J. Carol Petherick

External factors and causation of dustbathing in domestic hens.

Dustbathing is known to be motivated by complex interactions between internal factors which build up over time and external factors, such as the sight of a dusty substrate. In this study, the effects of other external factors were investigated. Environmental temperature was shown to be important; frequencies of dustbathing were greater when hens were held at 22 than at 10°C (P<0.01). In a second experiment, a radiant heat source or a radiant heat+light source, balanced to give the same radiant heat, resulted in more dustbathing behaviour during a 1-h stimulus period than during the same period with no stimulus (P<0.05). Components of dustbathing were increased more by the heat+light stimulus than by the heat stimulus alone (P<0.03). In a third experiment, the amount of dustbathing performed by individual hens in cages with dustbaths was increased by the presence of a group of hens dustbathing in an adjoining pen with a dustbath compared with the amount occurring when the hens were absent from the pen.

Quantifying motivation using a computer- controlled push-door

A computer-controlled push-door system was designed and tested as a method for measuring motivation. Eleven domestic hens were trained to use the push-door to gain access to food. They were deprived of food for 12 h or 43 h on 12 occasions and the push-door was used to measure the amount of “work” (measured as force × time) that they performed to gain access to a food reward. When deprived of food for 12 h the hens took significantly longer (P<0.01) to reach the required threshold of work, than when deprived for 43 h. This difference arose from the amount of time that the hens spent not pushing at the door. The problems encountered with this system and such an approach to measuring motivation are discussed.

Influence of motivational state on choice of food or a dustbathing/foraging substrate by domestic hens

Domestic hens were trained to run a Y-maze and make an association between differently coloured doorways and access to food pellets or sand. The hens were tested for their choice of doorway when the goals were not visible from the choice point and when they were food or sand deprived. Hens made the choice appropriate to their deprivation state (correct choice) significantly more often for food than sand and were faster at choosing and entering the goal box when food deprived. In a follow up experiment, the goals were visible from the choice point. Again the hens chose correctly significantly more often when food than sand deprived and made the choice and entered the goal box faster when food deprived. Thus, failure to choose sand in the first experiment was not due to an inability to learn the association, but appears to result from a strong motivation to feed in the Y-maze, even when not food deprived, and a weak motivation to dustbathe or forage, even when sand deprived.

Previous experience with different floors influences choice of peat in a Y-maze by domestic fowl

Chicks of two strains of domestic fowl were reared on either floors of wire (wire reared) or concrete covered with wood shavings with access to peat (litter reared). At 13 weeks of age, the birds were given a choice of wire or peat in a Y-maze. The wire-reared birds tended to choose wire and the litter-reared birds tended to choose peat.

Can domestic fowl (Gallus gallus domesticus) anticipate a period of food deprivation

Abstract Forty ISA Brown pullets were individually housed and fed in an environment designed to eliminate circadian cues. On Days 17–47, half of the birds were presented with a cue (a coloured card) during the final hour of food availability, prior to a period of deprivation of either 8 or 12 h. Food intakes were recorded to determine whether the cued birds showed anticipatory crop-filling. There was no indication that the birds learned that the cue predicted a period without food, as their intake did not increase during the final hour of feeding. These results are discussed in relation to the cognitive abilities of fowl and the implications for their welfare.

Failure of domestic fowl to show contrast in learning: the implications for welfare

Three groups of hens were trained to run an alleyway for five (Group 5), 20 (Group 20) and 80 (Group 80) grains of wheat. When the running speeds had reached an asymptote the hens were given a further 10 trials each. Groups 5 and 80 then had their reward changed to 20 grains. The running speeds of the three groups differed significantly during the 10 trials prior to the reward change (P < 0.001), but there was no difference for the final 10 trials. The running speed of Group 5 increased (P < 0.005), that of Group 80 decreased (P <0.025), and there was no significant change in the speeds of Group 20. The changes in running speed can be explained in mechanistic terms, but there is no evidence for a cognitive explanation invoking the formation of expectations by the hens.

Measuring the motivation of domestic fowl in response to a positive and a negative reinforcer

Ten ISA Brown hens were trained to run an alleyway of 14.4 m in length to obtain a food reward. Each hen was deprived of food for each of 0, 6, 12 and 18 h on four occasions and the times taken to run the alleyway were recorded. The three deprivation periods resulted in greater speeds than the control (P<0.001), but there was no difference between the speeds for the deprivations. In a second experiment, 15 ISA Brown hens were trained to run the same alleyway for a food reward and then allocated to three groups which received differing numbers of exposures to a feather duster (negative reinforcement) on entry to the goal box. The three groups (0, 1 and 2) were given zero, four or eight exposures, respectively, during a 32 day period. The speeds of Groups 0 and 1 increased linearly during the experiment, but the slopes were not statistically distinguishable. The speeds of Group 2 showed a curvilinear pattern, with no overall change between the start and end of the experiment, but with a decrease in speeds during the middle part of the experiment.