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J Devenport

Publications and source records attributed to J Devenport.

4 recordsLinked to original sources
PubMed1999

The role of urine marking in the foraging behaviour of least chipmunks.

Least chipmunks Tamias minimus, occasionally deposit urine on buried patches of seeds after sampling the patch, a behaviour never before reported for rodents. The results of these experiments show that (1) patch-marking is a deliberate act, bearing no resemblance to routine excretion, (2) marking deters both the marker and conspecifics from harvesting attempts, (3) chipmunks can discriminate their own marks from those of others, and (4) the incidence of marking in the wild is at least as frequent, and its deterrent effect as strong as in the laboratory. Although the message conveyed by a mark is clearly exploited by conspecifics, and may benefit kin, the results accord best with prevailing theory advanced for canids, that an olfactory reminder of patch value improves the marker's foraging efficiency. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Future value and patch choice in least chipmunks.

Animals subsisting on non-renewing patches confront a unique valuation problem, in which the objective value of a patch is inversely related to the amount already harvested. We investigated whether the subjective patch valuations of captive least chipmunks, Tamias minimus, reflected this environmental constraint as they foraged for buried patches of seeds. On the day following partial depletion of two patches, chipmunks spontaneously selected the least depleted patch, despite having no direct information about its former or present value. These findings held across experiments in which the order and extent of patch depletion were under the forager's control or experimental control. The animals consistently chose sites from which they had taken the fewest items, despite experiencing no difference in relative capture rate, suggesting that they discounted patch value on the basis of amount harvested or harvest time. Furthermore, the animals refused to return to patches they had completely depleted, and when induced to re-dig depleted patches by placing seeds above them, the animals chose randomly despite a three-fold difference in the number of items previously taken from each, suggesting that they disregarded rewards taken, attending only to the amount remaining. Subsequent experiments showed that chipmunks can take past reward history into account. When we refilled previously depleted patches and induced chipmunks to re-dig and deplete them again, they treated the patches as renewable types and represented their value in terms of the amount removed, not the amount left. Thus, the assessment mechanism of least chipmunks is facultative: they expect that patches will not replenish, but are prepared for exceptions. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1979

Effects of cortical, hypothalamic, and hippocampal lesions on chronic alcohol intake and preference in rats.

The effects of cortical, hippocampal, and suprachiasmatic (hypothalamic) lesions on forced alcohol consumption, alcohol preference and the distribution of alcohol intake throughout the day were examined in rats. Controls included by hypothalamic sham-operated and unoperated groups. Baseline water intake during light and dark and initial alcohol preference (10% alcohol versus water) were determined. All animals then were placed on a forced alcohol consumption regimen consisting of ad lib lab-chow and 10% ethanol in water. On the sixth day of each week during the alcoholization regimen, light and dark phase alcohol intake was assessed and on the seventh day of each week, a 24-hr, two-bottle alcohol preference test (10% ethanol) was given. After nine weeks on the forced alcohol regimen, all animals were given a seven day "withdrawal" period consisting of access to plain water and to 10% alcohol in water. Throughout both the forced alcoholization and withdrawal periods, the lesioned groups, especially the cortically lesioned group, displayed a significantly greater preference for the 10% alcohol solution than any of the control groups. Control and lesion groups did not differ significantly in their preference for a 5% alcohol solution or for a quinine solution, suggesting that simple taste threshold changes probably would not account for these data. The results are discussed in terms of the possibility that the brain lesions may have rendered the animals more sensitive to the "addictive" and/or reinforcing properties of ethanol.

Alcohol Drinking↗