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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Reproductive parameters for nine avian species at Moore Creek, Merritt Island National Wildlife Refuge

Girard, G. Tanner 01 1900 (has links) (PDF)
Florida Technological University College of Natural Sciences Thesis / M.S. / Masters / Graduate Studies Program / College of Natural Sciences / Biological Science / 64 p. / vi, 59 l. : tables. ; 29 cm.
2

Ecology and behaviour of Great Skuas breeding on Foula (Shetland)

Catry, Paulo X. January 1997 (has links)
No description available.
3

Determinants of fitness in an island population of song sparrows

Hochachka, Wesley Michael January 1990 (has links)
Patterns and causes of variation in the reproductive success of Song Sparrows (Melospiza melodia) are investigated in this thesis. The two general patterns looked for were: inter-annual variation in reproductive success, and repeatability of reproductive success of individual parents. The specific problems addressed were: (1) whether intra-seasonal variation in reproductive success was the result of differences in the quality of parents or their territories; (2) whether nutritional condition of nestlings affected their subsequent survival; (3) whether variation in morphology of adult sparrows was influenced by the conditions under which birds grew up; and (4) given the patterns discovered in the first three sections, how trade-offs between present and future reproduction constrain the effort expended by adult sparrows in reproduction. Data used in this thesis came from a long-term (1975-present) descriptive study of the population of Song Sparrows living on Mandarte Island, B.C., Canada. Data on survival, reproductive success, and nestling and adult morphology were all available. The approach taken in the thesis was to search for systematic variation in the data, and from these patterns to make inferences about cause and effect. The following conclusions are made: (1) the intra-seasonal decline in clutch size, observed in populations of many species of birds, was the result of poor birds or birds on poor quality territories both nesting later and laying smaller clutches; (2) nestlings in better nutritional condition had a higher probability of survival while under the care of their parents, than nestlings in poor nutritional condition; (3) the probability of survival of offspring after they left their parents' care was lower for young born later in the year, but this pattern is not caused by variation among parents or their territories (contrary to the cause of seasonal decline in clutch size); (4) morphology of birds as adults was affected by the environment that birds grew up in, with nutritional condition and population density while a nestling both affecting adult morphology; (5) the effort that parents expend on reproduction is constrained by ability to vary reproductive effort with date of nesting and parental age. / Science, Faculty of / Zoology, Department of / Graduate
4

Energetic constraints on avian incubation : studies of three passerine species

Bryan, Susan M. January 1996 (has links)
Field studies were conducted with "three species of passerine, in order to investigate the possibility that an energetic constraint limits reproduction during incubation. Swallows (Hirundo rustiea), Dippers (Cinelus einelus) and Great Tits (Parus nlajor) were studied at sites in Central Scotland. All three species exhibit gynelateral intermittent incubation, so time and energy must be allocated between the conflicting demands of reproduction and selfmaintenance. An assessment of incubation ability in the Swallow was conducted by the manipulation of clutch size during incubation. There was evidence of a clutch size dependent cost, as the duration of the incubation period was prolonged for enlarged (15.6d) compared to reduced (14.8d) clutches. The proportion of eggs hatching successfully was also lower in enlarged (81 %) than in reduced (92%) clutches, though enlarged clutches still produced the greatest number of hatched young. Clutch manipulation did not influence patterns of nest attendance, or female body condition. No effects of incubation effort were detected posthatch on either parents or offspring. The effects of clutch size on field metabolism during incubation were investigated in the Dipper. Clutch size was manipulated and energy use measured by means of the doubly labelled water technique. The results were combined with previous data collected for incubating Dippers. The field metabolic rate of 33 incubating females averaged 5.41 ± 1.34 cm3 CO2 g-l h-1 , equivalent to a daily energy expenditure of 211.52" ± 51.25kJ ind-1 d-1 , e.3 times the basal metabolic rate. Clutch enlargement resulted in an increase in energy use to 4-6 times basal metabolism for some birds," but not for others. While the mean energy use did not differ between groups, the variation amongst birds was significantly greater for enlarged than control clutches. Energy use was also influenced by river flow rates, the duration of incubation sessions and behaviour during incubation recesses. Manipulation of the energy budget of incubating Great Tits was achieved by the reduction of thermoregulatory demands. Treated nest boxes were supplied with additional heat during the hours of darkness, resulting in an elevation of nest air temperature of e.4°C above the corresponding temperature for a control group, lasting for a period of 9 hours. This produced an estimated energetic saving of 10kJ per night. Heated birds increased the duration of both the ~period of continuous incubation overnight and of incubation sessions throughout the following day, resulting in an additional 51 minutes per day spent incubating compared to the control group. The metabolic rate of22 incubating Great Tits was 7.79 ± 2.43 cm3 C02 g-1 h- 1 , or 106.4 ± 32.2 kJ ind-1 d- 1 , equivalent to e.3 times basal metabolism. Energy use escalated for control, but not for heated birds at low ambient temperatures. The importance of reserve storage and utilisation, and of provisioning by the mate were evaluated in each species. A combined hypothesis was proposed to account for body condition during incubation, incorporating elements of programmed reserve utilisation, mass adjustment, maintenance of an insurance reserve and reproductive stress. In summary, the study found "evidence of an energetic constraint acting during incubation in these species." Energy use increased in a probabilistic manner with increasing clutch size, such that birds with large clutches increased their risk of being unable to incubate the entire clutch successfully. It was suggested that such a constraint could contribute to the determination of an upper limit for avian clutch size.
5

Population ecology and lifetime reproductive success of dippers Cinclus cinclus

Logie, John W. January 1998 (has links)
Acidified catchments are known to hold significantly reduced dipper Cinclus cinclus populations throughout the year relative to circum-neutral rivers, although the processes leading to these declines remain unclear. This study considered the population ecology of dippers within the circumneutral River Devon catchment, Central Scotland, and focused primarily on determining the factors influencing survival, breeding probabilities and reproductive success. It aimed to examine the role of spatial variation in 'habitat quality' on the population (and meta-population) dynamics of dippers, based on measures of seasonal and lifetime reproductive success, and the balance between survival and reproduction; in particular, to assess if the reduced reproductive success of dippers on acid rivers is likely to lead to population declines. Within the Devon catchment, approximately 81% of all adults survived from spring (March/April) to autumn (September/October), with 65% of these birds surviving from autumn to the following breeding season. Overall, these estimates predicted annual adult survival rates of c.53%, with no significant differences between years. Population density had no detectable effect on adult mortality rates, although juvenile over-winter survival was significantly lower than the adult rate at between 40 and 58%, and negatively related to the total size of the autumn population. There was no evidence of sex differences in juvenile over-winter survival, or any significant influence of weather or river flows on the rates for adults or juveniles. The local post-fledging survival of females was significantly lower than for males, however, apparently reflecting sex differences in post-natal dispersal. On average, less than 6.5% of all eggs laid, or 10.4-14.5% of male and 6.3-9.2% of female fledglings raised within the Devon catchment survived locally to breeding age. Juvenile, although not adult, recapture rates in spring were significantly lower than for birds known to have bred previously and negatively related to spring river flows. This suggested that with recapture dependent on a breeding attempt that was successful at least until laying, either more first year birds failed during the initial stages of nesting or that full breeding was not achieved at age one. The birds fledging the most young, both within a season and over a lifetime, all bred at 'prime' lowland sites characterised by wide, shallow rivers of intermediate gradient, although with less than 10% of all birds attempting to raise a second brood each year, no significant habitat differences were identified in any component of reproductive output measured until fledging. River width, altitude and gradient were all significantly inter-correlated and related to laying date, however, and post-fledging survival was significantly reduced for late fledged young. On average, lowland birds laid earlier than upland breeders, and were significantly more likely to produce autumn 'recruits' due to the enhanced post-fledging survival prospects of their young. This suggested that broad measures of river structure can provide a biologically appropriate classification of habitat quality. The size of the breeding population of dippers within the Devon catchment appeared to be related to the availability of critical resources, most likely food, roost sites and ultimately breeding territories through density-dependent changes in over-winter mortality and recruitment. The relative importance of resource abundance and recruitment levels in determining autumn population densities on acid streams still remained unclear, although reference to published relationships between acidity and reproductive success suggested that with adult survival at the rate estimated for the Devon catchment, many dipper populations are unlikely to produce sufficient recruits to match all adult losses, and may only persist with continued immigration from more productive (circumneutral) catchments elsewhere.
6

Life history trade-offs between survival, moult and breeding in a tropical season environment

Stevens, Matthew C. January 2011 (has links)
The trade-off between current and future investment in reproduction lies at the heart of life history theory. The need to differentially allocate resources between these two options arises generally as a result of environmental pressures. Higher risk of mortality in adults is linked with increased investment in current reproduction, whereas the opposite is true where adults are long-lived (the r- K selection paradigm). Perhaps the most obvious factors influencing the environment stem from seasonality of the climate, since rainfall and temperature affect food availability, resulting in a higher risk of mortality. The available trade-offs that an organism can make will therefore be constrained by environmental variability potentially resulting in general adaptation and so ultimately influencing evolution of biome-specific life-history traits. In this thesis, I examine how the seasonality of a West African tropical savannah environment influences moult and breeding timing and duration, and survival in West African tropical savannah bird species. I show that moult in tropical birds follows the same basic descendant pattern through the wing feathers, but is a much lengthier process than for temperate species (mean = 131 ± 11 days, N = 29 species), and that it frequently overlaps with breeding activities. This suggests either that either the feathers of tropical species take longer to grow; that it is a relatively low-cost activity and has little influence on life history trade-offs; or that individuals further aim to reduce mortality risk by attempting to maintain high flight capability at all times. Breeding also occurred over a longer season than for temperate species, although an obvious peak in occurrence was identified to coincide with the food-abundant period of the late rains and early dry season. Lengthy breeding seasons may indicate an increased tendency to re-nest (possibly as a result of higher nest predation levels), and we also identified a prolonged immature plumage phase – potentially indicating an extended duration of parental care. Survival rates were calculated from mark-recapture models based on mist-netting data. Previous work has focussed on the use of incorporating mark-resighting data alongside that obtained by standard mark-recapture techniques. Here, I assess the models applied in those methods, identify problems associated with over-paramaterisation, goodness of fit and the generation of biologically unrealistic estimates, and so provide suggestions on how to improve the protocol. Average survival from my study (40 species: 0.63 ± 0.02) was higher than previous estimates obtained from this site and were comparable with estimates from other Afrotropical and Neotropical areas, although rates varied greatly between species. Juvenile survival (13 species) was similar or possibly lower than adult survival. I then used my empirically derived estimates of moult, breeding and survival life history traits to identify potential trade-offs between traits. Overall I was unable to identify significant relationships between any of the life history trait estimates, other than between adult survival and clutch size. In this, the results followed those of previous researchers in identifying a pattern of lower investment in current reproduction (clutch size) and maximisation of adult survival in tropical species. My study, however, demonstrates for the first time how moult and breeding duration are likely to be less constrained in tropical environments.
7

Reproductive effort strategies in passerine birds : the role of body state

Spencer, Karen January 2000 (has links)
State-dependent life history theory predicts a trade-off between an individual's state and reproductive effort. The identification and effects of key state variables, however, have not been explored empirically in depth. Although there are some studies which have provided evidence that state-dependent behaviour indeed occurs, the bulk of this work is neither experimental, nor related to reproduction. Furthermore, the quantitative effects of manipulations of specific state variables are invariably unknown (McNamara & Houston 1996). This thesis explores potential trade-offs between state and behaviour and determines if energy reserves can be employed as a useful state variable. In contrast to other empirical studies, parental states (energy reserve at dawn) were experimentally manipulated using a direct method, namely changes in overnight temperature (Warming, Chilling and Control). The effects of these temperature changes were quantified using indirect calorimetry. Responses to these experimental manipulations were measured by behavioural observations, a common method in behavioural ecology, but were also quantified in terms of energy expenditure, with the aid of the doubly labelled water technique. Thus, this thesis provides a unique quantitative approach, in that it measures both manipulations and responses in the currency of energy. Individual energy reserves at dawn significantly affected resource allocation decisions the subsequent day. Birds with surplus energy upon release increased the number of feeding visits to their nestlings whilst in parallel increasing energy expenditure. Those with an energy deficit at dawn, conversely decreased nest visitation rates along with energy expenditure. There were no effects of temperature manipulations upon mass or fatscore changes over the trial period, suggesting a regulation of somatic investment at a threshold level, whilst reproductive effort was varied depending on parental state. The responses to positive manipulations (warming) were congruent across two species with differing foraging ecologies: the swallow, an aerial feeder foraging in a variable environment; and the great tit, foraging in relatively stable woodland. Thus, the behavioural and energetic responses seen here were not the result of species-specific strategies. This points the way towards a general rule within state-dependent behaviour. The trade-off identified here implies that reproduction carries a cost, and that reproductive effort will be reduced if an animal's survival is jeopardized and vice versa: a life history response, mediated by an individual's body-state. Furthermore, the response of birds to positive and negative manipulations was large enough to be readily detected, even amongst the considerable variation in energy expenditure related to individual differences. This suggests that body-state not only plays a key role in allocation decisions, but that it is comparable in the scale of its effects to other major influences on energy expenditure of free-living animals.
8

Ecology of the endemic migratory passerine Cyprus Wheatear Oenanthe cypriaca : the effects of climate change on a restricted range species

Xenophontos, Marina January 2015 (has links)
Migrant birds may be vulnerable to climate change at different stages of their annual cycles especially on the breeding grounds, where changes in phenology may affect their ability to synchronise breeding with the peak of resources availability. Understanding how phenology of breeding, survival and productivity varies between and within years is therefore crucial to understand migrant population dynamics. This thesis describes this variation in the Cyprus Wheatear Oenanthe cypriaca, with particular emphasis on a colour-ringed population at Troodos, Cyprus, 2010-2012. Our results suggest that the phenology of breeding of Cyprus Wheatear is variable with breeding onset and number of breeding attempts probably varying with annual temperature variation. Minimum true survival rates were very high for a small passerine migrant, although they were probably sufficiently annually variable to profoundly affect annual population dynamics. For productivity, nest survival was very high and did not vary between years, or nesting attempts, or with clutch initiation date but it was significantly higher in the chick stage versus the egg stage. Post-fledging survival in the first 4 weeks was very high. Renesting probability was significantly different in all years, yet total productivity per pair was the same in each of three years. Cyprus Wheatears at Troodos showed such high productivity and survival that the population must be a major source population and this was reflected in the very high density of breeding pairs at the study site. Finally we used altitude as a proxy for variation in temperature and investigated how abundance, productivity and phenology in Cyprus Wheatears varied between and within years, from sea level to 1952m, using transect surveys to record breeding birds across Cyprus. Cyprus Wheatears were common in all habitats and altitudes; altitudinal temperature variation probably affected the occurrence of double brooding and so the timing of chick production, but not the onset of breeding. The results suggest that Cyprus Wheatears are already very well adapted to high variation in temperature within and between seasons, changing investment accordingly.
9

História natural das aves em um parque urbano no Sudeste do Brasil / Natural history of the birds at urban park in a Southeastern Brazil

D'Angelo, Giulia Bagarolli, 1982- 03 December 2014 (has links)
Orientador: Ivan Sazima / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-24T19:31:06Z (GMT). No. of bitstreams: 1 D'Angelo_GiuliaBagarolli_M.pdf: 26225858 bytes, checksum: a6b9b77b3bd66a3d80fd5d3157a3fef5 (MD5) Previous issue date: 2014 / Resumo: O processo de urbanização no Brasil aumenta rapidamente e as áreas verdes fornecem refúgio para a fauna local, na qual as aves são o elemento mais evidente. Aves são agentes importantes de dispersão e polinização, controle de pragas, além de ciclagem de nutrientes e adubação do solo, exercendo diversos serviços ambientais. Embora essas funções possam ser vistas como tendo pouca importância no ambiente urbano, aves apresentam grande mobilidade, o que significa que suas funções podem ser transportadas de uma área verde para outra. Estudamos a história natural das aves em um parque urbano em Campinas, São Paulo. Alimentação, reprodução e repouso foram os focos deste estudo, além de outras atividades como higiene e conforto. As atividades alimentares que observamos seguem, em linhas gerais, o que está relatado na literatura sobre aves brasileiras. Entretanto, observamos alguns fenômenos não relatados ou pouco conhecidos Associações alimentares de aves piscívoras seguindo lontras em atividade de caça não estavam relatadas para América do Sul. Disputa por área de caça entre fêmeas de biguatinga Anhinga anhinga foi outra novidade relacionada à atividade alimentar, assim como a predação de um bivalve asiático invasor por aves aquáticas. A inclusão de uma categoria de presa (répteis) na dieta do sabiá Turdus leucomelas também representou uma novidade. As atividades reprodutivas que observamos no parque também seguem, em linhas gerais, as informações disponíveis na literatura sobre aves brasileiras. Todavia, observamos eventos pouco conhecidos ou não relatados na literatura. A corte do urubu Coragyps atratus está relatada para a América do Norte apenas. Também pouco conhecida é a disputa territorial "simbólica" entre fêmeas do pica-pau Colaptes melanochloros, comportamento relatado para machos de outras espécies. Outra novidade foi a pressão de predação pelo lagarto Salvator merianae em ninhos de aves que nidificam no chão ou em vegetação próxima a margem de lagoa. Atividades de higiene e conforto são bem conhecidas e ilustradas na literatura e acreditamos que não tenhamos observado algum comportamento de higiene e conforto que não esteja relatado, ainda que de passagem, para as aves brasileiras. Estudos sobre história natural de aves proporcionam um conhecimento mais adequado das relações entre as aves, o ambiente urbano e a população humana. Em parques e áreas verdes, as aves representam uma parcela de lazer para a população urbana. O número de observadores de aves aumenta no Brasil e, paralelamente, há uma valorização da conservação ambiental. Portanto, estudos em parques urbanos resultam em conhecimento sobre a avifauna, além de valorizar as áreas verdes e popularizar o conhecimento sobre as aves e a sua importância biológica / Abstract: The urbanization process in Brazil is quickly changing the landscape and so called green areas provide refuge for the local fauna, of which birds are the most conspicuous part. Birds are important agents of plant dispersal and pollination, pest control, as well as nutrient cycling and soil fertilizing, which result in ecosystem services. Although these functions may be viewed as having little or no importance in the urban landscape, birds are highly mobile and their functions may connect several green areas. We studied the natural history of birds in an urban park in Campinas, São Paulo, Southeastern Brazil. We focused on feeding, reproducing, and resting, besides preening and comfort activities. In general, feeding activities we observed followed what is published about Brazilian birds. However, we observed a few little known or until recently unpublished events. Feeding associations of piscivorous birds following foraging otters were unreported for South America. Contests for hunting area between females of the darter Anhinga anhinga was another novelty related to feeding activity, as well as the predation of an Asiatic invasive clam by water birds. Predation of reptiles by the thrush Turdus leucomelas was also a novelty. In general, reproductive activities we observed followed what is published for Brazilian birds. However, we observed a few little known or unpublished behaviors. For example the courtship of the vulture Coragyps atratus is reported for the North America only. Also little known is the territorial "symbolic" contest between females of the woodpecker Colaptes melanochloros, a behavior reported for males of other species. Another novelty was the predation pressure on birds that nest on the ground or bank vegetation by the large lizard Salvator merianae. Preening and comfort behaviors are well known and illustrated in literature and we believe that we did not record any behavior that is not reported in the literature on Brazilian birds, even if en passant. Studies on natural history of birds provide a better knowledge on the relationships between the birds, the urban landscape, and the human population. In urban parks and green areas, birds are part of leisure activities for urban people. The number of birdwatchers is increasing in Brazil and, at the same time, there is a growing awareness of environment conservation among people who are in contact with nature. Therefore, studies on natural history of birds in urban parks and other green areas result in knowledge of the bird fauna, besides increasing the intrinsic value of these environments and making available details of the life of birds and their biological significance / Mestrado / Biodiversidade Animal / Mestra em Biologia Animal

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