of six other pairs of hornbills, from different institutions in the United States, that did not reproduce successfully that season. The study investigates the estradiol, corticosterone, and testosterone profiles of these seven pairs of birds, establishing a base of knowledge from which endocrine data may be used to improve the success of captive breeding programs. The estradiol profiles from this study indicate a difference in hormonal patterns between laying and non‐laying female great hornbills. Egg‐laying females had significantly higher estradiol concentrations during the breeding season than the non‐laying females (P<0.003). Testosterone concentrations of the males were not significantly different between the mates of egg‐laying and non‐egg‐laying females. The corticosterone concentrations tended to be lower in the females that laid eggs vs. the non‐egg‐laying group. The males of the egg‐laying pairs showed a significantly lower (P<0.036) corticosterone concentration than the non‐egg‐laying male pairs. This, combined with the extremely low corticosterone levels (compared to the other birds in the study) of the pair of hornbills that hatched a chick in the 1999–2000 breeding season, suggests that adrenal activity may play a role in the reproductive failure of some captive great hornbills. Zoo Biol 22:135–145, 2003. © 2003 Wiley‐Liss, Inc.     

Artificial incubation of trumpeter swan eggs: Selected factors affecting hatchability

Eggs collected from captive trumpeter swans (Cygnus buccinator) in 1993 (n = 33) and 1994 (n = 42) were artificially incubated with careful monitoring to identify factors contributing to the low hatch success reported by the Ontario Trumpeter Swan Restoration Program. Fertility was > 80% in both years, whereas hatch success of fertile eggs was 14.3% (n = 4) of 28 eggs in 1993 and 37.1% (n = 13) of 35 eggs in 1994. Necropsy of non‐viable eggs indicated a high incidence of embryonic mortality during early and late incubation. Early embryonic mortality was associated with egg storage times exceeding 7 days (P < 0.05) and bacterial contamination of eggs (P < 0.01). Late mortality was associated with (P < 0.001) increased weight loss during incubation period and may have resulted from incubator temperature and humidity fluctuations. We established patterns of weight loss for eggs and determined that hatched eggs lost 11–15% of initial mass and that weight loss >15% resulted in embryo mortality. Results from this study indicate that collection and handling of eggs before incubation and precise control of the incubator environment are critical to hatchability of eggs. Zoo Biol 18:403–414, 1999. © 1999 Wiley‐Liss, Inc.     

CLUTCH SIZE, EGG SIZE, HATCH WEIGHT AND LAYING DATE IN RELATION TO EARLY MORTALITY IN RED GROUSE LAGOPUS LAGOPUS SCOTICUS CHICKS

Clutches of Red Grouse eggs were collected from the wild and subsequent hatching and rearing done in standard conditions in captivity. Variations in chick survival from one clutch to another in the same year were related to differences in hatch weight. Hatch weight was determined only partly by egg size. Weight loss between laying and hatching was related to survival independently of egg size. Variation in this weight loss obscured any simple relationship between egg size and survival, except in eggs laid by captive hens. Intrinsic differences amongst hens caused some variations in laying date, egg size, hatch weight and chick survival. Variations in egg size and hatch weight accounted for less than half the variation in survival; other unmeasured intrinsic factors were also important. Big clutches hatched earlier than small ones. The commonest clutches were of seven and eight eggs, with six and nine frequent. Very big clutches of ten or more eggs were infrequent and chicks from them sometimes survived worse than from smaller clutches. As in other species, the commonest clutch sizes were not the most productive. There was no simple relationship between egg size and clutch size.     

Effect of elevated carbon dioxide on chicken eggs during the early and late incubation periods

Carbon dioxide (CO₂) is always maintained at ambient levels by ventilation in commercial egg incubators. However, elevated CO₂ levels during the early and late periods have been reported to improve the quality of chicks and shorten the hatch window. This study investigated the effect of precise CO₂ supplementation during the early and late periods of incubation on embryo growth and incubation performance by developing and using a CO₂ supplementation system to increase the CO₂ level in an experimental egg incubator. The CO₂ level was maintained at 1% in the early period (from the beginning to the 10th day of incubation, E0–E10) and in the late period (from internal pipping (IP) to the 21st day of incubation (E21), IP–E21) in an incubator for the treatment group, whereas the CO₂ level was maintained at the ambient level in the other incubators for the control group. A comparative assessment of embryonic development, hatching characteristics, and hormone and nutrient levels was conducted for each trial. The experiment comprised three trials, with 300 Jing Hong No. 1 breeding eggs in each incubator. The elevated CO₂ treatment significantly shortened the chick hatching time (H0) by 4 h (P < 0.05) and the hatch window by 3 h (P < 0.05) without affecting hatchability, chick weight at 1 d of age, brooding period, or quality score. At external pipping (EP), the heart weight, intestinal weight, relative intestinal weight, and relative heart weight in the treatment group were significantly higher than those in the control group (P < 0.05). In addition, the embryonic intestine, relative intestine, and relative heart weights of the newly hatched chicks in the treatment group were significantly higher than those in the control group (P < 0.05) at H0. The treatment significantly increased the concentration of corticosterone in the embryonic plasma during the period from IP to EP (P < 0.05), promoted the secretion of triiodothyronine and tetraiodothyronine (P < 0.05), and increased the glycogen content of the embryonic liver on E21 (P < 0.05). This result indicates that elevated CO₂ (1%) during the early and late periods of incubation accelerated embryonic organ development and shortened the chick hatching time and hatch window without affecting hatchability or hatchling quality, which can be explained by the synergistic functions of the secretion of plasma corticosterone and thyroid hormones and the accumulation of liver glycogen between the early and late periods of incubation.     

Physiological status of broiler chicks at pulling time and the relationship to duration of holding period

Newly hatched chicks may be held longer than 48 h and experience long periods of fasting in commercial hatcheries. Limited information is known about the physiological status of chicks in such situations, due to the difficulty of precisely recording time of hatch. This study investigated the effect of the time from hatch to pulling (holding period) on physiological measures/parameters in 109 broiler chicks. Fertile Ross 308 eggs were incubated in a custom built small-scale incubator. The individual hatching time of each focal chick was determined using eggshell temperature monitoring. At ‘pulling’ (512 h of incubation time), the quality of focal chicks was assessed using the chick scoring method and physiological parameters were measured including BW, organ (heart, liver and stomach) weights, blood values and plasma corticosterone level. The time from hatch to pulling varied from 7.58 to 44.97 h. Egg weight at setting was significantly correlated with chick BW and weight of organs at pulling, but had no effect on chick quality, blood values and plasma corticosterone. Relative BW at pulling was negatively associated with the duration of holding period (P=0.002). However, there was a positive correlation between relative stomach weight and the duration of the holding period (P<0.001). As the holding period duration increased, there was a trend that blood partial pressure of oxygen, haematocrit and haemoglobin also increased, and blood partial pressure of carbon dioxide, total carbon dioxide and bicarbonate decreased (P<0.05). A wide range of plasma corticosterone was observed from chicks that had experienced different durations of holding period. We conclude that shortening the hatch window and minimising the number of chicks that experience a long holding period before pulling may improve chick quality and physiological status, which may be due to unfavourable environmental conditions that include feed and water deprivation.     

NOTES ON THE BIRDS OF THE CAPE L'AGULHAS REGION

Gargett, V. 1982. Synchronous hatching and the Cain and Abel struggle in the Black Eagle. Ostrich 53:147-150.

An experiment was conducted to cause two Black Eagle Aquila verrreauxii chicks to hatch synchronously. There was ample food on the nest and the female offered it to both chicks, but the smaller chick, from the smaller second-laid egg, died. The greater reach of the chick from the first-laid egg enabled it to obtain more of the food offered, so that it gained weight. Its greater mass then enabled it to prevent its sibling from taking food. Both chicks showed aggression, but that of the heavier chick was more effective.     

Rapid and improved method for windowing eggs accessing the stage X chicken embryo

The chick stage X blastoderm is routinely accessed through a small window in a freshly laid egg. However, windowing severely compromises embryo survival with hatch rates as low as a few percent. We previously reported a simple modification to the standard method that reduced introduction of air into the sealed egg and improved the hatchability to 32%. Here, we describe an even simpler and more rapid method for sealing a windowed egg using hot glue or paraffin in which the hatch rate increased to an average of 63% of the unwindowed control eggs. The primary reason for low hatchability can be attributed to air trapped within the egg during windowing and/or leakage during incubation, as shown by increased lethality by artificially introducing air into windowed and sealed eggs. Although the hatch rate was considerably improved, air can still enter the egg during incubation and is likely to account for less than 100% hatchability of the sealed eggs. The success of this new windowing method will facilitate high throughput for the production of transgenic birds and find use in developmental biology, toxicity testing, and avian disease research.     

Effects of short term exposure of eggs to magnetic field before incubation on hatchability and post-hatch performance of meat chickens

The effects of exposing meat-type breeder eggs to magnetic field (MF) before incubation on hatchability traits (percents of hatchability and hatchability failures of eggs), chick weight at hatch, and post-hatch performance (weight gain, feed intake, and feed conversion ratio (FCR)) from 1 to 39 d of age were investigated. Eggs from a Ross flock at 38 weeks of age were exposed to MF of 18 Gauss (1.8 mT) at 50 Hz for 0, 15, 30, 45, 60, and 75 min (MF0, MF15, MF30, MF45, MF60, and MF75) before incubation.Exposing eggs to MF did not influence hatchability of eggs and chick weight at hatch. However, chickens of MF60 and MF75 treatments had lower weight gain and feed intake than those of the non-exposed treatment at 39 d of age. MF exposure of eggs did not influence FCR of chickens between 1 and 21 d of age, but tended to increase FCR, albeit non-significantly, between 22 and 39 d of age.It is concluded that exposing meat-type breeder eggs to MF of 18 Gauss (1.8 mT) at 50 Hz for up to 75 min did not influence hatchability traits and chick weight at hatch. However, MF exposure of eggs for 60 and 75 min reduced body weight gain and feed intake of chickens over the 39-d experimental period.     

In ovo silver nanoparticle supplementation for improving the post-hatch immunity status of broiler chickens

Silver nanoparticles (AgNano) are known for their unique physical, chemical and biological properties, enabling cell penetration and anti-inflammatory response. In Experiment 1, the effect of an in ovo administration of AgNano (15 µg/egg; n = 360) at different incubation times (d 7 and d 18) on hatchability parameters was explored. In Experiment 2, post-hatch performance of broilers (42 d, n = 250) was studied after in ovo AgNano administration: Group T1 remained un-injected, Group T2 was the sham control and Groups T3, T4 and T5 were injected with 12.5, 25 and 50 µg AgNano, respectively, at 18 d of incubation. Chick weight, chick to egg weight ratio and hatchability as well average daily gain, average daily feed intake and feed conversion ratio were similar in all treatment groups. No variation was seen in the weight of thymus; however, the bursa and spleen weight was increased (p < 0.05) in Groups T4 and T5 in comparison to Group T1. The in vivo immune response to phytohaemagglutinin-P was increased in Group T3 in comparison to Groups T1 and T2 (p < 0.05), while the response to sheep red blood cells was increased in all AgNano-treated groups in comparison with Group T1 (p < 0.01). The expression of toll-like receptors 2 and 4 genes was up-regulated in AgNano groups in comparison with Groups T1 and T2 (p < 0.01). In summary, an in ovo supplementation of AgNano carried out at d 18 of incubation is effective and modulates the post-hatch immune response without affecting the hatchability, growth and other performance parameters in broilers.     

A Meta-Analysis of Experiments Linking Incubation Conditions with Subsequent Leg Weakness in Broiler Chickens

A series of incubation and broiler growth studies were conducted using one strain of broiler chicken (fast feathering dam line) observing incubation effects on femoral bone ash % at hatch and the ability of the bird to remain standing at 6 weeks of age (Latency-To-Lie). Egg shell temperatures during incubation were consistently recorded. Parsimonious models were developed across eight studies using stepwise multiple linear regression of egg shell temperatures over 3-day periods and both bone ash at hatch and Latency-To-Lie. A model for bone ash at hatch explained 70% of the variation in this factor and revealed an association with lower egg shell temperatures during days 4–6 and 13–15 and higher egg shell temperatures during days 16–18 of incubation. Bone ash at hatch and subsequent Latency-To-Lie were positively correlated (r = 0.57, P<0.05). A model described 66% of the variation Latency-To-Lie showing significant association of the interaction of femoral ash at hatch and lower average egg shell temperatures over the first 15 days of incubation. Lower egg shell temperature in the early to mid incubation process (days 1–15) and higher egg shell temperatures at a later stage (days 16–18) will both tend to delay the hatch time of incubating eggs. Incubation profiles that resulted in later hatching chicks produced birds which could remain standing for a longer time at 6 weeks of age. This supports a contention that the effects of incubation observed in many studies may in fact relate more to earlier hatching and longer sojourn of the hatched chick in the final stage incubator. The implication of these outcomes are that the optimum egg shell temperature during incubation for broiler leg strength development may be lower than that regarded as ideal (37.8°C) for maximum hatchability and chick growth.     

Factors affecting piping plover hatching success on Long Island,New York

Low hatching success may limit progress towards reaching productivity goals for Atlantic Coast piping plover (Charadrius melodus) recovery, despite management strategies to protect eggs from predators and decrease human disturbance of birds on nests. We measured piping plover hatching success on Eastern Long Island beaches and identified the major causes of egg failure to better understand why eggs that were otherwise intact (not depredated or destroyed by tidal flooding) failed to hatch. We documented egg and nest fates, dissected contents of unhatched eggs to determine viability, and recorded human and predator activity near a subset of plover nests on Suffolk County Parks properties. The low hatching success we recorded (0.60) in 2006 and 2007 would require higher chick survival rates than are typically observed for piping plovers to meet recovery targets for productivity. Few eggs showed signs of poor viability and overall egg hatchability was comparable to other ground nesting birds. Most egg failure was due to either depredation at unexclosed nests or nest abandonment by adults. The best predictor of nest abandonment was the maximum number of red fox tracks (Vulpes vulpes) counted on nearby transects (β = −1.16, 95% CI: −2.0 to −0.3) and we found evidence that plovers abandoned eggs in response to predation risk (e.g., a fox circling a nest exclosure). Adults from abandoned nests may have deserted eggs or been depredated. In either case, intact and viable eggs were abandoned. Nest abandonment was not related to human activity near nests, which were buffered from human disturbance by symbolic string fencing. Our results suggest that depredation and nest abandonment (e.g., desertion or death of adults) due to predator disturbance, not human disturbance or poor egg viability, contributed to the low hatching success we recorded. Active predator removal in addition to modification of predator exclosure use and design may be necessary to prevent direct (egg depredation) and indirect (nest abandonment) negative effects of predators on hatching success. © 2010 The Wildlife Society.     

Parental Nutrition and Chick Production in Captive Willow Ptarmigan (Lagopus L. Lagopus)

The breeding performance of captive willow ptarmigan on different diets has been studied. The nutritional factors tested were protein concentration, natural feed supplement and grass meal and flavonoid admixture, and effects on egg numbers, fertility, hatchability, chick weights at hatching and 0–14 days mortality have been recorded. The breeding performance of ptarmigan hen in captivity showed great individual variations. Egg numbers were not statistically different in groups fed the different diets. Hens fed a 15 % crude protein died tended to produce smaller chicks with significantly lower viability than chicks from hens fed a 20 % crude protein diet. Supplement of natural feed tended to increase the number of chicks hatched through a combination of tendency to higher egg numbers and improved fertility. These tendencies were, however, statistically nonsignificant. Inclusion of 34 % grass meal to the diet also tended (non-significantly) to improve fertility and hatchability, while inclusion of flavonoids had no positive effect on reproduction. Eggs from captive hens showed significantly lower fertility, and a tendency to lower hatchability than eggs from wild hens. The former difference was probably caused by the close cage confinements for the captive ptarmigan, while the latter condition probably was due to different start of incubation, most of the eggs from wild hens being started naturally.     

The nematicidal potential of local Bacillus species against the root-knot nematode infecting greenhouse tomatoes

Bacillus spp. were isolated from Iranian tomato fields and evaluated for their efficacy against root-knot nematodes, Meloidogyne javanica. The 52 spore-forming bacterium isolates were obtained from tomato rhizosphere following heat treatment. Eight isolates were chosen based on their potency in prevention of M. javanica egg hatch and juvenile mortality and production of proteolytic enzymes in Petri plates. Their ability to form biofilms were also determined in pot experiments. According to phenotypic traits and 16s rDNA sequencing, all selected isolates belonged to Bacillus spp. including B. cereus and B. pumilus. Treatment with bacterial culture filtrates in vitro caused juvenile mortality of 72 to 99% after 48 h. After four days, the percentage of egg hatch ranged from 1.6 to 59% depending on the isolate. Bacillus pumilus (ToIr-MA) and Bacillus sp. (ToIr-10) were found to have significant ability to produce extracellular proteases and to form maximum biofilm, considerably reducing the number of egg masses and root gall index (P = 0.05) in comparison to untreated plants. Application of ToIr-MA and ToIr-10 enhanced the fresh and dry weights of shoot and root systems. There was significant enhancement in dry root weight (45 and 50%) and shoot weight (67 and 75%). Results suggest that these two Bacillus spp. have potential as biocontrol agents against root-knot disease in tomato production.     

Reproductive Biology of Captive Green Sea Turtles Chelonia mydas

A captive colony of green sea turtles, Chelonia mydas, has beenmaintained and observed at a commercial sea turtle farm on GrandCayman Island, B.W.I., since 1973. Observations of this breedingcolony show that the mating and nesting behaviour of the captivegreen sea turtle is similar to that observed in wild populations.Evidence indicates that mating observed prior to a female'snesting in a given season determines the hatchabilityof thatseason's egg production. Annual per female egg production ofthe captive colony appears to be two to five times greater thanthat reported for wild colonies. Observations on the reproductivebiology of green sea turtles hatched and raised under farm conditionssuggests that the minimum age of sexual maturity is eight tonine years of age. The number of eggs per nest, the number ofnests per season per female and hatch rate tend to increasewith successive seasons nesting for these turtles reaching sexualmaturity.     

The reproductive traits of brown trout (Salmo trutta fario L.) from the Yadong River, Tibet

Some key aspects of the reproductive strategy of the brown trout (Salmo trutta fario L.) in the Yadong River, Tibet, including spawning season, age at sexual maturity, fecundity and egg size, have been studied. The majority of the samples were less than 215 mm and age ranged from 1 to 4 in both sexes, indicating that the majority of the fish were younger and the pressure by overfishing was high. The spawning periodicity was determined to be between the end of October and January, mainly in November and December. The ratio of male to female brown trout population (1.29:1 with P > 0.05) suggested no sex significant differences, although males were significantly more abundant than females in October (P < 0.0001) on monthly basis. Age and size of males and females at maturity was different and males matured earlier than females. Fecundity was markedly correlated with their body weight (P < 0.001, r = 0.9255), standard length (P < 0.01, r = 0.8879), and gonad weight (P < 0.001, r = 0.9366). The mean size of mature eggs in the spawning season was: 4.0 ± 0.45 mm and tended to increase along with the female spawners size (P < 0.001, r = 0.9641). Further researches about the brown trout population in the Yadong River should be conducted on issues such as artificial reproduction, culture, conservation, management, and restocking.     

Viability and behaviour of translocations that suppress female recombination in the Mediterranean fruit fly,Ceratitis capitata (Wied.)

Summary The viability of a series of recombination suppressor (RS) strains in Ceratitis capitata, all previously found to contain a reciprocal autosomal translocation, was assessed for egg hatchability and adult emergence in both the homozygous and heterozygous state. Except in T 30C, which contains a Y-autosome translocation in addition to the A-A translocation, egg hatch was significantly reduced in all heterozygous translocation strains, and ranged from 42.4% to 58.5% in seeded eggs compared to a control value of 82.8%. Adult emergence from hatched eggs was affected to a lesser extent, but with a range of 59.5% to 84.2%, compared to the control value of 83.1%, remained significantly reduced in 4 of the 6 translocation strains, as well as in the male line of T 30C. In the homozygous configuration all strains, except T 19 and T 109, showed a significant reduction in egg hatchability, whereas adult emergence was not adversely affected. A significant reduction in the egg hatchability of the translocation heterozygotes compared to that of the homozygotes was observed in 5 of the 7 strains, the observed reduction in T 55/109 being non-significant while that of T 30C was significantly increased. The behaviour of translocations as recombination suppressors and their suitability for inclusion in breeding schemes for the isolation of induced recessive mutations is discussed.This work forms part of a Joint FAO/IAEA research programme on the development of genetic sexing mechanisms for the Mediterranean fruit fly, Ceratitis capitata (Wied.)     

Provisioning and growth in chicks of Wilson's storm-petrels (Oceanites oceanicus) on King George Island, South Shetland Islands

We present data on chick growth and chick feeding in Wilson's storm-petrel (Oceanites oceanicus) in a colony on King George Island, South Shetland Islands. Chicks were repeatedly weighed and the weight differences over 24 h were corrected for metabolic loss in order to obtain an estimation of meal sizes. Chicks were fed on 93% of the nights (n=688 nights). The average meal size for a single feeding was 8.5 g. Chicks received on average 1.2 feedings per night. These results are compared with data for this species from other locations. There was a trend for increased meal sizes from northern to southern populations, parallel to an increase in the adult mass, indicating that Wilson's storm-petrels carry optimal meal sizes according to their body size and may take advantage of increased food abundance by increasing feeding frequencies. We describe chick growth and discuss the influence of egg size, hatching date and feeding frequency on chick growth. The egg size had a positive influence on tarsus growth and body mass of chicks. Later-hatched chicks started wing growth and finished mass growth at a younger age and reached lower peak masses, indicating that late chicks may adapt to the restricted breeding season in their Antarctic breeding grounds by a more rapid development, but will fledge with a lower degree of development and less resources. Accepted: 22 May 2000     

Differences in Fecal Androgen Patterns of Breeding and Nonbreeding Kori Bustards (Ardeotis kori)

To better understand breeding conditions to promote reproduction in captive kori bustards, fundamental endocrine studies measuring fecal androgen metabolites in male and female kori bustards were conducted. Feces collected weekly from males and females were analyzed for testosterone using enzyme‐linked immunoassay. Results from adult males (n = 5), adult females (n = 10), immature males (n = 10), and immature females (n = 10) revealed seasonally elevated testosterone concentrations in fertile, but not nonfertile adult males and females (P > 0.05). Adult females that were not maintained in a breeding group, or that did not produce eggs, did not demonstrate increases in testosterone compared to egg laying counterparts. In males, but not females, seasonal testosterone increases were accompanied by weight gain. Peaks in male fecal androgen metabolites ranged from 10‐ to 22‐fold higher than nonbreeding season (181.5 ± 19.1 vs. 17.0 ± 0.94 ng/g; P < 0.05). Mean breeding season values for adult males were 83.6 ± 6.1 ng/g vs. nonbreeding season values of 12.3 ± 0.73 ng/g (P < 0.05). In females, average breeding season testosterone concentrations were approximately 4‐fold higher than nonbreeding season (55.9 ± 6.0 vs. 14.5 ± 1.8 ng/g), with peaks 10‐ to 30‐fold higher. Results show that noninvasive fecal androgen metabolite analysis can provide a means of predicting fertility potential of male and female kori bustards and might be utilized to assess effects of modifying captive environments to promote reproduction in this species. Zoo Biol. 32:54‐62, 2013. © 2012 Wiley Periodicals, Inc.     

Unexpected weight gain in resident Antarctic Terns Sterna vittata during the austral winter

Antarctic Terns Sterna oittata (Fig. 1) may display two very different migratory behaviours. According to Cooper (1976), the terns breeding on Tristan da Cunha in the South Atlantic fly thousands of kilometers to the coasts of Africa where they moult. Antarctic Terns that inhabit the more southern and colder Antarctic Peninsula region moult on their breeding grounds. An early account of these seemingly resident peninsular terns (Holdgate 1963) leaves little doubt that at least part of the tern population wintered in the vicinity of Arthur Harbor (64°46′S 64°03′W), Anvers Island, west of the Antarctic Peninsula. Watson (1975) stated that adult Antarctic Terns are generally sedentary around many insular breeding stations, moving only to the nearest open water in winter. During the year 1975 through 1978, 19 tern specimens of different sexes and ages were collected at Arthur Harbor in the non-breeding season near U.S. Palmer Station. An additional eight terns were collected at a sea short distance from Anvers Island during the non-breeding season in 1985 (Pietz & Strong, in press). I found that the adult birds taken at the height of winter weighed significantly more than the 150-180g of a normal breeding Antarctic Tern. This unexpected discovery prompted me to examine the weights of an additional 34 specimens that had been collected at or near Anvers Island during several breeding seasons. By comparing the weights of adult terns by sex, age, and collection date (Fig. 2, Table 1) I found that both males and females weighed significantly more in the winter non-breeding season (April-September) than in the summer breeding season (October-March) (t₂₄= 6.57, P < 0.001, and t₁₆= 5.71, P < 0.001, respectively). No significant differences were detected between male and female weights in summer(t₂₃=0.76, P >0.20) or winter (t₁₇=1.16, P0.20). In short, it appears that body-weights of adult terns rise rather dramatically following breeding, attain a peak in mid-winter, and then fall at the approach of the next breeding season (Fig. 2). I suggest that this increased body-weight is an adaptation to the austral winter rather than simply a recovery from weight loss due to energetic costs of breeding and moulting.