Seasonal changes of reproductive behavior and fecal steroid concentrations in Père David's deer.

From July 1997 to September 1997 and from March 1998 to July 1998, we studied reproductive behaviors of Père David's deer in Dafeng, China. During the field behavioral observations, we collected fresh voided fecal samples from the Père David's stags and hinds periodically and kept those samples under -20 degrees C until laboratory analysis. We analyzed the fecal testosterone, estradiol, and progesterone concentrations in those samples using radioimmunoassay. During this study, we also recorded 17 types of male reproductive behaviors and nine types of female reproductive behaviors. Reproductive behaviors and the fecal steroid concentrations showed overt seasonal fluctuations. There were statistically significant correlations between some male reproductive behaviors, such as anogenital sniffing, urine sniffing, urine spraying, wallowing, bellowing, antler adorning, Antler swags mud, chasing, herding hinds, chin resting, mounting and copulating, with the fecal testosterone concentrations. These results suggested that seasonal reproductive behaviors in stags are strongly associated with circulating testosterone. We also found that some female reproductive behaviors fluctuate corresponding with changes in fecal estrogen concentrations. Although there was no direct evidence to confirm the correlations between female reproductive behaviors and fecal estrogen in our experiment, we could not rule out that reproductive activities of hinds were largely related to ovarian estrogen secretion, and estrogen is necessary for inducing female reproductive behaviors.     

Seasonal changes in fecal testosterone concentrations and their relationship to the reproductive behavior, antler cycle and grouping patterns in free-ranging male Pampas deer (Ozotoceros bezoarticus bezoarticus)

The purpose of this study was to validate noninvasive endocrine monitoring techniques for Pampas deer and to evaluate seasonal changes in testicular steroidogenic activity and their correlation to reproductive behavior, antler cycle and group size. Thus, fecal samples, behavioral data and observations of antler status were collected at monthly intervals during 1 year from free-ranging Pampas deer stags (three radio-collared individuals and 15 random individuals) living in Emas National Park, Brazil (18 degrees S latitude). Fecal steroids were extracted using 80% methanol and steroid concentrations were quantified by a commercial enzyme immunoassay (EIA). Fecal testosterone concentrations peaked in December-January (summer), March (early autumn) and in August-September (winter-spring), with minimal values from April-July. Reproductive behavior had two peaks, the first in December-January, characterized by predominately anogenital sniffing, flehmen, urine sniffing, chasing and mounting behavior, and the second peak in July-September (behavior primarily related to gland marking). There were significant correlations between fecal testosterone and reproductive behavior (r=0.490), and between fecal testosterone and antler phases (r=0.239). Antler casting and regrowth occurred under low testosterone concentrations, whereas velvet shedding was associated with high concentrations of testosterone. We inferred that Pampas deer stags exhibited a seasonal cycle that modulated sexual behavior and the antler cycle, and we concluded that fecal steroid analysis was a practical and reliable non-invasive method for the evaluation of the endocrine status of free-ranging Pampas deer.     

雄性麋鹿的交配机会、社会等级和皮质醇水平

我们在北京麋鹿苑研究了发情期雄性麋鹿的社会行为、社会等级和血清皮质醇水平,并分析了三者间的相互关系。按照雄性麋鹿的行为,将雄性麋鹿分为优势群和从属群。优势群包括群主和挑战者,从属群包括单身汉和被淘汰群主。使用SJ—Ⅰ型事件记录器进行常规行为取样,用放射免疫分析法测定血清皮质醇含量。发现：(1)优势雄鹿的发情行为频次明显高于从属雄鹿;(2)攻击行为的发生频次在两组间无显著差异;(3)血清皮质醇含量在两组间也无显著差异。由此我们认为,发情期雄性麋鹿的社会等级序位影响许多行为的表达,优势雄鹿成功交配的机会比从属雄鹿多。而攻击行为和肾上腺皮质醇的分泌与社群等级无明显相关,可能是麋鹿在圈养状态下的一种适应策略,这将有利于缓解发情期雄鹿的紧张,从而允许更多的能量投放在发情交配上。     

Requirement of thyroid function for the expression of seasonal reproductive and related changes in red deer (Cervus elaphus) stags.

The effect of thyroid function on regulation of seasonal reproduction was investigated in three red deer stags thyroidectomized (THX) in summer (January 1988) in comparison with five thyroid-intact controls. Responses of luteinizing hormone (LH) and testosterone to a bolus injection of 10 micrograms gonadotrophin-releasing hormone (GnRH) were tested in July, October, December, February and April. Blood samples were collected at weekly intervals from December 1987 to June 1989 for measurement of testosterone, triiodothyronine (T3) and prolactin concentrations. Testis diameters were measured every 2 weeks. In October 1988 (spring), plasma LH concentrations of control stags were less responsive (P less than 0.01) to stimulation by GnRH than those of THX stags; plasma testosterone concentrations and testis diameters were low and there was no increase in plasma testosterone concentrations after injection of GnRH in control stags during October or December (spring, early-summer). In contrast, THX stags maintained a testosterone response (P less than 0.01) in these 2 months and did not exhibit any signs of a seasonal lack of reproductive activity at this time of year. Control stags cast antlers in spring whereas THX stags maintained hard antlers throughout the study. Concentrations of plasma T3 were not detected in THX stags from June 1988 onwards, but exhibited a seasonal pattern in control stags, with low concentrations during autumn and winter (April to July) and high concentrations in spring and summer (August to February). There was no effect of thyroidectomy on the seasonal pattern of prolactin secretion.(ABSTRACT TRUNCATED AT 250 WORDS)     

雄性小熊猫粪便中睾酮水平的变化与繁殖周期的关系

1999 年12 月至2000 年9 月, 使用放射免疫分析法, 测定了成都动物园和成都大熊猫繁育研究基地的4 只雄性小熊猫粪样中睾酮水平变化情况, 同时对其行为进行了观察。研究结果表明, 雄性粪样中睾酮水平在繁殖期(12 月～3 月) 显著高于非繁殖期(4 月～9 月) (P < 0.01) , 且睾酮水平变化与繁殖行为密切相关。在非繁殖期,雄性小熊猫的睾酮水平处于基础的较低水平时, 其繁殖行为如蹭阴、舔阴、舔标记物和咩叫等几乎没有发生或很少发生; 而在繁殖期, 雄性小熊猫的睾酮水平明显升高, 这些繁殖行为频繁发生。以上结果说明, 睾酮是调节雄性小熊猫繁殖行为季节性变化的生理因子。     

Seasonal dynamics of agonistic behavior and hormones in an ex situ all‐male colony of large flying foxes

Large flying foxes (Pteropus vampyrus) are a socially complex species. In situ colonies typically comprise thousands of individuals in small harems of one male to many females. In ex situ environments, all‐male colonies are becoming more common due to a surplus of males in the population. There is limited information describing the hormonal and behavioral patterns of all‐male colonies during the breeding season. We assessed seasonal changes in hormones and behavior in an all‐male colony of 12 large flying foxes at Disney's Animal Kingdom^®. We validated hormone assays using morning urine and fecal samples to assess seasonal changes in excreted immunoreactive testosterone and glucocorticoid metabolites. We collected behavior data using an all‐occurrence method, recording agonistic behaviors related to territorial defense (hooking, biting, wing flexing, vocalizing, and wrestling), and sexual behavior (mounting and frontal grabbing). Results indicated that (i) we could reliably measure testosterone and glucocorticoid metabolites concentrations from fecal and urine samples collected from individual bats; (ii) there were distinct relationships between changes in levels of agonism and hormone concentrations throughout the year; and (iii) three agonistic behaviors (chasing, wrestling, and open‐mouth threat) peaked prior to the increase in testosterone and glucocorticoid hormones measured during the breeding season. These three behaviors could potentially be used as early indicators to signal the onset of the breeding season and allow time to implement ex situ management changes to reduce the incidence of agonism between individuals.     

Non-invasive assessment of reproductive status in Chinese water deer (Hydropotes inermis): Correlation with sexual behaviour

The annual reproductive cycle of Chinese water deer (Hydropotes inermis), a nearly threatened small cervid species, was studied by means of fecal steroid analysis coupled with behavioural observations. Data showed a clearly seasonal reproductive pattern. In adult males, the onset of androgen secretion, in October, was concomitant with the first manifestations of territoriality. Androgen metabolites concentrations reached significant peak values in December, when matings occurred. In mature females, there was a close synchrony in reproductive states: lactational/seasonal anoestrus from June to November, pregnancy from December to May. Fecal progesterone metabolites profiles suggested that silent ovulations occurred at the onset of breeding season and that females conceived at their first ovulation with behavioural estrus. The female sexual receptivity state might last only a few hours. High levels of sniffing, parades and pursuits, concomitant of the highest concentrations of androgen, could allow the males to detect the furtive estrus in the females present in their territory. We concluded that the non-invasive method applied for the first time in this species was useful for the evaluation of the endocrine status and its relation with behaviour.     

Relationship between Serum Testosterone, Dominance and Mating Success in Père David's Deer Stags

We conducted an experiment in the Beijing Milu Park to study the social behavior of male Père David's deer, and related social behavior to social position and serum testosterone level of the stags during rut. We classified the stags into three rank classes according to their rutting behavior: ‘harem master’, ‘challenger’ and ‘bachelor’. We monitored the behaviors of four ‘harem masters’, five ‘challengers’ and five ‘bachelors’, and analyzed serum testosterone levels in blood samples of those 14 stags using radioimmunoassay. We defined the effectiveness value, E = A/T, to assess the effectiveness of herding or mating attempts made by stags (‘T’ represents the frequency of herding or mating attempts made by a stag and ‘A’ represents the frequency of herding or mating attempts accepted by hinds). We found that: (1) the ‘harem masters’ and the ‘challengers’ displayed more frequent rut and locomotive behaviors but fewer ingestion behaviors than the ‘bachelors’; (2) serum testosterone levels in the ‘harem masters’ and the ‘challengers’ were higher than that in the ‘bachelors’; (3) effectiveness value of herding attempts differed significantly between the three types of stags, being highest in the ‘harem masters’ and the lowest in the ‘bachelors’; and (4) effectiveness value of mating attempts was significantly greater for the ‘harem masters’ than for the ‘challengers’. We conclude that: (1) reproductive behavior of the Père David's deer stags is strongly associated with social rank; (2) social roles of Père David's deer stags during the rut are related to the testosterone secretion; and (3) rank class affects the mating opportunity of the stags.     

Reproductive seasonality in female Iberian red deer (Cervus elaphus hispanicus)

This study characterized the seasonal pattern of luteal cyclicity in Iberian red deer (n=16), by measuring plasma progesterone concentrations in hinds (female red deer) twice per week from calving (May and June) 1996 until May 1997. In eight of these hinds we also examined plasma prolactin profiles to assess seasonal responses to photoperiod. Plasma progesterone concentration in the 16 hinds studied indicated that the reproductive pattern is seasonal, and lasts for 5.73 +/- 0.27 months. After calving, progesterone levels remained basal (no luteal activity) for several months, except in a hind that lost her calf just after calving, and thus did not have to suckle it. This hind showed two consecutive estrus cycles in the month following calving, which suggests that suckling has an inhibiting effect on the resumption of ovarian activity. These results also showed that as long as the hinds do not become pregnant, they show between 5 and 10 estrus cycles per reproductive season (8.06 +/- 0.35), ranging between 105 and 249 days from onset of the first cycle to end of the last one. Uninterrupted cycling lasted for 3.5-6.4 months (mean, 4.6 +/- 0.24). Cyclic luteal activity was found from October to February in all hinds, with a smaller, but notable proportion in September (56.25%) and March (68.8%), whereas it was negligible in the remaining period. Our results show a reproductive season similar to or longer than that recorded by other authors. Prolactin plasma concentrations showed a yearly trend following that of photoperiod, with peak concentrations from April to July, a decrease in August, minimal concentrations from September to February and a sharp increase in March.     

The reproductive endocrinology and behavior of Vancouver Island marmot (Marmota vancouverensis)

The Vancouver Island marmot (Marmota vancouverensis; VIM) is one of North America's most endangered species with fewer than 150 individuals remaining in the wild. A captive breeding program was established across four facilities in Canada as an insurance population and source of animals for reintroduction to the wild. The purpose of this study was to gather information about the basic reproductive biology and behavior of this species, which is essential to improve captive breeding programs. Regular fecal samples were obtained from adult female (n = 14) and male (n = 10) marmots, 2 years of age and older, over 1-3 breeding seasons (2-3 months duration posthibernation) for steroid hormone analysis. Enzyme immunoassays were validated for quantifying fecal testosterone metabolite concentrations for males, and fecal estrogen and progesterone metabolite concentrations for females. Results indicated that fecal progesterone metabolite concentrations can be used to monitor ovulation and pregnancy. Behavioral monitoring through infrared video surveillance was conducted in four breeding pairs over a 2-year period (n = 7 behavioral profiles). Breeding behaviors correlated strongly with changes in reproductive endocrine profiles. A high frequency of play behavior or "wrestling" was observed in conjunction with breeding activity before an elevation in progesterone metabolite concentrations. Impending parturition was associated with increased aggression and exclusion of the male from the maternal nestbox as well as an increase in nesting activity. Observational data combined with hormonal analysis suggest that female VIMs are induced ovulators and that multiple breeding attempts may be required for ovulation and conception. Gestation appears to be approximately 34 days from peak breeding activity (32 days from estimated ovulation). Fecal testosterone concentrations suggest that testicular activity is seasonal with the reproductive activity occurring immediately posthibernation. Monitoring breeding behavior is a useful means of indicating estrus, conception and pregnancy, which can also be supported by the hormonal analysis of daily fecal samples of individual animals.     

布氏田鼠在不同光周期下对陌生个体尿液和粪便的气味辨别

研究了成年布氏田鼠在10min内,对不同光照周期下（长光照：LD;短光照：SD）陌生雌／雄个体尿液和粪便两种单一个体气味源的气味行为反应,实验发现：所有雌雄被试鼠对LD气味源比SD气味源表现出更多的嗅闻行为。LD和SD被试鼠对同性／异性尿液气味的嗅闻行为没有表现出明显的差别,但LD被试雄鼠对陌生雌鼠粪便的嗅闻频次显多于SD被试雄鼠,从嗅闻行为特征量（嗅闻行为占所有行为的百分比）来看,所有LD和SD被试雌,雄鼠对尿液的嗅 明显多于粪便,除SD粪便气味外,被试鼠对异性气味源的嗅闻明显多于同性,实验结果表明：作为两种个体气味源,尿液和粪便都带有季节性信息,而且是具有性别特性的。异性的个体气味源比同性的个体气味源更具吸引力;长光照动物的个体气味比短光照动物的气味更具吸引力。     

Testing for Links Between Female Urine Odor and Male Sexual Behaviors in Japanese Macaques (<Emphasis Type="Italic">Macaca fuscata</Emphasis>)

Urine is involved in sexual communication in New World monkeys and lemurs, but most studies of the role of olfaction in sexual communication in Old World monkeys have focused on vaginal secretions rather than urine. We investigated whether female urine promotes male sexual behaviors (approaches and inspections of genital area) in Japanese macaques (Macaca fuscata). We used a sequential presentation paradigm in behavioral experiments, presenting unfamiliar female urine and control cotton swabs to males living in a social group with cycling females. We tested whether males (N = 3) showed more processing behaviors (licking, sniffing, tasting) toward female urine (22 stimuli per male from prefertile, fertile, and postfertile phases, based on urinary estrone and progesterone conjugate profiles) than control odor (8 stimuli per male). We then compared male sexual behaviors toward resident females pre- and post-exposure to stimuli and in relation to the females’ reproductive status (perifertile, nonfertile, and pregnancy periods, based on fecal estrone and progesterone conjugate profiles). We found that males showed significantly more processing behaviors toward urine stimuli than to controls but that male behavior did not vary across urine samples from prefertile, fertile, and postfertile phases. Exposure to unfamiliar female urine stimuli did not modulate male approaches to and inspections of resident females at any stage of the female reproductive cycle. Although our study is limited by its small sample size, the results suggest that female urine contains compounds that males detect, but we found no evidence that female urine is related to male sexual behaviors.     

Activity pattern, reproductive behaviors and gonadal hormones in the raccoon dog (Nyctereutes procyonoides)

The objectives of this study were to (1) assess year-round behaviors and activity patterns of captive raccoon dogs (Nyctereutes procyonoides) and (2) characterize the species' reproductive endocrinology. Behaviors and activity patterns of 12 (5.7) animals were recorded over a 1-year period. During that time, fecal samples were collected 2-7 times/week from 16 (7.9) individuals (six of these were included in the behavioral study) for the analysis of testosterone, progesterone and estrogen metabolite concentrations. Activity pattern and excretion of gonadal steroids followed a seasonal pattern. Specifically, dogs were cathemeral in summer, and primarily nocturnal in winter. In the males, testosterone concentrations were at baseline from April through September, began to rise in October and reached peak concentrations in February (P<0.05). In the females, elevated estrogen (P<0.05) was observed in March followed by an increase in progestagen concentrations from March through May (P<0.05) in both pregnant and pseudopregnant animals. Gender significantly influenced monthly testosterone/estrogen ratio (P<0.01); values were higher in males than in females throughout the year with overall percentage of overlapping values between males and females being 28%. In summary, this study characterized cirannual fluctuations in behaviors and gonadal steroid metabolites in the raccoon dog maintained in captivity. Because there is no obvious sexual dimorphism, the differences in testosterone/estrogen ratio may be useful for gender differentiation (72% accuracy), especially among individuals living in the wild.     

Excretion and measurement of estradiol and progesterone metabolites in the feces and urine of female squirrel monkeys (Saimiri sciureus)

The first objective of the present study was to determine the metabolic form and rate of excretion of ovarian hormone metabolites in the urine and feces of female squirrel monkeys injected with radiolabeled progesterone (Po) and estradiol. The major portion of the urinary metabolites of both hormones was excreted within 16-24 hr post-injection. Estrogen and Po isotopes in feces exhibited an excretion peak at 16 hr post-injection. The majority of recovered radiolabel of both hormones was excreted in feces. Chromatographic separation of fecal extractions indicated that the major estrogen metabolites in feces are in the free as opposed to the conjugated form. The radioactivity and immunoreactivity for estrone and estradiol (E(1) and E(2), respectively) in eluates of fecal samples subjected to celite co-chromatography indicated that both free E(1) and E(2) exist as excretion products in the feces of female squirrel monkeys. The major radioactive peaks for Po metabolites showed peaks in the elution profile at or very near the Po standard, and corresponded with the celite co-chromatography elution profile of Po standard when subjected to enzyme immunoassay (EIA). The second objective was to validate the application of EIA systems to measure fecal metabolites. Reproductive events of one female squirrel monkey across one annual reproductive cycle are described using the endocrine profile generated from fecal steroid assays. Examination of this profile confirmed that longitudinal fecal sampling and steroid hormone metabolite measurement in feces was not only feasible and practical, but accurately detected known reproductive events as well.     

Fecal steroid analysis of ovarian cycles in free-ranging baboons

This paper reports field and laboratory tests of serial sampling, solid phase extraction, and microradioimmunoassay methods for the collection, preservation, and analysis of fecal steroids. The field study was conducted in a troop of 87 yellow baboons (Papio cynocephalus) in the Tana River Primate Reserve, Kenya. Serial samples of four focal females and opportunistic sampling of 18 additional females over 22 days of sampling yielded a total of 62 samples, X = 3.1 ± 0.4/day, demonstrating the feasibility of regular field collection and extraction. Estradiol and progesterone concentrations in the field-extracted samples exhibited high recovery and statistically significant correlations (P < 0.05) with concentrations in the lab-extracted samples, suggesting that solid phase extraction could provide a useful alternative to freezing in sites where electricity or liquid nitrogen is not available. Tests of microradioimmunoassays demonstrated that these assays were sensitive, accurate, and precise when applied to the assay of fecal extracts, providing estimates of ovarian steroids that varied significantly with reproductive state. The demonstration that testosterone could be accurately and reliably assayed in fecal extracts suggests that these techniques also could be applied to the study of male reproductive function. Parallels between fecal profiles of cycling and pregnant baboons with patterns reported for serum steroids in baboons suggest that fecal steroids might be useful in distinguishing amenorrhea from early pregnancy in free-ranging baboons as well as in species lacking external indices of reproductive state. © 1995 Wiley-Liss, Inc.     

Urinary hormone analysis assists reproductive monitoring and sex identification of bell frogs (Litoria raniformis)

With the world currently facing a global amphibian extinction crisis, the development of techniques to help meet the needs of conservation managers and researchers studying the reproductive biology of amphibians is needed. Here, we developed enzyme immunoassays to measure estrone, testosterone, and progesterone hormone metabolites in the urine of Litoria raniformis, the southern bell frog. Concentrations of urinary estrone, testosterone, and progesterone increased during the breeding season for females (P < 0.05). Concentrations of urinary testosterone and progesterone increased for males during the breeding season compared with that for months where no reproductive behaviors were observed (P < 0.05). Furthermore, urinary estrone concentrations proved to be a reliable sexing tool for adult frogs, with no overlap between the sexes in 98% of cases, regardless of season. There was no difference in estrone (P = 0.204) or testosterone (P = 0.485) metabolite concentrations between samples taken immediately upon capture and those taken 12 to 24 h later from the same individual. Progesterone metabolite concentrations were lower on Day 2 than upon collection (P = 0.004). This is the first study to show that urinary hormone analysis can be a useful technique for reproductive monitoring in an amphibian. Additionally, hormone metabolite measures offer promise as sex identification tools for monomorphic species and for those whose secondary sex characteristics are visible only during the breeding season.     

Changes in Fecal Estrogen Levels and Sexual Behavior in Captive Sichuan Snub‐Nosed Monkeys (Rhinopithecus roxellana) Following a Male Replacement

Rhinopithecus roxellana are generally seasonal breeders, although copulation can occur throughout the year. Previous studies suggest that estradiol modulates female sexual behavior during the mating season. However, the effects of social context on estrogen levels and behavior have not been fully explored. We studied the relationship between sexual behaviors and fecal estrogens in a group of captive R. roxellana during a period of social instability. We collected behavioral data for six months and collected fecal samples at 2–3‐day intervals for four months spanning the mating and nonmating seasons, and analyzed fecal estrogen levels via RIA. Females showed clear cyclic solicitation and copulation peaks in the mating season, which corresponded with sharp peaks in fecal estrogens. During the nonmating season, solicitation rates, copulation rates, and fecal estrogens were generally low. However, one nonpregnant female displayed a sharp peak in solicitations, copulations, and estrogens during the nonmating season 10–14 days after a male replacement. Our results provide preliminary evidence that social and behavioral changes affect estrogen levels in R. roxellana. Zoo Biol. 32:342–346, 2013. © 2012 Wiley Periodicals, Inc.     

Induction of early rutting in male red deer (Cervus elaphus) by melatonin and its dependence on LHRH

Eight red deer stags, 2 control, 3 control-immunized (i.e. a low titre of LHRH antibodies after active immunization 2 years earlier) and 3 superior cervical ganglionectomized, were given a s.c. implant of melatonin in May at the nadir of the sexual cycle; 5 other stags remained untreated. All the melatonin-treated animals shed the velvet-like skin from the antlers in June or July at least 1 month before the untreated controls, and had an early increase in blood plasma testosterone concentrations. The treated stags were also precocious in the development of rutting behaviour, although this inductive effect was blocked dramatically in the control-immunized stags after a booster immunization against LHRH; these animals failed to show any further reproductive development and cast their antlers. It is concluded that continuous exposure to melatonin in early summer will induce premature seasonal testicular development, an effect dependent on the secretion of LHRH, and similar to that produced by exposure to short daylengths.     

Endocrine correlates of sexual behavior in the Mohor gazelle (Gazella dama mhorr)

In this study, we quantitatively examined male sexual behavior in relation to fecal estrogen and progesterone concentrations in female Mohor gazelles. We investigated the hypothesis that, during natural mating, males detect cues relating to the potential for successful conception and pregnancy. Time series analysis revealed that males could detect the approach of estrus 2-3 days before female fecal estrogens and estrogen/progestagen (E/P) ratio reached their peak values. Males also paid closer attention to those females excreting higher fecal estrogen concentrations. Mounting and copulation frequencies were positively correlated with both peri-ovulatory fecal estrogen concentrations, and the frequency of pre-copulatory courtship behaviors. These data suggested that males invest their reproductive effort selectively by mating the most fertile females, assuming that estrogen is a valid index of fertility. This assumption was investigated by examining sequential phases of the reproductive cycle for evidence that oocytes and follicles produced in a more estrogenic environment would lead to the formation of the most competent corpora lutea, thereby maximizing the chance of sustaining pregnancy. Associations between sexual behavior and hormone excretion support the hypothesis that males may use this mechanism to assess female fertility.     

Characterization of seasonal reproduction patterns in female pichis Zaedyus pichiy (Xenarthra: Dasypodidae) estimated by fecal sex steroid metabolites and ovarian histology

Reproductive strategies vary considerably among species, but most studies have focused on a very limited number of mammalian species. Knowledge of the reproductive cycle and behavior is essential for developing and implementing in situ and ex situ conservation strategies for threatened and endangered species. This study aimed at characterizing the seasonal reproductive pattern of female pichis Zaedyus pichiy, a threatened small armadillo native to arid regions of Argentina and Chile, through direct observations, histological studies, and by measuring fecal immunoreactive estrogens, progestagens and glucocorticoids in 10 wild-born, captive pichis and in free-ranging individuals. Results suggest that pichis are seasonal breeders that give birth to one yearly litter of 1–2 offspring, which do not leave the burrow until they are weaned at approximately 37 days. Ovarian follicular growth seems to occur throughout the year. Fecal progestagen, estrogen and glucocorticoid concentrations were minimal during the first half of pregnancy, increased to peak concentrations of up to 3500, 200 and 200 ng/g dry feces, respectively, and decreased before parturition. Postpartum progestagen concentrations were greater in lactating females than females that aborted or did not raise their offspring (p < 0.0001), which is probably related to an elevated corticosteroid synthesis that contributes to maintain lactation, given that fecal glucocorticoid concentrations were of similar pattern. Observations of a second pregnancy after late abortion or death of the newborn litter and sustained follicular growth during pregnancy and lactation suggest that female pichis can become receptive briefly after having lost their litter. Fecal estrogen and progestagen concentrations of non-pregnant, non-lactating females did not have a well-defined hormonal cyclic pattern, and corpora lutea were only observed in pregnant females.