Time budgets in growing chicks

The behavioural priorities of laying hens: the effect of cost/no cost multi-choice tests on time budgets

A multi-choice situation offering a number of presumably significant environmental features may reveal an animal's immediate preferences concerning its environment and how it wants to distribute its time budget. In this study the time budgets of hens (Gallus gallus domesticus) were examined in a free access situation (no cost condition) and in a situation in which there was a cost for access (cost condition). The options consisted of six pens that could be entered from a middle pen which had no features except for space. The options were: (1) food and water; (2) woodchips; (3) grass (turf) or wheat seedlings; (4) a perch; (5) a nestbox; (6) a pen facing another pen with familiar hens. In the first experiment, hens were given a multi-choice test in a seven pen apparatus. The no cost condition gave free access to resources but in the cost condition hens had to squeeze through two dowels. The frequency of entering pens and initiating behaviours was greatly reduced in the cost condition. In the second experiment, hens were tested for their preferences after one of two treatments: (i) 'prior access' (and free access) to all pens for 22.5 h; (ii) 'no prior access' where hens were housed in a barren pen without food for 22.5 h. The duration of agonistic, pace/escape and stretch neck behaviours were greater in the 'no prior access' or cost condition. In both experiments, the amount of time pecking and scratching in litter did not differ between conditions. Thus, the imposition of a cost did not alter the amount of time spent pecking and scratching supporting the argument that this behaviour is an ethological need.

Place preferences of Japanese quail given a permanent choice between a social or a non-social but enriched situation

Japanese quail from two lines selected for high (HSR) or low (LSR) levels of social reinstatement behaviour were permanently placed from 2 days to 6 weeks of age in a situation where one tested animal had the choice between being in social contact with a stimulus animal in a bare compartment of the cage or out of visual contact with the stimulus animal in a relatively rich environment containing food, water and wood shavings. The young (1 or 2 weeks of age) quails spent most of their time (over 80%) in the social compartment, about 10% feeding and drinking, and about 10% performing other activities in the non-social compartment. Hardly any differences appeared between the two lines when 1 or 2 weeks old, but at 4 weeks of age the LSR quails started to decrease the time spent in the social compartment and this phenomenon only appeared at 6 weeks of age and to a lesser extent in the HSR quails. At 4 and 6 weeks the differences between lines were significant. The lack of difference between the two lines in young quails can be explained by the very high social motivation expressed even by LSR quails in the conditions of the study. When they are older line differences are expressed. This change coincides with the time when the natural coveys start to disperse and also with the beginning of sexual development. These results confirm the hypothesis of François et al. (François, N., Mills, A.D., Faure, J.M., 1997. Inter-individual distances in Japanese quail (Coturnix japonica) selected for high or low levels of sociability. Behav. Process. (in press)) that line differences in social motivation persist into adult or near adult life and can still be demonstrated, provided the circumstances are such that aggression does not prevent close social contact.

From an animal's point of view: Motivation, fitness, and animal welfare

To study animal welfare empirically we need an objective basis for deciding when an animal is suffering. Suffering includes a wide range ofunpleasant emotional states such as fear, boredom, pain, and hunger. Suffering has evolved as a mechanism for avoiding sources ofdanger and threats to fitness. Captive animals often suffer in situations in which they are prevented from doing something that they are highly motivated to do. The “price” an animal is prepared to pay to attain or to escape a situation is an index ofhow the animal “feels” about that situation. Withholding conditions or commodities for which an animal shows “inelastic demand” (i.e., for which it continues to work despite increasing costs) is very likely to cause suffering. In designing environments for animals in zoos, farms, and laboratories, priority should be given to features for which animals show inelastic demand. The care ofanimals can thereby be based on an objective, animal-centered assessment of their needs.

Prey size and prey density affect meal patterns of rats in depleting and nondepleting patches

We examined meal-ending decisions by rats feeding in depleting patches (where the rate of return decreased during a meal) and nondepleting patches (where the rate of return was constant) in a closed-economy, laboratory setting that allowed the precise measurement of feeding rates and meal patterns. The rats were free living in an environment where costs were imposed with bar-press requirements for (1) travelling to a patch to begin a meal and (2) earning prey during the ensuing meal in that patch. The prey in each patch were large or small, and dense or sparse. In both depleting and nondepleting patches, meals were larger as travel price increased. In nondepleting patches, meal size (in grams) was unaffected by the rate of return within the patch, but in depleting patches, meals were larger where the rate of return was higher. In depleting patches, the rats ate the same number of small and large prey per meal, suggesting that meals end when the rate of return reaches some level relative to a comparison value; however, the end-of-meal rate was lower than the average rate (calculated over foraging and feeding time), and thus meals were too large to maximize rate or minimize cost. No obvious rule of thumb explained meal size in both depleting and nondepleting patches. Copyright 1999 The Association for the Study of Animal Behaviour.

Voluntary wheel running: a review and novel interpretation

Voluntary wheel running by animals is an activity that has been observed and recorded in great detail for almost a century. This review shows that it is performed, often with startling intensity and coordination, by a wide variety of wild, laboratory and domestic species with diverse evolutionary histories. However, despite the plethora of published studies on wheel running, there is considerable disagreement between many findings, thus leading to a lack of consensus on explanations of the causality and function. In the initial part of this review, I discuss the internal and external factors that may be involved in the causality of this behaviour, with an emphasis on disparities in both the factual and theoretical development of the subject. I then address the various proposed functions of wheel running, again highlighting evidence to the contrary. This leads to the conclusion that any single theory on the basis of wheel running is likely to be simplistic with little generality. I then present a novel, behaviour-based interpretation in which it is argued that wheel running has no directly analogous naturally occurring behaviour, it is (sometimes) performed for its own sake per se rather than as a redirected or substitute activity, and studies on motivation show that wheel running is self-reinforcing and perceived by animals as 'important'. This review proposes that wheel running may be an artefact of captive environments or of the running-wheel itself, possibly resulting from feedback dysfunction. I also discuss the ubiquity and intensity of its performance, along with its great plasticity and maladaptiveness, all indicating that if it is an artefact, it is nevertheless one of great interest to behavioural science. Copyright 1998 The Association for the Study of Animal Behaviour.

Food and water intake as functions of resource consumption costs in a closed economy

In two experiments, rats living in a closed economy were offered continuous, concurrent access to four resources: food, water, a nest, and a running wheel. Costs of consuming food and water were imposed with bar-press requirements, and the price of either one or both resources was raised. As the consumption cost increased, less was consumed in each bout of resource use. Bout frequency increased, but not sufficiently to compensate for the fall in bout size, and total intake fell. Food and water tended to be complementary resources, in that as intake of one fell with its price, intake of the other also decreased. This interaction was accounted for by the defense of the ratio of body water to lean body mass. As amount consumed decreased, increases in feed efficiency (weight gain per unit of food ingested) and the use of stored calories compensated for the reduced energy intake. There was evidence of competition between feeding and drinking at the higher costs: When both commodities were expensive, the decline in the intake of each one was greater than when only one commodity was expensive. Although the time spent nesting, running, and in unmonitored activity was adjusted when feeding or drinking took more of the rat's day, there was no particular activity that was sacrificed.

Diet selection by chicks

Seven experiments with 324 chicks tested their ability to select a nutritionally adequate diet from separate sources of purified casein and various supplements, including gelatin (a source of two amino acids), a gelatin-creatine mixture (a source of three amino acids), and fiber (nonnutritive bulk). Nonselecting controls consumed the basal purified-casein diet or a supplemented purified-casein diet. Chicks in all selection conditions composed diets that yielded normal intake, normal body temperature, normal activity, and the maximum growth possible for their intake. They also selected components in the same percentages as in premixed diets. In all instances, their selection was nonrandom and regulated. What chicks included in their diet depended on what else was available. Although the specific percentage taken from each dietary component varied across different selection alternatives, these differences affected neither intake nor growth. Selection, per se, incurred a caloric cost. Chicks selecting from fractions of a corn-and-soy diet offset this cost by increasing intake compensatorily, but chicks with a purified-casein fraction did not, suggesting that some unspecified property of casein placed a ceiling on its intake. These findings unequivocally demonstrate that immature chicks not only can self-select nutritionally adequate diets, but can do so with unexpected precision by exploiting different but equally successful strategies.

Tonic immobility and high-intensity calls in a precocial chick as a function of age, diet, and time of day

Tonic immobility (TI) and high-intensity vocalizations are two antipredator behaviors employed by domestic chicks (Gallus gallus) which vary in their function and the proximate mechanisms that govern them. In the present study, we sought to determine the influence of age (3 or 10 days old), diet (control or tryptophan-free), and time of testing (A.M. or P.M.) on the duration of TI and the number of calls produced in domestic chicks. Older chicks remained immobile significantly longer than younger chicks as did subjects on the control diet or those tested at night. However, 3-day-old chicks had significantly shorter TI durations only when tested in the A.M.: TI did not differ between age groups when subjects were tested in the P.M. Three-day-olds called significantly more than 10-day-olds when given the control diet and when tested in the P.M. but vocalization frequencies did not differ between age groups during the A.M. testing or when given the tryptophan-free diet (T-). Vocalization rate (calls/TI duration), however, was significantly greater during the A.M. testing. These results emphasize the importance of considering circadian rhythms and behavioral development. Furthermore, an integrative view of the proximate mechanisms and adaptive functions of TI and high-intensity vocalizations is presented.