Pecking of the Pigeon (Columba Livia L.)
TL;DR: The existence of a cerebral comparator-selector mechanism was assumed to describe decision making processes during the adjustment of the pecking system at the start of each step, which has the possibility to adapt each step to either the position and/or the size of the seed.
Abstract: 1. The pecking behaviour of pigeons is described from a frame-by-frame analysis of high speed films and X-ray motion pictures. 2. Each pecking scene has four discrete steps. These steps run from the fixation of the head above the seed to (1) the grasp of the seed by the beak tips to (2) the catching of the seed at the rictus level to (3) the positioning of the seed along the caudal palate to (4) its arrival in the rostral oesophagus. The bird is able to stop the sequence at the very beginning of each step. For example by a refusal to continue after the final fixation, by dropping the seed after the grasp, by ejecting it after the rictus catch when the seed is positioned on the lingual base, and probably also by an ejection following the positioning along the caudal palate. If necessary, an adjustment of the system takes place, prior to each step. Such an adjustment positions the structural elements and/or the seed in the correct mechanical arrangement for the initiation of the next step in the sequence. These adjustments are the preliminary approach at the final fixation, stationing at the grasp, repetition of transport through the mouth to the rictus level, and repetition of the transport type used in the pharynx. The bird has the possibility to adapt each step to either the position and/or the size of the seed. The final approach (step 1) can be a scooping, a straight or a swinging approach of the head depending upon the seed's position, while simultaneously the type of beak opening is adapted to the seed's position and the gape size to the seed's size. Transport through the mouth (step 2) is for a small seed a slide-and-glue mechanism by which the seed is adhered to the tongue and is carried to the rictus level. Usually large seeds are transported by the catch-and-throw mechanism. Intermediate types also occur. For small seeds transport to the caudal palate (step 3) is also a slide-and-glue mechanism, in which the lingual base serves as the adhering element. When large seeds are transported a head jerk is added to this mechanism. Transport into the oesophagus (step 4) for small seeds is a scraping mechanism of the ventral pharyngeal valves which are erected when they are in front of the seed prior to their retraction. An extra laryngeal transporting cycle and head jerk occur when large seeds are swallowed. 3. The slide-and-glue mechanism is extended by prediction of position and structure of glands deduced from the mechanical requirements of the mechanism. After comparison of the deduced glands with a microscopic and scanning electron microscopic analysis of the mouth and pharynx, the position and the structure of the gl. mandibularis anterior, the gl. mandibularis posterior, the gl. lingualis superior, the gl. lingualis inferior and the gl. palatina posterior externa were found to correspond with the prediction. 4. The existence of a cerebral comparator-selector mechanism was assumed to describe decision making processes during the adjustment of the pecking system at the start of each step. This is most clearly shown during stationing, which is a repositioning of the seed after the grasp. The registered position of the seed is compared with a pre-set cerebral template and after the comparison a selector recruits either mechanical units for a positive output (a head jerk and a gape cycle) transporting the seed somewhat caudad, or a negative output (a gape cycle and a lingual cycle) transporting the seed rostrad. 5. The close relationship between the particular positioning of the sensory units and the necessarily coupled recruitment of a set of mechanical units is analysed. For example, during final fixation the visual information must be gathered for the complete composition of the final appraoch. 6. From the stereotyped appearance of parts of the pecking behaviour it is shown that pecking better viewed as a variable sequence of fixed action patterns rather than just one such a pattern, by handling coupling of mechanical units as a constraint resulting from mechanical construction, mechanical operation, positioning of sense organs, availability of neuronal circuits and necessity to learn optimal combination of available mechanical units. Further, it is shown that the shift of the pigeon's food preference to larger sized seeds after trigeminal deafferentation can be explained as a preference for a catch-and-throw mechanism. Finally, it is shown that a partial refinement of an optimal foraging strategy is found even at the lower levels of organization of pecking.
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TL;DR: In this article, the authors compare the performance of the parameter-free delay-reduction hypothesis with those of optimal foraging theory, developed by behavioral ecologists, showing that, with two exceptions, the two positions make comparable predictions.
Abstract: Behaving organisms are continually choosing. Recently the theoretical and empirical study of decision making by behavioral ecologists and experimental psychologists have converged in the area of foraging, particularly food acquisition. This convergence has raised the interdisciplinary question of whether principles that have emerged from the study of decision making in the operant conditioning laboratory are consistent with decision making in naturally occurring foraging. One such principle, the “parameter-free delay-reduction hypothesis, ” developed in studies of choice in the operant conditioning laboratory, states that the effectiveness of a stimulus as a reinforcer may be predicted most accurately by calculating the decrease in time to food presentation correlated with the onset of the stimulus, relative to the length of time to food presentation measured from the onset of the preceding stimulus. Since foraging involves choice, the delay-reduction hypothesis may be extended to predict aspects of foraging. We discuss the strategy of assessing parameters of foraging with operant laboratory analogues to foraging. We then compare the predictions of the delay-reduction hypothesis with those of optimal foraging theory, developed by behavioral ecologists, showing that, with two exceptions, the two positions make comparable predictions. The delay-reduction hypothesis is also compared to several contemporary pscyhological accounts of choice. Results from several of our experiments with pigeons, designed as operant conditioning simulations of foraging, have shown the following: The more time subjects spend searching for or traveling between potential food sources, the less selective they become, that is, the more likely they are to accept the less preferred outcome; increasing time spent procuring (“handling”) food increases selectivity; how often the preferred outcome is available has a greater effect on choice then how often the less preferred outcome is available; subjects maximize reinforcement whether it is the rate, amount, or probability of reinforcement that is varied; there are no significant differences between subjects performing under different types of deprivation (open vs. closed economies). These results are all consistent with the delay-reduction hypothesis. Moreover, they suggest that the technology of the operant conditioning laboratory may have fruitful application in the study of foraging, and, in doing so, they underscore the importance of an interdisciplinary approach to behavior.
428 citations
TL;DR: It is concluded that superstitious behavior under periodic delivery of food probably develops from components of species-typical patterns of appetitive behavior related to feeding, which are elicited by a combination of frequent food presentations and the supporting stimuli present in the environment.
Abstract: This research examined three explanations for the "superstitious" behavior of pigeons under frequent fixed-time delivery of food: accidental response-reward contingency, stimulus substitution, and elicited species-typical appetitive behavior. The behavior observed in these studies consisted of occasional postfood locomotion away from the food hopper, and a predominant pattern of activity directed toward the hopper wall (wall-directed behavior), including approaching, stepping side to side, scratching with the feet, bumping with the breast, pendulum movements of the extended neck, and head bobbing, though not pecking. The consistency of these behavior patterns argued against explanation by accidental response contingencies, and the complexity of behavior was incompatible with the classic stimulus-substitution account. These studies also showed that: (1) response contingencies and prior stimulus experience can modify wall-directed behavior, but within definable limits; (2) pecking sometimes can be obtained in birds of specific strains, and by providing extended training; (3) placing the hopper in the floor at the center of a large chamber replaces wall-directed behavior with circling in a manner that resembles ground foraging for food. We conclude that superstitious behavior under periodic delivery of food probably develops from components of species-typical patterns of appetitive behavior related to feeding. These patterns are elicited by a combination of frequent food presentations and the supporting stimuli present in the environment.
206 citations
Cites background from "Pecking of the Pigeon (Columba Livi..."
...Head bobbing is pigeons' normal pattern of visual scanning (they have very limited eye movement), and mayor may not lead to pecking (see Zweers, 1982)....
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...…poke at ground cover, thus exposing new search areas (Whitman, 1919); (6) grasp certain-sized items in the beak; (7) mandibulate these items in predictable ways that test their suitablity as food before swallowing (Zweers, 1982); and (8) reject or accept objects with particular textures and tastes....
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...Even this pecking can be considered more manipulative than consummatory (cf. Delius, 1983), inasmuch as a peck of this force would be more likely to scatter food than pick it up U. D. Deich & H. P. Zeigler, personal communication, April, 1984; see also LaMon, 1981; Zweers, 1982)....
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...All complex behavior patterns are appetitive in that components vary with stimulus conditions (see Zweers, 1982, for a particularly pretty analysis of the appetitive nature of "consummatory" pecking in pigeons)....
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..., with exposed neck feathers (Murton, 1965 ]); (2) approach areas where pecking sounds and movements are displayed; (3) walk about a food area in patterns and postures that ordinarily would facilitate locating further food items; (4) search visually for predictive features in the substrate; (5) brush and poke at ground cover, thus exposing new search areas (Whitman, 1919); (6) grasp certain-sized items in the beak; (7) mandibulate these items in predictable ways that test their suitablity as food before swallowing (Zweers, 1982); and (8) reject or accept objects with particular textures...
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TL;DR: The results indicate that severe feather pecking derives from frustrated motivations to forage, not to dustbathe, and suggest that finely analysing fixed action pattern morphology can help elucidate the motivational bases of puzzling abnormal behaviours in captive animals.
92 citations
Cites background from "Pecking of the Pigeon (Columba Livi..."
...Thus, in pigeons, the stereotyped pecks involved in eating and drinking differ because motivation affects FAP morphology (Zweers 1982, 1992)....
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TL;DR: The uniocular retinal field of Strix aluco is highly asymmetrical and the significance of the owl eye's tubular shape, its nasad asymmetry, and the possible factors influencing binocular field width are discussed.
86 citations
01 Jan 2000
TL;DR: Most traditional assessments of crocodilian phylogeny are based on analysis of the numerous differences in head morphology and skull structure among different species, which means few reliable characters can be used for phylogenetic studies.
Abstract: Crocodilians are the last surviving reptilian representatives of the subclass Archosauria. The analysis of proteins, lipids, and nucleic acids and the most recent morphological studies agree in aligning crocodilians with birds and dinosaurs. Therefore, crocodilians and birds represent the only surviving archosaurian clades among the modern vertebrates. Crocodylia are traditionally placed into three subcategories: Protosuchia, Mesosuchia, and Eusuchia. Three morphological characteristics are used to distinguish these suborders: the development of the secondary palate, the morphology of the vertebral centra, and the exclusion of the pubis from the acetabulum. A major problem in resolving the systematics and evolution of the eusuchian crocodilians is their tendency toward general morphological conservatism and convergence/parallelism in cranial morphology. The morphological conservatism is explicit in the postcranial region, where few reliable characters can be used for phylogenetic studies. Therefore, most traditional assessments of crocodilian phylogeny are based on analysis of the numerous differences in head morphology and skull structure among different species.
82 citations
References
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TL;DR: The role of association between a stimulus and a reinforcer in producing a resemblance of the auto-shaped response to the consummatory response is demonstrated.
Abstract: The relation between the form of auto-shaped responses to the lighting of a key and the consummatory responses of pecking grain and drinking water was examined in pigeons. Responses on the key were analyzed by means of high-speed photography, recordings of the force of contact, and judges' ratings of response-form based on film and videotape recordings. The first experiment showed that food-deprived birds presented grain as a reinforcer responded on the key with a grain-pecking movement, while water-deprived birds presented water as a reinforcer responded with drinking-like movements. The second and third experiments showed that the resemblance between auto-shaped and consummatory responses does not require the dominance of the deprivational state appropriate to the reinforcer. Changing the dominant state of deprivation did not immediately change the form of the key response, and in subjects simultaneously deprived of food and water, the form of response depended on the reinforcer. In the fourth and fifth experiments, subjects simultaneously deprived of food and water received one stimulus signalling food and another signalling water in a random series. In most subjects, the response to each stimulus resembled the consummatory response to the particular reinforcer that was signalled by the stimulus. This result demonstrates the role of association between a stimulus and a reinforcer in producing a resemblance of the auto-shaped response to the consummatory response.
480 citations
226 citations
TL;DR: In electric fish of the mormyrid family, an efference copy is present in the brain region that receives afferent input from ampullary electroreceptors, and it probably reduces the central effects of activity in Ampullary receptors evoked by the electric organ discharge.
Abstract: In electric fish of the mormyrid family, an efference copy is present in the brain region that receives afferent input from ampullary electroreceptors. The efference copy is elicited by the motor command to fire the electric organ. Its effect is always opposite that the ampullary afferents responding to the electric organ discharge, and it changes to match variations in this afferent input. It probably reduces the central effects of activity in ampullary receptors evoked by the electric organ discharge.
216 citations