The black-billed gull (Larus bulleri) is a small gull that nests in dense colonies on gravel-bedded rivers in southern New Zealand. This dissertation describes research undertaken in Southland in 2004-2006 that investigates black-billed gull population decline and its causes. Historical ground counts of nests were calibrated with aerial photography of colonies and population trends analysed. The decline in breeding birds on Southland's four main rivers was equivalent to 6.0%/year (SE 1.8) or 83.6% in 30 years justifying the species' present listing as Endangered. Aerial monitoring is a poor index of the breeding population and major temporal variation was identified in counts. All re-sighted second-year birds exhibited natal dispersal and -70% left the natal catchment. Forty one percent of birds banded as adults also dispersed to other catchments. Breeding dispersal is apparently unrelated to previous breeding success and the availability of the previous year's colony site, and dispersing birds did not move as groups. Southland's black-billed gulls constitute a single inter-mixing population. Black-billed gulls selected sites on islands and banks according to availability, and selected rivers consistent with the number of gravel patches. Site vulnerability to floods varied significantly. Re-use of colony sites was positively influenced by use in previous years, the extraction of gravel, site stability and low weed cover. Widespread introduced weeds on colony sites preventing nesting and may have increased flooding risk. Colony size was related to colony area, which was related to gravel patch size. Investigation of historical changes in breeding habitat availability in Southland indicated a major reduction in gravel habitat on the Lower Oreti River between 1976 and 2002 due to river works including gravel extraction. On the Waiau River, Manapouri Dam construction in 1970 initially increased gravel areas, since reversed in the mid Waiau, and caused a 75% decline in the number of islands. Gravel patch sizes are still declining on the Lower Oreti and possibly the Mid Waiau. Hundreds of gravel patches remain on Southland rivers. Over 5000 nests in 21 colonies were monitored during incubation. Colony nest success was most influenced by colony location, averaging 90.1% (SE 2.1) on islands within rivers, and 66.8% (SE 2.2) on riverbanks, indicating that terrestrial predators exert the greatest influence on productivity. Breeding success, the mean number of fledglings produced per nest by colony, varied between 0 and 0.88 fledglings (mean 0.32, SE 0.08). Both parameters were positively related to colony size. The three smallest colonies failed to breed successfully, suggesting the presence of an Allee effect. Deterministic matrix models were used to investigate population trends using survival and productivity estimates for the closely related Kaikoura red-billed gull (L. novaehollandiae scopulinus). Adult survival, followed by breeding success and survival of first year birds, had the greatest influence on population projections. Improvements in most parameters are probably required to reverse the decline of Southland's black-billed gulls. Predation and disturbance by introduced mammals and the native black-backed gull (L. dominicanus) had the greatest impact on black-billed gull productivity. Most human disturbance is insignificant compared to predator disturbance, but illegal shooting of large numbers of adult gulls has major impacts in smaller sub-populations. Damming and excessive water abstraction reduces island habitat due to lowering of flows. Major climatic events such as droughts, and chemical ingestion through a diet dominated by agricultural invertebrates, are potential major threats about which little is known. Management actions including the collation and analysis of all unpublished black-billed gull count datasets, a thorough test of the accuracy of aerial monitoring, trialling of decoys to attract colonies to nest on islands, predator control at bank colonies, targeted weed control on high quality sites, advocacy and education and further research are recommended.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2006. / Härtill 5 uppsatser.

Submitted by Izabel Franco (izabel-franco@ufscar.br) on 2016-09-21T12:47:40Z No. of bitstreams: 1 TeseLAE.pdf: 3287478 bytes, checksum: 9b61b467458f0dac58881db75ea56413 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2016-09-26T20:11:22Z (GMT) No. of bitstreams: 1 TeseLAE.pdf: 3287478 bytes, checksum: 9b61b467458f0dac58881db75ea56413 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2016-09-26T20:12:51Z (GMT) No. of bitstreams: 1 TeseLAE.pdf: 3287478 bytes, checksum: 9b61b467458f0dac58881db75ea56413 (MD5) / Made available in DSpace on 2016-09-26T20:19:40Z (GMT). No. of bitstreams: 1 TeseLAE.pdf: 3287478 bytes, checksum: 9b61b467458f0dac58881db75ea56413 (MD5) Previous issue date: 2015-03-20 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / The gull Larus dominicanus is a common shorebird in south and southeast of Brazil. Being opportunistic regarding the occupation of habitats and type of food, can expand their populations. After the reproductive period occupies beaches, estuaries and mangroves, where they feed and spend part of their life cycle. Aspects involving the reproductive biology of this species have been studied in this state, requiring update for the proper management. However, there are still gaps on exposure to chemical and microbiological contaminants, and how these variables could influence the populations of the species. The objective of this thesis was to analyze the association of L. dominicanus to the pathogenic bacteria, their vulnerability to heavy metals and aspects of reproductive biology in three breeding sites, located on the coast of Santa Catarina. In the first chapter cloacal samples of young gulls were analyzed, indicating the presence of harmful microrganisms. In this article, we discuss the diversity of bacteria isolated from samples obtained in the islands, as well as its relationship with the feeding habit of this birds. The second chapter is about the analysis of heavy metal contamination in young gulls feathers. The results showed contamination by lead in two of the three islands studied. There is evidence that L. dominicanus is in process of bioaccumulation of metals, arising from the exploration of coal, developed near to the study areas. The third chapter compares reproductive aspects of gulls, as hatching success, posture, volume of eggs and offspring development. No differences were observed when comparing the reproduction between the islands, and the data were similar to those reported by other authors. Considering the three articles, it appears that L. dominicanus acts as a reservoir of pathogenic bacteria, and is vulnerable to contamination by heavy metals of anthropogenic origin, and no evidence of change in reproductive success and population dynamics of species. / A gaivota Larus dominicanus é uma ave costeira comum no sudeste e sul do Brasil. Considerada oportunista na ocupação de hábitat e alimentação vêem expandido suas populações no litoral de Santa Catarina. Após o período reprodutivo ocupa praias, estuários e manguezais, período reprodutivo ocupa mangues, praias e estuários, onde alimentam-se e passam parte do seu ciclo de vida. Aspectos que envolvem a biologia reprodutiva desta espécie foram estudados nesse estado, necessitando de atualização das informações, para que o manejo adequado. Ainda existem lacunas sobre a exposição à contaminantes químicos e microbiológicos, e de que forma estas variáveis poderiam influenciar suas populações. Assim, teve-se por objetivo analisar a associação de L. dominicanus a bactérias patogênicas, sua vulnerabilidade à metais pesados e aspectos da biologia reprodutiva em três colônias de nidificação no litoral de Santa Catarina. No primeiro capítulo foram analisadas amostras cloacais de gaivotas jovens, indicando a presença de micro-organismos nocivos. Nesse artigo, discute-se a diversidade de bactérias isoladas das amostras obtidas nas ilhas, assim como a relação desta com sua alimentação. O segundo capítulo aborda a contaminação por metais pesados em penas de gaivotas jovens. Foi registrada concentração significativa de chumbo em duas das três ilhas analisadas. Existem evidências que L. dominicanus esteja em processo de bioacumulação de metais, oriundos da atividade de exploração do carvão mineral, desenvolvida nas proximidades das áreas de estudo. O terceiro capítulo compara aspectos reprodutivos da espécie, como sucesso de incubação nos sítios, tamanho da postura, biometria dos ovos e desenvolvimento dos filhotes. Não foram observadas diferenças marcantes entre as ilhas na reprodução, com dados próximos aos registrados por outros autores. Considerando os três artigos, verifica-se que L. dominicanus atua como reservatório de bactérias patogênicas, sendo vulnerável a contaminação por metais pesados de origem antrópica, e sem evidência de alteração do sucesso reprodutivo e dinâmica populacional da espécie.

In Karpfen sächsischer Karpfenteichwirtschaften spielen u.a. die Zestoden Neogryporhynchus cheilancristrotus und Paradilepis scolecina und der Trematode Diplostomum pseudospathaceum eine Rolle (KAPPE 2004, PIETROCK et al. 2006, KAPPE & SEIFERT unveröff.). Weitere Fischarten (Schleie, Plötze, Regenbogenforelle) sind mit den Trematoden Diplostomum sp., Hysteromorpha triloba, Posthodiplostomum cuticola infiziert (PIETROCK et al. 2006). Mit dieser Arbeit sollte der Versuch unternommen werden, die Bedeutung Fisch fressender Vögel als Vektor Fisch pathogener Helminthen in Sachsen aufzuklären. Dafür wurden im Zeitraum von Juni 2003 bis Dezember 2004 97 Kormorane (Phalacrocorax carbo) und 46 Graureiher (Ardea cinerea) aus dem Einzugsgebiet sächsischer Teichwirtschaften auf ihren Befall mit Endohelminthen untersucht. Im Winter 2004 konnte zusätzlich ein Silberreiher (Casmerodius albus) und eine Silbermöwe (Larus argentatus) in die Untersuchungen einbezogen werden. Während des Untersuchungszeitraumes konnten so insgesamt 29 Parasitengattungen bzw. -arten nachgewiesen werden, denen z.T. kommerziell genutzte Süßwasserfische als Zwischenwirte oder paratenische Wirte dienen. Die Parasiten des Kormorans umfassten 15 verschiedene Parasitenarten. Dabei handelte es sich um die beiden Zestoden Ligula intestinalis und Paradilepis scolecina, die sechs Nematoden Baruscapillaria spp., Contracaecum rudolphii, Cyathostoma microspiculum, Desmidocercella incognita, Eucoleus contortus und Syncuaria squamata und die sieben Trematoden Clinostomum complanatum, Holostephanus dubinini, Hysteromorpha triloba, Metorchis xanthosomus, Paryphostomum radiatum, Petasiger exaeretus und P. phalacrocoracis. Außerdem wurden die zwei Kratzer Corynosoma strumosum und Polymorphus sp. nachgewiesen. Im Graureiher konnten dagegen nur neun Helminthenarten nachgewiesen werden. So der Zestode Neogryporhynchus cheilancristrotus, die sechs Trematoden Apharyngostrigea cornu, Bilharziella polonica, Diplostomum sp., Echinoasmus belocephalus, Posthodiplostomum cuticola und Tylodelphis excavata und die drei Nematoden Avioserpens galliardi, Desmidocercella incognita und Desmidocercella numidica. In der Silbermöwe konnten der Zestode Echinocotyle verschureni, die vier Trematoden Apophallus mühlingi, Diplostomum pseudospathaceum, Renicola lari und Metorchis xanthosomus sowie die drei Nematoden Desmidocercella incognita, Cosmocephalus obvelatus und Paracuaria tridentata nachgewiesen werden. Die parasitologischen Befunde des Silberreihers beschränkten sich auf Apharyngostrigea sp., Desmidocercella incognita und Desmidocercella numidica. Eine Beeinflussung der Helminthenfauna von Karpfen durch Kormoran und Reiher als auch umgekehrt konnte anhand der eigenen Untersuchungen in sächsischen Teichwirtschaften nicht sicher nachgewiesen werden. / In Saxonian carp ponds the cestodes Neogryporhynchus cheilancristrotus and Paradilepis scolecina and the trematode Diplostomum pseudospathaceum occur amongst others in carps (KAPPE 2004, PIETROCK et al. 2006, KAPPE & SEIFERT unpublished). Further fish species (tench, roach, rainbow trout) are infected with the trematodes Diplostomum sp., Hysteromorpha triloba and Posthodiplostomum cuticola (PIETROCK et al. 2006). This work was performed to analyse the importance of fish eating birds as vectors of fish pathogenic helminths. For this purpose 97 common cormorants (Phalacrocorax carbo) and 46 grey herons (Ardea cinerea) were examined on their infestation with endohelminths during the term of June 2003 to December 2004. All these birds came from the vicinity of Saxonian fish ponds. In winter 2004 additionally an egret (Casmerodius albus) and an hering gull (Larus argentatus) were included into the investigations. Altogether 29 parasite species and genus respectively could be detected. Some of these endohelminths use fresh water fishes as intermediate or paratenic hosts. The cormorants harboured 15 different parasite species and genus respectively: the two cestodes Ligula intestinalis and Paradilepis scolecina, the six nematodes Baruscapillaria carbonis, Contracaecum rudolphii, Cyathostoma microspiculum, Desmidocercella incognita, Eucoleus contortus and Syncuaria squamata and seven trematodes the Clinostomum complanatum, Holostephanus dubinini, Hysteromorpha triloba, Metorchis xanthosomus, Paryphostomum radiatum, Petasiger exaeretus and P. phalacrocoracis. In addition the two acanthocephales Corynosoma strumosum and Polymorphus sp. were detected. In the grey heron nine helminth species/genus could be detected: the cestode Neogryporhynchus cheilancristrotus, the six trematodes Apharyngostrigea cornu, Bilharziella polonica, Diplostomum sp., Echinoasmus belocephalus, Posthodiplostomum cuticola and Tylodelphis excavata and the three nematodes Avioserpens galliardi, Desmidocercella incognita and Desmidocercella numidica. In the hering gull the cestode Echinocotyle verschureni, the four trematodes Apophallus muehlingi, Diplostomum pseudospathaceum, Renicola lari and Metorchis xanthosomus as well as the three nematodes Desmidocercella incognita, Cosmocephalus obvelatus and Paracuaria tridentata were detected. Merely three endohelminths could be demonstrated in the investigated egret: Apharyngostrigea sp., Desmidocercella incognita and D. numidica. Six of the 29 endohelminth species and genus respectively were found in this examination to infest both fish and birds in Saxonian fish ponds. Nevertheless the helminth fauna of the inestigated birds, in particular of cormorants and herons did not make a definite impact on the carps´ infestation with endohelminths. As well as the fish helminth fauna were not unequivocally linked to those of the birds.

In Karpfen sächsischer Karpfenteichwirtschaften spielen u.a. die Zestoden Neogryporhynchus cheilancristrotus und Paradilepis scolecina und der Trematode Diplostomum pseudospathaceum eine Rolle (KAPPE 2004, PIETROCK et al. 2006, KAPPE & SEIFERT unveröff.). Weitere Fischarten (Schleie, Plötze, Regenbogenforelle) sind mit den Trematoden Diplostomum sp., Hysteromorpha triloba, Posthodiplostomum cuticola infiziert (PIETROCK et al. 2006). Mit dieser Arbeit sollte der Versuch unternommen werden, die Bedeutung Fisch fressender Vögel als Vektor Fisch pathogener Helminthen in Sachsen aufzuklären. Dafür wurden im Zeitraum von Juni 2003 bis Dezember 2004 97 Kormorane (Phalacrocorax carbo) und 46 Graureiher (Ardea cinerea) aus dem Einzugsgebiet sächsischer Teichwirtschaften auf ihren Befall mit Endohelminthen untersucht. Im Winter 2004 konnte zusätzlich ein Silberreiher (Casmerodius albus) und eine Silbermöwe (Larus argentatus) in die Untersuchungen einbezogen werden. Während des Untersuchungszeitraumes konnten so insgesamt 29 Parasitengattungen bzw. -arten nachgewiesen werden, denen z.T. kommerziell genutzte Süßwasserfische als Zwischenwirte oder paratenische Wirte dienen. Die Parasiten des Kormorans umfassten 15 verschiedene Parasitenarten. Dabei handelte es sich um die beiden Zestoden Ligula intestinalis und Paradilepis scolecina, die sechs Nematoden Baruscapillaria spp., Contracaecum rudolphii, Cyathostoma microspiculum, Desmidocercella incognita, Eucoleus contortus und Syncuaria squamata und die sieben Trematoden Clinostomum complanatum, Holostephanus dubinini, Hysteromorpha triloba, Metorchis xanthosomus, Paryphostomum radiatum, Petasiger exaeretus und P. phalacrocoracis. Außerdem wurden die zwei Kratzer Corynosoma strumosum und Polymorphus sp. nachgewiesen. Im Graureiher konnten dagegen nur neun Helminthenarten nachgewiesen werden. So der Zestode Neogryporhynchus cheilancristrotus, die sechs Trematoden Apharyngostrigea cornu, Bilharziella polonica, Diplostomum sp., Echinoasmus belocephalus, Posthodiplostomum cuticola und Tylodelphis excavata und die drei Nematoden Avioserpens galliardi, Desmidocercella incognita und Desmidocercella numidica. In der Silbermöwe konnten der Zestode Echinocotyle verschureni, die vier Trematoden Apophallus mühlingi, Diplostomum pseudospathaceum, Renicola lari und Metorchis xanthosomus sowie die drei Nematoden Desmidocercella incognita, Cosmocephalus obvelatus und Paracuaria tridentata nachgewiesen werden. Die parasitologischen Befunde des Silberreihers beschränkten sich auf Apharyngostrigea sp., Desmidocercella incognita und Desmidocercella numidica. Eine Beeinflussung der Helminthenfauna von Karpfen durch Kormoran und Reiher als auch umgekehrt konnte anhand der eigenen Untersuchungen in sächsischen Teichwirtschaften nicht sicher nachgewiesen werden. / In Saxonian carp ponds the cestodes Neogryporhynchus cheilancristrotus and Paradilepis scolecina and the trematode Diplostomum pseudospathaceum occur amongst others in carps (KAPPE 2004, PIETROCK et al. 2006, KAPPE & SEIFERT unpublished). Further fish species (tench, roach, rainbow trout) are infected with the trematodes Diplostomum sp., Hysteromorpha triloba and Posthodiplostomum cuticola (PIETROCK et al. 2006). This work was performed to analyse the importance of fish eating birds as vectors of fish pathogenic helminths. For this purpose 97 common cormorants (Phalacrocorax carbo) and 46 grey herons (Ardea cinerea) were examined on their infestation with endohelminths during the term of June 2003 to December 2004. All these birds came from the vicinity of Saxonian fish ponds. In winter 2004 additionally an egret (Casmerodius albus) and an hering gull (Larus argentatus) were included into the investigations. Altogether 29 parasite species and genus respectively could be detected. Some of these endohelminths use fresh water fishes as intermediate or paratenic hosts. The cormorants harboured 15 different parasite species and genus respectively: the two cestodes Ligula intestinalis and Paradilepis scolecina, the six nematodes Baruscapillaria carbonis, Contracaecum rudolphii, Cyathostoma microspiculum, Desmidocercella incognita, Eucoleus contortus and Syncuaria squamata and seven trematodes the Clinostomum complanatum, Holostephanus dubinini, Hysteromorpha triloba, Metorchis xanthosomus, Paryphostomum radiatum, Petasiger exaeretus and P. phalacrocoracis. In addition the two acanthocephales Corynosoma strumosum and Polymorphus sp. were detected. In the grey heron nine helminth species/genus could be detected: the cestode Neogryporhynchus cheilancristrotus, the six trematodes Apharyngostrigea cornu, Bilharziella polonica, Diplostomum sp., Echinoasmus belocephalus, Posthodiplostomum cuticola and Tylodelphis excavata and the three nematodes Avioserpens galliardi, Desmidocercella incognita and Desmidocercella numidica. In the hering gull the cestode Echinocotyle verschureni, the four trematodes Apophallus muehlingi, Diplostomum pseudospathaceum, Renicola lari and Metorchis xanthosomus as well as the three nematodes Desmidocercella incognita, Cosmocephalus obvelatus and Paracuaria tridentata were detected. Merely three endohelminths could be demonstrated in the investigated egret: Apharyngostrigea sp., Desmidocercella incognita and D. numidica. Six of the 29 endohelminth species and genus respectively were found in this examination to infest both fish and birds in Saxonian fish ponds. Nevertheless the helminth fauna of the inestigated birds, in particular of cormorants and herons did not make a definite impact on the carps´ infestation with endohelminths. As well as the fish helminth fauna were not unequivocally linked to those of the birds.

L'objectif de ce travail a été d'analyser l'influence de la répartition géographique des ressources alimentaires d'origine anthropique (décharges à ciel ouvert) sur les distribution spatiale et la taille des colonies, la dynamique démographique, le régime alimentaire des adultes et des poussins et les paramètres reproducteurs des populations de Goélands leucophées Larus michahellis des îles rocheuses du littoral provençal. Pour la première fois, cette thématique a fait l'objet d'une approche conduite à une large échelle géographique (80 km de linéaire côtier) et sur un jeu important de sites de nidification et de zones d'alimentation. Les patrons d'utilisation des principales décharges situées dans la zone de prospection alimentaire de l'espèce ont été étudiés. Les aliments provenant des décharges dominent largement dans le régime alimentaire des oiseaux, aussi bien des adultes que des poussins. Cette prédominance est constante pour chacune des colonies étudiées malgré le gradient d'accessibilité aux décharges qui existe dans leur environnement proche. Les décharges constituent donc l'habitat d'alimentation préférentiel de l'espèce dans la zone d'étude. En outre, il a pu être mis en évidence que l'accessibilité et l'abondance des ressources anthropiques sur le continent conditionnent fortement la distribution spatiale et la taille des colonies ainsi que la dynamique démographique récente et les paramètres reproducteurs des colonies étudiées. Le suivi des goélands sur les décharges permet de confirmer l'importance de celles-ci comme zones d'alimentation de l'espèce. Au cours de la saison de reproduction les décharges sont fréquentées par l'essentiel des goélands reproducteurs de la zone considérée. Pour autant, les ressources alimentaires fournies par les décharges ne sont pas utilisées à saturation, de même que les sites de nidifications dont certains présentent des densités de goélands nicheurs encore faibles. Ceci laisse présager une poursuite probable de l'augmentation des effectifs de Goélands leucophées dans les prochaines années. Dans le cas d'une espèce surabondante comme le Goéland leucophée, l'augmentation probable des effectifs signifie une augmentation des interactions négatives avec les activités humaines et de ce fait, la mise en place de mesures de régulation de l'espèce ou d'atténuation des nuisances.

An individual’s life history is a sequence of events which eventually determine its contribution to the next generation, or fitness. These events are affected by environmental factors, genetic make-up and decisions made by an individual and its breeding partner. Recognition of these determinants helps to understand both short-term ecological changes and long-term evolutionary dynamics in a population. In this thesis long-term individual-based data on common gull (Larus canus) is used to study age-dependent reproductive success, survival, pair retention and breeding time. Collected pedigree data enabled to study genetic variation of traits and the selection on them. The reproductive success of common gulls increased steadily until very old age. This increase cannot be explained by selection effects, since individuals with lower breeding success were shown not to have lower survival. Consequently, this gain must be ascribed primarily to an age-related improvements of individual competence and/or increased reproductive effort. Annual survival of adult birds was age- and year-dependent. The latter was partly explained by winter severity. The size of the white spots on five outermost primaries predicted the bird’s future survival and divorce probabilities and hence, pair endurance capability. Gulls with larger spots enjoyed higher survival and lower divorce rates compared to birds with smaller spots. This suggests that the wing tip pattern might function as a condition dependent signal, revealing individual variation in quality. One of the advantages of persistent pair bond was the ability to start breeding early in the season. The timing of breeding of firm pairs advanced with time not only due to mates’ increasing age, but also owing to their experience together. Although both sexes had phenotypic effects on laying date, it was heritable only in females. On the phenotypic and genotypic level, early laying was under positive fecundity and survival selection in females.

This study investigated factors associated with two mortality events: avian botulism in waterfowl and mortality associated with hatching asynchrony in prefledgling Franklins gulls (Larus pipixcan). The initial focus of my research was on the spatiotemporal relationship between mortality of Franklins gulls and the onset of botulism outbreaks in waterfowl, and the suitability of gull carcasses for proliferation and toxigenesis of Clostridium botulinum. From 1999 to 2001, dead hatch-year Franklins gulls were by far the most abundant carcasses, and the only source of toxin-laden maggots found on transects prior to the occurrence of avian botulism in waterfowl. Nest density was a significant predictor of hatch-year gull carcass density. High density of toxic material from gull carcasses prior to the onset of botulism in waterfowl coincided with high densities of susceptible birds; hence, mortality of Franklins gulls has the potential to be a major initiating factor for botulism outbreaks at Eyebrow Lake, Saskatchewan. The causes of gull mortality were conditions or diseases associated with starvation, stress, or immunosuppression, and most mortality occurred in third-hatched chicks. To separate effects of laying order from effects of hatching asynchrony on prefledgling survival, a cross-fostering experiment was conducted to create clutches containing asynchronously hatching eggs of the same laying order, and of similar egg mass, egg volume, and female quality. Hatching order, independent of laying order, significantly affected survival to fledging, whereas laying order had no observable effect, indicating that intraclutch variation in egg quality does not predetermine the fate of prefledglings, and may be less important than hatching asynchrony for survival of prefledgling Franklins gulls. Relationships among hatching asynchrony, laying order, mass, corticosterone, immune function, growth, and survival at two stages of development were complex. Hatching asynchrony significantly affected early and late prefledgling survival, and was directly or indirectly associated with mass, corticosterone level, and cell-mediated immune responses at early and later stages of development. Both hatching asynchrony and mass appeared to play key roles in mediating life history trade-offs among cell-mediated immune function, growth, and survival. In contrast to cell-mediated immune responses, primary humoral immune response was not directly affected by hatching order or mass, nor was it associated with survival to fledging. Rather, it was associated with laying order, neonatal testosterone, corticosterone at 2 weeks, growth of leg length, and clutch initiation date, illustrating the importance of examining more than one branch of the immune system in studies of life history trade-offs. This study is a step toward using a multipronged and multidisciplinary approach to demonstrate interactions and trade-offs among life history traits, the physiological mechanisms that produce these relationships, and how these relationships may change depending on stage of development.

This study investigated factors associated with two mortality events: avian botulism in waterfowl and mortality associated with hatching asynchrony in prefledgling Franklins gulls (Larus pipixcan). The initial focus of my research was on the spatiotemporal relationship between mortality of Franklins gulls and the onset of botulism outbreaks in waterfowl, and the suitability of gull carcasses for proliferation and toxigenesis of Clostridium botulinum. From 1999 to 2001, dead hatch-year Franklins gulls were by far the most abundant carcasses, and the only source of toxin-laden maggots found on transects prior to the occurrence of avian botulism in waterfowl. Nest density was a significant predictor of hatch-year gull carcass density. High density of toxic material from gull carcasses prior to the onset of botulism in waterfowl coincided with high densities of susceptible birds; hence, mortality of Franklins gulls has the potential to be a major initiating factor for botulism outbreaks at Eyebrow Lake, Saskatchewan. The causes of gull mortality were conditions or diseases associated with starvation, stress, or immunosuppression, and most mortality occurred in third-hatched chicks. To separate effects of laying order from effects of hatching asynchrony on prefledgling survival, a cross-fostering experiment was conducted to create clutches containing asynchronously hatching eggs of the same laying order, and of similar egg mass, egg volume, and female quality. Hatching order, independent of laying order, significantly affected survival to fledging, whereas laying order had no observable effect, indicating that intraclutch variation in egg quality does not predetermine the fate of prefledglings, and may be less important than hatching asynchrony for survival of prefledgling Franklins gulls. Relationships among hatching asynchrony, laying order, mass, corticosterone, immune function, growth, and survival at two stages of development were complex. Hatching asynchrony significantly affected early and late prefledgling survival, and was directly or indirectly associated with mass, corticosterone level, and cell-mediated immune responses at early and later stages of development. Both hatching asynchrony and mass appeared to play key roles in mediating life history trade-offs among cell-mediated immune function, growth, and survival. In contrast to cell-mediated immune responses, primary humoral immune response was not directly affected by hatching order or mass, nor was it associated with survival to fledging. Rather, it was associated with laying order, neonatal testosterone, corticosterone at 2 weeks, growth of leg length, and clutch initiation date, illustrating the importance of examining more than one branch of the immune system in studies of life history trade-offs. This study is a step toward using a multipronged and multidisciplinary approach to demonstrate interactions and trade-offs among life history traits, the physiological mechanisms that produce these relationships, and how these relationships may change depending on stage of development.

The seasonal and diel feeding habits of the goosander, Mergus merganser, the red-breasted merganser, M. serrator, gulls (Larus canus, L. argentatus and L. fuscusj and terns, Sterna hirundo/paradisaea were studied at 64V05'N. Birds' activity patterns were influenced by the nocturnal spawning of the river lamprey (Lampetra fluviatilis). Food selection and food consumption by hand-raised mergansers together with aquarium studies of the diel activity patterns of their most important prey supplemented the field data. River lamprey dominated the diet of the goosander by weight and the sculpin Cottus gobio by number. The fish consumption of the goosanders was found to be about 12% of the available river lamprey biomass and about 17% of the sculpin biomass during the breeding season. In experimental situations the river lamprey was a low- pritority species compared with salmon , Salmo salar, brown trout, 53. trutta, and minnow, Phoxinus phoxinus, when presented to satiated birds of both Mergus species. When hungry, however, the birds caught the available prey irrespective of species, but they selected larger prey when two size classes were present. Experimental results were compared with field data on availability, consumption and the escape behaviour of the various fish species. The rivers emptying in the Bothnian Bay are regarded as important feeding areas for birds breeding along the coast. In early spring they get access to abundant and reliable food resources, e.g the river lamprey. Later on the three-spined stickleback, Gasterosteus aculeatus, supply both Mergus species with food in the river and also along the coast. From the middle of June potential food supply available to birds decreases in the rivers and becomes more abundant in the coastal area. / <p>S. 1-41: sammanfattning, s. 43-227: 7 uppsatser</p> / digitalisering@umu