Under the project of "Human-Led Migration," the authors had the unique opportunity to accompany hand-raised northern bald Iibises (NBIs; Geronticus eremita) during migration, which occurred in stages from Bavaria, Germany, to southern Tuscany, Italy. The aim of this study was to investigate the immediate effects of flight, with respect to flight duration, and the more delayed recovery effects on hematologic variables. A total of 31 birds were sampled. Blood samples were taken immediately before takeoff, after landing, and 1 day after the flight. Hematocrit was determined and blood smears were prepared to estimate the total white blood count (tWBC) with leukocyte concentrations (absolute [abs.]) and differential blood cell count (%). Postflight, significant decreases in hematocrit, tWBC, lymphocytes (abs., %), heterophils (abs.), eosinophils (abs., %), and monocytes (abs.) were observed. In contrast, heterophils (%), basophils (%), and the heterophil/lymphocyte (H/L) ratio increased significantly. With increasing flight duration, the H/L ratio increased further. One day postflight, there were still significant decreases in tWBC, lymphocytes (abs.), and eosinophils (abs., %) and significant increases in heterophils (%) and the H/L ratio. The hematocrit dropped even further. These data show that the decrease of tWBC is mainly caused by the lymphocyte fraction and that NBIs need more than 1 day to reverse the postflight changes in some hematologic values. Hematocrit changes postflight and on the recovery day are most likely to be explained by hemodynamics and the metabolic and hormonal changes caused by flight. The hematologic changes postflight in NBIs were largely consistent with those of other birds, but they differed from humans and mammals postexercise mainly in the levels of tWBC, heterophils (matching neutrophils in mammals), and lymphocytes.

Many migrating birds undertake extraordinary long flights. How birds are able to perform such endurance flights of over 100-hour durations is still poorly understood. We examined energy expenditure and physiological changes in Northern Bald Ibis Geronticus eremite during natural flights using birds trained to follow an ultra-light aircraft. Because these birds were tame, with foster parents, we were able to bleed them immediately prior to and after each flight. Flight duration was experimentally designed ranging between one and almost four hours continuous flights. Energy expenditure during flight was estimated using doubly-labelled-water while physiological properties were assessed through blood chemistry including plasma metabolites, enzymes, electrolytes, blood gases, and reactive oxygen compounds. Instantaneous energy expenditure decreased with flight duration, and the birds appeared to balance aerobic and anaerobic metabolism, using fat, carbohydrate and protein as fuel. This made flight both economic and tolerable. The observed effects resemble classical exercise adaptations that can limit duration of exercise while reducing energetic output. There were also in-flight benefits that enable power output variation from cruising to manoeuvring. These adaptations share characteristics with physiological processes that have facilitated other athletic feats in nature and might enable the extraordinary long flights of migratory birds as well.

The valley of the River Aim in the northern Alps is rich in natural wildlife. Particularly in winter, visiting birds of prey are com­ mon, including the Golden Eagle Aquila chrysaetos and the White-tailed Eagle Hali­ aeetus albicilla. From December to Febru­ ary, these eagles regularly visit the staging flock of semi-tame Greylag Geese Anser anser at the Konrad Lorenz-Forschungstelle, triggering alarms and flight reac­ tions. Eagles appeared in more than 80% of the days in January and caused up to ten flights per day. Coarsely estimated, eagles may have triggered some 200 escape responses of the flock during the months December 1991 and January 1992. No goose was lost. While these disturbances may be quite a nuisance for som e of our ongoing projects, their high frequency cer­ tainly provides an opportunity to highlight quantitatively some aspects of predatorprey interactions. W e therefore tried to capitalise on the unique combination of a semi-tame flock and the high density of potentially dangerous aerial predators. Predator-prey interactions in birds have frequently been studied with the back­ ground of AAM ’s (= sign stimuli; reviewed by Schleidt 1961) and optimal group size (ef. Bertram 1980, Kenward 1978). Howev­ er, no quantitative data on the response of bird flocks to repeated visits of aerial predators are available. From optimality theory (Krebs & Kacelnik 1991), one would predict that the escape reaction to any predator would be as effective in minimising the risk of preda­ tion as necessary and energetically as cheap as possible; flying is approximately 15 times more expensive than basic meta­ bolic rate (BMR), alert 2.1 times m ore cost­ ly than BMR (Williams 1982) and should therefore be kept to a necessary minimum. It was shown that disturbances may pose considerable costs upon geese (Belanger & Bedard 1990). The frequency of eagle visits may be used by the geese to judge the potential danger of falling victim to a predator. Therefore, geese may becom e increasingly wary with increasing numbers of predator visits and their behavioural response should becom e sensitised. This may be expressed by a positive correlation between air-times, vigilance rates and tightness of flock cohesion with distur­ bance frequency per day. An unlikely pos­ sibility would be the habituation of the response, as expressed by a decrease of reactivity with increasing number of predator visits. W e attempt to test these hypotheses. We also ask whether vigilance rates within the flock differ between days with many eagle visits as compared to days with only a few events.

Taking blood samples is a common method in biomedical and biological research using guinea pigs. However, most blood sampling techniques are complicated and highly invasive and may therefore not be appropriate for certain research topics concerning stress and reproduction. Thus, a non-invasive method to measure steroid hormones is critically needed. The aim of this study was the biological validation of corresponding enzyme immunoassays for the measurement of fecal cortisol, progesterone, estrogen, and testosterone metabolites in guinea pigs. We examined the effect of subcutaneous injections of ACTH or saline on fecal cortisol metabolites to investigate the suitability of fecal samples to monitor adrenocortical activity. Furthermore, we investigated whether fecal sex steroid metabolites accurately reflected endocrine changes observed in plasma samples during female estrous cycles and male puberty, respectively. In addition, we compared fecal testosterone metabolites of intact males, castrated males, and females to investigate the reliability of fecal samples in discriminating gonadal status of males. Concentrations of fecal cortisol metabolites were significantly increased following ACTH challenge, indicating that adrenocortical activity can be monitored via fecal samples. Secondly, in females, plasma and fecal gonadal steroids were significantly correlated in most subjects. The assay for testosterone metabolites, on the other hand, could not clearly discriminate between test groups. From these findings we conclude that fecal samples can be used for the non-invasive assessment of adrenocortical and female reproductive status in guinea pigs. Testosterone metabolism seems to be more complex and further investigations are needed to establish a more suitable assay.

Little is known about the effects of the early environment on the development of non-seasonally reproducing species like the domestic guinea pig (Cavia aperea f. porcellus).Although guinea pigs reproduce throughout the year, there is evidence for environmental sensitivity of their reproductive physiology.To investigate the sensitivity of juvenile body weight and puberty to differences in the prenatal and early postnatal environment, subjects were exposed to either of two experimental conditions mimicking seasonal variation: a long photoperiod with 25 °C ambient temperature ("LD/25 °C"), or a short photoperiod with 15 °C ("SD/15 °C").Mean body weight of F1-males from LD/25 °C-conditions was higher than that of SD/15 °C-males during the whole pubertal period, although the difference was significant only during the early growth phase.Testosterone concentrations also differed significantly between the two treatment groups, pointing to an earlier pubertal onset in LD/25 °C-than SD/15 °C-males.In F1-females, treatment effects on body weight or age at first estrus were absent.This indicates that the somatic and reproductive development is more sensitive to early photoperiod and temperature conditions in male than female guinea pigs, and that other environmental factors may also play a crucial role for reproductive maturation in this species.

Although all macaques have a multimale multifemale mating system, the degree of promiscuity shown by the Barbary macaque is considered to be extreme in terms of both mating frequency and number of mating partners. How mating activity is distributed throughout the female menstrual cycle and whether or not copulations are concentrated around the fertile phase as in other members of the genus is, however, not known. To examine this, we collected data on rates of copulation throughout 29 ovarian cycles from 13 free-ranging females of the Gibraltar Barbary macaque population and related them to the time of ovulation and the female fertile phase as determined from fecal hormone analysis. In addition, patterns of male inspection of females and time spent in consortship, both indicators of female attractivity, were also analyzed. The results indicate that both mating behavior and female attractivity vary predictably with ovarian cycle stage. Rates of copulation were found to increase toward the time of ovulation, with a distinct peak of ejaculatory (but not non-ejaculatory) copulations occurring in the fertile phase. Additionally, we show that frequency of inspection of females by males and time spent in consortship were also highest during the fertile phase and that ejaculatory copulations and male pericopulatory behaviors were significantly correlated with levels of female sex hormones. Our findings indicate that the Barbary macaque shows a mating pattern during the cycle similar to that described for other members of the genus. More importantly, however, our study provides clear evidence that despite an extreme degree of promiscuity Barbary macaque males concentrate their reproductive effort to the fertile phase, implying that they are able to discern this period and that thus timing of ovulation is not concealed from them. Estrogen-related cues appear to be involved in the process of recognition of female reproductive status by males, but the exact nature of these cues and how male Barbary macaques use them remains to be clarified.

Mate choice is a critical part of sexual selection. One constituent of mate choice is attractiveness, which serves as a projection surface for traits signalling quality and condition to prospective reproductive partners. In guinea pigs, females generally decide whom they will select as partner and when to switch to a new one. The aim of this study was to investigate for universality in male traits possibly associated with female preference. Characteristics of stress response were chosen, as they are relatively stable in their behavioural and physiological expression. Two consecutive experiments were done on isosexually kept males. In the first experiment, behavioural performance in a forced swim-test was noted, after basal endocrine status had been documented with three samples per individual. In a second experiment, the same males were presented to females in a round-robin choice paradigm. A discriminant analysis confirmed a categorization of males into groups that were preferred by different females either two times [more preferred (MP), n = 6] or less than that [less preferred (LP), n = 12]. Mean basal cortisol levels were comparable, but mean basal testosterone (T) was significantly higher in LP. This points at a scenario where higher T might be advantageous in male-male competition but perhaps less important for the formation of male-female bonds. Behaviourally, MP completed the swim-test significantly faster than LP, which may indicate greater goal directedness and motivation. We conclude that traits associated with stress responses may be components of male attractiveness, their stability perhaps reflecting adaptive qualities.

Polygynous mating systems can inflict considerable costs on males, often causing the emergence of alternative mating strategies to ensure reproductive success. These strategies can lead to different morphs of color, size, or behavior. The present work was done on guinea pigs, a polygynous rodent species. Some males can show a reduced readiness for conflict, perhaps employing an alternative mating strategy. To test this hypothesis, a two-stage experiment was set up, with males (N = 16) and females (N = 16) initially living in isosexual groups. Visual and olfactory contact was possible through a wire mesh. Male agonistic behavior was observed for 15 days, confirming the existence of less-conflict-involved (LCI, N = 7) and more-conflict-involved males (MCI, N = 9). Significant differences were found for a conditional parameter, body mass, and a morphometric one, testis width: LCI consistently surpassed MCI. Hormonally, cortisol was comparable, while testosterone was distinctly higher in MCI. Next, males and females were joined and observed for further 24 days. Males initially lost weight but reached original mass towards the end of the experiment. Testis width patterns were similar. Again, LCI had higher body mass. Cortisol was comparable, but testosterone release 3 days after merging was significantly higher in LCI. Behaviorally, LCI exhibited significantly less male–male aggression and more socio-sexual behavior than MCI. The former were more successful, with 57% capable of accessing females, in contrast to 11% of MCI. The existence of two distinct behavioral phenotypes in guinea pig males suggests that different reproductive strategies may exist in this species.

OBJECTIVEAdministered levonorgestrel enables contraception under normal cyclicity of the ovaries and does not suppress the development of cyclic perineal swellings. This study investigated the influence of levonorgestrel on fecal gonadal steroid excretion rates and the expression of perineal swelling size.SETTINGSTwo groups of Barbary macaque females were observed: Twenty-four implanted individuals under semifree conditions and five non-implanted individuals under caged conditions. Eight of the implanted females had large expressions of the perinea and sixteen reduced. The non-implanted group had no perineal swellings.METHODSTo determine the individual steroid excretion rates and exzymeimmunoassay for decal samples was established.RESULTSEstradiol excretion rates did not differ in distinctively swollen implanted females, but were increased when compared to non-implanted individuals (df=2; p=0.0002). Implanted females with large perineal swellings had lower progesterone concentrations in the feces compared to individuals with reduced swellings and did not differ from the non-swollen group (df=2; p=0.054). Females with large perineal swellings showed a higher calculated estradiol to progesterone ratio index than the other groups (df=2; p=0.0005). Non-implanted individuals showed increased testosterone excretion rates (df.=2; p=0.0001).MAIN FINDINGSThe results indicate a positive relationship between the perineal swelling size and levonorgestrel implantation.CONCLUSIONThe ratio of fecal estradiol and progesterone titers can be judged as an endocrine indicator for the expression rate of perineal swelling size.

Couples sleeping in pairs is a modern phenomenon with potential side-effects on sleep structure and circadian rhythms. In order to examine its effects, 10 healthy heterosexual couples with stable relationships who regularly sleep apart or together in their home environments were recruited. The participants were asked to spend at least 10 nights alone and 10 nights together over the course of the study. Their sleep was monitored over 28 days in their homes with actigraphic techniques and sleep diaries. Group analyses were performed on their sleep efficiency and subjective sleep quality according to sleep condition. The daily variations in sleep fragmentation indices of the partners were used as a measure of their nocturnal activity synchronization. Sharing a sleeping space with a partner had negative effects on sleep in women, as documented in the actigraphic measurements of sleep efficiency and subjective assessments of sleep and awakening quality. Sexual contact mitigated the negative subjective report, without changing the objective results. Subjective assessments of sleep quality were lower in men than women when sleeping alone. They increased to the same level as women while sleeping in pairs with or without sexual contact. The sleep efficiency in men was not reduced by the presence of their partner unless sexual contact occurred. Analyses of sleep fragmentation showed that there was no synchronization of deviation from the norm levels between the partners on individual nights either when they slept alone or in couples. The sex differences in the nocturnal sleep reactions to partner presence may be attributed to sex-specific behavioral traits associated with cultural norms or parenting in women and the desire for group sleep in men.

Urinary metabolites of androgens and cortisol were measured in free-living male and female bonobos. Sex differences and correlations between adrenal and gonadal steroid excretion were investigated. The immunoreactive concentrations of androgens were measured with two different androgen assays. One assay used a testosterone (T) antibody raised with a 17β-hydroxy group, and the other employed an antibody raised against a reduced form, 5α-androstane-17α-ol-3-one-CM (17α) with cross reactivity for epitestosterone and 5α-androstanedione. Both assays have been used in bonobo and chimpanzee studies where non-invasive techniques were employed. The levels of 17α-androgen metabolites were 1.7- and 3-fold higher than those of T-metabolites in males and females. The two androgen assay results correlated in males but not females. There was a sex difference in the T-metabolites measured. Male levels were significantly higher. Levels of 17α in the two sexes were similar. Cortisol metabolite levels (CORT) were similar between the sexes. The T-metabolites were significantly correlated with CORT in males but not in females. In females, the 17α-androgen metabolites correlated with CORT. This suggests that either androgen secretion or metabolism differs between the sexes. A parsimonious interpretation of the androgen assay cortisol/androgen correlation differences would be that larger components of dehydroepiandrosterone (DHEA), androstenedione or epitestosterone from the adrenal androgens were being excreted and measured in the females. The CORT/T metabolite interactions in males may reflect male-specific social or metabolic endocrine conditions.

BACKGROUND:Sex steroids affect many peripheral tissue sites in female mammals. Receptors for these hormones have been found in skin, fat, and bone. In women, these tissues can show morphological changes during the menstrual cycle that may be directly related to steroid secretion.METHODS:The present study was done on chimpanzees to document morphometric markers associated with these tissues (anogenital swelling volume, skin fold thickness as indicator of subcutaneous fat, bony diameters of mandible, wrist, and elbow) and to compare them with cyclic patterns of estradiol, progesterone, testosterone, gonadotropins, and prolactin.RESULTS:Swelling volume changed significantly over the menstrual cycle. All other morphometric parameters showed variation without statistical significance. Skin folds were thickest during the luteal phase. Bony diameters displayed similar but less distinctive changes. Testosterone correlated positively with diameter sites, inversely with subcutaneous fat. No relationships with either estradiol or progesterone were found. We assume that subcutaneous fat and morphometric bone parameters exhibit cycle-dependent changes that may be caused by changes in steroid secretion.

The neuropeptide oxytocin (OXT) is a key factor in the initiation and regulation of sociosexual behavior. The present study analyzes the effects of cohabitation and social challenge on plasma OXT concentration rates in guinea pig pairs in relation to male sociosexual behavior. The cohabitation phase lasted 3 days. On day 4, the pair was socially challenged by introducing an unfamiliar male. Displayed male sexual behavior varied significantly during cohabitation, with peaks on day 1. Sociopositive behavior, i.e., side-by-side contact, was increased on days 3 and 4. Cohabitation per se led to elevated plasma OXT concentrations only in males. In contrast, both sexes reacted with increased plasma OXT concentrations to the social challenge (day 4). At that time, male OXT was significantly correlated with sexual behavior and female OXT with sociosexual behavior received from the partner. Additionally, pairs were synchronized in their OXT release during days 3 and 4. We conclude that cohabitation causes sexually dimorphic plasma OXT concentration patterns in guinea pigs. Secondly, the conformity of OXT release in both sexes may represent an endocrine marker for long-term cohabitation, which is reflected behaviorally by increased spatial proximity.