Seed hoarding by rodents of the Monte Desert, Argentina

Abstract

Food storage is an important adaptation of several animal species to the temporally variable or unpredictable food supplies that are typical of desert environments. In the present study, whether Eligmodontia typus and Graomys griseoflavus inhabiting sand dunes in the Monte desert displayed scatter-hoarding was investigated. Both rodent species prepared surface caches by digging small holes (1-3 cm deep) in the soil. Caches were partially covered with sand and dry leaves, which meant that all of the cache sites at each station could be found. Most caches were found below shrubs, that is, in a sheltered microhabitat rather than near the food source. The mean distance between caches and seed sources was significantly higher than the mean distance from food sources to shrubs. The proportion of caches was significantly higher in shrubs with high safety cover. The adaptive significance of this foraging behaviour could be a competitive tactic for the rapid sequestering of food from a rich and ephemeral source. Such behaviour would reflect predation risk, which constitutes an important foraging cost in deserts, and could also influence plant community dynamics.

Effectiveness of rodents as local seed dispersers of Holm oaks

“…Rodents mostly moved acorns short distances, in agreement with many other studies of scatter-hoarding rodents in a variety of habitats (e.g., Sork 1984;Jensen 1985;Jensen and Nielsen 1986;Giannoni et al 2001;Li and Zhang 2003;Cheng et al 2005;Iida 2006;Takahashi et al 2006). Acorn weight aVected both dispersal and caching behavior.…”

“…This was somewhat surprising since most studies have shown that rodents prefer to forage under shrubs where they are well protected from predators rather than under trees (Jensen and Nielsen 1986;Alcántara et al 2000;Rey et al 2002;Fedriani and Manzaneda 2005; but see Muñoz and Bonal 2007). In addition, rodents frequently disperse seeds disproportionately to the cover of shrubs (Giannoni 2001;Vander Wall 2001;Li and Zhang 2003;Takahashi et al 2006).…”

The mammals of the Monte Desert revisited

“…the physical disturbance caused by herbivory) influences plant community structure and diversity in the Monte Desert (Tognelli , 1999). A common foraging behavior in deserts which is associated with ephemeral and unpredictable food resources is food hoarding, and it has been reported for two of the dominant rodents, the silky mouse, E. typus and the common pericote, G. griseoflavus (Giannoni et al, 2001). Taraborelli et al (2003) observed that the plant cover affects the foraging activity of rodents because both consumption and a higher number of caches occur below shrubs.…”

Pre- and post-dispersal seed loss and soil seed dynamics of the dominant Bulnesia retama (Zygophyllaceae) shrub in a sandy Monte desert of western Argentina

“…In arid shrublands where individual shrubs are widely spaced, wind-blown or watertransported soil, nutrients, litter and seeds accumulate under these long-lived shrubs or trees, producing a heterogeneous environment that exerts great influence on basic ecosystemic processes (Pucheta et al, 2006;Reynolds et al, 1999;Schlesinger and Pilmanis, 1998;Zaady et al, 1998). Moreover, many animals also cause seed redistribution by activities such as predation (Campos and Ojeda, 1997;Herrera, 1995;Milton and Dean, 2001;Villagra et al, 2002), burrowing, digging and seed hoarding (Armesto and Rozzi, 1989;Giannoni et al, 2001).…”