Diet of a sigmodontine rodent assemblage in a Peruvian montane forest

Abstract

Knowledge of feeding habits of small rodents is necessary for understanding food webs, trophic structure, and plant–animal interactions in Neotropical forests. Despite several studies that have investigated community structure and feeding behavior of rodents, large gaps remain in our understanding of their guild occupancy. Our objective was to investigate the diets of 7 species of small (< 100g) sympatric sigmodontine rodents in a high (3,500 m) Andean montane rainforest in Peru. We qualitatively and quantitatively assessed diet items in fecal samples from livetrapped rodents from 2009 to 2012. Frequency data for 4 diet categories indicated that all 7 species of rodents contained 4 diet categories in fecal samples: arthropods (88%), remains of leaves and fibers from plants (61%), intact seeds (with or without fruit pulp; 50%), and mycorrhizal spores (45%). Omnivory was found to be a strategy used by all species, although contingency table analysis revealed significant differences among and within species in diet categories. Cluster analysis showed 2 main groupings: that of the Thomasomys spp. plus Calomys sorellus group which included high amounts of intact seeds and plant parts in their fecal samples, and those of the genera Akodon, Microryzomys, Oligoryzomys, which included a greater proportion of arthropods in their fecal samples, but still consumed substantial amounts of fruit and plant parts. Intact seed remains from at least 17 plant species (9 families) were found in fecal samples. We concluded that this assemblage of sigmodontine rodents is omnivorous but that they likely play an important role as frugivores and in seed dispersal in tropical montane forests in Peru.El conocimiento de los hábitos alimenticios de roedores pequeños es necesario para comprender cadenas alimenticias, estructura trófica, e interacciones planta-animal en los bosques neotropicales. A pesar de que numerosos estudios han investigado la estructura de comunidades y el comportamiento de forrajeo en roedores, aún existen grandes vacíos en nuestra comprensión de sus gremios tróficos. Nuestro objetivo fue investigar las dietas de siete especies de pequeños (< 100 g) roedores sigmodontinos simpátricos en un bosque montano andino a 3.500] m en Perú. Cualitativamente y cuantitativamente evaluamos la dieta en muestras fecales de roedores capturados entre el 2009 y el 2012. Datos de frecuencia para cuatro categorías de dieta indicaron que las siete especies de roedores consumieron cuatro categorías de dieta: artrópodos (88%), pedazos de hojas y fibras de plantas (61%), semillas intactas (con o sin pulpa de frutos; 50%), y esporas de micorrizas (45%). Omnivoría fue la estrategia utilizada por todas las especies, aunque el análisis con tablas de contingencia reveló diferencias significativas entre y dentro de especies en categorías de dieta. El análisis de agrupación presentó 2 grupos principales: el grupo Thomasomys spp. y Calomys sorellus, que incluye una gran proporción de semillas intactas, y partes de plantas en las muestras fecales y el g...

Primary seed dispersal by a sigmodontine rodent assemblage in a Peruvian montane forest

“…Calomys sorellus, a rodent often considered to be insectivorous and commonly found in high Andean grassland habitat (Pizzimenti & de Salle 1980) was found to include fruit in its diet at our study site (Sahley et al 2015). The proportion of intact seeds (belonging to the genus Gaultheria) and seed viability in faecal samples was relatively high.…”

“…Five of six species of rodents passed intact and viable seeds of 13 morphospecies, eight families and nine genera of plants. Our estimate of primary seed dispersal occurrence is likely conservative because a longer-term study examining diet found seeds from 17 morphospecies and nine families in faecal samples of all seven species at the same study site (Sahley et al 2015). Primary seed dispersal for small rodents of the cricetid family has been noted only once, for Necromys lasiurus, which passed viable Miconia albicans seeds through its digestive tract (Brewer & Rejmánek 1999).…”

“…Despite these findings, only one published account for cricetid rodents (< 100 g) noted primary seed dispersal occurring via the digestive tract by Necromys lasiurus (formerly Bolomys lasiurus) after consumption of Miconia albicans fruit (Magnusson & Sanaiotti 1987). Data on diet of small-bodied rodents and their potential for primary seed dispersal are therefore limited (Sahley et al 2015).…”

“…During a study examining potential impacts on small-rodent populations due to construction of a natural gas pipeline through a montane tropical forest, Sahley et al (2015) found that seven species of sigmodontine rodent had intact seeds present in their faecal samples. In this study we tested the following hypotheses: (1) small rodents belonging to the subfamily Sigmodontinae (Cricetidae) have viable seeds in their faeces and function as seed dispersers; (2) based on a previous diet study (Sahley et al 2015) the genus Thomasomys would disperse a greater diversity and abundance of seeds as well as seeds with a higher viability, therefore species belonging to this genus would be the most effective seed dispersers at the site; and (3) small rodent-dispersed plant families and genera would be more similar to those dispersed by birds than by bats.…”

Food habits and endozoochorous seed dispersal by small rodents (Cricetidae and Echimyidae) in a riparian forest in southeastern Brazil

“…Small rodents are the most diverse group of Neotropical terrestrial mammals (Emmons and Feer 1997;Patton et al 2015). Knowledge of rodent feeding habits contributes not only to understanding their ecology, but it also allows us to obtain basic information that enables action on population conservation, management and restoration of rodent populations (Sahley et al 2015). Most of the small Neotropical rodents (Cricetidae and Echimyidae) have been regarded as omnivorous (may be primarily frugivorous, herbivorous or granivorous), consuming fruits, seeds, and vegetative plant parts (stems, leaves or roots) (see Grenha et al 2010;Paglia et al 2012;Sahley et al 2015).…”