Coping with rising food costs in a closed economy: feeding behavior and nocturnal hypothermia in pigeons.

The pigeon's response to increasing fixed-ratio schedules in a 24-hr closed economy is marked by changes in feeding behavior during the daily light phase and by changes in body temperature during the dark phase. The time course of these responses to increasing behavioral cost of obtaining food is very different. Feeding is most affected immediately, within the first day of exposure to moderate fixed ratios. The number of times the pigeons produce the food hopper each day decreases, and the rate at which they eat from the food hopper (grams per minute) when it is available increases, as the fixed ratio is raised. Body temperature is affected later, falling to progressively lower resting levels during the dark phase as body weight drops at the higher fixed ratios when food intake is reduced. The changes in feeding and in body temperature that occur as the fixed-ratio schedule increases seem to reduce daily energy expenditures, within the constraints imposed by the experiment. The ascending and descending limbs of the bitonic function obtained when total daily operant responding is plotted as a function of fixed-ratio schedule in the closed economy is possibly related to the occurrence of thermoregulatory strategies for energy conservation. The energetic analysis of performances in the closed economy requires consideration of a variety of energetic strategies available to the species being studied

Vocalizations of White Carneaux pigeons during experiments on schedule-induced aggression.

Two types of vocalizations of White Carneaux pigeons were identified in experiments on schedule-induced aggression and were given pictorial representation in sound spectrograms. Characteristics of these vocalizations are examined in the context of previous descriptions of vocalizations of several varieties of pigeons during aggressive and sexual encounters in naturalistic settings. These earlier descriptions portrayed vocalizations with mnemonic phrases and the symbolds of dictionary pronunciationmdata are presented that indicate that the analysis of social encounters between pigeons during schedule-induced aggression may be aided by employing these and other vocalizations as dependent variables

Development and maintenance of attack in pigeons during variable-interval reinforcement of key pecking

Key-peck responses of two pigeons were maintained on variable-interval schedules of food reinforcement in the presence of a stuffed pigeon to study the characteristics of attack induced by that schedule. The mean interval of the schedule was increased from 15 sec to 600 sec in eight steps before an intermediate interval was reintroduced. The principal characteristics of attack were: (1) substantial attack first occurred on a variable-interval schedule of 90 sec in one pigeon and at 180 sec in the other, (2) the highest attack rates occurred on variable-interval schedules of 300 sec and 600 sec, (3) attack rate generally increased to a maximum and then decreased to a lower level across sessions at each schedule, (4) attacks developed a postreinforcement locus across the initial sessions on all schedules and, except on variable-interval schedules of 300 and 600 sec, occurred primarily in the postreinforcement period during extended training, (5) attack rates and key-peck rates were not recovered when the intermediate-length schedules were reintroduced, and (6) attack rate and key-peck rates were negatively correlated. Except for the fact that the maximum attack rates occurred at interfood intervals of 300 and 600 sec, and that attack and key-peck rates were negatively correlated, these findings have counter-parts in experiments with other reinforcement schedules

Partial reinforcement (acquisition) effects within subjects

Acquisition performance of 22 rats in a straight alley runway was examined. The animals were subjected to partial reinforcement when the alley was black (B±) and continuous reinforcement when it was white (W+). The results indicated (a) higher terminal performance, for partial as against continuous reinforcement conditions, for starting-time and running-time measures, and (b) lower terminal performance under partial conditions for a goal-entry-time measure. These results confirm within subjects an effect previously demonstrated, in the runway, only in between-groups tests, where one group is run under partial reinforcement and a separate group is run under continuous reinforcement in the presence of the same external stimuli. Differences between the runway situation, employing a discrete-trial procedure and performance measures at three points in the response chain, and the Skinner box situation, used in its free-operant mode with a single performance measure, are discussed in relation to the present findings