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xxxxxx. [ABSTRACT FROM AUTHOR]

Lactation boosts reproductive costs by depleting maternal condition and delaying subsequent conception. However, some evidence suggests that giraffes (Giraffa camelopardalis) have evolved a mechanism to minimise the time allocated to suckling-induced suppression of ovulation. Here, we show for the first time that wild giraffe cows are impregnated while nursing a young calf. We suggest that a trio of traits (non-seasonal breeding, slow embryonic development and rapid calf growth) have promoted this unusual and flexible female reproductive strategy. [ABSTRACT FROM AUTHOR]

Giraffe are popular animals to watch while on wildlife safaris, and feature prominently in zoos, advertisements, toys and cartoons. Yet, until recently, few field studies have focused on giraffe. We introduce this giraffe topic issue with a review essay that explores five primary questions: How many (sub) species of giraffe exist? What are the dynamics of giraffe herds? How do giraffe communicate? What is the role of sexual selection in giraffe reproduction? How many giraffe reside in Africa? A confluence of causes has produced drastic declines in giraffe population numbers in Africa, and we conclude that guiding giraffe conservation plans depends upon evaluation of the five key quandaries that we pose. [ABSTRACT FROM AUTHOR]

In cohesive social groups, travel progressions are often led by dominant or older individuals, but the leadership traits of individuals residing in flexible social systems are poorly known. Giraffe reside in herds characterized by fission-fusion dynamics frequently mediated by kinship. We analyzed 41 years (1971-2012) of longitudinal data collected from a community of Thornicroft's giraffe ( Giraffa camelopardalis thornicrofti) living around South Luangwa National Park, Zambia, to assess the characteristics of herd leaders. Movement of giraffe in a single file progression was not associated with either season or time of day, but progressions were significantly more likely to occur when giraffe traveled in open areas. The oldest female in a herd was significantly more likely to be at the front position than expected, occupying the leadership niche on 79% of observations. We reason that matriarchal leadership in giraffe, as in African elephants, Loxodonta africana, is associated with resource learning. Giraffe societies are constructed on a heretofore unrecognized foundation that integrates relatedness and familiarity with matriarchal leadership in herd movement. [ABSTRACT FROM AUTHOR]

Temporary all-male social groups are formed in a number of animal species. We examined 34 years of data collected from 36 male Thornicroft's giraffe in the Luangwa Valley, Zambia, to test a set of predictions related to five possible functions of all-male herds (predator protection, practicing aggressive skills, prolonging life, nutritional demands and resource learning). We found that all-male herds were significantly smaller than mixed-sex herds, usually contained a mature bull, and were not dependent upon season or habitat. Dyadic associations between males in single sex herds were quite weak, with <25% of potential male dyads sighted together in an all-male herd. Our data are best explained as a resource learning strategy adopted by males to obtain more extensive knowledge about the habitat, including both food and female distribution. However, other benefits in the form of predator protection, dietary intake and sharpening competitive skills for future contests over estrous females also seem to mediate formation of giraffe all-male groups. We conclude that the primary advantage of roaming in all-male herds changes during the life history of males. [ABSTRACT FROM AUTHOR]

Birth site location can have enormous implications for female reproductive success. Some ungulate species demonstrate consistent birth site fidelity, while others shift birth locations during their lifetimes as a function of ecological and social factors. We plotted 39 years of birth records from a wild population of Thornicroft's giraffe, Giraffa camelopardalis thornicrofti, to test the hypothesis that giraffe use consistent locations for birth. Data from 29 calves born to nine females revealed that birth seasonality was absent and that ecological zone had no significant impact on birth locations. Consecutive births by individual females were not limited to certain locations, with the distance between sequential birth sites tending to be greater if a calf failed to survive the first year of life. Our evidence conflicts with the suggestion that giraffe cows regularly return to special locations for bearing calves. We suggest that the choice of birth location is a function of nonseasonal breeding, predator pressure and extensive variation in microhabitat characteristics within ecological zones. Female giraffe have evolved a flexible reproductive strategy, whereby they regulate choice of birth site location based upon their past reproductive history, current ecological conditions (including both resource availability and predator pressure) and present social surroundings. [ABSTRACT FROM AUTHOR]

A variety of social systems have evolved as a consequence of competition and cooperation among individuals. Giraffe ( Giraffa camelopardalis sp.) societies are an anomaly because the dearth of long-term data has produced two polar perspectives: a loose amalgamation of non-bonded individuals that sometimes coalesce into a herd and a structured social system with a fission-fusion process modifying herd composition within a community. We analysed 34 years of data collected from a population of Thornicroft's giraffe ( G. c. thornicrofti, Lydekker 1911) residing in South Luangwa, Zambia, to establish the nature of giraffe society. Our sample consisted of 52 individually recognized animals. We found that giraffe herd composition is based upon long-term social associations that often reflect kinship, with close relatives significantly more likely than non-relatives to establish herds. Mother/offspring dyads had the strongest associations, which persisted for years. Giraffe live in a complex society characterized by marked flexibility in herd size, with about 25% of the variance in herd composition owing to kinship and sex. We suggest that giraffe herds share many characteristics of fission-fusion social systems and propose that sophisticated communication systems are a crucial component regulating subgroup dynamics. [ABSTRACT FROM AUTHOR]

Ecological factors have a pervasive impact on animal population sizes and the structure of their social systems. In a number of ungulate species, predator pressure exerts a major influence on group size. Given that giraffe ( Giraffa camelopardalis) live in an extremely flexible social system, and that breeding is nonseasonal, they are an ideal species for examining how ecological variables contribute to fluctuations in herd size. We present an analysis of 34 years of data on a population of Thornicroft's giraffe ( G. c. thornicrofti Lydekker 1911) that reveal how herd size changes with season and habitat. Sex differences in herd size were apparent, with bulls often travelling as singletons, whereas cows were generally observed with conspecifics. Herds were larger during the wet than dry season, but herd size changed in a parallel fashion across habitats. Giraffe herds were smaller in woodland and thicket areas than in open habitats, regardless of season. We suggest that the regular fluctuations in herd size among giraffe indicate a fission/fusion social system embedded within a larger social community. We conclude that changes in herd size among giraffe reflect a dynamic process regulated by individuals adjusting the number of associates based upon an interaction of foraging, reproductive, social and antipredator strategies. [ABSTRACT FROM AUTHOR]

Knowledge of the reproductive life history of giraffe in the wild is sparse. Giraffe have two fairly unusual reproductive patterns among large mammals: they can become pregnant while lactating, and calf mortality is extremely high. Longitudinal records are largely absent, so tracking reproductive parameters tends to combine information from captive and field studies. In this study, we examine longitudinal data obtained over a 33-year period in one population of Thornicroft’s giraffe in order to chart their reproductive careers. We found that age at first parturition was 6.4 years, or slightly later than in captivity. Giraffe bred throughout the year, with cows producing offspring on average every 677.7 days. About half of the calves died before one year of age, but death of a calf did not reduce interbirth interval. We conclude that the lifetime reproductive success of giraffe is more dependent on longevity and calf survivorship than on reproductive rate. [ABSTRACT FROM AUTHOR]

Thornicroft's giraffe Giraffa camelopardalis thornicrofti is limited in distribution to a single population resident in the Luangwa Valley, Zambia. During 1973−2003 regular counts were recorded along the Luangwa River in the core section of the subspecies’ range. In 2013 we conducted a count in the same region for comparison with the earlier survey results. During the 30-year period 1973−2003 the giraffe index (no. of individuals per km surveyed) was relatively stable, with an increase in 1994 and 1995 coinciding with an influx of giraffes to the west bank following an exceptionally reduced flow of the Luangwa River. The mean giraffe index during this period was 0.51 km−1, whereas the 2013 count yielded an index of 0.44 km−1. Given the limited range of the Thornicroft's giraffe, we estimate that the population comprises c. 500–600 individuals. [ABSTRACT FROM PUBLISHER]

Abstract: Female distribution exerts a major impact on male mating tactics. Giraffe cows have a reproductive cycle, and a social system, that should favor a male roaming reproductive tactic. We conducted a 2-year study of female Rothschild''s giraffe (G. c. rothschildi) reproductive endocrinology in order to characterize attributes of the reproductive cycle and investigate how female endocrine and behavioral cues influence mating activity. We used non-invasive fecal steroid methods to determine reproductive state among females residing in a herd in a large outdoor enclosure. We found that females had an estrous cycle of 14.7 days and that they regularly had multiple ovarian cycles prior to conception. Adult males were more likely to associate with, and sexually investigate, females when they were cycling than when they were either pregnant or acyclic. During the estrous cycle, male–female proximity and sociosexual behavior were more pronounced during the probable fertile phase than the rest of the cycle. Sexual activity between giraffe coincided with the periovulatory period, with male interest in females peaking during the fertile window in the absence of proceptive behavior by females. We conclude that males detect reliable cues revealing female reproductive status and partition their reproductive effort in response to such cues. We propose that male giraffe adopt a roaming reproductive strategy with their large size, enabling them to search for and mate guard fertile females while minimizing metabolic costs. [Copyright &y& Elsevier]

Abstract: Zoological institutions provide an environment conducive to studying proximate mechanisms influencing reproduction that can provide guidance to both field and captive settings seeking to manage their stock. Both national parks and zoos have space limitations that sometimes require the use of reversible contraception in order to reduce reproductive rate or limit specific individuals from reproducing. We designed a study to test the efficacy of a long-lasting contraceptive in female giraffe by monitoring reproductive endocrinology and behavior. We implanted two animals with the GnRH agonist deslorelin and monitored their endocrine status using fecal steroid analysis. We have previously validated an assay for fecal pregnanes and here we report our validation for fecal estrogens. Both sex steroid concentrations were suppressed in two females, although one female exhibited an immediate post-implantation positive feedback response. Sexual activity nearly disappeared in one animal, whereas the other showed regular sexual behavior. The contraceptive effect lasted for at least 472 d, and successfully suppressed estrous cyclicity in one female for >2 y. We conclude that deslorelin implants provide a minimally invasive means for long-term suppression of reproduction in female giraffe. [Copyright &y& Elsevier]

Abstract: Gestation and lactation can impose substantial energetic costs on female mammals. We developed a non-invasive means to determine reproductive condition in female giraffe using fecal steroid analysis. Giraffe may be especially challenged during their reproductive cycle because of two characteristics: they are impregnated while lactating and they do not breed seasonally. We studied the social behavior and endocrinology of seven female giraffe in a large naturalistic outdoor enclosure in order to chart connections between maternal physiology and behavior across the reproductive cycle. We found that giraffe gestation averages 448 days among females producing a calf that survived, with fecal pregnane concentrations reaching a zenith during the last trimester of pregnancy. Resumption of ovarian cyclicity following parturition was accelerated after neonatal calf mortality, but ovarian cycles resumed as early as 39 days postparturition while nursing. Although time spent feeding was unaffected by reproductive state, pregnant females significantly reduced time allocated to social behavior and had a tendency to locomote less than when cycling or acyclic. We suggest that modifications in foraging strategies as a function of reproductive state among wild giraffe derive from antipredator activity rather than from metabolic demands. Female giraffe probably cope with simultaneous lactation and gestation by producing high quality milk for neonatal calves commensurate with slow fetal growth and accelerating fetal growth simultaneous with weaning of nursing calves. [Copyright &y& Elsevier]