Behavioral Response of Dolichotis patagonum to food density

Abstract

Abstract Optimal foraging models predict animals will consume more food from patches of higher initial densities. They also predict that when food is scarce in the environment, animals will have greater foraging efforts in the patch and hence shorter vigilance times. As an anti-predator behavior an increase in group size is correlated with a reduction of individual vigilance time. We evaluated Dolichotis patagonum ´s (mara) behaviors: feeding, vigilance, walking, and others (sniffing, grooming, resting) in relation to different food densities (100 g, 70 g and 40 g of alfalfa pellet, mixed with 5kg of sifted soil, offered in wooden box) in a field experiment by using camera traps. As a novelty, maras showed nocturnal activity. They also showed an increase in vigilance time when they were in pairs compared to when they were alone, by alternating feeding and vigilance behaviors. When food density changed, no variation in vigilance was observed and food intake only changed between 100 g and the other two food densities offered. We propose that: first, maras are cathemeral animals. Second, mara´s knowledge about patches is critical to assess patch quality. Finally, alternating feeding and vigilance when in pairs, could be and efficient anti-predator strategy in environments with high predator pressure. Key words: activity pattern, camera traps, Dolichotis patagonum , food consumption, San Luis, vigilance. Resumen Los modelos de forrajeo optimo predicen que los animales van a consumir mas alimento en aquellos parches con mayores densidades iniciales. Ademas, predicen que cuando el alimento sea escaso, los animales tendran mayores esfuerzos de forrajeo en cada parche y por tanto menores tiempos de vigilancia. La vigilancia individual tambien disminuira al aumentar el tamano de grupo. En este experimento de campo evaluamos, a traves de camaras trampa, el comportamiento de: alimentacion, vigilancia, desplazamiento y otros (ej.: olfatear, acicalarse, descansar) de Dolichotis patagonum (mara) en relacion a diferentes densidades de alimento (100 g, 70 g y 40 g de pelets de alfalfa mezclado con arena cernida dentro de cajones de madera). Como dato novedoso se observo actividad nocturna. Tambien se observo un aumento en la vigilancia cuando estaban en pareja que al estar solas, dado que alternaban la vigilancia y la alimentacion. Entre las densidades de alimento no se observo variacion en la vigilancia y la ingesta de alimento cambio solo entre 100 g y las otras dos densidades ofrecidas. Por lo cual proponemos que, primero, la mara es un animal catemeral. Segundo, el conocimiento que las maras tienen de los parches es critico para evaluar su calidad. Finalmente, la alternancia de comportamientos en la pareja podria ser una estrategia anti-predatoria en ambientes con altas presion de depredacion. Palabras clave: patron de actividad, camaras trampas, consumo de alimento, Dolichotis patagonum , vigilancia, San Luis.