Avian Geophagy and Soil Characteristics in Southeastern Peru

Abstract

We observed ten species of psittacids, three species of columbids, and two species of cracids consuming soil from banks of the lower Tambopata River in southeastern Peru. Our study used observations and soil analyses from eight exposed riverbank sections to test the predictions of three models to determine why birds consume clay: mechanical aid to digestion (grit), adsorption of dietary toxins, and mineral supplementation. We found that preferred soils were deficient in particles large enough to aid in the mechanical breakdown of food and help digestion. Percent clay content and cation exchange capacity (CEC), both predicted to correlate with adsorption of toxins, did not differ between used and unused sites as had been found in a similar study. Instead, preferred soils were more saline and had higher concentrations of exchangeable sodium. This suggests that the choice of soils at our site was based primarily on sodium content. Birds may be using the heavy, plastic texture of soils rich in clays and high in exchangeable sodium as a proximal cue for soil selection. Our findings suggest that avian soil selection decisions depend on the range of available soil characteristics.RESUMENObservamos diez especies de Psittasidos, trés especies de Columbidos, y dos especies de Cracidos consumiendo suelo de los bancos del bajo Rio Tambopata en el sureste del Perú. Nuestro estudio utiliza observaciones de aves y análisis de suelos de ocho secciones expuestas de los bancos de rio para probar las predicciones de tres modelos de porque las aves consumen arcilla: ayuda mecánica para la digestión (arena triturada), adsorción de toxinas en la dieta, y suplemento mineral. Encontramos que los suelos preferidos eran deficientes en particulas lo suficientemente grandes como para ayudar en la trituración mecánica del alimento y ayudar a la digestión. El porcentaje de contenido de arcilla y la capacidad de intercambio catiónico (CIC), ambos esperados para correlacionar con la adsorción de toxinas, no varió entre sitios usados y no usados como ha sido encontrado en un estudio similar. En cambio, los suelos preferidos fueron más salinos y con mayor concentracion de sodio intercambiable. Esto sugiere que la selección de suelos en nuestro sitio de estudio está basado principalmente en el contenido de sodio. Las aves pueden estar usando las texturas densas y plásticas de los suelos ricos en arcillas con alto contenido de sodio intercambiable como una señal próxima para la selección del suelo. Nuestros resultados sugieren que las decisiones de selección de suelos por las aves depende del rango de caracteristicas de suelos disponibles.

Social–ecological factors influencing tourist satisfaction in three ecotourism lodges in the southeastern Peruvian Amazon

“…(Brightsmith & Aramburú, 2004;Gilardi et al, 1999;Munn, 1998). The presence of large collpas facilitates the observation of psittacids, mainly large macaws of the genus Ara that capture greater tourist attention.…”

Mineral Licks Attract Neotropical Seed-Dispersing Bats

“…Among fruit-eating mammals, bats outnumber all other taxa in Neotropical mammal assemblages [26]. Fruit-eating bats usually feed on a mineral poor foods [21,27], but sometimes supplement their diet with leaves that are more enriched than the average diet of bats [27,28].…”

Anthropogenic changes in sodium affect neural and muscle development in butterflies

“…Sodium is a key component of animal development, important for the function of neural and muscle tissue (10)(11)(12) and affecting the development of traits, such as brain size (13)(14)(15)(16). However, sodium availability is limited in most ecosystems (17)(18)(19), which is thought to have led to the evolution of sodium cravings (20,21) and specific foraging behavior to acquire sodium (22)(23)(24)(25). Humans are increasing sodium availability, particularly through the application of road salt (26)(27)(28)(29) but also, through agricultural activity (30).…”