Autumn and Winter Movements and Sexual Segregation of Willow Ptarmigan

Ptarmigan (Lagopus lagopus alexandrae) in northern British Columbia leave their breeding areas during autumn and winter. The movements differ between males and females. In this study I examine the causes and extent of these differences. Ptarmigan did not leave their breeding grounds immediately after the breeding season, but remained on or near their territories until December. After chicks fledged, part of the population moved uphill from their territories. Coincident with moult into winter plumage, ptarmigan moved farther from their territories. Both movements were probably to areas with better protection against predators. After moulting, all tagged males and half of the tagged females returned to their territories, and males resumed territorial display. Ptarmigan remained on their territories until increasing snow cover depleted cover, forcing them to leave. Males left the breeding grounds later than females and returned earlier in spring. In winter females moved farther than males, supporting the reproductive strategy hypothesis, but segregation was not complete. Sexual segregation may not be related to migration alone, but could occur at any time ptarmigan are in flocks.Key words: willow ptarmigan (Lagopus lagopus alexandrue), autumn territoriality, winter movements, sexual segregation, northern British ColumbiaLe lagopède des saules (Lagopus lagopus alexandrae) de la Colombie-Britannique septentrionale quitte son aire de nidification durant l'automne et l'hiver. Les déplacements du mâle diffèrent de ceux de la femelle. Ces recherches portent sur le degré et les causes de cette différence. On a trouvé que le lagopède ne quitte pas son aire de nidification immédiatement après la saison nidificatrice. Il reste sur son territoire ou à proximité jusqu'au mois de décembre. Après que les jeunes se sont emplumés, une partie de la population migre vers un territoire plus élevé. En même temps qu'il revêt son plumage d'hiver, le lagopède s'éloigne de son territoire. Ces deux mouvements se font probablement en direction d'aires offrant une meilleure protection contre les prédateurs. Après la mue, tous les mâles marqués et la moitié des femelles marquées reviennent sur leur territoire et les mâles reprennent leur comportement territorial. Le lagopède reste sur son territoire jusqu'à ce que l'accumulation de neige cache le couvert, ce qui le force à partir. Le mâle quitte son aire de reproduction après la femelle et y revient avant elle au printemps. En hiver, la femelle s'éloigne plus loin que le mâle, ce qui appuie l'hypothèse de la stratégie reproductive, mais la ségrégation n'est pas totale. Il se peut que la ségrégation sexuelle ne soit pas reliée uniquement à la migration, mais qu'elle ait lieu chaque fois que le lagopède se retrouve dans une volée.Mots clés : lagopède des saules (Lagopus lagopus alexandrue), territorialité d’automne, déplacements hivernaux, ségrégation sexuelle, Colombie-Britannique septentrional

Combating malaria morbidity and mortality by reducing transmission

Jean-François Trape and Christophe Rogier present epidemiological data and an analysis of the relationship between transmission, morbidity from malaria which suggest that any intervention aiming to reduce transmission will not, on a long-term basis, reduce the burden of malaria in the majority of epidemiological contexts observed in tropical Africa. (Résumé d'auteur

Harmonic balance surrogate-based immunity modeling of a nonlinear analog circuit

A novel harmonic balance surrogate-based technique to create fast and accurate behavioral models predicting, in the early design stage, the performance of nonlinear analog devices during immunity tests is presented. The obtained immunity model hides the real netlist, reduces the simulation time, and avoids expensive and time-consuming measurements after tape-out, while still providing high accuracy. The model can easily be integrated into a circuit simulator together with additional subcircuits, e.g., board and package models, as such allowing to efficiently reproduce complete immunity test setups during the early design stage and without disclosing any intellectual property. The novel method is validated by means of application to an industrial case study, being an automotive voltage regulator, clearly showing the technique's capabilities and practical advantages

San Francisco

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