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Abstract: Identification of essential habitat is a fundamental component of amphibian conservation; however, species with complex life histories frequently move among habitats. To better understand dynamic habitat use, we evaluated [...]

Our study used historic marine-derived nutrient (MDN) delivery timing to simulate potential effects of restored connectivity on juvenile Atlantic salmon (ATS; Salmo salar) growth and condition. Four headwater streams were stocked with ATS young of the year (YOY) and received carcass analog additions (0.10 kg x [m.sup.-2] wetted area) in treatment reaches to match the timing of sea lamprey (Petromyzon marinus) spawning. Individual ATS mass was 33%-48% greater and standard length was 9%-15% greater in treatment reaches relative to control reaches for 4 months following nutrient additions. Percent total lipids in YOY ATS were twice as great in treatment reaches 1 month following carcass analog additions and remained elevated in treatment fish for 2 more months. Absolute growth rates, based on otolith microstructure analysis, correlated with water temperature fluctuations in all reaches and were elevated by an average of 0.07 mm x [day.sup.-1] in treatment reaches for 1 month following carcass analog additions. Simulated sea lamprey MDNs increased juvenile ATS growth, which, via potential increases in overwinter survival and decreases in smolt age, may contribute to population persistence and ecosystem productivity. Notre etude fait appel a des donnees historiques sur le moment de l'apport de nutriants de source marine (MDN) pour simuler les effets potentiels du retablissement de la connectivite sur la croissance et l'embonpoint des saumons atlantiques (ATS; Salmo salar) juveniles. Quatre cours d'eau d'amont ont ete empoissonnes avec des jeunes de l'annee (YOY) d'ATS et ont fait l'objet d'ajouts d'analogues de carcasses (0,10 kg x [m.sup.-2] de surface mouillee) dans des troncons traites pour simuler le moment du frai des lamproies (Petromyzon marinus). La masse d'ATS individuels etait de 33 % a 48 % plus importante et leur longueur standard, de 9 % a 15 % plus grande dans les troncons traites que dans les troncons temoins pour les 4 mois suivant l'ajout de nutriants. Le pourcentage de lipides totaux dans les YOY d'ATS etait deux fois plus eleve dans les troncons traites 1 mois apres l'ajout d'analogues de carcasses et est demeure eleve dans les poissons de troncons traites pendant 2 autres mois. Il y avait une correlation entre les taux de croissance absolue, tires de l'analyse de microstructures d'otolites, et les fluctuations de la temperature de l'eau dans tous les troncons, et ces taux etaient de 0,07 mm x [joui.sup.-1] en moyenne plus eleves dans les troncons traites pendant le mois suivant les ajouts d'analogues de carcasses. Les MDN de lamproies simules se sont traduits par une croissance accrue des ATS juveniles ce qui, par l'entremise d'augmentations potentielles de la survie hivernale et de reductions de l'age des saumoneaux, peut contribuer a accroitre la persistance des populations et la productivite des ecosystemes. [Traduit par la Redaction], Introduction Atlantic salmon (ATS; Salmo salar) populations have declined precipitously across much of their historic range largely because passage between marine and freshwater habitats has been reduced or blocked, decreasing [...]

Homogeneous, agriculturally intense landscapes have abundant records of pollinator community research, though similar studies in the forest-dominated, heterogeneous mixed-use landscape that dominates the northeastern United States are sparse. Trends of landscape effects on wild bees are consistent across homogeneous agricultural landscapes, whereas reported studies in the northeastern United States have not found this consistency. Additionally, the role of noncrop habitat in mixed-use landscapes is understudied. We assessed wild bee communities in the mixed-use lowbush blueberry (Vaccinium angustifolium Ait.) production landscape of Maine, United States at 56 sites in eight land cover types across two regional landscapes and analyzed effects of floral resources, landscape pattern, and spatial scale on bee abundance and species richness. Within survey sites, cover types with abundant floral resources, including lowbush blueberry fields and urban areas, promoted wild bee abundance and diversity. Cover types with few floral resources such as coniferous and deciduous/mixed forest reduced bee abundance and species richness. In the surrounding landscape, lowbush blueberry promoted bee abundance and diversity, while emergent wetland and forested land cover strongly decreased these measures. Our analysis of landscape configuration revealed that patch mixing can promote wild bee abundance and diversity; however, this was influenced by strong variation across our study landscape. More surveys at intra-regional scales may lead to better understanding of the influence of mixed-use landscapes on bee communities. [ABSTRACT FROM AUTHOR]

Most seabirds breed colonially and exhibit considerable site fidelity over the course of their long lifespans. Initial colony selection can therefore have substantial fitness consequences, but factors contributing to recruitment into colonies and subsequent fidelity remain unclear. We used multi-state capture-recapture models to test several hypotheses related to apparent fledgling survival, probability of recruitment to natal colonies, and apparent post-recruitment survival in Black-legged Kittiwakes Rissa tridactyla, using data from individuals banded as chicks and subsequently resighted at a colony in south-central Alaska over a 20-year period. Competitive models suggested that apparent fledgling survival declined throughout our study. This decline was likely driven by intrinsic, cohort-specific processes and was not explainable by post-fledging weather or climate conditions. Independent resightings at other colonies suggest the apparent decline may have been at least partially influenced by permanent emigration (natal dispersal), which occurred more frequently when the colony size was large. Recruitment was primarily age-dependent, with no detectable effects from early life experience or from annual changes in four factors: colony size, colony productivity, climate, or average weather conditions. We estimated an average recruitment age of seven years, which is older than typically reported for Atlantic kittiwake populations and which supports a more conservative life history strategy for kittiwakes in the Pacific. Variation in the apparent survival of recruits was cohort-specific and did not correlate with age or annual changes in the factors listed above. Instead, apparent survival of recruits was best explained by colony size during a cohort's second year, suggesting a degree of negative density dependence in post-recruitment survival or fidelity. This information could prove useful to managers deciding how to allocate resources among small, growing colonies and large, well-established colonies. [ABSTRACT FROM AUTHOR]