Comportamiento Alimentario De Ctenomys Mendocinus

R evista C hilena d e H istoria N atural
67: 257 - 263, 1 994

Feeding behavior o f the tuco-tuco ( Ctenomys
mendocinus):its modifications according to food
availability and the changes in the harvest pattern and
consumption

C omportamiento a limentario d el t uco-tuco ( Ctenomys m endocinus): su modificaci6n
e n f unci6n d e Ia o ferta y d iferencias e ntre p atrones d e c osecha y d ec onsumo
SERGIO R. CAMIN and LAURA A. MADOERY
U nidad d e Z oologfa y E cologfa A nimal
I ADIZA-CRICYT ( Mendoza)
C asilla d e C orreos 5 07, 5 500 M endoza, A rgentina
A BSTRACT

The foraging behavior o f Ctenomys mendocinus Philippi 1869 has been studied in the laboratory. It has been verified through
two experimental series that this behavior is modified according to the quality o fthe food available that are given to them.
Two different criteria were used to test food selection in order to verify coincidence between harvest patterns and
consumption patterns. T he u se o f more than one criterion o f selectivity precluded the confusion between removal
(harvesting) and consumption, allowing us to establish the feeding behavior o f Ctenomys mendocinus in a more reliable way.Tuco-tucos fed o n the aboveground parts o f grass avoiding shrubs and roots but they were opportunistic when they harvested
the available vegetation. This harvest pattern did not experience changes in response to changes in the offer; it would mean
selective advantages because the animal spends less time for aboveground feeding. On the other side, the difference between
harvest patterns andconsumption patterns suggest that C. mendocinus, r emove material fordistint uses (storage, construction
o f nest, etc.).
K ey w ords: rodents, fossorial, selectivity, opportunistic, foraging.
R ESUMEN

Se estudi6 el c omportamiento alimentario de Ctenomys mendocinus Philippi 1869 e n laboratorio. Se verific6 en dos series
experimentales si este comportamiento se modificaba en funci6n de Iacalidad de alimentos puestos a disposici6n. Ademas
se verific6 si los patrones de cosecha coinciden con los de consumo, utilizando dos criterios diferentes para poner a prueba
Ia selecci6n de alimento. L a consideraci6n de más de un criterio de selecci6n evit6 confundir remoci6n con consumo, lo que
permiti6 establecer con mayor confiabilidad el comportamiento alimentario de C. mendocinus. L ostuco-tucos consumieron
selectivamente Ia p arte aérea de las gramfneas, en detrimento de arbustos y de rafces en general, pero cosecharon el material
vegetal en forma oportunista. Este patron de cosecha no se modific6 con el cambia de oferta y podrfa presentar ventajas
selectivas a! d isminuir el tiempo de ex posicion fuera de Ia cueva del animal. P or otro !ado las diferencias entre patrones decosecha y patrones deconsumo sugieren que C. mendocinusremovi6 material para distintos usos (almacenamiento, construcci6n
de nido, etc.).
P alabras c lave: roedores, fosoriales, selectividad,oportunismo, forrajeo.

INTRODUCTION

The t heoretical a nd e mpirical l iterature
c oncerning t he t heory o f o ptimal f oraging
(Krebs 1978, Krebs e t al. 1 983, P yke e t al.
1977, P yke 1 984,S tephen & K rebs 1986,
Schoener 1987) has p roven t o b e c ontroversial ( Gould & L ewontin 1 979, G lasser
1984). P yke ( 1984) s uggested t hat t he
theory n eeds a dditional c ritical t ests t o

e valuate t he s uitability o f i ts a ssumptions
a nd predictions in describing and explaining
foraging b ehavior in v arious a nimal g roups
a nd e nvironments.
F oraging b ehavior o f subterranean
r odents i s a c hallenge t o t he c lassical
f oraging t heories. S impler o ptimal-diet
m odels b ased on m aximizing n et r ates o f
e nergy i ntake p er t ime u nit l ead t o t he
p rediction t hat a nimals s hould b ecome l ess

(Recibido e l 14 de e nero d e 1993; a ceptado el lO d e o ctubre d e 1993)

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C AMIN & M ADOERY

Mura e t al. 1 989), a nd p refer g...