Lynn W. Kaufman

The Economics of Seed Handling

The effects of food handling costs on the feeding behavior of domestic rats was explored in three experiments. Sunflower seeds with or without hulls were presented to the rats, either sequentially or simultaneously, along with a purified carbohydrate. Rats do not eat the hull of these seeds and, thus, must add the cost of removing the hulls from the seeds with hulls (handling) to any other costs associated with eating these seeds. The lower cost seeds without hulls were strongly preferred to the seeds with hulls in all conditions, but were not eaten exclusively. When the preferred seeds without hulls were made increasingly difficult to obtain, the rats eat an increasingly greater proportion of the seeds with hulls. The results indicated the importance of handling costs in determining prey selection and demonstrated that the omnivorous rat is relatively efficient forager.

Foraging cost and meal patterns in ferrets.

Abstract The response of ferrets to changes in the cost of obtaining food was studied by systematically increasing the number of responses necessary to gain access to a feeder. The results obtained were consistent with an ecological analysis of feeding. As cost increased, meal frequency declined and meal size increased. These changes in feeding allowed the ferrets to obtain sufficient food intake to maintain growth, while conserving total time and energy spent procuring food.

Selection of an adequate protein-carbohydrate ratio by the domestic chick.

Abstract Male broiler chicks, given access to high protein and high carbohydrate diet fractions, demonstrated an ability to select a protein-carbohydrate ratio sufficient to maintain growth at near control levels. The level of protein selected was below that present in either control diet and declined with age. It is hypothesized that a feedback loop involving learning controls the selection mechanism although the specific cues involved were not isolated in this study.

Meal cost and meal patterns in an uncaged domestic cat

Abstract As the cost of procuring access to food increases, caged laboratory animals have been found to reduce meal frequency and compensatorily increase meal size. Meal frequency and size, however, have been shown to be influenced by the availability of alternative activities. The present experiment tested the generality of the earlier findings to uncaged animals. The relationships obtained between meal procurement cost and meal frequency and size with a freely roaming cat were the same as those obtained with caged animals. Meal size and meal duration were highly correlated but no significant correlations were found between meal size and pre- or post-meal interval. The results of this research further support the ecological validity of a cost/benefit analysis of feeding behavior.

Periodicity of death feigning by domestic fowl in response to simulated predation

The presence and extent of periodicity in the manifestation of death feigning duration was assessed in 137 week-old White Leghorn chicks. Chicks were reared on an LD 12:12 regimen with light onset at 0800 hr. Each was tested only once at one of 13 clock hours spanning a 24 hr period. Death feigning duration varied significantly with clock hour of induction, being longest from 1300-1400 hr and briefest from 0600-1100 hr. Variability was also cyclic but was distributed bimodally, being greatest in the latter half of each L and D phase. There was no significant influence of management hour on death feigning duration. The adaptive significance of the periodicity for predator-prey interactions was discussed, as were methodological implications.

Components of predation defense behavior in chickens: Evidence for endogenous rhythmicity ☆

The manifestation of diurnal periodicity and the extent of its control by the photoperiod was assessed in three predation defense reactions which constitute either components or outcomes of a predator-prey interaction sequence. Two-hundred White Leghorn chicks were reared from hatching for one week in either 24L or 12L and then tested at one of two clock hours previously demonstrated to define peak and trough response for one of the components. Putative evidence was found for an endogenous source of the periodicity manifested in all reactions. Maintenance schedule did not entrain the periodicity, but simple room entry and handling elicited anti-predator reactions, the extent of which varied as a function of clock hour. A general model of predation defense behavior was proposed.

Influence of altered lighting regimes on the periodicity of death feigning

Abstract The extent to which the photoperiod influences diurnal fluctuation in death feigning was assessed in 181 week-old domestic chicks reared under one of three lighting regimes: 6L/18D, 18L/6D. Chicks subjected to simulated predation at one of eight clock hours exhibited significantly different diurnal patterns of death feigning as a function of lighting regime. Periodicity was uniformly suppressed by rearing in 6L/18D. The unnatural 6L/6D regime disrupted the typical unimodal diurnal function characteristic of chicks reared on 12L/12D and produced a bimodal function. The 18L/6D regime did not alter the general form of death feigning but delayed the occurrence of peak response by six hours. The results were discussed in terms of the hypothesis that the photoperiodic control of death feigning is indirect, mediated by competing activity associated with fasting-feeding which is under direct photoperiodic control.

Cost and meal patterns in wild-caught rats.

The effect of domestication upon behavior is not clearly understood and thus generalizations from domesticated laboratory animals to nondomesticated animals must be made with caution. Laboratory free-feeding studies with a variety of domesticated species have demonstrated that these animals reduce meal frequency and increase meal size as the cost of procuring access to food increases. The present experiment was conducted to determine if the same relations would be obtained with wild-caught rats. The results showed that laboratory-tested, wild-caught rats respond to changes in the cost of obtaining food in the same manner as domesticated rats. Wild-caught rats did, however, take longer to train and were less efficient than domesticated rats have proven to be in earlier research. In general, the results affirm the validity of laboratory simulations as a means of exploring parameters associated with foraging in natural settings.

Arousal-induced changes in the amplitude of death feigning and periodicity.

Abstract The influence of manipulations known to influence arousal was assessed in two studies of death feigning. In both, week-old domestic chicks, reared in a 12 hr photoperiod, were tested shortly following either light onset or offset, at times previously found to correspond to trough and peak durations of death feigning, respectively. Prior to testing, chicks were subjected to different durations of either predator pursuit (Experiment 1) or food deprivation (Experiment 2). In spite of the fact that only one of the manipulations was directly related to the predation defense sequence which terminates in death feigning, both significantly influenced the amplitude of the death feigning function but did not eliminate its periodicity. The implications of the findings were discussed in terms of both the disrupting effects of motoric excitations and the ambiguity of the concept of arousal in behavioral research.

The Critical Cues for Diurnal Death Feigning in Young Chicks: A Functional Analysis

The critical determinants of extended diurnal death feigning were assessed in a refinement experiment in which visual and tactile cues during rearing and/or testing were systematically eliminated. Ninety-five domestic chicks were reared in either a social environment or physical (tactile) isolation, and half in each rearing condition were reared and/or tested under conditions of visual restriction. As expected, social rearing was prerequisite to the manifestation of extended death feigning; however, the incidence and duration of death-feigning was attenuated by functional visual isolation of socially reared chicks during either rearing or testing. It was concluded that visual novelty of the environment is the minimal condition for sustained death feigning by young chicks in the daylight hours.