5/19/2023 0 Comments Flocks of sparrows![]() Les moineaux mâles caractérisés par des bavettes plus grandes, qui indiquent un statut de plus forte dominance, avaient tendance à passer moins de temps en état de vigilance et obtenaient de la nourriture à une plus grande fréquence, ce qui appuie une explication dépendante de l’état pour l’origine des profils individuels de vigilance. Une plasticité des ajustements de la vigilance aux variations de la taille de la volée a été observée en ce qui concerne la fréquence des postures de haute vigilance. Nous avons documenté, en ajustant les observations pour tenir compte de la densité de nourriture, de la taille de la volée, du moment de l’année et du sexe, des différences individuelles cohérentes pour diverses mesures de la vigilance. La baisse typique de vigilance avec l’augmentation de la taille de la volée se produisait à l’échelle de la population. Nous avons fait des observations dans un site approvisionné en nourriture et utilisé des observations répétées des mêmes individus ( n = 14) dans des volées de différentes tailles pendant deux mois consécutifs. Nous avons examiné les variations individuelles de la vigilance et ses motifs de plasticité dans des volées de moineaux domestiques ( Passer domesticus (Linnaeus, 1758)). Les individus pourraient par exemple maintenir des niveaux de vigilance différents dans l’ensemble et aussi réagir différemment à des variations de la taille du groupe. Cependant, la taille du groupe n’explique souvent qu’une petite partie des variations de la vigilance, donnant à penser que d’autres facteurs, comme des différences individuelles, pourraient aussi intervenir. La vigilance individuelle contre les menaces diminue typiquement à mesure que la taille du groupe augmente. Individual differences can contribute to explaining the large scatter in the relationship between vigilance and group size in many species. Male House Sparrows with larger bibs, which signal higher dominance status, tended to spend less time vigilant and obtained food at a higher rate, supporting a state-dependent explanation for the origin of individual vigilance profiles. Plasticity of vigilance adjustments to variation in flock size occurred for the frequency of high vigilance postures. Controlling for food density, flock size, time of year, and sex, we documented consistent individual differences in various measurements of vigilance. The typical decline in vigilance with flock size occurred at the population level. We carried out observations at one provisioned site and used multiple observations of the same individuals ( n = 14) in flocks of different sizes over two consecutive months. We investigated individual variation in vigilance and its patterns of plasticity in flocks of House Sparrows ( Passer domesticus (Linnaeus, 1758)). For instance, individuals could maintain different vigilance levels overall and also respond differently to variation in group size. ![]() However, group size often explains a small amount of variation in vigilance, suggesting that other factors such as individual differences might contribute. In flocks, males tend to dominate over females in fall and winter, but females assert themselves in spring and summer.Individual vigilance against threats typically decreases with group size. ![]() Sometimes, other males who spot such a display in progress will fly in and begin displaying as well. When males display to a prospective mate, they fluff up their chest, hold their wings partially open, fan the tail, and hop stiffly in front of the female, turning sideways and sometimes bowing up and down. Males with larger amounts of black on the throat tend to dominate over males with less black. This can intensify to a display with wings lifted, crown and throat feathers standing on end, tail fanned, and beak open. Aggravated birds crouch with the body horizontal, shove their head forward and partially spread and roll forward their wings, and hold the tail erect. From living in such close company, House Sparrows have developed many ways of indicating dominance and submission. House Sparrows are a common sight at bird feeders you may also see them bathing in street-side puddles or dustbathing on open ground, ruffling their feathers and flicking water or dust over themselves with similar motions. They are social, feeding in crowded flocks and squabbling over crumbs or seeds on the ground. House Sparrows hop rather than walk on the ground.
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