Polygyny is the most common mating system in mammalian species (95%), yet our understanding of polygynous systems and microevolutionary processes is still limited. Pinniped mating systems range from extreme polygyny (e.g. elephant seals) to sequential female defence by males and hence have often been used as models for mating system studies. Parentage analysis has enabled the examination of mating success, the identification of pedigrees, and the elucidation of social organisation, greatly enhancing our understanding of mating systems (Chapter 1). However, such analyses are not without pitfalls, with erroneous assignments common in open systems (i.e. when parental and offspring samplings are incomplete). We investigated the effects of the user-defined parameters on the accuracy of parental assignment using two commonly used parental allocation programme, CERVUS and PASOS (Chapter 2). We showed that inaccurate user-defined parameters in CERVUS and PASOS can lead to highly biased output e.g. the assignment rate at 95% CL of offspring with a sampled known mother to sampled males decreased from 58% to 32% when the proportion of candidate males sampled in the parameter options decreasing 4-fold. We found that the use of both CERVUS and PASOS for parentage assignment can increase the likelihood of correctly allocating offspring to sampled parents to 97% in our study system. Incorrect parental assignment can bias estimates of various biological parameters, such as lifetime reproductive success and mate choice preference, and hence bias ecological and evolutionary interpretations. Here, we propose solutions to increase the power of parentage assignment and hence decrease the bias in biological parameter estimates. In addition, we analysed the effects of the intrinsic bias in likelihood assignment approaches towards assigning higher probability of parentage on individuals with rare alleles and those with heightened offspring-parent matches, which increase with the number of homozygous loci (Chapter 3). We showed that, as a consequence of the algorithms employed in the programmes CERVUS and PASOS, heterozygote males with rare genotypes are assigned higher rates of parentage than males with common alleles. Consequently, where two males could both be biological fathers of a given offspring, parentage assignment will more often go to the male with the rarer alleles (most often in heterozygous loci). Thus, the commonly used parentage assignment methods may systematically bias the results of parentage analyses towards supporting the notion that females prefer more genetically unusual, most often heterozygous, males. Such a bias may sway investigators towards incorrectly supporting the concept that females choose genetically more unusual males for heterozygosity fitness benefits that underpin the good genes hypothesis, when in fact no such relationship may exist. In polygynous mammals, successful males mate with multiple females by competing with and limiting the access of other males to females. When the status of many males (age, size, health, genetic etc.) prevents them from achieving the primary mating tactic, theory predicts selection for a diversification of male mating tactics. Recent studies in pinnipeds have shown that observed male mating success was correlated to male paternity success in some species (elephant-seals), but not in others (grey seals). The existence of alternative mating strategies can explain those discrepancies. Chapter 4 implemented the guidelines provided in Chapter 2 and 3 and focused on the polygynous New Zealand fur seal Arctocephalus forsteri, predicting that 1) competition for females is likely to cause a diversification of male mating tactics; and 2) that alternative tactics can yield reproductive success. Our results indicated three male behavioural profiles; one corresponded to large territorial males and two illustrated a continuum of alternative tactics employed by non-territorial subordinate males. Our study highlights that holding a territory is not a necessary condition for reproductive success in a population of otariids. The degree of sexual size dimorphism in polygynous species is expected to increase with the degree of intra-sexual competition and in turn with the degree of polygyny. The life history of an individual is the pattern of resource allocations to growth, maintenance, and reproduction throughout its lifetime. Both females and males incur viability costs of mating and reproduction. However, male viability costs due to increase growth and male-male competition can be greater than female viability costs of mate choice and reproduction. Although an abundant literature on sexual dimorphism in morphology, physiology, and parasite infections is available, little is known on the intra-sexual differences in physiology and parasite infections associated to the reproductive success of different mating strategies in mammalian species. Chapter 5 examined the reproductive costs between territorial and subordinate males New Zealand fur seal related to their relative reproductive success using a multidisciplinary approach (behaviour, genetics, endocrinology, parasitology). We found that dominant New Zealand fur seal males endure higher reproductive costs due to the direct and indirect effects of high testosterone levels and parasite burdens. Our study highlights that holding a territory confers a higher reproductive success, but induces higher costs of reproduction that may impair survival. Understanding microevolutionary processes associated to polygynous systems is fundamental in light of the ongoing anthropogenic alteration of the environment through climatic variations and habitat reduction which ultimately affect opportunity for sexual selection and shape the life history trade-offs.

Survivorship of children is unsurprisingly dependent upon numerous variables, not least of which is the role that preferential treatment plays in biasing the birth and survival of sons and daughters across cultures. This study draws upon an evolutionary approach by examining the "Trivers-Willard hypothesis" concerning condition-dependent sex allocation and differential parental investment. The central idea is that within a polygynous social mating structure - where reproductive variance is higher for males than for females as an intrinsic function of polygyny - mothers in optimal condition (defined by high status, good health, and abundant resources) are more likely to produce and invest in male offspring whereas mothers in poor condition (defined by low status, poor health, and resource deprivation) are more likely to produce and invest in female offspring so as to maximize potential lifetime reproductive success. Previous research on humans concerning this hypothesis tends to be restricted to one cultural group and thereby limited in sample size. For this study, nationally representative household survey data collected by the Demographic and Health Surveys (DHS+) program across 35 countries was used to test biological, resource-oriented, and behavioral aspects affecting maternal condition, sex allocation, and parental investment in humans. Country samples ranged from 732 to 21,839 women interviewed within South Asia, Sub-Saharan Africa, the Caribbean/Latin America, and the Near East/North Africa. The units of analysis were the mothers and their lastborn child (N = 128,039 woman-child pairs). A sequence of hierarchical regressions theoretically pre-specified a causal model concerning four constructed scales measuring maternal socioeconomic resources, maternal biological condition, prenatal care for the lastborn child, and health-seeking for the lastborn child. In startling contrast to the predictions of the original hypothesis, analysis of the overall model revealed small, yet stable, cross-regional main effects suggesting that - for all four regions – maternal biology predicts lastborn daughters while maternal resources predict lastborn daughters for each region, with the exception of Sub-Saharan Africa. Moreover, protective/preventative health-related behaviors predict lastborn sons within South Asia and the Near East/North Africa, while prenatal care and health-seeking are differentially attributed to the prediction of sons and daughters within Sub-Saharan Africa and the Caribbean/Latin America.

Generally it is assumed, that sexual selection drives the evolution of elaborate traits. The strength of sexual selection has traditionally been attributed to varinace in reproductive success among individuals. This variance is mainly caused by the number of mating partners and the number of sired offspring. Both males and females can increase their reproductive success by alternative reproductive strategies - extrapair copulations and intraspecific brood parasitism. In our study we tested the relationship between male ornamentation and success in extra-pair and within-pair paternity and the total male reproductive success in barn swallow (Hirundo rustica), a socially monogamous species with high levels of extrapair paternity. The results suggest more colourful throat to indicate male reproductive success. Dark rusty males were less often cuckolded and they have higher total fertilization success than drab ones. Tail length did not affect neither within- nor extra-pair fertilization success, however, previous studies have concluded that reproductive success of male barn swallows is positively related to the tail ornaments. Our results confirm that extra-pair paternity considerably increase variance in reproductive success among barn swallow males. We show that within-pair success may increase the...

Humans have a large impact on biodiversity, especially by causing habitat loss and habitat degradation but also through human-induced climate change. Because of habitat loss and habitat degradation the Middle-spotted woodpecker (Dendrocopos medius) went extinct in Sweden 1983. Globally the Middle-spotted woodpecker is today listed as least concern but because of human-induced climate change the species might be threatened in the whole world in the future. Different ways to help the species is by protection of potential habitat, restoration or reintroduction. The aim of this study is to help the Middle-spotted woodpecker survive in the future by facilitate its potential progress to Sweden, Linköping. One way to help the species is by investigating if a reintroduction is possible. Therefore, I created a habitat model of the Middle-spotted woodpecker based on published studies and used the model to analyze the landscape for possible sites of reintroduction. Results from published studies showed that the species require at least 20 hectares oak forest per breeding pair, a high density of mature oak and more potential habitat to distribute to, within a 10-kilometer distance. Four areas in Linköping fulfilled all the requirements but only two of them were situated in less than 10 kilometers from each other. A successful reintroduction of the Middle-spotted woodpecker requires a landscape with at least 15-20 potential habitat in a near distance to each other. Therefore, a reintroduction of Middle-spotted woodpecker is not possible in Linköping unless more habitats is restored.

Neste estudo, avaliamos a distribuição espacial de recursos florais de Eriotheca gracilipes e suas conseqüências para a atividade de abelhas e florívoros no sucesso reprodutivo desta espécie de Cerrado. A distribuição de flores de Eriotheca gracilipes revelou que a disponibilidade destes recursos variou espacial e temporalmente. No ano em que a floração foi mais expressiva no cerrado, estas variações afetaram de modo distinto as abelhas grandes que visitam as flores de E. gracilipes à procura de néctar e pólen, quando estas abelhas responderam positivamente ao aumento na disponibilidade de flores, tanto na escala do indivíduo, como na escala da vizinhança. Independente da fase sexual das flores de E. gracilipes, a maior parte da variação na produção de energia do néctar é determinada pela variação entre flores e esta variação é determinada pela variação na produção de energia das flores na fase masculina. A maior produção de néctar na fase masculina das flores de Eriotheca gracilipes pode ser resultado de pressões seletivas distintas entre as funções sexuais. A incidência de florivoria em E. gracilipes diferiu entre os agentes e as fisionomias. As maiores taxas de sobrevivência das estruturas reprodutivas no cerrado e a correlação positiva entre o número de botões produzidos e o número de frutos formados nesta fisionomia reforçam a hipótese de que variações espaciais nas interações entre species, sejam elas mutualistas ou antagonistas, poderiam afetar diferentemente a reprodução sexuada de E. gracilipes, de acordo com as espécies antagonistas envolvidas. / In this study we evaluated the spatial distribution of Eriotheca gracilipes floral resources and its consequences for the bee foraging behavior, florivores and the reproductive output of this Cerrado species. Spatial and temporal variations were detected for Eriotheca gracilipes flower availability. At the cerrado physiognomy in 2005, this variation affected differently the large bees that visit E. gracilipes flowers, looking for pollen and nectar. Under this situation, we detected positive pollinator responses to the floral display of focal plants and also to its neighborhood. The greatest variation in energy production was explained by variation among flowers in male phase. The higher nectar production in male flowers indicated that distinct selective pressures might be occurring at each sexual function. The incidence of florivores reduced E. gracilipes flower availability and their action were different between agents and physionomies. Trigona spinipes had a major impact on buds and flowers of E. gracilipes at the campo cerrado. Our data indicate that spatial and temporal variation between plant-pollinator and plant-florivores occured even under low and almost homogeneous flower availability, affecting differently E. gracilipes reproductive success.

Anthropogenic climate change is one of the most important factors influencing population growth and survival. Therefore, to be able to predict the effect of climate change on ecosystem composition and function, it is important to understand its effect on demographic variables, such as productivity. As a measure of productivity, I related the proportion of yearling birds captured during bird ringing in southern Sweden with mean temperature during the breeding season. I then compared the relationship between temperature and productivity for species with different traits regarding number of broods produced per season, thermal niches and migration behaviours. For most species (72%), productivity positively related to temperature during the breeding season. The relationship was strongest for species with the ability to vary the number of broods per year and species with a warmer thermal niche, whereas there was no difference between long-distance migratory and short-distance migratory species. The results suggest that, for some bird species in the study area, climate warming can increase population sizes. However, long-term effects of climate change may be different than the interannual fluctuations of temperature considered in this study, especially when interacting effects of habitat losses are taken into account.

Viruses can affect plant-insect interactions by altering emission of plant volatile organic compounds (VOCs). Previous work in the lab suggested that VOCs emitted by tomato (Solanum lycopersicum) plants infected with cucumber mosaic virus (CMV) were more attractive to bumblebees (Bombus terrestris) in free choice assays. I extended this work using Arabidopsis thaliana mutants with lesions in genes encoding factors in RNA silencing. In conditioning assays, I confirmed that plant VOC emission is controlled in part by the microRNA regulatory pathway. I used gas chromatography coupled to mass spectrometry and principal component analysis to confirm that CMV infection caused changes in VOC emission by tomato. VOCs collected from non-flowering mock-inoculated and CMV-infected plants were qualitatively distinct from each other. CMV-infected plants also released greater quantities of VOCs than mock-inoculated plants. CMV appears to be both ‘turning up the volume’ of plant volatile emission, whilst ‘tuning’ volatile blend composition so as to diminish levels of a repellant signal. These data are likely to explain how bumblebees can discriminate between VOCs emitted by mock-inoculated and CMV-infected plants. To determine if CMV infection of tomato plants affects plant reproductive success, I carried out a series of bumblebee pollination experiments. Bumblebees pollinate tomato by ‘buzzing’ (sonicating) the flowers, which releases pollen and enhances self-fertilization and seed production as well as pollen export. First, I established that CMV-infected tomato plants produced fruits with a lower seed yield than mock-inoculated plants. When single bumblebees were allowed to buzz-pollinate flowers in a small flying arena, the fruit that developed from buzz-pollinated flowers on virus infected plants had significantly more seeds than fruit from non-visited flowers. Subsequent experiments were performed in a large flying arena. Bumblebees consistently spent longer foraging on the mock-inoculated tomato plants but seed yield was increased by bumblebee pollination in both mock-inoculated as well as virus-infected tomato plants. However, although buzz-pollination significantly enhanced seed yield from CMV-infected plants compared to fruit from non-buzz-pollinated flowers, the yield was higher in buzz-pollinated fruits from mock-inoculated plants. Similar experiments were carried out utilizing a transgenic line of tomato that constitutively expresses the green fluorescent protein in order to estimate the level of cross-pollination from either CMV-infected plants to mock-inoculated plants or vice versa. More pollen from virus-infected plants was transferred to mock-inoculated plants than the reciprocal cross. However, some caution is needed in the interpretation of the larger scale experiments because the tomato plants were affected by a fungal infection. I investigated if the defensive plant hormone salicylic acid (SA) affects bee-perceivable VOC emission. Exogenous SA treatment renders non-flowering tomato plants more attractive to bumblebees in free choice experiments in which bees could only perceive VOCs, but bumblebees spent less time visiting SA-treated flowering tomato plants in the glasshouse (when the bumblebees were allowed unimpeded access to the flowers). Taken together, these data provide evidence that virus infection can affect host-pollinator interactions. Speculatively, CMV infection may change the fitness of susceptible plants via changes in production of pollinator-attractive VOCs and this may affect the balance of resistant or susceptible plants within the host population.

Submitted by William Justo Figueiro (williamjf) on 2015-06-16T21:58:38Z No. of bitstreams: 1 24.pdf: 1349109 bytes, checksum: 36d23698c423b4482be0d6cdec8d15d0 (MD5) / Made available in DSpace on 2015-06-16T21:58:38Z (GMT). No. of bitstreams: 1 24.pdf: 1349109 bytes, checksum: 36d23698c423b4482be0d6cdec8d15d0 (MD5) Previous issue date: 2012 / Nenhuma / A Curicaca, Theristicus caudatus (Boddaert, 1783) é uma espécie que apresenta alta capacidade de adaptação, ocorrendo em diversos ambientes, sendo muito comuns em ambientes antropizados, nidificando até mesmo próximo a residências. Utiliza uma ampla gama de hábitats e por consequência, pode alcançar grandes áreas de distribuição, permitindo que um número maior de indivíduos se estabeleça, o que contrasta com a pequena quantidade de estudos existentes com esta espécie. A carência de dados populacionais não permite que se determine a situação real da espécie envolvida no estudo, dificultando a implementação de práticas de manejo e conservação eficazes para a Curicaca. Neste sentido conhecer o comportamento e a biologia reprodutiva auxilia na compreensão de padrões da historia natural e é fundamental em medidas conservacionistas. Este trabalho teve como objetivo avaliar o comportamento e o sucesso reprodutivo de grupos de nidificação de Theristicus caudatus no planalto do Rio Grande do Sul. Foi realizada a observação comportamental, contagem dos indivíduos, e foram estimadas as possíveis diferenças nos comportamentos entre os grupos, além de avaliar o sucesso reprodutivo. As diferenças encontradas entre os comportamentos e as taxas de sucesso reprodutivo mostraram que o ambiente, principalmente no que se refere à disponibilidade de alimento, influencia a frequência dos comportamentos e o sucesso reprodutivo. / The Curicaca, Theristicus caudatus (Boddaert, 1783) is a species that has a high capacity for adaptation, occurring in different environments, being very common in environments anthropized, nesting even close to residences. Uses a wide range of habitat and therefore can achieve great distribution areas, allowing a greater number of individuals has been established, wich contrasts with the small amount of existing studies with this species. The lack of population data does not allow to determinate the real situation of the species involved in the study, making it difficult the implementation of management practices and effective conservation for the Curicaca. Thus understand the behavior and reproductive biology supports in the comprehension of patterns of natural history and is fundamental to conservation measures. This study aimed to evaluate the behavior and reproductive success of nesting groups of Theristicus caudatus on the upland of Rio Grande do Sul. We conducted behavioral observation and counting of individuals, and were assessed differences in behavior between groups, and evaluate reproductive success. The differences between the behavior and reproductive success rates showed that the environment, especially with regard to availability of food influences the frequency of behaviors and reproductive success.

Nest box programs provide supplemental nest sites for American Kestrels, Falco sparverius. When the availability of nest sites is a limiting factor, the addition of nest boxes can increase local breeding populations. These programs also facilitate the collection of data on breeding kestrels. This study focuses on an American Kestrel (Falco sparverius) nest box trail along Interstate 26 in northeastern Tennessee during the breeding seasons of 1998, 1999, 2000, 2003, 2004, 2006, and 2009. Productivity measures and reproductive success of nesting birds are provided and compared to other programs. The data are analyzed across years and by box. Finally, a discussion of the habitat surrounding the most and least active boxes provides recommendations for increased efficiency of the program.

Zum Erhalt vom Aussterben bedrohter Papageienvögel (Psittaciformes) ist die Nachzucht in Menschenobhut neben dem Erhalt freilebender Populationen von großer Bedeutung, die Reproduktion bestimmter Arten gelingt allerdings nur unzureichend. Als Hauptgrund dafür gilt die Zwangsverpaarung im Rahmen von Zuchtprogrammen (Beispiel: Europäisches Erhaltungszuchtprogramm, EEP), hier werden Brutpaare hauptsächlich nach genetischen Aspekten zusammengestellt. Der reproduktive Erfolg ist bei den meisten Papageienarten, die in dauerhaften Paarbindungen leben (perennial monogamy), eng der Paarbindung korreliert. Eine freie Partnerwahl ist demnach von großer Bedeutung für die Zucht in Menschenobhut, im Rahmen von Erhaltungszuchtprogrammen jedoch nur selten möglich. Das Ziel der Untersuchung war, eine wissenschaftlich begründete Methode zu entwickeln, durch die es möglich sein soll, das Fortpflanzungspotential von Brutpaaren der Gattung Ara anhand der Paarbindung zu bestimmen. Dafür wurde die Bedeutung der Qualität der Paarbindung der Brutpaare für den Lebens-Reproduktionserfolg (Lifetime-reproductive success, LRS) untersucht. Die Datenaufnahme erfolgte in dem Zuchtzentrum 'La Vera' der Loro Parque Fundación auf Teneriffa/ Spanien. Hier wurden in den Jahren 2006 und 2007 21 Brutpaare der Gattung Ara untersucht. Die Paarbindung wurde zum Einen durch typisches Paarbindungsverhalten und zum Anderen durch die physiologische Abstimmung der einzelnen Brutpaare anhand der Ausschüttung des Steroidhormons Testosteron dargestellt. Das Paarbindungsverhalten setzte sich aus der ‚Abstimmung der Tagesaktivität’, dem ‚Kontaktverhalten’ und den ‚sozialen Interaktionen’ zusammen. Zur Abstimmung der Tagesaktivität zählten die Verhaltensweisen Ruhen, Sitzen, Nahrungsaufnahme, Gefiederpflege, Beschäftigung und Lokomotion. Unter Kontaktverhalten wurden das Überschreiten der Individualdistanz bei bestimmten Verhaltensweisen und die Rollenverteilung der Geschlechter untersucht. Unter ‚sozialen Interaktionen’ wurden die Dauer und der Häufigkeit der sozialen Gefiederpflege und der Sozialen Index zusammengefasst. Bei der sozialen Gefiederpflege wurde die Dauer und die Häufigkeit der Phasen erhoben, sowie der jeweilige Initiator dieser Interaktion. Zusätzlich wurde untersucht, welches Geschlecht, wie häufig und mit welcher Dauer aktiv an der sozialen Gefiederpflege beteiligt war. Aus den Beobachtungen wurde der soziale Index berechnet, der angibt, wie das Verhältnis sozio-positiver zu agonistischen Interaktionen für jedes Individuum, sowie das Paar an sich ist. Zur Messung der Testosteron-Ausschüttung der Partnertiere wurden von September bis November 2007 über einen Zeitraum von 9 Wochen jede Woche einmal für jedes Individuum Kotproben gesammelt. Mit der Analyse der Proben wurde das Veterinär-Physiologisch-Chemische-Institut der Universität Leipzig unter der Leitung von Prof. Dr. Almuth Einspanier beauftragt. Zur Ermittlung des Hormongehalts in den gewonnenen Kotproben diente ein kompetitiver Doppelantikörper-Enzymimmunoassay (EIA). Das Fortpflanzungspotential wurde über die Anzahl der Eier, Gelege und Jungtiere, sowie über die Gelegegröße dargestellt. Diese Daten geben, bezogen auf die Dauer der Paarbindung, Auskunft über die Produktivität eines Brutpaares, anhand dessen zusätzlich ein Produktivitäts-Koeffizient berechnet wurde. Des weiteren sollte die Anzahl der von einem Brutpaar selbständig großgezogenen Jungtiere Auskunft über die Fähigkeit zur kooperativen Jungenaufzucht geben. Zur Untersuchung der Bedeutung der Paarbindungsqualität wurden Diskriminanzfunktionsanalysen und Regressionsanalysen durchgeführt, wozu die untersuchten Brutpaare anhand ihres Fortpflanzungspotentials in verschiedene Gruppen eingeteilt wurden. Anhand der Ergebnisse der Studie konnte gezeigt werden, dass das Fortpflanzungspotential von Brutpaaren von verschiedenen Kriterien, die die Paarbindungsqualität charakterisieren, abhängt. Dabei ist zwischen der Produktivität und der Fähigkeit zur kooperativen Jungenaufzucht zu unterscheiden. Die Produktivität eines Paares wurde hinsichtlich der abgestimmten Tagesaktivität positiv vom synchronen Ruhen mit dem Partner beeinflusst, sowie von der Häufigkeit und Dauer der vom Weibchen ausgehenden sozialen Gefiederpflege. Brutpaare mit hoher Produktivität waren zudem über eine hohe ‚intra-Paar Fluktuation’ des Steroidhormons Testosteron gekennzeichnet. Die Brutpaare, die in der Lage sind, ihre Jungtiere in Kooperation großzuziehen, zeigten ebenfalls einen hohen Anteil zeitlich mit dem Partner abgestimmter Ruhephasen, zudem häufiges Ruheverhalten in Körperkontakt zum Partner und ein hohes zeitliches Investment der Männchen bei der Initiierung und Durchführung sozialer Gefiederpflege. Darüber hinaus zeigten Männchen, die einen Beitrag zur kooperativen Jungenaufzucht leisten, eine wesentlich geringere durchschnittliche Testosteron-Konzentration – bezogen auf den Untersuchungszeitraum, als Männchen, die Brutpaaren angehören, die nicht zur selbständigen Jungenaufzucht fähig sind. Dieses Ergebnis spiegelt die Bedeutung von Testosteron bei der elterlichen Fürsorge wider und bietet einen Anhaltspunkt für weitere Untersuchungen. Die Untersuchung konnte zeigen, dass es möglich und sinnvoll ist, das individuelle Verhalten von Tieren in Menschenobhut für den Erhalt bedrohter Tierarten einzusetzen. Weitere, auf dieser Studie aufbauende Untersuchungen sollten zum Ziel haben, zuverlässig die Brutpaare erkennbar zu machen, die über ein gutes Fortpflanzungspotential verfügen. Auf diese Weise kann unzureichender Reproduktionserfolg bedrohter Papageienarten in Menschenobhut infolge von Zwangsverpaarung minimiert werden. / In addition to preserve wild populations, captive breeding of certain species is important for the conservation of endangered parrots (Psittaciformes). However, captive breeding of parrot species is rarely successful. The main reason for this failure is that forced pairings are applied under the context of breeding programs such as European Endangered Species Program, EEP, in which breeding pairs are primarily selected under genetic aspects. Bond quality affects the reproductive success of most perennial monogamous parrot species significantly. A free mate selection is therefore important for successful breeding in captivity; however, it is hard to achieve as a part of conservation breeding programs. The aim of this study is to develop a scientific method to determine the reproductive potential of breeding pairs of the genus Ara based on the pair bond. Therefore, the relationship of the pair bond quality in breeding pairs for lifetime reproductive success (LRS) is investigated in this study. The data of 21 breeding pairs was collected in the breeding facility 'La Vera' of the Loro Parque Fundación in Tenerife, Spain between 2006 and 2007. The pair bond was characterized firstly by the typical pair bonding behaviour and secondly by the physiological adaptation of each breeding pair based on the steroid hormone testosterone releases. The pair bonding behaviour consisted in ‘daily activity', ‘contact behaviour' and 'social interactions'. The ‘daily activity' included the behaviours: resting, sitting, eating, preening, activity and movement. Certain individual behaviours and gender roles were examined for the ‘contact behaviour'. The duration and frequency of social preening and the social index were summarized as 'social interactions'. In the social preening the duration and frequency of the phases was recorded, and the respective initiator of this interaction. In addition, gender of the individual, frequency, and duration of the social preening was recorded. Furthermore the social index was calculated, which indicates the relationship between agonistic and socio-positive interactions. To measure the testosterone release in the pair members over 9 weeks (September to November 2007), faecal samples were collected from each individual once a week. The faecal samples were analyzed at the Institute for Physiological Chemistry at the University of Leipzig under supervision of Prof. Dr. Almuth Einspanier. Competitive double-Antibody Enzyme Immunoassay (EIA) was applied to determine the testosteronecontent of the faecal samples. Reproductive success was represented by number of eggs, nests and chicks, and the clutch size. These data provide, based on the duration of the pair bond, information about the productivity of breeding pairs. Furthermore, the number of chicks reared by one breeding pair independently should provide information about the capacity for cooperative breeding. Breeding pairs were classified into different groups depending on their reproductive potential. This classification was verified by discriminant analysis and regression analysis to investigate the importance of the quality of the pair bond for reproductive success. I found that the reproductive potential of breeding pairs is related to various criteria that characterize the quality of a pair bond, but it is essential to distinguish between the productivity itself and the ability to cooperative breeding. The synchronous resting with a partner according to the daily activity, as well as the frequency and duration of social preening initiated by the female positively influenced the productivity of a pair. Breeding pairs with high productivity also showed a high ‚intra-pair fluctuation' of the steroid hormone testosterone level. The breeding pairs which are able to raise their young in cooperation also showed a high percentage of time with coordinated phases of resting, also frequent resting behaviour in physical contact with the partner and a high investment of males in the initiation and implementation of social preening. In addition, males, which actively contribute to cooperative breeding, showed significantly lower testosterone concentrations than males, which were members of breeding pairs not capable of raising chicks on its own. This result emphasizes the importance of testosterone during the parental care, especially in males, and provides a starting point for further investigations. My investigation shows that it is possible and useful to apply the individual behaviour of animals in captivity for the conservation of endangered species. Based on this study, further research should be aimed to expose reliable breeding pairs with good reproductive potential, by behaviour and by measuring hormonal states. In this way, poor reproductive success of endangered parrot species in captivity as a result of forced parings can be minimized.