Article

Foraging cost and meal patterns in ferrets (Mustela putorius furo)

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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.

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... Hunting with ferrets is called ferreting (Thompson, 1951). With their lean bodies, ferrets can chase their prey easily out of their burrows (Kaufman, 1980). In most countries, this hunting technique is only permitted with a licence enacted by law. ...
... The European polecat, the most probable ancestor, lives in wooded and semi-wooded areas mostly near the water (Blandford, 1987;Lodé, 1999;Davison et al., 1999), feeding on small mammals, amphibians and birds (Kaufman, 1980). Furthermore, some useful information about social organisation, territoriality and prey choices is available from several studies on feral ferrets (e.g. ...
... Feeding patterns can be adapted and are related to the amount of food available, group size and caloric value of given diet. When food is ample and freely available, ferrets will typically eat 9-10 meals per day (Kaufman, 1980). Deficiencies in the diet (i.e. ...
Article
Applied Animal Behaviour Science j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / a p p l a n i m Review The welfare of ferrets (Mustela putorius furo T) A review on the housing and management of pet ferrets a b s t r a c t Ferrets are very agile and lively animals, and their behavioural needs are not easily met in housing conditions like our living rooms. Nevertheless, ferrets are increasingly popular as pets. The present paper aims to review and discuss the available knowledge on our pet fer-ret. Topics are discussed like ferrets' behaviour priorities, common housing conditions and management conditions. Behaviour problems, as well as medical topics that are considered important to optimise the welfare of pet ferrets, are elucidated. The topics are discussed in consideration of ferrets' behavioural priorities, physical and physiological needs and/or capacities. We conclude that the main points of interest in a pet ferrets' behaviour in relation to welfare are: (1) their high motivation to explore and forage, (2) the necessity of available adequate resting opportunities, (3) play opportunities, and (4) their social organisation with respect to interspecies aggression and territoriality. Therefore, good socialisation is of the utmost importance to prepare a young ferret for its life in a human surrounding. The provision of a daily activity program, variable (food) enrichments and comfortable hiding and resting places, might be helpful to fulfil ferrets' behaviour priorities to a higher extent and may prevent behavioural disorders and problems for the owner. Social matching in ferrets should always be carefully done. The focus of the medical topics is on those for which potential preventive measures can be taken, such as routine annual examination by a veterinarian and subsequent treatment of parasites, vaccination against viruses and prevention of endocrine disorders through pre-ventive (chemical) neutering. Referring to medical issues, the main points of interest for the pet ferrets' welfare are nutrition, hyperoestrogenism, hyperadrenocorticism, insulin-oma and Helicobacter infection and gastric ulcers. The latter infection appears to be often associated to the presence of stress in the ferret's environment.
... Hunting with ferrets is called ferreting (Thompson, 1951). With their lean bodies, ferrets can chase their prey easily out of their burrows (Kaufman, 1980). In most countries, this hunting technique is only permitted with a licence enacted by law. ...
... The European polecat, the most probable ancestor, lives in wooded and semi-wooded areas mostly near the water (Blandford, 1987;Lodé, 1999;Davison et al., 1999), feeding on small mammals, amphibians and birds (Kaufman, 1980). Furthermore, some useful information about social organisation, territoriality and prey choices is available from several studies on feral ferrets (e.g. ...
... Feeding patterns can be adapted and are related to the amount of food available, group size and caloric value of given diet. When food is ample and freely available, ferrets will typically eat 9-10 meals per day (Kaufman, 1980). Deficiencies in the diet (i.e. ...
Chapter
Ferrets are members of the class Mammalia, order Carnivora, and family Mustelidae, which also includes mink and polecats. Ferrets are considered obligate carnivores, indicating that they need to be provided with food sources of animal origin to fulfil their nutrient requirements. Ferrets can be housed indoors and outdoors, as long as protection against the elements is provided. Pet ferrets may react aggressively to each other, and this can be the most frequently reported behavioural problem. Ferrets may be fearful of humans, which can manifest as avoidance or aggression. Ferrets can suffer from several diseases, including many infectious agents. Influenza is a common primary cause for respiratory disease in ferrets. Ferrets in pain are often lethargic, immobile, and anorexic, although some ferrets may become more anxious and restless. Signs of discomfort or pain also include crying and whimpering. Ferrets in fear, frustration, or pain may also squeal and scream.
... Work-related response costs are an important factor influencing choice behavior (Staddon, 1979;Kaufman, 1980;Kaufman et al., 1980;Salamone, 1986Salamone, , 1987Salamone, , 1992Hursh et al., 1988;Foltin, 1991;Tustin, 1995;Madden et al., 2000;, and considerable research has focused on the brain mechanisms that are involved in the exertion of effort and effort-related choice. This paper will review the literature on how various drugs and neurochemical manipulations affect effort-based choice, with a particular emphasis on drugs that alter dopamine (DA) transmission. ...
... Several investigators have emphasized how response costs or constraints affected operant response output (Staddon, 1979;Kaufman, 1980;Kaufman et al., 1980;Foltin, 1991;Tustin, 1995). Work requirements such as the number of lever presses required for obtaining food have been shown to act as determinants of instrumental response output and also to affect food consumption (Collier and Jennings, 1969;Johnson and Collier, 1987). ...
Article
This review paper is focused upon the involvement of mesolimbic dopamine (DA) and related brain systems in effort-based processes. Interference with DA transmission affects instrumental behavior in a manner that interacts with the response requirements of the task, such that rats with impaired DA transmission show a heightened sensitivity to ratio requirements. Impaired DA transmission also affects effort-related choice behavior, which is assessed by tasks that offer a choice between a preferred reinforcer that has a high work requirement vs. less preferred reinforcer that can be obtained with minimal effort. Rats and mice with impaired DA transmission reallocate instrumental behavior away from food-reinforced tasks with high response costs, and show increased selection of low reinforcement/low cost options. Tests of effort-related choice have been developed into models of pathological symptoms of motivation that are seen in disorders such as depression and schizophrenia. These models are being employed to explore the effects of conditions associated with various psychopathologies, and to assess drugs for their potential utility as treatments for effort-related symptoms. Studies of the pharmacology of effort-based choice may contribute to the development of treatments for symptoms such as psychomotor slowing, fatigue or anergia, which are seen in depression and other disorders.
... Each of these measures was analyzed by a 3 3 factorial ANOVA with repeated measures on the week factor. For Experiments 2 and 3, planned comparisons involving the overall error term (26) were used to identify group differences. The Pearson product-moment correlation was used to study the relation between various neurochemical and behavioral measures. ...
... Accumbens DA depletions do not appear to blunt the unconditioned reinforcing properties of food, but instead these depletions alter the relative allocation of instrumental responses with different requirements (8,9,12,58). Several behavioral studies have demonstrated that operant responding is an adaptation to constraint, and that economic variables such as response "costs" affect behavioral output (1,17,21,22,26,29,30,39,43,61,62). Although it is not certain which precise factors underlie the shift in response allocation produced by accumbens DA depletions, it has been suggested that accumbens DA participates in the sensorimotor/motivational processes that enable organisms to overcome response constraints (8,9,(50)(51)(52)(53)58). ...
Article
Three experiments investigated the behavioral effects of injections of the neurotoxic agent 6-hydroxydopamine (6-OHDA) into the core or shell of the nucleus accumbens. In the first experiment, it was observed that injections of 6-OHDA into either core or shell had no significant effect on variable interval 30-s responding. In Experiment 2, responding on a fixed ratio 5 (FR5) schedule was impaired by 6-OHDA injections in the core, but not the shell. Rats with core injections of 6-OHDA showed significant alterations in the relative distribution of interresponse times, which were indicative of reductions in the maximal rate of responding and increases in the number of pauses. In the third experiment, rats were tested using a lever-pressing/chow-feeding procedure, in which a preferred food (Bioserve pellets) was available by pressing a lever on a FR5 schedule, but a less preferred food (lab chow) was also available concurrently in the test chamber. Untreated rats usually pressed the lever at high rates to obtain the food pellets and ate little of the lab chow. After training, dopamine depletions were produced by injections of 6-OHDA directly into the core or dorsomedial shell subregions. Injections of 6-OHDA into the core significantly decreased lever pressing for food pellets, increased lab chow consumption, and decreased the relative amount of food obtained by lever pressing. Dorsomedial shell injections of 6-OHDA had no significant effects on either lever pressing or lab chow consumption. Neurochemical results indicate that injections of 6-OHDA in the shell produced substantial depletions in the shell that were somewhat selective; however, injections of 6-OHDA into the core tended to deplete both core and shell. Correlational analyses revealed that decreases in FR5 lever pressing were associated with dopamine levels in the core, but not the shell. The present results indicate that substantial depletions of dopamine in the dorsomedial shell are not sufficient for suppressing reinforced lever pressing, and indicate that dopamine depletions must include the core area to impair performance on these tasks. The lack of effect of accumbens dopamine depletions on VI30 responding are consistent with the notion that accumbens dopamine depletions affect responding on schedules that generate a high rate of responding (FR5), but not those that generate a moderate rate of responding (e.g., VI30 s). The results of the concurrent FR5/chow-feeding experiment indicate that rats with accumbens dopamine depletions remain directed towards the acquisition and consumption of food. These results suggest that dopamine in the core region of accumbens sets constraints upon the selection of food-related behaviors, and that core dopamine depletions alter the relative allocation of food-related responses.
... This recognition of dopaminergic involvement in the exertion of effort, and effort-based choices related to cost benefit analyses, fit nicely with an emerging emphasis in the behavioral literature on work, response costs or constraints, and economic models of operant behavior. Several behavioral investigators have emphasized how response costs or constraints affect operant response output (Staddon, 1979; Kaufman, 1980; Kaufman et al., 1980; Foltin, 1991). Collier and colleagues studied how work requirements, such as the number of lever presses necessary for obtaining food, could serve as determinants of response output and affect consumption parameters (Collier and Jennings, 1969; Johnson and Collier, 1987). ...
Article
Full-text available
There are numerous problems with the hypothesis that brain dopamine (DA) systems, particularly in the nucleus accumbens, directly mediate the rewarding or primary motivational characteristics of natural stimuli such as food. Research and theory related to the functions of mesolimbic DA are undergoing a substantial conceptual restructuring, with the traditional emphasis on hedonia and primary reward yielding to other concepts and lines of inquiry. The present review is focused upon the involvement of nucleus accumbens DA in behavioral activation and effort-related processes. Viewed from the framework of behavioral economics, the effects of accumbens DA depletions and antagonism on food-reinforced behavior are highly dependent upon the work requirements of the instrumental task, and DA depleted rats are more sensitive to increases in response costs (i.e., ratio requirements). Moreover, interference with accumbens DA transmission exerts a powerful influence over effort-related choice behavior. Rats with accumbens DA depletions or antagonism reallocate their instrumental behavior away from food-reinforced tasks that have high response requirements, and instead these rats select a less-effortful type of food-seeking behavior. Nucleus accumbens DA and adenosine interact in the regulation of effort-related functions, and other brain structures (anterior cingulate cortex, amygdala, ventral pallidum) also are involved. Studies of the brain systems regulating effort-based processes may have implications for understanding drug abuse, as well as energy-related disorders such as psychomotor slowing, fatigue or anergia in depression and other neurological disorders.
... Ferrets need to eat and drink multiple times per day, as they have a short intestinal tract (i.e. their gastrointestinal transit time is approximately 3 h, Bleavins & Aulerich, 1981;Kaufman, 1980) and also need a place to sleep multiple times per day, as they are polycyclic sleepers with sleep cycles of 2e4 h (Marks & Shaffery, 1996). Therefore, when water and foraging enrichments were tested in the ABO set-up, the ferrets would frequently return to the home chamber to sleep in the hammock (which was determined to be the most valued enrichment, Reijgwart et al., 2016) after visiting one of the other chambers. ...
Article
Ferrets, Mustela putorius furo, are increasingly used in infectious disease studies, particularly in influenza research. Which specific housing conditions and environmental enrichments are of particular importance for ferrets have not been part of a systematic evaluation. The motivation ferrets showed to reach different enrichments was assessed in multiple consumer demand study set-ups. To address the question whether these consumer demand set-ups give similar results, we assessed the effects of two ways of offering enrichments concurrently instead of consecutively. Six ovariectomized female ferrets were successively tested in a seven-chamber (7Ch), three-chamber (3Ch) and three-chamber ‘all-but-one’ (ABO) set-up. We compared the maximum price paid, visit number, visit duration and interaction time with the enrichments in the 3Ch versus the 7Ch and ABO set-ups, respectively. Compared to the 3Ch set-up, the ferrets in the ABO and 7Ch set-up showed a lower motivation to access, paid fewer and shorter visits to and interacted less with the enrichments. In the 7Ch, the ferrets especially showed a lower motivation for the less preferred enrichments and the empty chamber. These findings indicate that testing all the enrichments concurrently in the 7Ch set-up forced the ferrets to make more economic decisions, thereby providing more valuable information on how different enrichments are valued relative to one other. Adding preferred enrichment items to the home chamber, as was done in the ABO set-up, might have reduced the motivation to access or look for additional enrichment items. However, this set-up might not have a closed economy, making the ABO set-up unsuitable. Based on these findings, we advise testing all the enrichment categories concurrently instead of consecutively and keeping the number of items in the home cage to a minimum when performing a consumer demand study, as this appears the most optimal set-up to determine motivational priorities for resources in ferrets. Open access via: https://dspace.library.uu.nl/handle/1874/363476
... There is no evidence that rats with accumbens DA depletions are particularly sensitive to the time requirement in intermittent schedules (Correa et al., in press), but they may be very sensitive to the work requirements of each ratio that must be completed in order to receive each unit of reinforcement. Consid- NSC 5092 21-8-01 J. D. Salamone et al. 868 erable evidence in the behavioral literature indicates that animals are sensitive to work-related response costs in operant procedures (Collier and Jennings, 1969; Staddon, 1979, 1983; Kaufman, 1980; Hursh et al., 1988; Salamone, 1992) and it is possible that accumbens DA depletions enhance this sensitivity (Salamone, 1987, 1991, 1992; Salamone et al., 1991, 1997). Accumbens DA depletions appear to render the animals much more dependent upon the direct feedback or behavioral activation provided by primary reinforcement, perhaps by a¡ecting the higher order sensorimotor and conditioning processes that must sustain responding in the absence of primary reinforcement. ...
Article
It has been suggested that dopamine in nucleus accumbens is involved in the process of enabling organisms to overcome work-related response costs. One way of controlling work costs with operant schedules is to use fixed ratio schedules with different ratio requirements. In the present study, the effects of nucleus accumbens dopamine depletions were investigated using six schedules: fixed ratio 5, 20, 50, 100, 200, and 300. In the first three schedules the food reinforcement consisted of one 45 mg food pellet per ratio completed. In the remaining schedules the food reinforcement per ratio completed was increased to two pellets for fixed ratio 100, four pellets for fixed ratio 200, and six pellets for fixed ratio 300. All rats were trained extensively prior to surgery, and rats were able to maintain high levels of responding on all schedules up to the fixed ratio 300. After training, rats were injected with either ascorbate vehicle or 6-hydroxydopamine into the nucleus accumbens. Rats were tested post-surgically on each of the schedules, with 3 days of testing per schedule.
... These suggestions include the presence of subtle motor deficits, a lack of sensitivity to the activating effects of conditioned stimuli that normally induce responding, a general tendency towards response slowing, or a reduction in the tendency to overcome work-related response costs attached to instrumental contingencies Salamone, 1991Salamone, , 1992Salamone et al., 1997Salamone et al., , 1999. Indeed, instrumental behavior is a complex phenomenon, and many factors influence response output, including associative factors, motivational processes, and work requirements of the schedule Berridge and Robinson, 1998;Hursh et al., 1988;Kaufman, 1980;Koob et al., 1978;Salamone, 1987Salamone, , 1991Salamone, , 1992Salamone et al., 1997Salamone et al., , 1999Sokolowski and Salamone, 1998;Staddon, 1979Staddon, , 1983Timberlake, 1993;Timberlake and Allison, 1974). Further research must be conducted to identify more precisely the behavioral effects of interference with accumbens DA transmission. ...
Article
Although interference with dopamine (DA) systems can suppress lever pressing for food reinforcement, it is not clear whether this effect occurs because of a general disruption of food motivation. One way of assessing this has been a choice procedure in which a rat responds on an fixed ratio 5 (FR5) schedule for preferred Bioserve pellets while a less preferred lab chow is concurrently available in the operant chamber. Untreated rats consume little of the chow, preferring to respond for the Bioserve pellets. Previous studies have shown that depleting DA in the accumbens substantially decreased lever pressing while increasing chow consumption. In the present study, low doses (0.0625-1.0 microg) of the D1 antagonist SCH 23390 or the D2 antagonist raclopride were injected into the either the core or shell subregions of nucleus accumbens, and rats were tested on the concurrent lever pressing/feeding task. Analysis of the dose response curves showed that injections of SCH 23390 into the core were more potent than injections into the shell for suppressing lever pressing (i.e., the ED(50) was lower in the core). Nevertheless, injections of either drug into either site suppressed lever pressing and increased intake of the concurrently available chow. Across both drugs and at both sites, the amount of chow consumed was negatively correlated with the total number of responses. Neither drug significantly increased response duration, suggesting that accumbens DA antagonism did not produce the type of motor impairment that leads to severe alterations in the form of lever pressing. In summary, the blockade of D1 or D2 receptors in nucleus accumbens core or shell decreased lever pressing for food reinforcers, but rats remained directed toward the acquisition and consumption of food. These results indicate that accumbens D1 antagonism does not decrease lever pressing because of a general reduction in food motivation. Nevertheless, interference with accumbens DA does appear to set constraints upon which responses are selected for obtaining food, and may impair the ability of animals to overcome work-related response costs in order to obtain food.
... In diet studies, a popular method for simplifying the study of selection is multiple-choice feeding preference experiments, in which animals are offered an array of food items representative of forage/prey encountered under natural conditions. Multiple-choice feeding preference experiments have been used with both herbivores and carnivores across a wide array of taxa, including terrestrial invertebrates (barnES 1963, GriME et al. 1968, DuDGEon et al. 1990), fish (colGan & SMith 1985), birds (hohf et al. 1987hohf et al. , MurPhy & kinG 1987 ), littoral marine animals (see PEtErSon & rEnauD 1989; roa 1992 for review), and mammals (kaufMan 1980, Swihart 1990, PyarE et al. 1993). Coupled with this diversity of feeding preference experiments are an equivalent number of varied techniques and statistical analyses to examine the results of these experiments . ...
Article
Understanding how animals select resources provides important information regarding their requirements for survival. One method for studying diet selection is multiple-choice feeding preference experiments, in which animals are offered multiple food items simultaneously. However, because food items are offered simultaneously, the consumer's choices are not independent. They therefore violate assumptions of univariate statistical tests, such as ANOVAs and t-tests, which are most often used in such studies. I used multivariate statistics to examine diet selection of yellowbellied marmots (Marmota flaviventris) for the 7 plants most commonly found in their foraging areas. Using Hotelling's T2, I rejected the null hypothesis that the proportions of plant species consumed were equal to the expected value of 1/7 (T2 = 180.63, P = 0.025). Cafeteria-style feeding trials indicated that dandelions (Taraxacum officianale) were selected significantly more often than expected by a random distribution (P = 0.001), whereas grasses (Bromus spp. and Poa spp.) and cinquefoil (Potentilla gracilis) were avoided (P = 0.002). Use of the remaining species, cow parsnip (Heracleum lanatum), yarrow (Achillea millefolium), mountain blue bells (Mertensia fusiformis), and wild sweet pea (Lathyrus leucanthus), did not differ significantly from random, although cow parsnip and wild sweet pea tended to be more preferred and avoided, respectively, than the remaining species. Preferences in these marmots may have been based on fatty acid content, which is important for hibernation.
Article
Two experiments were conducted to study the role of dopamine in the performance of a novel cost/benefit procedure. Rats were trained on a T-maze task in which one arm contained a high reinforcement density (4 x 45 mg Bioserve pellets) and the other arm contained a low reinforcement density (2 x 45 mg pellets). Different groups of rats were trained either with unobstructed access to both arms from the start area, or under a condition in which a large vertical barrier (44 cm) was placed in the arm that contained the high density of food reinforcement. In the first experiment, rats trained under each procedure received injections of 0.1 mg/kg haloperidol and tartaric acid vehicle as a control procedure. Analysis of variance indicated that there was a significant effect of the barrier on maze arm choice, a significant effect of haloperidol, and a significant drug x barrier interaction. Haloperidol did not affect arm choice in rats tested without the barrier present, but this drug significantly reduced the number of selections of the arm with high reinforcement density when the barrier was present. In the second experiment, groups of rats were trained as described above, and then received intraaccumbens injections of 6-hydroxydopamine or ascorbate vehicle. Nucleus accumbens dopamine depletions produced by 6-hydroxydopamine decreased the number of selections of the arm with high reinforcement density when the barrier was present, but had no effect on arm choice when the barrier was not present.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
Rats were tested on days 1, 3, and 5 of a 5-day test week in an operant chamber in which they could either lever press on a fixed-ratio 5 (FR5) schedule to obtain food pellets (Bioserve) or approach and consume lab chow that was also available in the chamber (Teklad Premier). Rats typically pressed at high rates to obtain the food pellets and ate little of the lab chow. On days 2 and 4 of each week lab chow was not concurrently available, and rats could only lever press on the FR5 schedule for pellets to obtain food. Dopamine depletions produced by intraaccumbens injections of the neurotoxic agent 6-hydroxydopamine produced a dramatic decrease in lever pressing and increase in chow consumption on days when lab chow was available. Lever pressing was not significantly reduced in dopamine-depleted rats on days when chow was not available, although there was a significant correlation between lever pressing and accumbens dopamine levels. These results suggest that nucleus accumbens dopamine depletions do not produce a general deficit in food motivation. Moreover, accumbens dopamine depletions do not appear to produce severe deficits in fine motor control that impair the execution of individual motor acts involved in lever pressing. Rather, the present results are consistent with the notion that accumbens dopamine sets constraints upon which food-related response is selected in a particular situation, and that these depletions alter the relative allocation of food-related responses.
Article
This article addresses the common ferret diseases encountered by the veterinarian. An introductory section familiarizes the veterinarian with management and preventive health aspects of the pet ferret. Associated clinical techniques are described. Diseases most frequently seen in pet ferrets are discussed.
Article
Nucleus accumbens (DA) has been implicated in a number of different behavioral functions, but most commonly it is said to be involved in "reward" or "reinforcement". In the present article, the putative reinforcement functions of accumbens DA are summarized in a manner described as the "General Anhedonia Model". According to this model, the DA innervation of the nucleus accumbens is conceived of as a crucial link in the "reward system", which evolved to mediate the reinforcing effects of natural stimuli such as food. The reward system is said to be activated by natural reinforcing stimuli, and this activation mediates the reinforcing effects of these natural stimuli. According to this view, other stimuli such as brain stimulation and drugs can activate this system, which leads to these stimuli being reinforcing as well. Interference with DA systems is said to blunt the reinforcing effects of these rewarding stimuli, leading to "extinction". This general model of the behavioral functions of accumbens DA is utilized widely as a theoretical framework for integrating research findings. Nevertheless, there are several difficulties with the General Anhedonia Model. Several studies have observed substantial differences between the effects of extinction and the effects of DA antagonism or accumbens DA depletions. Studies involving aversive conditions indicate that DA antagonists and accumbens DA depletions can interfere with avoidance behavior, and also have demonstrated that accumbens DA release is increased by stressful or aversive stimuli. Although accumbens DA is important for drug abuse phenomena, particularly stimulant self-administration, studies that involve other reinforcers are more problematic. A large body of evidence indicates that low doses of dopamine antagonists, or depletions of accumbens DA, do not impair fundamental aspects of food motivation such as chow consumption and simple instrumental responses for food. This is particularly important, in view of the fact that many behavioral researchers consider the regulation of food motivation to be a fundamental aspect of food reinforcement. Finally, studies employing cost/benefit analyses are reviewed, and in these studies considerable evidence indicates that accumbens DA is involved in the allocation of responses in relation to various reinforcers. Nucleus accumbens DA participates in the function of enabling organisms to overcome response costs, or obstacles, in order to obtain access to stimuli such as food. In summary, nucleus accumbens DA is not seen as directly mediating food reinforcement, but instead is seen as a higher order sensorimotor integrator that is involved in modulating response output in relation to motivational factors and response constraints. Interfering with accumbens DA appears to partially dissociate the process of primary reinforcement from processes regulating instrumental response initiation, maintenance and selection.
Article
This experiment was undertaken to investigate dopaminergic involvement in food-related instrumental behavior. Rats were tested in an operant chamber in which there was a choice between pressing a lever to receive a preferred food (Bioserve pellets) or feeding upon a less preferred food (lab chow). The lever-pressing schedule was a fixed ratio 5 (FR5). Rats usually pressed the lever at high rates to obtain the preferred food, and typically ate little of the lab chow even though it was freely available in the chamber concurrently with the lever-pressing schedule. The neurotoxic agent 6-hydroxydopamine was injected directly into the nucleus accumbens, medial striatum, or ventrolateral striatum to determine the effects of dopamine depletion on the performance of this task. Depletion of dopamine in the nucleus accumbens led to a dramatic shift in behavior in which there was a significant decrease in lever pressing but a significant increase in consumption of lab chow. The shift away from lever pressing and towards chow consumption in rats with accumbens DA depletions was significantly correlated with a decrease in spontaneous locomotor activity. Dopamine depletions in the medial striatum did not significantly affect lever pressing or chow consumption. Ventrolateral striatal dopamine depletions decreased lever pressing but also tended to reduce consumption of lab chow. Rats with ventrolateral striatal dopamine depletions also showed profound deficits in home-cage feeding, and these rats had to receive wet mash or tube feeding to maintain body weight.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
This experiment was conducted to study the role of nucleus accumbens dopamine in the performance of a novel T-maze cost/benefit procedure. Rats were trained on a T-maze task for food reinforcement. Under one of the test conditions, one arm of the maze contained a high reinforcement density (4 x 45 mg Bioserve pellets) and the other arm contained a low reinforcement density (2 x 45 mg pellets). A large vertical barrier (44 cm) was placed in the arm that contained the high density of food reinforcement. In the second test condition, a separate group of rats was trained in the same T-maze, in which there were 4 food pellets in the arm that was obstructed by the barrier, yet there were no food pellets in the unobstructed arm. After training rats received intra-accumbens of injections 6-hydroxydopamine or ascorbate vehicle. Nucleus accumbens dopamine depletions substantially decreased the number of selections of the obstructed arm with the high reinforcement density when the unobstructed arm also contained 2 food pellets. Dopamine-depleted rats in this condition showed increased selection of the no-barrier arm as well as decreased entry into the arm that contained the barrier. These effects persisted throughout the 3 weeks of post-surgical testing. Nevertheless, when the unobstructed arm contained no food pellets, and the only way to obtain food was to climb the barrier, rats with nucleus accumbens dopamine depletions showed only a modest effect on selections of the obstructed arm, which recovered by the second week of testing. Dopamine-depleted rats that were tested with food in the unobstructed arm showed significantly fewer barrier crossings than dopamine-depleted rats that were tested with no food in the unobstructed arm. Thus, the present findings are not consistent with the notion that nucleus accumbens dopamine depletion rendered the animals unable to climb the barrier, or set an absolute ceiling on the number of barrier crossings the animals could perform. Instead, the present results indicate that nucleus accumbens dopamine depletions affected the relative allocation of barrier climbing responses if alternative food sources were available.
Article
Feeding and drinking patterns of six immature female pigs, weighing from 10 to 130 kg, operantly obtaining feed and water at a fixed ratio of 10, were determined. It was found by log survivorship analysis that 10 min was the minimum interbout interval defining separate eating bouts. As the pigs grew through this weight range, daily feed intake increased nearly threefold, while eating bout frequency fell from 14 to 7 per day; consequently both eating bout size and interbout interval increased. However, bout size was increased primarily by an increased rate of eating during bouts without any consistent increase in bout duration. Neither premeal nor postmeal intervals were correlated with meal size. Of the pigs' daily water intake, 75% was closely associated with eating bouts and over 1/3 of this (25%) was preprandial. Sixty-four percent of daily food intake and 68% of water intake was during the 12-hr light period. Nocturnal eating bouts were less frequent, but larger.
Article
Four experiments were conducted to determine the effects of dopamine (DA) antagonists and DA depletions on progressive-ratio responding for food reinforcement. On this schedule, ratio requirement increased by one response after each reinforcer was obtained, and rats were tested in 30-min sessions. Response rates and highest ratio completed were reduced in a dose-related manner by systemic injections of the D1 antagonist SCH 23390, and also by the D2 antagonists haloperidol and raclopride. Drug-treated rats also showed reductions in time to complete the last ratio, demonstrating that they had stopped responding before the end of the session. DA depletions produced by injections of 6-OHDA directly into the nucleus accumbens substantially decreased both the number of responses and the highest ratio completed. The deficits in response number and highest ratio completed induced by DA depletions persisted through the first 3 weeks of postsurgical testing, with some recovery by the fourth week. However, the deficits resulting from dopamine depletions were largely a manifestation of a decrease in response rate; although time to complete the last ratio was significantly reduced by dopamine depletions in the first few days of testing, rats recovered on this measure by the fifth day after surgery. Although previous work has shown that performance on several schedules (e.g., continuous, low value ratios, variable interval) is relatively unaffected by accumbens DA depletions, the present data demonstrate that such depletions do produce a substantial and persistent impairment of progressive ratio response output. Rats with accumbens DA depletions appear to have deficits in maintaining the high work output necessary for responding at large ratio values. The relative sparing of responding on some simple schedules, together with the present progressive ratio results, suggest that rats with accumbens DA depletions remain directed toward the acquisition and consumption of food, but they show deficits in work output for food.
Article
It has been suggested that nucleus accumbens dopamine is involved in the process of enabling organisms to overcome work-related response costs. One way of controlling work requirements in operant schedules is to use fixed ratio schedules with different ratio requirements. In the present study, the effects of nucleus accumbens dopamine depletions were assessed using four schedules: fixed ratio 1, 4, 16, and 64. Rats with nucleus accumbens dopamine depletions showed behavioral deficits that were highly dependent upon the ratio value; there were no effects of dopamine depletions on fixed ratio 1 lever pressing, but as ratio value got larger, the impairment became much greater. In a separate experiment, pre-feeding to reduce food motivation was shown to produce a different pattern, such that performance on all ratio schedules was substantially impaired. Thus, aspects of food reinforcement that are involved in fixed ratio 1 performance are highly sensitive to food motivation, but are largely unaffected by nucleus accumbens dopamine depletions. Nevertheless, nucleus accumbens dopamine depletions affected the elasticity of demand for food, and enhanced "ratio strain", i.e. they exacerbated the response-suppressing effects of increasing ratio value.
Article
Two experiments were conducted to determine the effects of accumbens dopamine (DA) depletions on progressive ratio responding for food reinforcement. In one version of this schedule, ratio requirement increased by one response after each reinforcer was obtained (PROG1). In the other version, ratio requirement increased by five responses after each reinforcer was obtained (PROG5). For both versions, 60-min sessions were conducted. Accumbens DA depletions produced by local injections of 6-OHDA substantially decreased the number of responses on both schedules. The deficits in the response number induced by DA depletions persisted through the two weeks of postsurgical testing for both the PROG1 and PROG5 schedules. However, there were differences between the effects of DA depletions on the two schedules in terms of the time to complete the last ratio. Although time to complete the last ratio was significantly reduced by DA depletions only in the first week of testing on the PROG1 schedule, rats recovered on this measure by the second week after surgery. In contrast, DA-depleted rats on the PROG5 schedule showed a more persistent suppression of the time to complete the last ratio, which lasted through both weeks of postsurgical testing. Performance on schedules that generate low baseline rates of responding (e.g., continuous, fixed, and variable interval) is relatively unaffected by accumbens DA depletions; nevertheless, accumbens DA depletions substantially impair progressive ratio response output. The high work output necessary for responding on the PROG5 schedule may make these animals more sensitive to the effects of accumbens DA depletions.
Article
George Collier is known for promoting the incorporation of an ecological framework into the study of feeding behavior. He has tirelessly reminded psychologists and physiologists that the animals they study are members of species designed by evolution to solve problems of acquiring, handling and storing energy in particular ways. A less-appreciated contribution is the comparative approach within his laboratory. George and his students used laboratory simulations of foraging, but ranged far beyond the laboratory rat to examine the responses of a variety of species representing different dietary needs and foraging strategies. Species comparisons enhance our ability to test the generality of responses to challenges, apply ecological theory to the explanation of behavior, and incorporate the feeding strategy of a species in the study of its ingestive behavior.
Article
The location of vagal preganglionic neurones (VPN) has been determined in nine ferrets (Mustela putorius furo) and seven mink (M. vison) using neuronal tract-tracing techniques employing horseradish peroxidase (HRP) and wheat-germ agglutinin conjugated HRP (WGA-HRP) mixtures injected into the nodose ganglion of the vagus nerve. Labelled VPN were located ipsilaterally in the dorsal motor nucleus of the vagus (DmnX), nucleus ambiguus (nA), and reticular formation (rf) of the medulla oblongata. In four of the ferrets, labelled VPN were also identified in the nucleus dorsomedialis (ndm) and the nucleus of the spinal accessory nerve (nspa). In a single mink a few labelled cells were observed in the ndm but no labelled VPN were found in the nspa. Labelling of afferent components of the vagus nerve was seen in two ferrets and two mink with the best labelling obtained following an injection of an HRP/WGA-HRP mixture into the nodose ganglion. Labelled afferents were observed to cross the ipsilateral spinal trigeminal tract (SpV) before entering the tractus solitarius (TS) in regions separate from the motor axons which exit the medulla in separate fasicles. Sensory terminal fields were identified bilaterally in the nucleus of the tractus solitarius (nTS) in both species and bilaterally in the area postrema (ap) of the ferret; however, the contralateral labelling was sparse in comparison to the densely labelled ipsilateral nTS/ap. Maximal terminal labelling was seen in regions just rostral and caudal to obex in both species.
Article
The dopamine‐depleting agent tetrabenazine alters effort‐based choice, suppressing food‐reinforced behaviors with high response requirements, while increasing selection of low‐cost options. In the present experiments, rats were tested on a concurrent fixed ratio 5/chow feeding choice task, in which high‐carbohydrate Bio‐serv pellets reinforced lever pressing and lab chow was concurrently available. Detailed timing of lever pressing was monitored with an event recording system, and the temporal characteristics of operant behavior seen after 1.0 mg/kg tetrabenazine or vehicle injections were analyzed. Tetrabenazine shifted choice, decreasing lever pressing but increasing chow intake. There was a small effect on the interresponse‐time distribution within ratios, but marked increases in the total duration of pauses in responding. The postreinforcement‐pause (PRP) distribution was bimodal, but tetrabenazine did not increase the duration of PRPs. Tetrabenazine increased time feeding and duration and number of feeding bouts, but did not affect feeding rate or total time spent lever pressing for pellets and consuming chow. Thus, TBZ appears to predominantly affect the relative allocation of lever pressing versus chow, with little alteration in consummatory motor acts involved in chow intake. Tetrabenazine is used to model motivational symptoms in psychopathology, and these effects in rats could have implications for psychiatric research.
Article
There is still much more to be learned about ferret behavior, nutrition, and physiologic responses associated with aging, disease, and environmental stimuli. The many similarities in the clinical disorders of ferrets and other small companion animals should emphasize the importance of using the same diagnostic methods developed for common companion animals in examinations of ferrets. There is still very little known of the efficacy of a wide spectrum of drugs in ferrets, and judicious use of pharmacodynamic agents that are safe for cats would be a reasonable approach to drug therapy.
Article
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An important aspect of motivated behavior is that organisms will perform complex instrumental behaviors to gain access to stimuli such as food. In the present study, food-deprived rats were tested in an operant chamber in which the animals had a choice between pressing a lever to obtain a more-preferred food (Bioserve pellets), or free feeding on a less-preferred food (lab chow). Typically, rats pressed the lever to obtain the preferred food pellets, and ate little of the less-preferred food even though it was freely available. Pre-fed rats showed suppression of both lever pressing and feeding. Systemic administration of 0.1 mg/kg haloperidol (HP) led to a dramatic shift in the behavior of these rats, such that the number of lever presses was substantially reduced, but the amount of less-preferred food consumed showed a significant increase. This result occurred if the rats pressed a lever on either a CRF or FR5 schedule. Injection of 3.5-7.0 micrograms HP directly into the nucleus accumbens, or intra-accumbens injections of 6-hydroxy-dopamine, also decreased lever pressing for food and increased feeding on laboratory chow. Thus, interference with brain dopamine suppressed a highly active instrumental response for food, although the behavior of the animal was still directed towards food acquisition and consumption.
Article
The suggestions that dopamine (DA) systems are involved in "motor control" and "reward" represent the classic working hypotheses on the behavioral functions of these systems. The research generated by these hypotheses has yielded results that are far more complicated than the simplest form of either hypothesis would indicate. Pharmacological or lesion-induced interference with DA function does not suppress all aspects of movement control, nor all aspects of reward, nor all aspects of motivation. The deficits produced by interference with DA systems are selective and dissociative in nature, affecting some aspects of motor or motivational function, but leaving others basically intact. In some sense the hypotheses that DA is involved in "motor" or "reward" or "motivational" processes are partly correct, but the processes to which these terms refer are too broad to offer an accurate and detailed description of the behavioral functions of brain DA. A review of the literature on the behavioral pharmacology of DA suggests that the behaviors most easily disrupted by DA antagonists are highly activated and complex learned instrumental responses that are elicited or supported by mild conditioned stimuli, and maintained for considerable periods of time. It is proposed that DA in accumbens and striatum modulates the ability of neocortical and limbic areas involved in sensory, associative, and affective processes to influence complex aspects of motor function, and also modulates the execution of complex motor acts organized by the neocortex. Thus, interference with DA systems produces a "subcortical apraxia", which dissociates complex stimulus processes from complex motor processes, but leaves aspects of those processes intact.
Article
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For many years, it has been suggested that drugs that interfere with dopamine (DA) transmission alter the "rewarding" impact of primary reinforcers such as food. Research and theory related to the functions of mesolimbic DA are undergoing a substantial conceptual restructuring, with the traditional emphasis on hedonia and primary reward yielding to other concepts and lines of inquiry. The present review is focused upon the involvement of nucleus accumbens DA in effort-related choice behavior. Viewed from the framework of behavioral economics, the effects of accumbens DA depletions and antagonism on food-reinforced behavior are highly dependent upon the work requirements of the instrumental task, and DA-depleted rats show a heightened sensitivity to response costs, especially ratio requirements. Moreover, interference with accumbens DA transmission exerts a powerful influence over effort-related choice behavior. Rats with accumbens DA depletions or antagonism reallocate their instrumental behavior away from food-reinforced tasks that have high response requirements, and show increased selection of low reinforcement/low cost options. Nucleus accumbens DA and adenosine interact in the regulation of effort-related functions, and other brain structures (anterior cingulate cortex, amygdala, ventral pallidum) also are involved. Studies of the brain systems regulating effort-based processes may have implications for understanding drug abuse, as well as symptoms such as psychomotor slowing, fatigue or anergia in depression and other neurological disorders.
Article
The available literature on the biology of the European Polecat (Mustela putorius) is collated. Aspects covered are general biology and systematics, distribution, physical characteristics, variation, skeletal characteristics, habitat, general behaviour, diet and predatory behaviour, breeding, juvenile development, population structure, mortality, parasites and diseases, relations with man, and history in Britain. Notes on field signs are also included. Recent and current research on Polecats both in Great Britain and on the European continent are then reviewed and some new information is reported. An extended bibliography lists all major and many minor publications on M. putorius, together with selected references to feral Ferrets (M. furo) and Polecat-Ferrets (M. putorius x M.furo).
Article
Ferrets can be characterized by a relative short gastrointestinal tract, a short time of chyme passage as well as a poor distinguished microflora inside the intestinal tract. Data on the nutrition physiology show a lot of things in common with cats. Protein and fat are digested to a great extent, but the digestibility of starch is much lower. That's why the starch content of the ration should be limited. For the whole ration an upper starch content of 30-35 % is recommended (NAISMITH and CURSITER, 1972). The digestibility would be much better, if the starch is thermal treated. The feed intake aims at a constant energy intake. For example, a diet with a high energy content leads to a lower feed intake. Therefore the nutrient contents of the diet should be higher, to meet the individual nutrient requirements of the ferret (BELL, 1996). Water should be offered always ad libitum. If the ferrets are fed by a dry food for cats exclusively an insufficient water supply can result in risks of urolithiasis, especially struvite stones (KAMPHUES, 1999).
Article
It has been suggested that accumbens dopamine (DA) is involved in the process of enabling organisms to expend energy in various situations, including foraging, maze running, and leverpressing. Although accumbens DA depletions impair stimulant self-administration, the effects of these depletions on various food-reinforced operant schedules are highly variable. Accumbens DA depletions have little or no effect on total response output in rats responding on the simplest schedule of food reinforcement (i.e., the fixed ratio 1). In addition, it has been shown clearly that the effects of accumbens DA depletions do not resemble the effects of extinction or prefeeding to reduce food motivation. Over the last several years, our laboratory has investigated the effects of accumbens DA depletions on several schedules, including fixed ratio 1, variable interval 30 sec, fixed interval 30 sec, progressive ratio, and fixed ratio 4, 5, 16, and 64. These schedules generate very different rates of responding, ranging from 300 to 3,000 responses per 30 min. Regression analyses of all these studies indicates a significant linear relation between control rates of responding and the degree of suppression of responding produced by accumbens DA depletions. Schedules that generate relatively low response rates, such as fixed ratio 1 or variable interval 30 sec, are little affected by accumbens DA depletions, yet schedules that generate high response rates (e.g., fixed ratio 64) are severely disrupted. Prefeeding shows different patterns of suppression as a function of response rate. Microanalysis of the temporal characteristics of leverpressing has shown that accumbens DA depletions produce a response slowing, as measured by the interresponse time; extinction and prefeeding produce a different pattern of effects. These results indicate that accumbens DA depletions do not blunt the reinforcing effects of food, but do suppress responding in a rate-dependent manner. In addition, microdialysis studies have shown that accumbens DA release is positively correlated with leverpressing response rate. Accumbens DA appears to be involved in energy expenditure, behavioral activation, or maintenance of high local rates of responding, which are functions that represent an area of overlap between motor and motivational processes.
Article
Ferrets have become companion animals during the last thirty years. Although the animal does not exist in its natural environment and there is limited research about the species available, some behavioural aspects have been identified that should be taken into account by the veterinarian. Numerous physiological and behavioural characteristics differentiate this species from other carnivores. Ferrets need a higher energy requirement and several meals per day. Ferrets sleep up to 18 hours per day. However, when awake they are highly active displaying exploratory and play behaviour even in adults. Aggression by biting is never pre-empted by menace behaviour. Owners should be aware of these characteristics and should provide the animals with a suitable space and environment.
Article
The principles of housing, management, and breeding practices for ferrets are discussed in this chapter. It lists the various factors that need to be considered in regard to safe and adequate housing for the ferret. To raise large numbers of specific pathogen free (SPF) ferrets, especially for influenza work, it is desirable to have separate facilities or at least different rooms that can be handled by dedicated personnel. It is important for prospective ferret owners to consider the complexity of having a pet ferret because of its behavioral traits and specialized husbandry needs. The chapter details the factors that have to be considered for the proper management of ferrets. The animal is often handled without protective gloves, and in pet settings, is commonly allowed free access to the household; caging can be used at night, though, or for periods when the owner wants the animal to be confined.
Chapter
Scientific study of the behavioral effects of neuroleptic drugs involves many different disciplines. Psychiatric treatment of psychoses has been revolutionized by the use of these agents to combat schizophrenia. The common pharmacological ground that most neuroleptic drugs share is an opposition to the action of dopamine (DA), usually by blockade of DA receptors. In this regard, pharmacologists have utilized the reliable behavioral sequelae of neuroleptic action to serve as “behavioral assays” for evaluating the potency of known neuroleptic drugs and identifying new ones. To the physiological psychologist, neuroleptics are a tool—a means of investigating the behavioral processes in which DA is involved. Although any substantial review of this area must employ views obtained from the different disciplines involved, it is largely from the latter perspective that the present chapter is derived.
Article
Ferrets have become companion animals during the last thirty years. Although the animal does not exist in its natural environment and there is limited research about the species available, some behavioural aspects have been identified that Should be taken into account by the veterinarian. Numerous Physiological and behavioural characteristics differentiate this species from other carnivores. Ferrets need a higher energy requirement and several meals per day. Ferrets sleep Lip to 18 hours per day However, when awake they are highly active displaying exploratory and play behaviour even in adults. Aggression by biting is never pre-empted by menace behaviour. Owners should be aware of these characteristics and should provide the animals with a suitable space and environment.
Article
Although the Skinnerian 'Empirical Law of Effect' does not directly consider the fundamental properties of stimuli that enable them to act as reinforcers, such considerations are critical for determining if nucleus accumbens dopamine systems mediate reinforcement processes. Researchers who have attempted to identify the critical characteristics of reinforcing stimuli or activities have generally arrived at an emphasis upon motivational factors. A thorough review of the behavioral literature indicates that, across several different investigators offering a multitude of theoretical approaches, motivation is seen by many as being fundamental to the process of reinforcement. The reinforcer has been described as a goal, a commodity, an incentive, or a stimulus that is being approached, self-administered, attained or preserved. Reinforcers also have been described as activities that are preferred, deprived or in some way being regulated. It is evident that this 'motivational' or 'regulatory' view of reinforcement has had enormous influence over the hypothesis that DA directly mediates 'reward' or 'reinforcement' processes. Indeed, proponents of the DA/reward hypothesis regularly cite motivational theorists and employ their language. Nevertheless, considerable evidence indicates that low/moderate doses of DA antagonists, and depletions of DA in nucleus accumbens, can suppress instrumental responding for food while, at the same time, these conditions leave fundamental aspects of reinforcement (i.e. primary or unconditioned reinforcement; primary motivation or primary incentive properties of natural reinforcers) intact. Several complex features of the literature on dopaminergic involvement in reinforcement are examined below, and it is argued that the assertions that DA mediates 'reward' or 'reinforcement' are inaccurate and grossly oversimplified. Thus, it appears as though it is no longer tenable to assert that drugs of abuse are simply turning on the brain's natural 'reward system'. In relation to the hypothesis that DA systems are involved in 'wanting', but not 'liking', it is suggested in the present review that 'wanting' has both directional aspects (e.g. appetite to consume food) and activational aspects (e.g. activation for initiating and sustaining instrumental actions; tendency to work for food). The present paper reviews findings in support of the hypothesis that low doses of DA antagonists and accumbens DA depletions do not impair appetite to consume food, but do impair activational aspects of motivation. This suggestion is consistent with the studies showing that low doses of DA antagonists and accumbens DA depletions alter the relative allocation of instrumental responses, making the animals less likely to engage in instrumental responses that have a high degree of work-related response costs. In addition, this observation is consistent with studies demonstrating that accumbens DA depletions make rats highly sensitive to ratio requirements on operant schedules. Although accumbens DA is not seen as directly mediating appetite to consume food, principles of behavioral economics indicate that accumbens DA could be involved in the elasticity of demand for food in terms of the tendency to pay work-related response costs. Future research must focus upon how specific aspects of task requirements (i.e. ratio requirements, intermittence of reinforcement, temporal features of response requirements, dependence upon conditioned stimuli) interact with the effects of accumbens DA depletions, and which particular factors determine sensitivity to the effects of DA antagonism or depletion.
Article
Full-text available
Science Citation Classic Award Beginning with Emlen (1966) and MacArthur and Pianka (1966) and extending through the last ten years, several authors have sought to predict the foraging behavior of animals by menas of mathematical models. These models are very similar, in that they all assume that the fitness of a foraging animal is a function of the efficiency of foraging measured in terms of some "currency" (Schoener, 1971) - usually energy - and that natural selection has resulted in animals that forage so as to maximize this fitness. As a result of these similarities, the models have become known as "optimal foraging models"; and the theory that embodies them, "optimal foraging theory." The situations to which optimal foraging theory has been applied, with the exception of a few recent studies, can be divided into the following four categories: (1) choice by an animal of which food types to eat (i.e. optimal diet); (2) choice of which patch type to feed in (i.e. optimal patch choice); (3) optimal allocation of time to different patches; and (4) optimal patterns and speed of movements. In this review we discuss each of these categories separately, dealing with both the theoretical developments and the data that permit tests of the predictions. The review is selective in the sense that we emphasize studies that either develop testable predictions or that attempt to test such predictions in a precise quantitative manner. We also discuss what we see to be some of the future developments in the area of optimal foraging theory and how this theory can be related to other areas of biology. Our general conclusion is that the simple models so far formulated are supported reasonably well by available data and that we are optimistic about the value both now and in the future of optimal foraging theory. We argue, however, that these simple models will require much modification, especially to deal with situations that either cannot easily be put into one or another of the above four categories or entail currencies more complicated than just energy.
Article
The food habits of 44 tagged ferrets at a wildlife management reserve in the Manawatu dune country were examined from analysis of 333 scats, collected over a period of 34 months. Of the 203 scats containing prey, mammals occurred in 54.7%, birds and eggs in 33.5%, frogs in 17.2%, and eels in 13.3%. The 21 insects occurring in 10.3 % of the scats may have been taken as prey, but their importance in the diet is probably minimal. There was significant monthly variation in the occurrence of all prey groups, related to changes in availability or vulnerability of the prey populations. Female ferrets apparently ate the smaller prey items more often than males, but the differences were significant only for mice. No assessment of the effects ferrets have as predators on any of the prey populations is possible from this study.
Article
The intake of a freely feeding animal can be characterized by four parameters: frequency of meals, duration of meals, rate or intensity of eating, and choice of items eaten. The values of these parameters characterize species and the ecological niche they occupy. Constraints on any one of these parameters leads to compensatory changes in other parameters over the feeding cycle. Any change in performance of the instrumental behavior ancillary to feeding which causes the values of these parameters to recover their optimum or privileged value, defined by their niche, will be strengthened. These changes in performance reflect what is usually meant by motivation and the process of reinforcement.
Article
Free feeding was continuously recorded in rats, using a pellet-detecting eatometer which delivered a pellet to the rat each time one was eaten. No arbitrary responses were required. Normal rats and desalivate rats ate discrete meals, but rats which had recovered from lateral hypothalamic lesions nibbled in prolonged episodes, alternately eating small amounts and pausing for short periods. When normal rats were required to press a bar for food, they increased the number of short pauses in feeding. Criteria for intermeal interval influenced the distributions of meal sizes during feeding monitored by bar-press, but not during free feeding. Frequency distributions of meal sizes were much more sensitive to changes in the feeding situation than were mean meal sizes. It was concluded that both internal and external factors control spontaneous meal patterns, and that the lateral hypothalamus is essential for the maintenance of the regularity in sizes and temporal distribution of spontaneous meals.
Article
The feeding patterns of male albino rats were observed following either a 24 hr or 48 hr fast, during and following water restriction, during and following the addition of quinine to the food supply, and when given access to an activity wheel. Following any reduction of food intake imposed either by the experimenter or as a result of water restriction or the consumption of an unpalatable diet, food intake was adjusted almost entirely by increasing meal size. Meal frequency was not affected by the previous deprivations but was significantly reduced by the addition of the running wheel. During water restriction neither meal frequency nor the distribution of meals during the 24 hr period was affected. The addition of quinine sulfate to the food resulted in smaller but more frequent meals.
The Carnivores. London: Weidenfeld and Nichol-son
  • R F Ewer
Ewer, R. F. The Carnivores. London: Weidenfeld and Nichol-son, 1973.
The Biomedical Use of Ferrets in Research
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  • R C Webster
Hahn, E. W. and R. C. Webster. The Biomedical Use of Ferrets in Research. North Rose, NY: Marshall Research Animals, Inc., 1969.
Foraging cost and meal patterns in the domestic chicken (Gallus gallus)
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Kaufman, L. W., G. Collier and D. Brashier. Foraging cost and meal patterns in the domestic chicken (Gallus gallus). Manu-script submitted for publication.
The Biological Use of Ferrets in Research, Supplement I. North Rose
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Marshall, K. R. and G. W. Marshall. The Biological Use of Ferrets in Research, Supplement I. North Rose, NY: Marshall Research Animals, Inc., 1973.
Parameters of reproduction
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Peplow, A. M., P. V. Peplow and E. S. E. Hafez. Parameters of reproduction. In: Handbook of Laboratory Animal Science, Vol. 1, edited by E. C. Melby, Jr. and N. H. Altman. Cleveland: CRC Press, 1974.
Au-lerich. A Bibliography of Mustelids: Part I: Ferrets and Polecats
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Shump, A. U., K. A. Shump, Jr., G. A. Heidt and R. J. Au-lerich. A Bibliography of Mustelids: Part I: Ferrets and Polecats. East Lansing, MI: Michigan Agricultural Experi-mental Station, no date.
Parameters of reproduction
  • Peplow
A Bibliography of Mustelids: Part I: Ferrets and Polecats
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A history of the ferret
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