R.Bryan Jones

Fear and adaptability in poultry: insights, implications and imperatives

Fear is now widely regarded as an undesirable state of suffering by many members of the public, the scientific community, welfare and policy groups, as well as by a growing number of farmers. At fi...

The tonic immobility reaction of the domestic fowl: a review

SummaryTonic immobility (TI) is an unlearned state of profound but reversible motor inhibition and reduced responsiveness which is induced by physical restraint. It is thought to represent the term...

Olfaction in the domestic fowl: a critical review.

It has been known for some time that many species of birds, including domestic fowl Gallus domesticus, have an olfactory sense. However, the functional significance of avian olfaction is less clear. We review neurobiological, embryological and behavioral evidence relevant to the question of how domestic fowl use the sense of smell. Evidence suggests a potential role for olfaction in the formation of attachments to familiar objects or environments; in the elicitation of fear responses by alarm and predator-related odors; in the control of feeding and drinking; and in avoidance of noxious substances. The fact that domestic fowl can detect and respond to a wide range of odors, in a variety of behavioral contexts, has important practical implications, especially in relation to welfare and husbandry.

Tonic immobility and heterophil/lymphocyte responses of the domestic fowl to corticosterone infusion.

The tonic immobility (TI) fear reactions, plasma corticosterone concentrations and heterophil/lymphocyte (H/L) ratios of adults laying hens were measured before and at intervals of 4 and 11 days after the subcutaneous implantation of osmotic minipumps delivering either corticosterone solution (15 micrograms/hr) or only polyethylene glycol vehicle. The dummy pumps exerted no apparent behavioral or endocrine effects, whereas tonic immobility was significantly prolonged and circulating corticosterone concentrations significantly elevated at 4 and 11 days after implantation of the corticosterone minipumps. H/L ratios were significantly elevated from pre-treatment levels in both groups. However, H/L ratios were considerably higher at both post-treatment points among birds receiving corticosterone rather than vehicle. The present findings suggest that chronic elevations of plasma corticosterone not only alter the haematological profile but may also predispose birds to react more fearfully to alarming stimulation.

The effects of regular handling on fear responses in the domestic chick

Reduction of fear in the domestic chick by regular handling was assessed and an attempt was made to determine whether such an effect was due specifically to reduced fear of human beings or to a general reduction in fearfulness. Regular handling decreased the tonic immobility response, a fear-potentiated phenomenon, and increased approach to a human being, but had no effect on approach towards an inanimate object. These findings were common to three strains (two layer, one broiler), and suggest that handling does not depress general fearfulness, but specifically reduces fear of human beings, presumably through habituation.

Fear of humans in Japanese quail selected for low or high adrenocortical response

Behavioral reactions to a nearby human were recorded in male Japanese quail of two lines selected for reduced (LS; low stress) or exaggerated (HS; high stress) plasma corticosterone (B) response to brief mechanical immobilization. Their adrenocortical responses to one of three treatments were then examined. These were: no human disturbance (undisturbed controls, CON), capture and return to the home cage before recapture and bleeding after 5 min (CR), or capture and manual restraint for 5 min before blood sampling (CREST). Quail of the HS line showed more fear-related behavior (crouching, escape) and avoidance of the experimenter than did their LS counterparts. Plasma B concentrations were markedly elevated following each capture treatment (CREST > CR) and the response appeared to be more pronounced in quail of the HS than the LS line. These findings indicate that HS quail perceived human contact to be more aversive than did those of the LS line. Avoidance scores and the adrenocortical responses to capture were positively correlated within individual birds. Therefore, simple behavioral tests of fear may have predictive value concerning physiological responsiveness to stressful stimulation.

Restraint, fear, and distress in Japanese quail genetically selected for long or short tonic immobility reactions

Japanese quail genetically selected for long (LTI) rather than short (STI) tonic immobility reactions showed more pronounced overt fear-responses in a number of putatively frightening situations. Greater fear has also been found in Japanese quail selected, in an independent program, for exaggerated (HS, high stress) rather than reduced (LS, low stress) plasma corticosterone response to brief mechanical restraint. The present study examined tonic immobility (TI) and adrenocortical responses in male and female quail of the LTI, STI and CON (control) lines which had either remained undisturbed or had been briefly exposed to a mechanical restraint stressor similar to that used for selection of the HS and LS lines. Behavioral strategies during restraint differed across lines, i.e., struggling followed the pattern STI > CON > LTI. The LTI quail showed more pronounced TI reactions than did CON and STI birds. Mechanical restraint prolonged subsequent TI responses and markedly elevated plasma corticosterone concentrations in all lines, but there were no line x treatment interactions. The results are discussed in terms of the parallels between the four selected lines and of the likelihood that the independent selection programs may have affected the same intervening variable.

Estimation of fear in two lines of the domestic chick: Correlations between various methods

The assessment of fear is a controversial issue and low levels of correlation between different measures have been used to criticise the fear concept. The present study assessed fear levels in individual domestic chicks of each of two lines, flighty and docile, using four commonly employed methods of estimating fear. They were the hole-in-the-wall box, the open field, response to a bell and tonic immobility. On the basis of a wide variety of behavioural responses each chick was ranked for fearfulness in each of the four tests. The degrees of association or correlation between these ranking within lines were then calculated. The significant intra-individual correlations found in both lines provides some support for the use of these tests as methods of estimating fear, at least within the lines used. Differences in the degree or form of fear-responding between the lines are also discussed in terms of reactions to handling and to sudden auditory stimuli.

Responses to isolation in Japanese quail genetically selected for high or low sociality

The adrenocortical, behavioral, and leucocytic responses to isolation, for 1, 3, or 72 h, of 7-10-day-old Japanese quail chicks, of lines selected for high (HSR) or low (LSR) levels of social reinstatement (SR) behavior, were studied. Isolation had no effect on plasma corticosterone levels of heterophil/lymphocyte measures in LSR line chicks. Conversely, circulating corticosterone levels were increased after 1 h of isolation in the HSR line, although they fell to control levels thereafter. Heterophil/lymphocyte ratios of HSR line chicks were also increased after 3 h of isolation but decreased to control levels thereafter. Isolated HSR line chicks were consistently more active and showed more peeping and jumping than LSR line chicks in which sitting and lying were more frequent. However, no such behavioral divergence was observed when HSR and LSR line chicks were housed in same-line groups. These results indicate that selection for SR behavior has influenced both underlying social motivation and responses to short-term isolation. Social separation appeared to be more stressful for HSR than LSR line chicks.

Behavioural and adrenocortical responses of domestic chicks to systematic reductions in group size and to sequential disturbance of companions by the experimenter.

Disruption of an animals social environment often causes distress and the effects of systematic reductions in group size on the behaviour and plasma corticosterone concentrations of domestic chicks were assessed in Experiment 1. Because this procedure also exposed the chicks to repeated disturbance by the experimenter, the behavioural and adrenocortical consequences of sequential capture and replacement of social companions were examined in Experiment 2. Female White Leghorn chicks were housed in groups of eight and remained undisturbed in both experiments until testing began at 14 d of age. Systematic reduction of group size was accompanied by both endocrine and behavioural modifications in Experiment 1. Thus, plasma corticosterone levels rose, feeding, drinking, preening and pecking at the environment gradually ceased whereas defaecation, ambulation, jumping and peeping became increasingly prevalent. These modifications were generally abrupt rather than progressive. Endocrine changes preceded behavioural ones which generally became evident when only two or fewer chicks remained. Conversely, the sequential capture and temporary removal of chicks from established groups in Experiment 2 elicited no significant effects in their uncaptured companions. The results are discussed in terms of social disruption, disturbance of companions by the experimenter, social motivation, predator evasion, individual recognition and fear.