Habitat selection in population of cricetine rodents in the region Delta (Argentina)

Abstract

We employed a live trapping grid to analyse the effect of heterogeneity habitat on dispersion of Akodon azarae, Oxymycterus rutilans and Oryzomys delticola. The reproduction and survival of three species are associated with their residency in the grassland, avoided the use of woodland. A. azarae reproductive and non-reproductive individuals preferentially use the sites dominated by Ambrosia scabra (microhabitat 1). Their residency at those sites would present nutritional advantages due to higher availability of seeds. This species begins to use other microhabitats more frequently only after the population peak. O. delticola preferentially uses the sites dominated by Lonicera japonicaBaccharis spicata (microhabitat 3). As both species present similarities in their diets, the differential use of the grassland microhabitat would contributate to diminish competitive interactions between them. O. rutilans reproductive individuals do not show preference for either microhabitat. During autumn-winter, non-reproductive individuals are more frequently captured in microhabitat 1. The important diminution herbaceous cover among Cortaderia selloana bushes (microhabitat 2) and under the dominant shrubs of microhabitat 3, led as to think that predation could be an important factor regarding the habitat use pattern of A. azarae and O. rutilans during autumn and winter. The climbing ability of O. delticola would contribute to diminish the impact of predation it could suffer at microhabitat 3.Resume. -Les auteurs ont etudie ä Paide d'une grille de piegeage 1'effet d'un habitat heterogene sur la dispersion a'Akodon azarae, Oxymycterus rutilans et Oryzomys delticola. Les trois especes vivent dans la prairie et evitent la foret, ce qui assure leur reproduction et leur survie. A. azarae, qu'il soit ou non en reproduction, utilise de preference des sites ou domine Ambrosia scabra (microhabitat 1) oil il doit trouver des graines tres nourrissantes. Cette espece ne commence ä utiliser d'autres sites qu'apres le pic de population. O. delticola frequente de preference les sites ou dominent Lonicera japonica et Baccharis spicata (microhabitat 3). Les deux especes ayant des regimes alimentaires compa- Mammalia, t. 55, n° 3, 199L Brought to you by | University of Arizona Authenticated Download Date | 6/3/15 4:49 PM 340 MAMMALIA rabies, la frequentation par chacune de microhabitats differents dans la prairie peut contribuer ä diminuer la competition entre elles. O. rutilans en periode de reproduction ne montre pas de preference pour Tun ou Pautre microhabitat. En automne et hiver, les individus non reproducteurs sont plus frequemment captures dans le microhabitat 1. Une importante reduction du couvert herbace entre les buissons de Cortaderia selloana (microhabitat 2) et sous les plantes dominantes du microhabitat 3, conduit ä penser que la predation peut etre un facteur important d'utilisation de Phabitat a 1 A. azarae et de . rutilans en automne et en hiver. L'aptitude au grimper que presente O. delticola doit contribuer ä diminuer Pimpact...

Population demography of Oxymycterus rufus (Rodentia: Cricetidae) inhabiting a patchy environment of the delta of the Parana River, Argentina

“…However, O. rufus is not dependent on the floristic composition of the microhabitats, because it uses sites dominated by grass (eg C. selloana) or shrubs (eg B. spicata). Bonaventura et al (1991) observed that reproductive individuals of O. rufus were not associated with the foliage availability. Considering O. rufus is mainly an insectivorous rodent (Barlow 1969, Kravetz 1972, Dalby 1975, the use of the microhabitats 1, 2, and 3 is likely to be due to the fact that such sites are more favorable for feeding on account of the greater availability of arthropods (Fig.…”

“…In the delta of the Paraná River Bonaventura et al (1991) have studied the spatial distribution of O. rufus, and they could not find factors influencing the habitat selection of this rodent which were related to objective measurements of the quality of such habitats.…”

Interrelationship between ectoparasites and wild rodents from northeastern Buenos Aires province, Argentina

“…Comparing presence/absence of ectoparasites associated with every host species in this study, A. azarae showed the least similarity with every other rodent species. In contrast with the remaining rodents, which are associated with aquatic microhabitats, A. azarae is mostly associated with grassland, where seeds are dominant (Bonaventura et al 1991). However, the remaining host rodents which have similar ecological and ethological characteristics, showed higher similarities in relation to their ectoparasite species and particularly H. brasiliensis and S. aquaticus, the most semiaquatic rodents (Massoia & Fornes 1964, Massoia 1976, showed the same five ectoparasite species, although all of them preferred the first host species.…”

Ectoparasite occurrence associated with males and females of wild rodents Oligoryzomys flavescens (Waterhouse) and Akodon azarae (Fischer) (Rodentia: Cricetidae: Sigmodontinae) in the Punta Lara wetlands, Argentina

“…This result suggests that particular characteristics and strategies of this rodent sex would influence its ectoparasite population. Studies on the home range size and overlapping of wild rodents show that the average distance traveled by males in the breeding season is greater than that traveled by females (Bonaventura et al 1990). Furthermore, interspecific competition limits the use of territory by females during the reproductive season (Dalby 1975).…”