BIRDS COMPORTAMENT

The environmental degradation, due to human activity, modifies the communities of species that inhabit it. Therefore, this might has a straight effect on the feeding behavior of granivorous birds. This study aims to evaluate the feeding habits, specifically, the preferences, and their causes, of grass seeds by three bird species: Poospiza ornata, Saltatricula multicolor and Diuca diuca from the desert of Mendoza (Argentina). According to Optimal Foraging Theory (OFT), an animal must prefer items that maximize its energy per unit of handling time. Our hypothesis is that birds prefer seeds that allow them to optimize handling time, handling efficiency and the profitability of the diet. The experimental evaluation of seeds preferences was carried out by a combination of choice and non-choice trials, that were correlated with handling times (s), handling efficiency (g/s), and profitability (kJ/s) of seeds. According to the protocol applied, the handling time of all the seeds was different in each bird species; however, the handling time did not affect the preferences of the three birds observed. The results obtained show that the species with larger beaks preferred the most profitable seeds and the seeds that they handled more efficiently, which are the largest seeds in the range of seeds offered. In contrast, the species with the smallest beak preferred seeds of all sizes; therefore, there was no effect of profitability or handling efficiency on the foraging behavior of the smallest bird. This could be due to the fact that the seeds that P. ornata handles more easily would be too small to meet their energy requirements, while the more profitable seeds would take too long to handle. Consequently, this bird could prefer seeds that compensate both variables and that together maximize the efficiency of the diet, given its behavioral flexibility. In contrast, the diet of the larger species, S. multicolor and D. diuca, could be affected in disturbed sites where there is a decrease in larger seeds, that is, those preferred by these birds.

Al igual que nuestra sociedad contemporánea busca en determinados comportamientos de los animales caminos para la empatía interespecies, en el origen de nuestro pensamiento simbólico hubo estrategias empáticas hacia los demás seres con los que compartíamos hábitat, comportamientos que, por apropiación mimética, son el inicio de nuestro pensamiento místico y de las manifestaciones estéticas asociadas a él. Analizando el comportamiento cosmético del quebrantahuesos (Gypaetus barbatus) y el registro fósil neandertal y el del inicio de la colonización de Europa por el sapiens, donde aparecen los primeros instrumentos musicales del continente, presentamos algunas de esas estrategias en el origen de la conciencia simbólica en relación con el sueño arquetípico de vuelo y con la observación de aves.