Thwarting of behaviour in different contexts and the gakel-call in the laying hen

Earlier studies have shown that thwarting of feeding behaviour in the laying hen is expressed through a specific vocalisation, the gakel-call. The first aim of this study was to investigate whether the effect of deprivation per se on the occurrence of gakel-calls can be distinguished from the effect of the additional frustration. Frustration is defined as the state of an animal that results from nonreward in the expectancy of reward. The second aim was to investigate whether the occurrence of gakel-calls is restricted to a food context or whether it can be regarded as an expression of frustration in general. For this purpose, 20 hens were deprived of food, water and dustbath. After deprivation at a fixed time, a cue was given and the hens were rewarded with access to food, water or dust during a 15-min session on 4 consecutive days. On the fifth day, they were thwarted in the associated behaviours by blocking the access to these commodities, after the hens had been presented the signal that previously preceded the reward. We then recorded behaviours that might reflect the state of frustration in three 15-min periods. The period "Pre-Frustration" started 15 min before "Frustration". This, in turn, was followed by the period "Post-frustration" in which the hens were rewarded again. Nesting behaviour was thwarted by blocking the access to the nest (Frustration) after a hen had reached the last stage of its prelaying behaviour.In the food, water and dustbath context, deprivation elicited gakel-calls. The additional frustration resulted in a higher number of gakel-calls in all contexts except the food context. However, together with the findings of previous experiments, the results of this study suggest that frustration, in general, is expressed through the gakel-call. Frustration in the nest context elicited more gakel-calls than the other contexts. This latter finding is discussed in the light of the occurrence of the gakel-call under natural circumstances.     

The Effect of Previous Experience Over Control of Access to Food and Light on the Level of Frustration-Induced Aggression in the Domestic Hen

Animals have been shown to respond to frustration with increased aggression and activity. Aversive environmental conditions are also known to affect reaction to frustrating events. One pertinent and aversive environmental factor that has been shown to affect aggression is exposure to uncontrollable rewards and punishments. Although used largely in experimental contexts, this situation is similar to that found in modern intensive farming systems, where environmental and social conditions are largely controlled. The aim of this experiment was to determine if previous experience of lack of control influences the expression of aggression and frustration in domestic hens (Gallus gallus). The two treatment groups of hens used had previously been exposed to control (C) or lack of control (LC) over access to food and light, additional to a restricted regime, continuously for 9 wk. Dominant‐subordinate pairs of birds were tested under water deprivation. After training, the pairs were tested for two rotations of 4:3 d of free access to the water followed by a thwarting trial. Dominant birds showed significantly more aggression in thwarting trials compared with non‐thwarting trials. While there was no main effect of treatment on the aggression shown during non‐thwarting trials, an interaction between treatment and trial type (thwarting and non‐thwarting) indicated that the LC group showed a smaller rise in aggression from non‐thwarting to thwarting trials than the C birds did. However, there was a great deal of variation shown between birds in the amount of aggression. As the home pen conditions were set up to model those found in commercial practice, this possibility that a lack of control leads to some degree of learned helplessness in intensively farmed animals needs to be considered further as it has serious negative implications for animal welfare.     

Motivation to dust-bathe of laying hens housed in cages and in aviaries

New housing systems for commercial egg production, furnished cages and non-cage systems, should improve the welfare of laying hens. In particular, thanks to the presence of a litter area, these new housing systems are thought to satisfy the dust-bathing motivation of hens more than in conventional cages, in which no litter area is present. However, although apparently obvious, there is no concrete evidence that non-cage systems, particularly aviaries, satisfy hens' motivation to dust-bathe and thus improve hens' welfare in terms of dust-bathing behaviour. The aim of this study was to compare hens' dust-bathing motivation when housed for a long time under similar conditions to commercial conditions in laying aviaries (with litter) and in conventional cages (without litter). Three treatments were compared: hens reared in floor pens then housed in conventional cages, hens reared in furnished floor pens then housed in a laying aviary, and hens reared in rearing aviaries then housed in a laying aviary. All three treatments provided access to litter during the rearing period. After transfer to the laying systems, access to litter was maintained for the aviary hens but stopped for the cage hens. Twelve groups of four hens per treatment were tested 36 to 43 weeks after transfer. The hens were placed in sawdust-filled testing arenas, and latency to dust-bathe, duration and number of dust baths, and number of hens dust-bathing were recorded. Latency to dust-bathe was shorter, dust baths were longer and more numerous and more hens dust-bathed among cage hens than among aviary hens. Our results indicate that hens' motivation to dust-bathe was more satisfied in laying aviaries than in conventional cages. Thus, laying aviaries improve hens' welfare in term of dust-bathing behaviour compared with conventional cages.     

Stereotyped behaviour,adjunctive drinking and the feeding periods of tethered sows

The behaviour of 25 tethered sows in an intensive piggery was observed for 1 h before and 1 h after the delivery of food to determine if behavioural stereotypies appeared as adjunctive behaviours. The different components of behavioural stereotypies were found to have different associations with the feeding period. Head-waving, bar-biting, and rubbing the snout against the cage were most common before feeding, and were shown particularly by the older sows. Manipulating the drinker and, for some sows, rubbing were most common after. There was some evidence of polydipsia. Vacuum chewing, playing with the chain, and aggressive behaviours, however, did not appear to be associated with the feeding period. The last two behaviours occurred only rarely. Seven sows showed stereotyped sequences of rapid rubbing or rapid drinking after the delivery of food, and these sows showed more excitement before food was delivered. Rooting was common for the full hour after all food had been consumed, and occurred in conjunction with long duration drinking. I suggest that the occurrence of adjunctive drinking by sows results from the persistence of feeding motivation, perhaps because concentrated food does not provide sufficient stomach distension, combined with the knowledge that food will definitely not be forthcoming. Stereotyped sequences of behaviour may be a means of reducing the arousal generated by the expectation of food.     

Factors influencing Cinnamon Teal nest attendance patterns

Patterns of nest attendance in birds result from complex behaviours and influence the success of reproductive events. Incubation behaviours vary based on individual body condition, energy requirements and environmental factors. We assessed nest attendance patterns in Cinnamon Teal Spatula cyanoptera breeding in the San Luis Valley of Colorado in 2016–2017 using trail and video cameras to observe behaviours throughout incubation. We evaluated the effect of temporal, life‐history and environmental covariates on the frequency and duration of incubation recesses as well as the incubation constancy. There was considerable model uncertainty among the models used to evaluate recess frequency. Recess duration varied according to the interaction between nest age and a quadratic effect of time of day, with hens on older nests taking longer recesses in the afternoon and hens on nests earlier in incubation taking longer recesses in the morning and evening. Incubation constancy decreased with higher ambient temperatures in the study area. This study provides evidence that Cinnamon Teal modify their behaviour during incubation according to the age of the nest and the time of day. These results improve our knowledge of Cinnamon Teal breeding ecology and shed light on the behaviours that fast‐lived species may use to cope with environmental factors during nesting.     

Stereotypies,aggression and the feeding schedules of tethered sows

Thirty tethered sows were observed for 5 min every half-hour for 9 h spanning the two feeding periods. Activity, consisting largely of food searching behaviour and drinking, was largely restricted to two 2-h periods following each feed. Three categories of stereotyped behaviour were observed and these were closely tied to the feeding periods. Short-duration bouts of rubbing, head-waving and bar-biting occurred during food delivery, while long-duration bouts of highly stereotyped and idiosyncratic sequences of rubbing and drinking were shown by older sows immediately after feeding. Vaccuum chewing tended to occur slightly later. I suggest that frustration of feeding motivation rather than under-stimulation underlies stereotypies in pigs, and that the different forms may represent stereotype of the appetitive and consummatory phases. Aggression was rare and was not closely related to the feeding periods or to stereotypies.     

Measuring Motivation for Appetitive Behaviour: Food-Restricted Broiler Breeder Chickens Cross a Water Barrier to Forage in an Area of Wood Shavings without Food

Broiler breeders (parents of meat chickens) are selected for fast growth and become obese if fed ad libitum. To avoid this and maintain good health and reproductive ability, they are feed restricted to about 1/3 of what they would eat ad libitum. As a result, they experience chronic hunger and exhibit abnormal behaviour patterns that may indicate stress and frustration. One approach to measuring hunger is to observe how much birds will work, such as pecking a key, for access to more or different types of food. However, the sight, smell, and feedback from consumption of the feed reward changes the context and may artificially raise feeding motivation. To avoid this, we tested broiler breeders in an apparatus in which they could work for access to a wooden platform covered in wood shavings by crossing a water runway which increased in length and depth in 8 successive tests. In the wood shavings area, they could perform exploratory and foraging behaviour (the appetitive phase of feeding) but were never rewarded with feed. Sixty birds were divided into three feed quantity treatments: commercial restriction (R), and twice (2R) or three times (3R) this amount. Overall, birds fed R worked harder to reach the wood shavings area (reached it in a larger number of tests) than 2R and 3R birds (P<0.001). More restricted birds took less time to reach the area (P<0.001, R<2R<3R) and spent more time foraging while there (P<0.001, R>2R>3R). This indicates that restricted-fed birds were hungry and willing to work for the opportunity to forage even though food was never provided, suggesting that their motivation to perform the appetitive component of feeding behaviour (foraging/food searching) was sufficient to sustain their response. Thus food restriction in broiler breeders is a welfare concern. However these methods could be used to test alternative feeding regimes to attempt to find ways of alleviating hunger while still maintaining healthy growth and reproduction in these birds.     

On the feeding and social behaviour of the laying hen

This paper describes a study of the influences of early husbandry conditions, social attraction and social rank on various aspects of the feeding behaviour of laying hens.Birds were raised in flocks of 10, 60 or 500. Groups of 3 birds, selected from flocks of the same size, were then housed in pens. Some groups consisted of hens raised in the same flock, and some of birds raised in different flocks. The feeding and agonistic behaviour of each group at each of 5 types of feeder was observed and compared with the behaviour shown when the birds had free access to a 1-m long food trough. Each of the 5 feeders offered the same area of feeding space, but differed in its partitioning and spatial distribution. One feeder had a single unpartitioned feeding space. The other 4 feeders had 3 partioned feeding spaces which were adjacent, or separated by distances of 10, 20 or 40 cm, respectively.For the 5 feeders, total feeding times and lengths of feeding bouts were greatest, and the number of feeding bouts least, when the feeding space was unpartitioned. Synchrony of feeding behaviour was low when the feeding space was unpartitioned or the partitioned spaces adjacent, but was comparable to that at the 1-m long food trough when the distance between partitioned feeding spaces was 10 cm or greater. When feeding space was partitioned, the likelihood that 2 birds would eat together at the same site increased with the distance between feeding space. Dominant birds always exhibited the longest feeding bouts and greatest total feeding times, but were less likely to feed in the same space as another bird, and exhibited less synchrony of feeding behaviour than subordinates. The size of the flock in which the birds were raised, and whether or not the birds in a group had been raised together or apart, had no clear effect on behaviour.These results indicate that, within the limits of this experiment, early husbandry conditions do not influence behaviour shown during feeding in later life, and that social attraction has a greater influence on the feeding behaviour of hens than is generally assumed. In view of this latter finding, it is postulated that in attempting to determine the requirements of laying hens for feeding space, attention must be paid to social attraction as well as to competition at the feeder.     

Accuracy of laying hens in jumping upwards and downwards between perches in different light environments

Eighty Lohmann Brown layer hens were reared in floor pens fitted with perches from 1 day of age. After the peak of lay (25 weeks of age), their ability to jump to and from perches in different light environments was assessed in two experiments using digital video techniques that allowed detailed measurements of take-off, flight and landing behaviours.In Experiment 1, birds jumped up or down (angles of 10 and 18°) between two horizontal perches that were separated by a gap of 60 cm under different lighting conditions (5, 10 or 20 lux; incandescent or high- or low-frequency fluorescent). In Experiment 2, the horizontal distance was increased to 80 cm and contrast between perch and background was varied. Fifty-two hens (65%) achieved the training criterion for Experiment 1: jumping a 60 cm gap five times of which three in a row. Thirty-two of these hens (62%) subsequently failed to achieve the 80 cm jump criterion for Experiment 2.In Experiment 1, birds took off sooner (P<0.001), turned their heads further downward relative to the landing perch (P<0.001), beat their wings more often during flight (P<0.001), and took longer to achieve balance (P<0.001) when jumping downward rather than upward. In Experiment 2, refusals to jump, and clumsy or missed landings, occurred more frequently on downward than upward jumps (P<0.001). These behaviours were unaffected by lighting conditions, or by the amount of contrast between the perch and its background.In conclusion, behaviours indicating inaccurate control of landing were more frequent on downward than on upward jumps (P<0.001). However, these behaviours were not affected by light intensity, light type or contrast. The results suggest that there is a difference between the two types of jumps in the risk of injury to hens housed in aviaries where perches must be used to gain access to resources.     

Behaviour and welfare of broiler breeders fed qualitatively restricted diets during rearing: Are there viable alternatives to quantitative restriction?

This study investigated whether feeding female broiler breeders on qualitatively, rather than quantitatively, restricted diets during rearing could improve their welfare while also achieving desired growth rates. There were six treatments, each with four replicate pens of 12 birds. From 1 to 20 weeks of age, birds in a control treatment (T1) received a quantitatively restricted amount of a standard mash diet while birds in five additional treatments (T2–T6) had ad libitum access to experimental diets. The latter were based on standard mash and contained supplements of calcium propionate (CaP, an appetite suppressant), or oat hulls (OH, a dietary diluent), or both, that were increased with bird age. Birds received diets with either increasing CaP (T2), low protein and increasing CaP (T3), OH and increasing CaP (T4), CaP and increasing OH (T5), or increasing both CaP and OH (T6). Effects of treatment on body weight, behaviour, response to a feeding motivation test, and blood indices of stress were recorded. Results showed that different qualitative restriction treatments can limit growth rate close to target. T4, with 40% OH and increasing CaP, limited body weight closest to the desired level. Between 6 and 20 weeks of age, control birds (T1) spent 47–54% of their time in object pecking, which was almost absent (<1%) in all experimental treatment groups. Time spent inactive (sitting) and total time observed in all oral behaviours differed little between treatments. In a feeding motivation test, T1 birds consumed more food in 2 min after 2 or 4 h of food deprivation than did birds in any experimental treatment group. Treatment had no effect on the ratio of heterophils to lymphocytes or on the frequencies of other white blood cells. Plasma corticosterone level was raised in T5 birds, whose mean body weight was suppressed to below the commercial target for most of the study, but was otherwise unaffected by treatment. The results suggest that appropriate appetite suppression, with or without dietary dilution, can be an effective method of controlling broiler breeder growth rate. However, although there was some indication that such dietary treatments may be beneficial for bird welfare (e.g. the absence of abnormal pecking at non-food objects), other behaviours and physiological indices of stress did not differ consistently between experimental and control birds.     

Starting from scratch: A first look at a “displacement activity” in group-living rhesus monkeys

Data on scratching behavior were collected from a group of rhesus monkeys living in spacious surroundings. Juveniles scratched more often than adults. Adults scratched most often in social contexts and in close temporal association with a change of behavior. Subjects of intermediate dominance rank, in particular, scratched around the time of a behavioral change, and these subjects were the only ones to show increased scratching during tests involving restricted access to food (thwarting or frustration). The outer thighs, lower back, and sides were the sites scratched most frequently, not necessarily matching sites reported to be preferred for self-grooming. Scratching in monkeys has certain characteristics in common with some well-studied displacement activities in other species, and it possibly also serves as a signal that the individual is preparing to change behavior.     

Reaction to frustration in high and low feather pecking lines of laying hens from commercial or semi-natural rearing conditions

The effect of rearing conditions on feather pecking and reaction to frustration was studied in two lines of laying hens. From commercial rearing conditions (large group, no mother hen), seven birds from a high feather pecking line (HC birds) and eight birds from a low feather pecking line (LC birds) were used. From semi-natural rearing conditions (small group, mother hen present) seven birds from the high feather pecking line (HN birds) were used. Feather pecking behaviour of HC, LC, and HN groups was recorded for 30 min. After that, each bird was food deprived and trained to peck a key for a food reward in a Skinnerbox. After training, each bird was subjected to a frustration session in a Skinnerbox, where the feeder was covered with Perspex. Three HC birds showed severe feather pecking, compared with one HN bird and zero LC birds. Differences in reaction to frustration were found between birds from different lines, but not in birds from different rearing conditions. LC birds tended to put their head in the feeder more frequently than HC birds over all sessions. Although limited, this study indicates that rearing conditions influence feather pecking, but not reaction to frustration.     

Effects of qualitative and quantitative food restriction treatments on feeding motivational state and general activity level of growing broiler breeders

Growing broiler breeder chickens are fed restricted rations to limit body weight at sexual maturity. This experiment tested a proposal (Brouns, F., Edwards, S.A., English, P.R., 1994. Effect of dietary fibre and feeding system on activity and oral behaviour of group housed gilts. Appl. Anim. Behav. Sci. 39, 215-223.) that feeding motivation is reduced by using qualitative rather than quantitative food restriction, and it examined relationships among suppression of growth rate, feeding motivational state and general activity level. From 2 to 15 weeks of age, female broiler breeders were reared in six groups of 20, each with a different feeding treatment. The six treatments were: high and low levels of diet dilution (600-700 g/kg and 300-350 g/kg oat feed, ad libitum), appetite suppression (50-60 g/kg and 25-30 g/kg calcium propionate, ad libitum) and quantitative restriction (recommended daily ration and twice that amount). Birds were conditioned to an operant (PR1 schedule) feeding procedure with their respective treatment diets from 3 to 7 weeks, and this was used to measure feeding motivation in 12-min tests at three times of day (1000, 1300 and 1600 h) at 8, 10, 12 and 14 weeks. Proportions of time spent sitting were measured as an index of general inactivity in systematic observations at 9, 11, 13 and 15 weeks. Although the diet dilution and appetite suppression (qualitative) treatments did not limit growth rates as intended, they and the quantitative treatments produced a range of mean body weights to compare with feeding motivation whenever birds were tested. With body weight as a covariate, there were significant effects on numbers of operant responses in 12 min (the measure of feeding motivation) of weight, age, time of day and treatmentxtime interaction, but not treatment. Feeding motivation was positively correlated with suppression of growth rate, regardless of how that suppression was achieved. However, the experimental procedure required all test birds to be without food from 0900 or 0915 h, and motivation was lowest in the earliest (1000 h) test with qualitative but not quantitative treatments. Hence, there was some evidence that feeding motivation may be partially suppressed with qualitative food restriction; distinction can be made between short-term and longer-term feeding motivation. General activity level (inversely reflected by time spent sitting) was closely correlated positively with both suppression of growth rate and feeding motivation. As a fundamental relationship between feeding motivation and reduction of growth rate was not altered by using qualitative rather than quantitative food restriction, these results support an earlier conclusion (Savory, C.J., Hocking, P.M., Mann, J.S., Maxwell, M.H., 1996. Is broiler breeder welfare improved by using qualitative rather than quantitative food restriction to limit growth rate? Anim. Welfare 5, 105-127.) that broiler breeder welfare is not improved with qualitative restriction methods.     

Variation of bar-press duration: Where do new responses come from?

Instrumental learning involves both variation and selection: variation of what the animal does, and selection by reward from among the variation. Four experiments with rats suggested a rule about how variation is controlled by recent events. Experiment 1 used the peak procedure. Measurements of bar-press durations showed a sharp increase in mean duration after the time that food was sometimes given. The increase was triggered by the omission of expected food. Our first explanation of the increase was that it was a frustration effect. Experiment 2 tested this explanation with a procedure in which the first response of a trial usually produced food, ending the trial. In Experiment 2, unlike Experiment 1, omission of expected food did not produce a large increase in bar-press duration, which cast doubt on the frustration explanation. Experiments 3 and 4 tested an alternative explanation: a decrease in expectation of reward increases variation. Both used two signals associated with different probabilities of reward. Bar presses were more variable in duration during the signal with the lower probability of reward, supporting this alternative. These experiments show how variation can be studied with ordinary equipment and responses.     

Ontogeny of Acoustic and Feeding Behaviour in the Grey Gurnard, Eutrigla gurnardus

Although sound production in teleost fish is often associated with territorial behaviour, little is known of fish acoustic behaviour in other agonistic contexts such as competitive feeding and how it changes during ontogeny. The grey gurnard, Eutrigla gurnardus, frequently emits knock and grunt sounds during competitive feeding and seems to adopt both contest and scramble tactics under defensible resource conditions. Here we examine, for the first time, the effect of fish size on sound production and agonistic behaviour during competitive feeding. We have made sound (alone) and video (synchronized image and sound) recordings of grey gurnards during competitive feeding interactions. Experimental fish ranged from small juveniles to large adults and were grouped in four size classes: 10–15, 15–20, 25–30 and 30–40 cm in total length. We show that, in this species, both sound production and feeding behaviour change with fish size. Sound production rate decreased in larger fish. Sound duration, pulse duration and the number of pulses increased whereas the peak frequency decreased with fish size, in both sound types (knocks and grunts). Interaction rate and the frequency of agonistic behaviour decreased with increasing fish size during competitive feeding sessions. The proportion of feeding interactions accompanied by sound production was similar in all size classes. However, the proportion of interactions accompanied by knocks (less aggressive sounds) and by grunts (more aggressive) increased and decreased with fish size, respectively. Taken together, these results suggest that smaller grey gurnards compete for food by contest tactics whereas larger specimens predominantly scramble for food, probably because body size gives an advantage in locating, capturing and handling prey. We further suggest that sounds emitted during feeding may potentially give information on the motivation and ability of the individual to compete for food resources.     

Night-time roosting in laying hens and the effect of thwarting access to perches

Free-living hens roost on branches in trees at night, and laying hens in aviary systems or cages provided with perches also make extensive use of these for night-time roosting. It is therefore suggested that roosting on perches is important to the hens and that domestic hens should be provided with perches in order to promote welfare. However, no study has addressed the question of motivation for roosting. In the present experiment, we studied undisturbed roosting behaviour and the reaction of commercial laying hens when roosting on perches was thwarted. Fifty-two adult hens (Lohmann Selected Leghorn, LSL) were kept in two groups of 26 hens in litter pens with perches at heights of 23, 43 and 63 cm. Behaviour was observed for 60 min starting at lights-off, registering the number of hens on each perch level. The hens started to get onto the perch immediately and within 10 min after lights-off, more than 90% of the hens were on the perch. All hens roosted close together on the top perch. In a second experiment, 24 hens were kept in eight groups of three birds each in experimental pens equipped with perches. Birds were tested in four different situations: (1) the pen unchanged (Base), (2) the perch covered with plexiglass (PCov), (3) the perch removed (PRem) and (4) the unchanged pen (Post). The order of PCov and PRem alternated between groups in a balanced manner and all groups of birds experienced all four treatments. The hens were observed for 60 min from lights-off using focal sampling. For comparisons, the Post treatment served as the control. In the treatments where perching was not possible, the hens spent less time sitting (p=0.042), and also tended to spend more time standing (p=0.06), than in the control. Furthermore, the hens moved more (p=0.042) when the perch was inaccessible, and when the perch was visible but inaccessible they also showed more attempts to take off (p=0.042). These findings can be interpreted as increased frustration and/or exploration, probably to find an alternative roosting site. Together with the high use of perches for night-time roosting under undisturbed conditions, these results indicate that laying hens are motivated to perch and imply that hens kept under conditions where perching is not possible may experience reduced welfare.     

Reaction to frustration in high and low feather pecking laying hens

Reaction to frustration of high (HFP) and low feather pecking (LFP) laying hens was investigated. From a HFP- and a LFP-line five birds with a HFP- and five birds with a LFP-phenotype were selected. Birds from the HFP-line were expected to show more key pecking and covered feeder pecking during frustration than birds from the LFP-line. When a bunch of feathers was presented, birds with a HFP-phenotype were expected to redirect their pecks at the bunch. Birds were trained to peck a key for a food reward in an automated Skinnerbox and subjected to two sessions: a control session, where food was available, and a frustration session, where the feeder was covered with Perspex. These two sessions were repeated in the presence of a bunch of feathers. Unexpectedly, birds from the LFP-line had a stronger reaction to frustration than birds from the HFP-line, expressed in pecking behaviour. When a bunch of feathers was offered, birds with a HFP-phenotype did not show more bunch pecking during frustration than birds with a LFP-phenotype.     

Foraging strategy in a social bird, the alpine chough: effect of variation in quantity and distribution of food

I conducted feeding experiments to determine the effect of variations in food availability on individual flocking behaviour and foraging efficiency in a social corvid, the alpine chough Pyrrhocorax graculus, which lives in large flocks all year round. In 37 trials I varied both food quantity and the number of food patches. A decrease in the amount of available food reduced the mean flock size, the proportion of birds that had access to food, and their mean pecking rate. A decrease in the number of patches, on the other hand, reduced only the proportion of birds that had access to food. The number of choughs foraging was not influenced by food competition but depended only on the number visiting the site. Females competed less well than males: when food was made scarce, they frequented the site in the same proportion as did males, but had less access to food. I suggest that in this social corvid, long-term advantages to flocking related to social bonds, such as the maintenance of pair bonds, may compensate for short-term costs such as a reduction in foraging efficiency. Copyright 1999 The Association for the Study of Animal Behaviour.     

The effect of delayed feeding on the post-feeding behaviour of sows

Previous research into oral persistence in pigs has shown that the relationship between motivation and performance of stereotypy is not a simple one, and that non-specific motivational factors such as arousal may be important. For chronically food-restricted sows the time before food arrives is characterised by increasing excitement and arousal which may be carried over into the post-feeding period facilitating the performance of persistent oral behaviour. To investigate this possibility, arousal was manipulated by delaying feeding. Five and 15 min delays were used and sows experienced delayed feeding 1 day in every 4. Principal components analysis (PCA) was used to group the behaviour data into two factors, ACTIVITY/CHEW and NOSE/ROOT/PEN and these scores were then analysed using ANOVA as well as the appropriate individual behaviours. The delay of feeding increased the rate of eating, presumably reflecting increased arousal (P<0.05). ACTIVITY/CHEW scores were highest in 5 min delay sets, and an interaction between day of set and delay length indicated that ACTIVITY/CHEW scores peaked on different days within a set (P<0.05). Time spent chewing was highest on the day of delay (P<0.05), while standing was highest in days 1 and 2 post-delay (P<0.05). The NOSE/ROOT/PEN scores were lower on the day of delay than on other days (P<0.05), and were lowest in the first delay set than in sets later in the trial (P<0.01). It appeared that increasing arousal in the pre-feeding period does affect activity and oral behaviours in the post-feeding period. However, some of the effects appeared in a more extended and diffuse manner, perhaps due to the general disturbance created by the experimental regime and the sows' experience of long-term food restriction.     

The effects of operant control over food and light on the behaviour of domestic hens

In intensive farming systems, the animals have little control over important elements in their environments. For instance, food of a pre-set type is delivered at set times, and the lighting schedule is controlled by the farmer. It has been suggested that low levels of environmental control over important events may reduce welfare by increasing passivity and stress. This study aimed to evaluate the effect of providing control over food and lighting additional to a restricted regime on the behaviour of small groups of laying hens (Gallus gallus domesticus). Twelve pens, each containing five birds, were paired to give six controlling and six non-controlling pens. These pairs of pens were yoked, such that birds in the controlling pens were able to make an operant response to gain access to extra food and light, whilst the yoked pens also received these outcomes but were unable to control their occurrence. The birds were kept continuously in the experimental conditions for 9 weeks. Records were made of general behaviour and activity, aggression and plumage damage scores, every 2 weeks. Data on key-pecking and egg production were continuously recorded throughout the experiment. The controlling birds used the operant keys to open the feeder for an average of 92min and to turn on the light for 46min per pen per day. The high number of key-pecks indicates that the birds were motivated to make use of the keys to control access to additional food and light. The non-controlling treatment pens showed significantly higher levels of preening and resting. Contrary to previous studies the use of operant feeders in this experiment did not induce a high level of feather pecking or aggressive interactions, as there was no significant difference between treatments. During the experiment the non-controlling hens laid significantly more eggs than the controlling hens. The results suggest that lack of control over these particular environmental events induced mild stress in the non-controlling pens of birds, and that further investigations into the effect of lack of control on welfare would be warranted.