Thesis (M.S.)--Rutgers University, 2009. / "Graduate Program in Geography." Includes bibliographical references (p. 38-50).

Following catastrophic exploitation throughout the North Atlantic, breeding seabird populations have begun to recover thanks to regulatory protection and restoration and management efforts. As bird populations increase, new challenges emerge, including overgrowth of vegetation that limits the open nesting habitat favored by most tern species. Though managers have used a variety of measures to reduce vegetation cover, these techniques have rarely been quantified or compared experimentally. During the summers of 2009 and 2010, I applied two different techniques, controlled burning and artificial weed barriers (muslin fabric and artificial turf) to experimental plots on Eastern Egg Rock and Outer Green Island, near-shore seabird nesting islands in mid-coastal Maine. I then monitored vegetation regrowth and use by nesting terns to assess the effectiveness of these techniques for opening and maintaining Common Tern nesting habitat during a full breeding season, comparing treated plots to vegetated control plots and existing tern nesting habitat. Burned areas did not remain open for the full nesting season, but regrew shortly after laying, leading to near-complete nest failure in these plots. Tern nest and fledging success was similar in weed barrier (1.37 chicks/pair) and untreated tern nesting habitat (1.38 chicks/pair) plots. Replacement of existing vegetation, tested at a limited scale on Outer Green Island, did not succeed. These three techniques represent only a small fraction of vegetation management techniques used throughout the North Atlantic region. Through literature review and consultation with North Atlantic colony managers, I collected information on vegetation management on 34 tern nesting islands between 33 and 55° N latitude and developed a summary of different vegetation control techniques used. I identified 14 technique types suitable for use in nesting colonies: i.e., that can be applied before and after (but not during) the nesting period of May-July, that do not cause destructive impacts to the surrounding ecosystem, and that involve materials and labor that can be transported to inaccessible offshore islands. Of these techniques, 8 created usable tern nesting habitat for a full breeding season, and the most successful techniques required constructing habitat over existing vegetation. The success of different methods depended heavily on the plant communities and soil types involved. In general, vegetation management options were more limited and less successful for elevated, rocky islands than for low, sandy islands. Often, techniques that successfully removed one species or group of species (i.e., perennial grasses) failed due to rapid colonization by other species (i.e., herbaceous annuals). This review of past and ongoing vegetation management techniques used on seabird nesting islands, including their costs, methods for application, and effectiveness, provides seabird managers a reference when evaluating current and future vegetation management programs.

Mémoire numérisée par la Direction des bibliothèques de l'Université de Montréal.

En écologie évolutive, les comportements de reproduction sont particulièrement intéressants de part leur impact sur le succès reproducteur et donc leur lien étroit avec la valeur sélective individuelle. En s'appuyant sur des suivis individuels à long-terme de populations naturelles d'un rongeur hibernant et d'un oiseau marin migrateur, cette thèse a eu pour objectif 1) de déterminer la présence de sélection de parentèle et le lien entre l'environnement social et la philopatrie chez le spermophile du Columbia (Urocitellus columbianus) et 2) d'estimer le potentiel évolutif de la phénologie de la migration et la reproduction chez la sterne pierregarin (Sterna hirundo).Alors que la dispersion à longue distance a été largement étudiée chez de nombreux taxa, notre compréhension des mouvements au sein d'une colonie, en particulier en tenant compte de l'environnement social, reste limitée. Pourtant l'organisation spatiale des individus apparentés peut être fortement liée à l'évolution de la coopération, qui a pour condition nécessaire la présence de sélection de parentèle. Les travaux de cette thèse montrent que les femelles spermophiles du Columbia coopérant avec des apparentées ont une valeur sélective inclusive plus élevée que les autres femelles, révélant une forte influence de la sélection de parentèle. Les femelles sont fortement philopatriques au sein de la colonie et les mouvements à courte distance semblent liés à un partage de l'espace avec les apparentées. La philopatrie et les ajustements spatiaux permettent une forte proximité entre apparentées, qui est à la base de leur coopération. Ces résultats ouvrent des perspectives prometteuses pour explorer les mécanismes proximaux et ultimes de la coopération, en particulier en lien avec l'évolution des personnalités.Dans le contexte des changements climatiques, de nombreuses études chez les oiseaux documentent un avancement de la phénologie. L'étude d'une population déclinante de sternes pierregarins montrant un retard progressif des dates de ponte soulève l'importance d'évaluer les changements évolutifs attendus ainsi que les contraintes évolutives pour la phénologie de la migration et de la reproduction. Ces travaux montrent une diminution des variances phénotypique et génétique additive de la date d'arrivée de la migration printanière avec l'avancement du stade reproducteur. Ce résultat révèle un cas original de forte sélection passée pour la canalisation d'un trait comportemental, pouvant représenter une contrainte évolutive pour ce caractère. En outre, alors que la phénologie de la reproduction est classiquement considérée comme un caractère femelle-spécifique, l'analyse révèle un effet environnemental indirect du mâle sur la date de ponte, lié à la nécessité d'une synchronisation entre les partenaires pour l'arrivée de la migration printanière. Malgré d'une part l'absence de contraintes génétiques et d'autre part une héritabilité et une variance génétique additive significatives, les changements évolutifs attendus pour des dates de ponte plus précoces sont restreints du fait d'une sélection faible. De même, le potentiel évolutif de la date d'arrivée de la migration est limité. Des recherches futures explorant la plasticité phénotypique et la désynchronisation entre la phénologie des sternes et de leurs proies pourraient expliquer le retard de la phénologie de la reproduction en contraste avec nos prédictions. / In evolutionary ecology, behaviours associated with reproduction are particularly interesting because of their impact on reproductive success, and thus their close link to individual fitness. Using long-term individual monitoring of natural populations of a hibernating rodent and a migratory seabird, the aims of this PhD were 1) to determine presence of kin selection and relationship between social environment and philopatry in Columbian ground squirrels (Urocitellus columbianus) and 2) estimate the evolutionary potential of the migratory and reproductive phenology in common terns (Sterna hirundo).While long-distance dispersal has been well studied in numerous taxa, our understanding of within-colony movements is still limited, particularly with respect to the social environment. However, spatial organization of kin can be strongly related to the evolution of nepotistic cooperation, which requires kin selection as a necessary condition. My studies show that female Columbian ground squirrels that cooperate with kin have higher inclusive fitness, revealing a strong influence of kin selection. Females are strongly philopatric within the colony and short-distance movements seemed to be linked to sharing of space with kin. Philopatry and spatial accommodation promote strong proximity between kin, which is the basis of their cooperation. These results offer promising research perspectives for the exploration of proximate and ultimate mechanisms of cooperation, particularly linked with the evolution of personality.In the context of climate change, numerous studies in birds document advances of avian phenology. The study of a declining population of common terns exhibiting a progressive delay of laying dates indicates the importance of evaluating expected evolutionary changes, as well as constraints on migratory and reproductive phenology. My studies found a decrease of the phenotypic and additive genetic variances in arrival date from spring migration with advancing reproductive stage. This result reveals an original case of strong past selection for canalization of a behavioural trait, perhaps representing an evolutionary constraint. Also, while phenology of reproduction is classically considered a female-specific trait, analyses show an indirect environmental effect of male on laying date, linked to the need of partners to be synchronized when arriving from spring migration. In spite of, on one hand, lack of genetic constraints, and on the other hand, significant heritability and genetic variance, expected evolutionary changes for earlier laying dates are limited due to a weak selection. Similarly, the evolutionary potential of arrival date from spring migration is limited. Future research exploring phenotypic plasticity and the mismatch between the phenology of terns and their prey might explain the delay of the reproduction phenology, in contrast with our expectations.