Habitat selection theory presumes that organisms are not distributed randomly in their environments because of habitat-specific differences in reproductive success and survival; unfortunately, many previous studies were either unable or failed to look for evidence of processes shaping nest site selection patterns. Furthermore, little is known about adaptive nest site selection in northern environments where habitats often have little vegetation and time and climatic constraints may be pronounced. Therefore, I investigated patterns of nest site selection by common eider ducks (<i>Somateria mollissima</i>) at an island colony in Canadas Eastern Arctic, and looked for evidence of selective processes underlying these patterns by employing experimental and observational techniques.<p>I characterized physical features of (a) non-nest sites (b) active nest sites and (c) unoccupied nest sites that had been used in previous years. Habitat features that distinguished non-nest sites from unoccupied nest sites were also important in distinguishing between active and unoccupied nest sites during the breeding season. Active nest sites were closer to herring gull (<i>Larus argentatus</i>) nests, farther from the ocean and had organic substrates. In general, habitat features associated with nest use were not strongly associated with success after the onset of incubation. Nests near fresh water ponds were more successful in one study year, but in the other two study years successful nests were initiated earlier and more synchronously than were unsuccessful nests. Common eiders settled to nest first near the geographic centre of the colony, whereas sites near the largest fresh water pond were occupied later; distance to ocean had no observable effect on timing of nesting. Nest density was greater farther from the ocean, but timing of nest establishment did not differ between high and low density plots. <p>I tested whether moss or duck down placed in nest bowls could increase nest establishment, or advance laying date. I placed this extraneous material in bowls before nesting and found no difference in likelihood of nest establishment; however, bowls containing duck down were initiated earlier (or had higher survival) than those containing no nesting material. To investigate the role of nest shelter and microclimate in nest site choices and female body condition, I placed plywood nest shelters over established nests. Temperature probes indicated that artificially-sheltered females experienced more moderate thermal environments and maintained higher body weight during late incubation than did unsheltered females. However, few eiders nested at naturally-sheltered sites, possibly because nest concealment increases susceptibility to mammalian predators. My results suggest that eider nest choices likely reflect trade-offs among selective pressures that involve the local predator community, egg concealment, nest microclimate and energy use.

Habitat selection theory presumes that organisms are not distributed randomly in their environments because of habitat-specific differences in reproductive success and survival; unfortunately, many previous studies were either unable or failed to look for evidence of processes shaping nest site selection patterns. Furthermore, little is known about adaptive nest site selection in northern environments where habitats often have little vegetation and time and climatic constraints may be pronounced. Therefore, I investigated patterns of nest site selection by common eider ducks (<i>Somateria mollissima</i>) at an island colony in Canadas Eastern Arctic, and looked for evidence of selective processes underlying these patterns by employing experimental and observational techniques.<p>I characterized physical features of (a) non-nest sites (b) active nest sites and (c) unoccupied nest sites that had been used in previous years. Habitat features that distinguished non-nest sites from unoccupied nest sites were also important in distinguishing between active and unoccupied nest sites during the breeding season. Active nest sites were closer to herring gull (<i>Larus argentatus</i>) nests, farther from the ocean and had organic substrates. In general, habitat features associated with nest use were not strongly associated with success after the onset of incubation. Nests near fresh water ponds were more successful in one study year, but in the other two study years successful nests were initiated earlier and more synchronously than were unsuccessful nests. Common eiders settled to nest first near the geographic centre of the colony, whereas sites near the largest fresh water pond were occupied later; distance to ocean had no observable effect on timing of nesting. Nest density was greater farther from the ocean, but timing of nest establishment did not differ between high and low density plots. <p>I tested whether moss or duck down placed in nest bowls could increase nest establishment, or advance laying date. I placed this extraneous material in bowls before nesting and found no difference in likelihood of nest establishment; however, bowls containing duck down were initiated earlier (or had higher survival) than those containing no nesting material. To investigate the role of nest shelter and microclimate in nest site choices and female body condition, I placed plywood nest shelters over established nests. Temperature probes indicated that artificially-sheltered females experienced more moderate thermal environments and maintained higher body weight during late incubation than did unsheltered females. However, few eiders nested at naturally-sheltered sites, possibly because nest concealment increases susceptibility to mammalian predators. My results suggest that eider nest choices likely reflect trade-offs among selective pressures that involve the local predator community, egg concealment, nest microclimate and energy use.

Abstract Social information use is a widespread phenomenon across the animal kingdom and it affects various important aspects of animal behaviour. Animals observe and copy the behaviour of conspecifics and other species on the same trophic level in their own decision-making, e.g., in habitat or mate choice. Copying is adaptive only when it is selective. Thus, it would be important to understand when and which individuals should copy others, and which individuals they choose to copy and what are the consequences of social information use. In this thesis, I experimentally study these questions in wild animals living in natural conditions. By simulating arbitrary preference of great tits (Parus major), I demonstrated that the portrayed fitness does not affect the nest site choices of conspecifics, but the tit pairs with an old male prefer the nest site choices of good and poor conspecifics. Social information use among tits appears to be age- and sex-dependent. Pied flycatchers (Ficedula hypoleuca), however, selectively copy or reject a novel nest site feature preference (symbol attached to the nest box) of great tits experimentally manipulated to exhibit high or low fitness (clutch size), respectively. By offering pied flycatchers choice in nest boxes with alternative contents, I showed that nest take-overs of flycatchers are not a form of social information use, but seem to result from the reduced building effort required. Furthermore, by conducting a decoy and playback experiment, I showed that great tits covered eggs more efficiently in the presence of pied flycatchers. One function of egg covering behaviour seems to be a counter-adaptation to reduce information parasitism by pied flycatchers. My results demonstrate that the social transmission of behaviours across species can be highly selective in response to observed fitness, plausibly making the phenomenon adaptive. In contrast with the current theory of species coexistence, overlap between realized niches of species could dynamically increase or decrease, depending on the observed success of surrounding individuals. The social information revealed by success and behaviour of animals is a resource that can be used or concealed. It is a new kind of evolutionary and ecological factor which may affect the formation of ecosystems and species coevolution. / Tiivistelmä Sosiaalinen informaationkäyttö on yleinen ilmiö eläinkunnassa, ja sitä tavataan aina hyönteisistä valaisiin. Yksilöt tarkkailevat ja kopioivat sekä lajitovereiden että toisen ekologialtaan samankaltaisen lajin yksilöiden käyttäytymistä erilaisissa tilanteissa, kuten pesäpaikan tai parittelukumppanin valinnassa. Sosiaalinen informaationkäyttö on adaptiivista ainoastaan ollessaan valikoivaa. Siksi on tärkeää selvittää kenen, koska ja ketä kannattaa kopioida, ja mitä ekologisia ja evolutiivisia seurauksia siitä koituu informaation lähteelle ja käyttäjälle. Väitöskirjassani tutkin kokeellisesti informaation hankkijan (kirjosieppo Ficedula hypoleuca) valikoivaa kopioimista ja siitä mahdollisesti johtuvaa informaation lähteen (talitiainen Parus major) vasta-adaptaatiota luonnonoloissa. Symbolikokeilla selvitin, että talitiaisten lajinsisäinen kopiointi on iästä ja sukupuolesta riippuvaa, mutta informaationlähteen havaittu kelpoisuus ei vaikuta kopioinnin todennäköisyyteen. Kirjosiepot puolestaan kopioivat valikoivasti keinotekoisesti luotuja tiaisten mieltymyksiä pesäpönttöön kiinnitettyjä symboleja kohtaan, riippuen tiaisten havaitusta manipuloidusta kelpoisuudesta (munamäärästä pesässä). Siepot kopioivat tiaisia, joiden pesässä on paljon munia (13 munaa), ja rejektoivat tiaisia (valitsevat vaihtoehtoisen symbolin), joilla munia on vähän (5 munaa). Tarjoamalla kirjosiepoille vaihtoehtoisia pesäpönttöjä osoitin, että sieppojen luontainen mieltymys vallata ja rakentaa pesänsä toisten pesien päälle ei ole sosiaalisen informaationkäytön muoto, vaan se näyttää olevan pesänrakennuksen kustannusten minimointia. Playback-kokeilla osoitin, että talitiaisten munienpeittelykäyttäytymisellä on useita funktioita. Se on vasta-adaptaatio kirjosiepon informaatioloisintaa vastaan ja toimii mahdollisesti suojana kylmää vastaan. Väitöskirjani tulokset osoittavat, että eläinten käyttäytymisen paljastama sosiaalinen informaatio on resurssi, jota voidaan hyödyntää tai salata. Se on myös uudenlainen ekologinen ja evolutiivinen tekijä, joka vaikuttaa eliöyhteisöjen muodostumiseen ja lajien koevoluutioon. Lajienvälinen valikoiva sosiaalinen informaationkäyttö -hypoteesi haastaa nykyisen koevoluutioteorian. Se ennustaa, että informaatiota hyödyntävän lajin ja informaationlähteen ominaisuudet voivat joko samankaltaistua tai erilaistua, informaationlähteen havaittavasta menestyksestä riippuen.

No description available.

Au cours de leur vie, les individus doivent constamment prendre des décisions qui peuvent fortement affecter leur valeur sélective. Pour optimiser leur prise de décisions, ces individus peuvent utiliser des informations soit issues de leurs propres interactions avec l’environnement (informations personnelles), soit issues de l’observation d’autres individus (informations sociales). La propension à utiliser des informations sociales et leur signification dépend certainement de paramètres individuels et environnementaux. Pour comprendre le potentiel évolutif de ce comportement à priori adaptatif, il est nécessaire de comprendre les causes de ces variations inter- et intra-individuelles. Le but de cette thèse était donc de déterminer les sources de variations individuelles dans l’utilisation d’information sociales hétérospécifiques pour le choix d’habitat de reproduction, chez le gobe-mouche à collier (Ficedula albicollis). A partir de données à long terme et d’expérimentations en nature dans la population de Gotland (Suède), j’ai montré que l’utilisation d’informations sociales n’est pas héritable dans cette population, mais dépend de l’âge et de l’agressivité des mâles, ainsi que de la taille de ponte des compétiteurs au moment où les gobe-mouches font leur choix. A partir d’une expérience de repasse, j’ai également montré que les femelles peuvent ajuster, en fonction de leur propre niveau d’agressivité, leur choix de site de nidification en fonction de caractéristiques de chants supposément liés à la qualité des mésanges charbonnières (Parus major). Cette thèse souligne l’importance de la personnalité dans l’utilisation d’informations sociales hétérospecifiques pour la sélection d’habitat de reproduction dans cette population, et montre que des caractéristiques fines de signaux à l’intention de congénères peuvent aussi être utilisées par d’autres espèces. Cela nous aide ainsi à mieux comprendre les mécanismes évolutifs de ce comportement / All their life, individuals have to make decisions that may strongly affect their fitness. To optimize their decisions, they can use personally acquired information but also information obtained from observing other individuals (“social information”). The propensity to gather and use social information and the information meaning might depend on both individual and environmental factors. Studying what drives within- and between-individual differences in social information use should help us understand the evolutionary potential of this supposedly adaptive behaviour. The aim of my PhD was to empirically investigate sources of variability in heterospecific social information use for breeding habitat selection. I worked on a natural population of collared flycatchers (Ficedula albicollis, Gotland Island, Sweden), a passerine species shown to cue on the presence, density, reproductive investment and nest site preference of dominant titmice for settlement decisions. Using both long term and experimental data, I showed that the use of heterospecific social information, measured as the probability to copy tit nest preference, is not heritable but depends on male age and aggressiveness and on tit apparent breeding investment at the time of flycatcher settlement. Using a playback experiment, I also showed that female flycatchers can fine-tune nest site choice according to (i) song features supposedly reflecting great tit (Parus major) quality and (ii) their own aggressiveness level. This thesis highlights the importance of personality in the use of heterospecific social information for breeding site selection in this population, and broadens the traditionally known sources of heterospecific information to fine song characteristics reflecting heterospecifics’ quality. To fully understand the evolutionary mechanisms and consequences of heterospecific social information use, genetically based plasticity and fitness consequences remains to be explored