Birds and bats employ a variety of advanced wing motions in the efficient production of thrust. The purpose of this thesis is to quantify the benefit of these advanced wing motions, determine the optimal theoretical wing kinematics for a given flight condition, and to develop a methodology for applying the results in the optimal design of flapping-wing aircraft (ornithopters). To this end, a medium-fidelity, combined aero-structural model has been developed that is capable of simulating the advanced kinematics seen in bird flight, as well as the highly non-linear structural deformations typical of high-aspect ratio wings. Five unique methods of thrust production observed in natural species have been isolated, quantified and thoroughly investigated for their dependence on Reynolds number, airfoil selection, frequency, amplitude and relative phasing. A gradient-based optimization algorithm has been employed to determined the wing kinematics that result in the minimum required power for a generalized aircraft or species in any given flight condition. In addition to the theoretical work, with the help of an extended team, the methodology was applied to the design and construction of the world's first successful human-powered ornithopter. The Snowbird Human-Powered Ornithopter, is used as an example aircraft to show how additional design constraints can pose limits on the optimal kinematics. The results show significant trends that give insight into the kinematic operation of natural species. The general result is that additional complexity, whether it be larger twisting deformations or advanced wing-folding mechanisms, allows for the possibility of more efficient flight. At its theoretical optimum, the efficiency of flapping-wings exceeds that of current rotors and propellers, although these efficiencies are quite difficult to achieve in practice.

Birds and bats employ a variety of advanced wing motions in the efficient production of thrust. The purpose of this thesis is to quantify the benefit of these advanced wing motions, determine the optimal theoretical wing kinematics for a given flight condition, and to develop a methodology for applying the results in the optimal design of flapping-wing aircraft (ornithopters). To this end, a medium-fidelity, combined aero-structural model has been developed that is capable of simulating the advanced kinematics seen in bird flight, as well as the highly non-linear structural deformations typical of high-aspect ratio wings. Five unique methods of thrust production observed in natural species have been isolated, quantified and thoroughly investigated for their dependence on Reynolds number, airfoil selection, frequency, amplitude and relative phasing. A gradient-based optimization algorithm has been employed to determined the wing kinematics that result in the minimum required power for a generalized aircraft or species in any given flight condition. In addition to the theoretical work, with the help of an extended team, the methodology was applied to the design and construction of the world's first successful human-powered ornithopter. The Snowbird Human-Powered Ornithopter, is used as an example aircraft to show how additional design constraints can pose limits on the optimal kinematics. The results show significant trends that give insight into the kinematic operation of natural species. The general result is that additional complexity, whether it be larger twisting deformations or advanced wing-folding mechanisms, allows for the possibility of more efficient flight. At its theoretical optimum, the efficiency of flapping-wings exceeds that of current rotors and propellers, although these efficiencies are quite difficult to achieve in practice.

This thesis addresses issues related to surveillance for disease in commercial and non-commercial poultry populations. The motivation for this work has largely arisen from the unprecedented outbreaks of highly pathogenic avian influenza (HPAI) H5N1 that have occurred in 52 countries in Asia, Africa and Europe since 2003. A series of studies are presented using data derived from two countries, Vietnam and New Zealand. The two Vietnamese studies provide in-depth epidemiological analyses of the outbreak of HPAI H5N1 from December 2003 to March 2004. The three New Zealand studies deal with issues related to the development of effective surveillance strategies for HPAI — informed both directly and indirectly by the findings from the Vietnamese studies. This approach provides an example of how ‘lessons’ learnt from countries that have experienced large scale infectious disease epidemics can be used to assist in the design of surveillance activities in (as yet) unaffected countries. The descriptive analyses of the 2003 – 2004 outbreak of HPAI H5N1 in Vietnam indicate that the epidemic was seeded simultaneously in the north and south of the country in the later part of 2003 with 87% of provinces affected by February 2004. HPAI risk was concentrated around the Mekong and Red River Deltas. The broad scale spatial distribution of disease is likely to have been associated with regional differences in the poultry farming, trade in poultry, and environmental conditions such as the presence of bodies of water which would support reservoir species for the virus. A Bayesian zero-inflated Poisson regression model was used to quantify the influence of environmental and demographic factors on the spatial distribution of HPAI positive communes. In areas where disease was reported, our results show that HPAI risk was positively associated with the presence of irrigation and negatively associated with elevation. After controlling for these fixed effects, a single large area of elevated risk in the Red River Delta area was identified, presumably arising from similarities in the likelihood of reporting disease or the presence of factors increasing disease transmission and spread. Further investigations to elucidate likely transmission mechanisms, targeting this area of the country, would be a profitable area of future research. The second part of this thesis presents three studies that address issues related to the development of effective surveillance strategies for HPAI in New Zealand. The first was a cross-sectional study to enumerate the prevalence of backyard poultry ownership in two areas (one urban and the other rural) close to a large provincial city in the North Island of New Zealand. The prevalence of poultry ownership was 2% (95% CI 1% – 4%) in the urban area and 19% (95% CI 12% – 30%) in the rural area. The relatively low numbers of land parcels where poultry are present indicates that these areas, in the event of an infectious disease incursion, would be unlikely to pose a risk for spread of infectious agent. A cross-sectional survey of all members of the Poultry Industry Association of New Zealand was conducted in the later half of 2007. Respondents were asked to document contacts made with other enterprises related to feed, live birds and hatching eggs, table eggs and poultry product, and waste litter and manure. Patterns of contact were analysed using social network analyses. Each of the four networks had scale-free properties, meaning that for each movement type there were small numbers of enterprises that had contacts with large numbers of enterprises (potential ‘super-spreaders’ of disease). The presence of an undetected infectious disease in enterprises with super-spreader characteristics increases the likelihood that an epidemic will propagate rapidly through the population, assuming there is a directly proportional relationship between the number of contacts an enterprise makes and the probability that disease will be transferred from one location to another. While the finding that feed suppliers had large numbers of poultry farm contacts in the feed network came as no surprise, what was of greater interest was that there were small numbers of poultry farms that reported off-farm movements of feed. This should serve as an important reminder for disease control authorities: movement (and other) restrictions applied during the course of an animal health emergency should be applied across a range of industry sectors, recognising that some industry participants may practice activities that are not entirely typical for their enterprise type (e.g. poultry farms on-selling feed to other farms). In the absence of perfect and up-to-date network data, knowledge of the characteristics of individual enterprises that render them more likely to be atypical (e.g. size, type, and geographic location) would be of value, since this information could be used to inform a risk based approach to disease surveillance and control. A scenario tree model was developed as an approach for evaluating the effectiveness of New Zealand’s passive surveillance system for HPAI. The model was developed in two stages. In the first, factors thought to influence the geographic distribution of NAI risk of introduction and spread (and therefore surveillance strategy) were combined to create a spatial risk surface. In the second stage, a scenario tree model of the passive surveillance system for NAI was developed using the spatial risk surface and the HPAI surveillance strategy prescribed by Biosecurity New Zealand. The model was most sensitive to farmers reporting the presence of suspected cases of disease. This implies that the sensitivity of the system as a whole stands to increase if the importance of reporting suspicious clinical signs is reiterated to poultry producers. The studies presented in this thesis have presented a range of techniques and methodological approaches that are sufficiently generic to be used in any country to inform the design of surveillance strategies for a variety of animal diseases, not just those of poultry. Although epidemiology, as a discipline, is endoured with a vast range of analytical techniques that can be used to enhance the understanding of factors influencing the spread of disease among animal populations, the quality of data used to support these techniques is often lacking. The challenge in the years ahead, for both developed and developing countries, is to set in place the appropriate infrastructures to collect details of animal populations consistent in quality over time and space.

Eight studies of the epidemiological dynamics of avian influenza viruses were conducted on poultry in Hong Kong, with special focus on the movement of birds through the live poultry marketing system, and the implications for avian influenza transmission. The first involved analysis of virus isolation data from faecal samples obtained from cooperating stalls in live poultry markets in Hong Kong in a routine sampling program undertaken between 1999 and 2001. This showed that two subtypes of avian influenza viruses, H9N2 and H6N1, have become well established in the Hong Kong live poultry markets, especially in chickens (mainly H9N2) and quail (mainly H6N1). In addition, a wave of H5N1 virus infection occurred in 2001 after it had been absent through the earlier period of the study. The second study was an evaluation of long term changes in the marketing systems for live poultry in Hong Kong, their likely effects on avian influenza epidemiology, and documented evidence of the prevalence of various H subtypes of avian influenza in sampling undertaken during three periods from 1975 to 2001. The third project involved two cross-sectional studies and one longitudinal study on local quail farms in Hong Kong. Results showed that quail could act as a reservoir host for H9N2 and H6N1 subtype viruses, but each subtype differed in its epidemiology. H9 virus usually infected quail at around 10 days of age, whereas H6 infected quail at 15-20 days of age. At 35 days of age (usual market age in Hong Kong), a proportion of market quail were likely to be susceptible to H6 (50%) and H9 viruses (20%), and were able to transmit the virus in the markets. Due to these findings, the Hong Kong Government closed the quail farming operations and restricted the sale of quail in live poultry markets. A longitudinal study was conducted on three live poultry market stalls to assess the time from stall entry to sale, and evaluate the influence of this delay on avian influenza virus transmission to other poultry in the same stall. Participating stalls varied from high volume/rapid turnover to low volume/slow turnover. Turnover for tagged poultry was rapid, although some chickens became infected with H9 virus before sale. Birds which stayed longer, such as quail, became infected and maintained infection in the stall. As well as spread by direct contact and on typical fomites, keeping of pet roosters and re-use of washing water were identified as factors increasing the ability of avian influenza strains to persist in market stalls. An experimental replica of a market stall was created to study the transmission of low pathogenic avian influenza virus (H9N2) in a controlled environment, with different rates of population turnover and different immune status with respect to both H5 and H9 subtypes. Transmission was influenced by distance between birds, the proportion of birds carrying antibody to H9 and the rate of introduction of susceptible birds, but not by the use of H5N2 vaccine. In order to assess the effectiveness of temporary depopulation of stalls, a study was conducted to compare the prevalence of avian influenza virus and Newcastle disease virus before and shortly after the monthly rest day in live poultry markets in Hong Kong, by virus isolation. Prevalence of H9N2 avian influenza virus was reduced by the rest day, but Newcastle disease virus prevalence was unaffected. During the 2002 avian influenza H5N1 outbreak in local chicken farms, a case-control study was undertaken to identify risk factors that may have contributed to this outbreak. A questionnaire was administered by interview to collect the data for this study. Multivariate logistic regression models showed that movement of people and fomites from live poultry markets to farms were important influences on transmission, and that the live bird markets were the likely source of virus for farms. A spatial stochastic computer model was constructed to predict the spread of avian influenza virus in local chicken farms and live poultry markets in Hong Kong, and the effectiveness of control measures. The data used in model parameter setting was derived from the case-control study. The reference model produced an epidemic curve which was similar to the true epidemic curve in the 2002 outbreak. Control strategies such as rest day and vaccination were evaluated within the model, and found to produce results comparable with field experience. Results from these studies clarify various aspects of the epidemiological features and transmission dynamics of avian influenza viruses, and provide guidance on appropriate control and prevention strategies for highly pathogenic avian influenza viruses within poultry marketing systems in Asia.

Habitat loss and fragmentation are recognised worldwide as contributing to declines and extinctions of species. However, the biological factors underlying the effects of fragmentation are still often poorly understood, possibly due to the diversity of scales and approaches taken by researchers. I propose in this thesis an integrative approach that can be applied to any taxa and landscape, using a metapopulation of North Island robins (Petroica longipes) inhabiting forest patches of a fragmented agricultural landscape of New Zealand. In particular, I attempt to integrate the effects of habitat fragmentation on both habitat quality and the dispersal-driven broad scale dynamics of populations. I first analysed the distribution of robins based on presence-absence data, relating presence-absence to local habitat factors as well as size and isolation of forest patches (Chapter 2). Their distribution was found to be primarily limited by the isolation of forest patches, but was also related to some habitat factors. However, habitat fragmentation was not found to affect habitat quality, as the factors found to affect survival and productivity were unrelated to size and isolation, independent from the size or isolation of forest patches (Chapter 3). Based on the radio-tracking of juvenile robins, I applied a choice analysis technique to show that robins need woody vegetation for their natal dispersal and that they are unlikely to cross stretches of pasture greater than 150 m (Chapter 4). Juveniles dispersed a median Euclidean distance of 1129 m with a maximum of 11 km, whereas I predicted from the data that they would have dispersed a median distance of 3 km in continuous forest with a maximum of 20 km (Chapter 5). The consequences of this dispersal limitation and of variations in habitat quality were assessed using a spatially-explicit individual-based metapopulation model that incorporated realistic gap-limited dispersal behaviour of juvenile robins (Chapter 6). Whereas the movement of individuals between patches is commonly assumed to improve the persistence of populations, I found that a weaker gap-crossing ability, and therefore reduced landscape connectivity, increased the metapopulation size at equilibrium. This study highlights the complex effects of habitat loss and fragmentation on the distribution of species, but also the limits of excessive model simplification.

Improvements in breeding success are needed for conservation of endangered birds such as the New Zealand kakapo. A potential method to stimulate breeding is treatment with exogenous hormones. Hormone treatment is used in captive breeding programmes for endangered mammals but reliable techniques are not available for birds. Gonadotropin releasing hormone (GnRH), the principal hormone controlling reproduction, has been used to induce ovarian growth and ovulation in seasonally anoestrous mammals. The goal of the research in this thesis was to determine the potential of GnRH for hormone treatment in birds. The Japanese quail (Coturnix coturnix japonica) was used in the current research. Female quail held outdoors with male quail and with access to nesting materials and nest sites showed clear seasonal patterns in the width of the cloacal opening (indicative of oviduct development) and FSH concentrations, whilst LH concentrations were low during winter and increased during spring and summer. Prolactin concentrations were elevated in birds incubating eggs in nests and birds caring for young. Photoperiodically induced gonadal growth and regression were described in detail for male and female quail under controlled conditions. Testicular and ovarian growth was preceded by increased LH and FSH concentrations and accompanied by increased gonadal steroid concentrations. Administration of various types of GnRH stimulated luteinising hormone (LH) secretion in sexually regressed female Japanese quail. LH responses to cGnRH-II were greater than those to cGnRH-I. Low doses of buserelin stimulated similar LH responses to cGnRH-II, whilst high doses of buserelin and D-Lys6Trp7Tyr8-GnRH induced sustained LH secretion. Single daily injections of various doses of cGnRH-II, buserelin or D-Lys6Trp7Tyr8-GnRH in saline or polyvinylpyrrolidone (PVP) did not induce elevated baseline LH or stimulate ovarian growth. Repeated injections of D-Lys6Trp7Tyr8-GnRH did not increase LH concentrations over a short-term period. Continuous infusion of D-Lys6Trp7Tyr8-GnRH by osmotic mini-pump severely blunted the LH response and did not stimulate ovarian growth. Future studies using quail exposed to marginally stimulatory photoperiods will offer the opportunities to determine the effects of GnRH in birds under conditions which mimic photoperiod changes during the breeding season. Further studies on the potential development of a hormone treatment programme will continue to offer a promising future for endangered avian species including the New Zealand kakapo.

This thesis addresses issues related to surveillance for disease in commercial and non-commercial poultry populations. The motivation for this work has largely arisen from the unprecedented outbreaks of highly pathogenic avian influenza (HPAI) H5N1 that have occurred in 52 countries in Asia, Africa and Europe since 2003. A series of studies are presented using data derived from two countries, Vietnam and New Zealand. The two Vietnamese studies provide in-depth epidemiological analyses of the outbreak of HPAI H5N1 from December 2003 to March 2004. The three New Zealand studies deal with issues related to the development of effective surveillance strategies for HPAI — informed both directly and indirectly by the findings from the Vietnamese studies. This approach provides an example of how ‘lessons’ learnt from countries that have experienced large scale infectious disease epidemics can be used to assist in the design of surveillance activities in (as yet) unaffected countries. The descriptive analyses of the 2003 – 2004 outbreak of HPAI H5N1 in Vietnam indicate that the epidemic was seeded simultaneously in the north and south of the country in the later part of 2003 with 87% of provinces affected by February 2004. HPAI risk was concentrated around the Mekong and Red River Deltas. The broad scale spatial distribution of disease is likely to have been associated with regional differences in the poultry farming, trade in poultry, and environmental conditions such as the presence of bodies of water which would support reservoir species for the virus. A Bayesian zero-inflated Poisson regression model was used to quantify the influence of environmental and demographic factors on the spatial distribution of HPAI positive communes. In areas where disease was reported, our results show that HPAI risk was positively associated with the presence of irrigation and negatively associated with elevation. After controlling for these fixed effects, a single large area of elevated risk in the Red River Delta area was identified, presumably arising from similarities in the likelihood of reporting disease or the presence of factors increasing disease transmission and spread. Further investigations to elucidate likely transmission mechanisms, targeting this area of the country, would be a profitable area of future research. The second part of this thesis presents three studies that address issues related to the development of effective surveillance strategies for HPAI in New Zealand. The first was a cross-sectional study to enumerate the prevalence of backyard poultry ownership in two areas (one urban and the other rural) close to a large provincial city in the North Island of New Zealand. The prevalence of poultry ownership was 2% (95% CI 1% – 4%) in the urban area and 19% (95% CI 12% – 30%) in the rural area. The relatively low numbers of land parcels where poultry are present indicates that these areas, in the event of an infectious disease incursion, would be unlikely to pose a risk for spread of infectious agent. A cross-sectional survey of all members of the Poultry Industry Association of New Zealand was conducted in the later half of 2007. Respondents were asked to document contacts made with other enterprises related to feed, live birds and hatching eggs, table eggs and poultry product, and waste litter and manure. Patterns of contact were analysed using social network analyses. Each of the four networks had scale-free properties, meaning that for each movement type there were small numbers of enterprises that had contacts with large numbers of enterprises (potential ‘super-spreaders’ of disease). The presence of an undetected infectious disease in enterprises with super-spreader characteristics increases the likelihood that an epidemic will propagate rapidly through the population, assuming there is a directly proportional relationship between the number of contacts an enterprise makes and the probability that disease will be transferred from one location to another. While the finding that feed suppliers had large numbers of poultry farm contacts in the feed network came as no surprise, what was of greater interest was that there were small numbers of poultry farms that reported off-farm movements of feed. This should serve as an important reminder for disease control authorities: movement (and other) restrictions applied during the course of an animal health emergency should be applied across a range of industry sectors, recognising that some industry participants may practice activities that are not entirely typical for their enterprise type (e.g. poultry farms on-selling feed to other farms). In the absence of perfect and up-to-date network data, knowledge of the characteristics of individual enterprises that render them more likely to be atypical (e.g. size, type, and geographic location) would be of value, since this information could be used to inform a risk based approach to disease surveillance and control. A scenario tree model was developed as an approach for evaluating the effectiveness of New Zealand’s passive surveillance system for HPAI. The model was developed in two stages. In the first, factors thought to influence the geographic distribution of NAI risk of introduction and spread (and therefore surveillance strategy) were combined to create a spatial risk surface. In the second stage, a scenario tree model of the passive surveillance system for NAI was developed using the spatial risk surface and the HPAI surveillance strategy prescribed by Biosecurity New Zealand. The model was most sensitive to farmers reporting the presence of suspected cases of disease. This implies that the sensitivity of the system as a whole stands to increase if the importance of reporting suspicious clinical signs is reiterated to poultry producers. The studies presented in this thesis have presented a range of techniques and methodological approaches that are sufficiently generic to be used in any country to inform the design of surveillance strategies for a variety of animal diseases, not just those of poultry. Although epidemiology, as a discipline, is endoured with a vast range of analytical techniques that can be used to enhance the understanding of factors influencing the spread of disease among animal populations, the quality of data used to support these techniques is often lacking. The challenge in the years ahead, for both developed and developing countries, is to set in place the appropriate infrastructures to collect details of animal populations consistent in quality over time and space.

Thesis (Ph. D.)--University of Melbourne, 1978. / Includes bibliographical references (leaves 265-279).

La metformine est utilisée chez les patients et patientes atteints du diabète de type II. Elle est également administrée lors d’une infertilité liée à une insulino-résistance ou à un désordre métabolique. Mon projet de recherche a été d’analyser les effets de cet antidiabétique sur la fonction gonadique administré au stade foetal ou à la puberté. Nous avons montré par une approche in vivo sur deux modèles animaux: 1) qu'une administration orale de metformine à des poulets pré-pubères entraine un retard de puberté. Il se caractérise par une réduction du poids testiculaire, du diamètre des tubes séminifères et par une baisse de la testostérone sérique. 2) qu’une exposition des foetus mâles à de la metformine, chez la souris, conduit une fois adulte a une diminution de la taille des portées de 30%. Ce dysfonctionnement est associé à des marques épigénétiques sur l’ADN et des anomalies morphologiques de la tête des spermatozoïdes. Des techniques à haut débit (protéomique et métabolomique) réalisées sur des cultures de cellules de Sertoli immatures traitées ou non à la metformine ont permis de démontrer : 1) que le traitement mène à un métabolisme cellulaire de type Warburglike. 2) que des protéines présentent des différences d’abondance entre les deux conditions et qu’elles sont impliquées dans l’organisation du cytosquelette, de l’adhésion cellulaire, de la compaction de l’ADN, de la régulation de la réponse cellulaire à l’hypoxie et de l’immunité. Les résultats obtenus suggèrent que les grandes fonctions de sécrétion, de support et de protection des cellules de Sertoli sont modifiées par cet antidiabétique et qu’une exposition in utero à la metformine pourrait agir sur la fertilité et sur le métabolisme. / Metformin is used to treat patients with type II diabetes, it could be also administered to improve infertility associated to insulin-resistance or metabolic disorder. My research project was to analyse the consequence of a metformin exposure on gonad function from fetal to adult period. We showed by an in vivo approach on two animal models: 1) that oral administration of metformin to young chickens delay the puberty. It is characterized by a reduction in the testis weight, diameter of seminiferous tubule and decrease in testosterone level. 2) that mice, exposed in utero with metformin leads at adulte age to a lower fertility. This dysfunction is associated with morphological abnormalities of the sperm head and epigenetic marks on DNA. The second approach used proteomic and metabolomic strategy on cultured Sertoli cells treated or not with metformin. We demonstrated : 1) that the treatment leads to Warburg-like cellular metabolism. 2) that proteins present differences of abundances are involved in cytoskeleton organization, cell adhesion, DNA compaction, reponsiveness to hypoxia and immunity. The results suggest that the main function of secretion, support and protection of germ cell by Sertoli cells are modified by this antidiabetic, and that in utero exposure to metformin could act on the fertility and metabolism.

Submitted by Lara Oliveira (lara@ufersa.edu.br) on 2017-05-06T00:00:17Z No. of bitstreams: 1 AnyellePRE_DISSERT.pdf: 3332574 bytes, checksum: 6eba66f5232c1024161e4faadd9f882f (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-05-16T12:04:56Z (GMT) No. of bitstreams: 1 AnyellePRE_DISSERT.pdf: 3332574 bytes, checksum: 6eba66f5232c1024161e4faadd9f882f (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-05-16T12:05:16Z (GMT) No. of bitstreams: 1 AnyellePRE_DISSERT.pdf: 3332574 bytes, checksum: 6eba66f5232c1024161e4faadd9f882f (MD5) / Made available in DSpace on 2017-05-16T12:05:44Z (GMT). No. of bitstreams: 1 AnyellePRE_DISSERT.pdf: 3332574 bytes, checksum: 6eba66f5232c1024161e4faadd9f882f (MD5) Previous issue date: 2017-02-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The increasing degradation of natural wetlands has led many shorebirds populations to use alternative or complementary habitats. The artificial salines are one of the most common alternative habitats used by shorebird to feed and rest in coastal areas. The aim of this study was to investigate the richness, composition, habitat use and seasonal variation of shorebirds species associated with the artificial salines of the Apodi-Mossoró Estuary, Brazilian semiarid. Between August 2012 and July 2016, fortnightly shorebirds Charadriiformes censuses were conducted (2 h duration) in an area of 145 ha of saline from this Estuary (04°57’S; 37°08’O), in periods of high and low tide. A cumulative total of 28,868 records of individuals of 19 species Charadriiformes were obtained during 192 censuses. The number of records of shorebirds per census in the summer (2nd fortnight of August to the first fortnight of March: 167.9 ± 16.9 records, mean ± SE, N = 112 censuses) was similar to that sighted in the winter (2nd fortnight of March to the 1st fortnight of August: 125.7 ± 11.4, N = 80) (U = 4221; p = 0.495). In the summer period, the number of shorebirds records per census did not vary between periods of high tide and low tide (U = 1280; p = 0.094). On the other hand, in the winter, the number of shorebird records at high tide was higher than at low tide (U = 501.5; p = 0.004). Comparing the use of microhabitats over the studied saline area, shorebirds were more frequent in the evaporation ponds (85% of total records), and less frequent in pumping (9%) and crystallization (6%) ponds. There was a significant difference in the number of records of individuals/ha (density), with the highest density of individuals per census in the evaporation ponds (H = 246; p < 0.0001). The evaporation and pumping ponds were used mainly for foraging (respectively 79% and 76% of the records by microhabitat) and the crystallization pond for resting (75%). Our results shows that the Apodi-Mossoró Estuary may be recognized as an important area for the conservation of migratory and resident Charadriiformes populations in the South America. The use of artificial salines of this Estuary by shorebirds as alternative habitats for feeding and resting makes important to implement a continuous environmental monitoring program in the salines in order to ensure the maintenance of species-specific ecological requirements and to avoid chemical contamination of these animals / A crescente degradação de áreas úmidas naturais tem levado muitas populações de aves limícolas a buscarem habitats alternativos ou complementares, sendo as salinas artificiais um dos locais mais utilizados por estes animais para alimentação e descanso. O objetivo deste estudo foi investigar a riqueza, a composição, o uso do habitat e a variação sazonal de espécies de aves limícolas associadas às salinas artificiais do Estuário Apodi-Mossoró, semiárido brasileiro. Entre agosto de 2012 e julho de 2016, foram realizados quinzenalmente censos (2 h duração) de aves limícolas Charadriiformes em uma área de 145 ha de salina deste Estuário (04°57’S; 37°08’O), em períodos de maré alta e baixa. Um total acumulado de 28.868 registros de indivíduos de 19 espécies Charadriiformes foram obtidos em 192 censos. O número de registros de aves limícolas por censo no verão (2ª quinzena de agosto a 1ª quinzena de março: 167,9 ± 16,9 registros, média ± EP, N = 112 censos) foi semelhante ao registrado no inverno (2ª quinzena de março a 1ª quinzena de agosto: 125,7 ± 11,4, N = 80) (U = 4221; p = 0,495). No período do verão, o número de registros de aves limícolas por censo não variou entre períodos de maré alta e de maré baixa (U = 1280; p = 0,094). Por outro lado, no inverno, o número de registros em maré alta foi maior que em maré baixa (U = 501,5; p = 0,004). Em comparação ao uso de microhabitats na salina, as aves limícolas foram mais frequentes nos tanques de evaporação (85% do total de registros), e menos frequentes nos tanques de bombeamento (9%) e de cristalização (6%). Houve diferença significativa no número de registros de indivíduos/ha (densidade), com a maior densidade de indivíduos por censo nos microhabitats de evaporação (H = 246; p < 0,0001). Os tanques de evaporação e bombeamento foram utilizados principalmente para o forrageamento (respectivamente, 79% e 76% dos registros em cada um dos tipos de microhabitat) e os de cristalização para o descanso (75%). A partir destes resultados, o Estuário Apodi-Mossoró pode ser reconhecido como uma relevante área para a conservação de populações de Charadriiformes migratórias e residentes na América do Sul. O uso das salinas deste Estuário como habitats alternativos para alimentação e descanso por aves limícolas implica na necessidade de implementação de um programa de monitoramento ambiental continuado nas salinas, a fim de garantir a manutenção dos requerimentos ecológicos espécie-específicos e a não contaminação química destes animais / 2017-05-05