Free Standard AU & NZ Shipping For All Book Orders Over $80!
Register      Login
Animal Production Science Animal Production Science Society
Food, fibre and pharmaceuticals from animals
REVIEW

Natural behaviours, their drivers and their implications for laying hen welfare

Paul H. Hemsworth https://orcid.org/0000-0002-0211-0751 A B and Lauren E. Edwards https://orcid.org/0000-0002-7411-9659 A
+ Author Affiliations
- Author Affiliations

A Animal Welfare Science Centre, Faculty of Veterinary and Agricultural Sciences, Building 400, Corner Flemington Road and Park Drive, The University of Melbourne, Parkville, Vic. 3010, Australia.

B Corresponding author. Email: phh@unimelb.edu.au

Animal Production Science 61(10) 915-930 https://doi.org/10.1071/AN19630
Submitted: 1 November 2019  Accepted: 5 May 2020   Published: 21 July 2020

Abstract

Some believe that farm animals need to be kept in conditions that provide ‘natural’ aspects in the animal’s environment and, thus, provide the opportunity for the animals to perform their full ‘behavioural repertoire’. Captivity may restrict either behaviours that animals have instinctive, intrinsic propensities to perform whatever the environment or behaviours that are elicited by deficits in the animals’ environment. Behavioural restriction may also thwart general motivation to seek variety and/or avoid monotonous conditions. Appreciating whether an animal suffers if deprived of the opportunity to perform natural behaviour requires, first, an understanding of how the behaviour in question is elicited and controlled, the effects of early experience and genetics on the behaviour and the behaviour of the species in the wild, and, second, the behavioural, physiological and fitness effects of deprivation of the behaviour. Housing laying hens in conventional cages compromises their behavioural repertoire, such as nesting in a nest box, dust bathing, perching and foraging, and the present review focuses on the welfare implications if these natural behaviours are thwarted in modern poultry production. A floor space of <561 cm2/hen increases physiological stress, reduces egg production and increases mortality in laying hens. There is also evidence of behavioural restriction in terms of reduced wing stretching, leg stretching, tail wagging, locomotion, floor and object pecking and preening with floor space in the range of 542–750 cm2/hen. Preference and motivation research has indicated that laying hens value resources such as nest boxes for oviposition, substrates for foraging and dust bathing, and perches for roosting. However, there is no convincing evidence that deprivation of these resources results in physiological stress. Furthermore, apart from adverse effects of the absence of perches on bone strength, there is no evidence that deprivation of nest boxes, perches, and foraging and dust-bathing substrates results in reduction in fitness such as reduced egg production or health. Nevertheless, preference research has indicated that the opportunity to utilise these resources, particularly nest boxes, may elicit positive emotional states in laying hens. Therefore, it is important to understand both how motivated the animal is to choose an option or perform a behaviour as well as the consequences of depriving the animal of this opportunity.

Additional keywords: management, poultry, stress physiology.


References

Abrahamsson P, Tauson R (1998) Performance and egg quality of laying hens in an aviary system. Journal of Applied Poultry Research 7, 225–232.
Performance and egg quality of laying hens in an aviary system.Crossref | GoogleScholarGoogle Scholar |

Ali ABA, Campbell DLM, Karcher DM, Siegford JM (2019) Daytime occupancy of resources and flooring types by 4 laying hen strains in a commercial-style aviary. Journal of Veterinary Behavior 31, 59–66.
Daytime occupancy of resources and flooring types by 4 laying hen strains in a commercial-style aviary.Crossref | GoogleScholarGoogle Scholar |

Alm M, Tauson R, Holm L, Wichman A, Kallioski O, Wall H (2016) Welfare indicators in laying hens in relation to nest exclusion. Poultry Science 95, 1238–1247.
Welfare indicators in laying hens in relation to nest exclusion.Crossref | GoogleScholarGoogle Scholar | 26994207PubMed |

Appleby MC, Smith SF, Hughes BO (1992) Individual perching behaviour of laying hens and its effects in cages. British Poultry Science 33, 227–238.
Individual perching behaviour of laying hens and its effects in cages.Crossref | GoogleScholarGoogle Scholar | 1623413PubMed |

Appleby MC, Walker AW, Nicol CJ, Lindberg AC, Freire R, Hughes BO, Elson HA (2002) Development of furnished cages for laying hens. British Poultry Science 43, 489–500.
Development of furnished cages for laying hens.Crossref | GoogleScholarGoogle Scholar | 12365505PubMed |

Appleby MC, Mench JA, Hughes BO (2004) ‘Poultry behaviour and welfare.’ (CABI Publishing: Wallingford, UK)

Archer GS, Moreira M, Farnell MB (2017) Evaluation of fear and stress in white layers housed in either conventional cages or enriched colony cage. International Journal of Poultry Science 16, 467–474.
Evaluation of fear and stress in white layers housed in either conventional cages or enriched colony cage.Crossref | GoogleScholarGoogle Scholar |

Arnold NA, Hemsworth PH (2013) Examining the usefulness of a Y maze choice method to measure the preferences of laying hens. Animal Production Science 53, 1283–1290.
Examining the usefulness of a Y maze choice method to measure the preferences of laying hens.Crossref | GoogleScholarGoogle Scholar |

Barnett JL, Hemsworth PH (1990) The validity of physiological and behavioural measures of animal welfare. Applied Animal Behaviour Science 25, 177–187.
The validity of physiological and behavioural measures of animal welfare.Crossref | GoogleScholarGoogle Scholar |

Barnett JL, Hemsworth PH, Newman EA (1992) Fear of humans and its relationships with productivity in laying hens at commercial farms. British Poultry Science 33, 699–710.
Fear of humans and its relationships with productivity in laying hens at commercial farms.Crossref | GoogleScholarGoogle Scholar | 1393665PubMed |

Barnett JL, Hemsworth PH, Hennessy DP, McCallum TH, Newman EA (1994) The effects of modifying the amount of human contact on behavioural, physiological and production responses of laying hens. Applied Animal Behaviour Science 41, 87–100.
The effects of modifying the amount of human contact on behavioural, physiological and production responses of laying hens.Crossref | GoogleScholarGoogle Scholar |

Barnett JL, Hemsworth PH, Cronin GM, Jongman EC, Hutson GD (2001) A review of the welfare issues for sows and piglets in relation to housing. Australian Journal of Agricultural Research 52, 1–28.
A review of the welfare issues for sows and piglets in relation to housing.Crossref | GoogleScholarGoogle Scholar |

Barnett JL, Tauson R, Downing JA, Janardhana V, Lowenthal JW, Butler KL, Cronin GM (2009) The effects of a perch, dust bath, and nest box, either alone or in combination as used in furnished cages, on the welfare of laying hens. Poultry Science 88, 456–470.
The effects of a perch, dust bath, and nest box, either alone or in combination as used in furnished cages, on the welfare of laying hens.Crossref | GoogleScholarGoogle Scholar | 19211513PubMed |

Berlyne DE (1960) ‘Conflict, arousal and curiosity.’ (McGraw-Hill: New York)

Beuving G (1980) Corticosteroids in laying hens. In ‘The laying hen and its environment’. (Ed. R Moss) pp. 65–82. (Martinus Nijhoff Publishers: The Hague, The Netherlands)

Blokhuis HJ, Beuving G, Rommers JM (1993) Individual variation of stereotyped pecking in laying hens. In ‘Proceedings of the 4th European symposium on poultry welfare’, 18-21 September 1993. (Eds CJ Savory, BO Hughes) pp. 19–26. (Universities Federation for Animal Welfare: Potters Bar, UK)

Boissy A (1998) Fear and fearfulness in determining behavior. In ‘Genetics and the behaviour of domestic animals’. (Ed. T Grandin) pp. 67–111. (Academic Press: San Diego, CA, USA)

Boissy A, Manteuffel G, Jensen MB, Oppermann M, Spruijt B, Keeling LJ, Winckler C, Forkman B, Dimitrov I, Langbein J, Bakken M, Veissier I, Aubert A (2007) Assessment of positive emotions in animals to improve their welfare. Physiology & Behavior 92, 375–397.
Assessment of positive emotions in animals to improve their welfare.Crossref | GoogleScholarGoogle Scholar |

Borchelt PL, Hoffman T, Hurrell RM, McCarthy R (1979) Regulation of dustbathing in Japanese quail (Cofumix cotumin). Journal of Comparative and Physiological Psychology 93, 134–139.
Regulation of dustbathing in Japanese quail (Cofumix cotumin).Crossref | GoogleScholarGoogle Scholar |

Brantsæter M, Tahamtani FM, Moe RO, Hansen TB, Orritt R, Nicol C, Janczak AM (2016) Rearing laying hens in aviaries reduces fearfulness following transfer to furnished cages. Frontiers in Veterinary Science 3, 13
Rearing laying hens in aviaries reduces fearfulness following transfer to furnished cages.Crossref | GoogleScholarGoogle Scholar | 26955634PubMed |

Broom DM (1986) Indicators of poor welfare. The British Veterinary Journal 142, 524–526.
Indicators of poor welfare.Crossref | GoogleScholarGoogle Scholar | 3594185PubMed |

Broom DM (2000) Coping, stress and welfare. In ‘Coping with challenge: welfare in animals including humans’. (Ed. DM Broom) pp. 1–9. (Daglem University Press: Berlin)

Broom DM, Johnson KG (1993) ‘Stress and animal welfare.’ (Chapman and Hall: London)

Campbell DLM, Makagon MM, Swanson JC, Siegford JM (2016) Perch use by laying hens in a commercial aviary. Poultry Science 95, 1736–1742.
Perch use by laying hens in a commercial aviary.Crossref | GoogleScholarGoogle Scholar |

Campbell DLM, de Haas EN, Lee C (2019) A review of environmental enrichment for laying hens during rearing in relation to their behavioral and physiological development. Poultry Science 98, 9–28.
A review of environmental enrichment for laying hens during rearing in relation to their behavioral and physiological development.Crossref | GoogleScholarGoogle Scholar | 30107615PubMed |

Cockrem JF (2007) Stress, corticosterone responses and avian personalities. Journal of Ornithology 148, S169–S178.
Stress, corticosterone responses and avian personalities.Crossref | GoogleScholarGoogle Scholar |

Colson S, Michel V, Arnould C (2006) Welfare of laying hens housed in cages and in aviaries: what about fearfulness? Archiv für Geflügelkunde 70, 261–269.

Colson S, Michel V, Arnould C (2008) Influence of rearing conditions of pullets on space use and performance of hens placed in aviaries at the beginning of the laying period. Applied Animal Behaviour Science 111, 286–300.
Influence of rearing conditions of pullets on space use and performance of hens placed in aviaries at the beginning of the laying period.Crossref | GoogleScholarGoogle Scholar |

Cooper JJ, Albentosa MJ (2003) Behavioural priorities of laying hens. Avian and Poultry Biology Reviews 14, 127–149.
Behavioural priorities of laying hens.Crossref | GoogleScholarGoogle Scholar |

Cooper JJ, Appleby MC (1996) Demand for nest boxes in laying hens. Behavioural Processes 36, 171–182.
Demand for nest boxes in laying hens.Crossref | GoogleScholarGoogle Scholar | 24896684PubMed |

Cooper JJ, Appleby MC (1997) Motivational aspects of individual variation in response to nest boxes by laying hens. Animal Behaviour 54, 1245–1253.
Motivational aspects of individual variation in response to nest boxes by laying hens.Crossref | GoogleScholarGoogle Scholar | 9398377PubMed |

Cooper JJ, Appleby MC (2003) The value of environmental resources to domestic hens: a comparison of the work-rate for food and for nests as a function of time. Animal Welfare (South Mimms, England) 12, 39–52.

Cordiner LS, Savory CJ (2001) Use of perches and nestboxes by laying hens in relation to social status, based on examination of consistency of ranking orders and frequency of interactions. Applied Animal Behaviour Science 71, 305–317.
Use of perches and nestboxes by laying hens in relation to social status, based on examination of consistency of ranking orders and frequency of interactions.Crossref | GoogleScholarGoogle Scholar | 11248380PubMed |

Cronin GM, Glatz PC (2020) Causes of feather pecking and subsequent welfare issues for the laying hen: a review. Animal Production Science.
Causes of feather pecking and subsequent welfare issues for the laying hen: a review.Crossref | GoogleScholarGoogle Scholar |

Cronin GM, Butler KL, Desnoyers MA, Barnett JL (2005) The use of nest boxes by laying hens in cages: what does it mean for welfare? Animal Science Papers and Reports 23, 121–128.

Cronin GM, Borg SS, Fourdin SP, Storey TH, Barnett JL (2007) Consistent nest site selection for egg laying in cages with a nest box. In ‘Proceedings of the 19th Australian poultry science symposium’, 12–14 February 2007, Sydney, NSW, Australia. pp. 37–40. (University of Sydney: Sydney, NSW, Australia)

Cronin GM, Downing J, Borg SS, Storey TH, Schirmer BN, Butler KL, Barnett JL (2008) The importance of nest-boxes to young adult laying hens. In ‘Proceedings XXIII world’s poultry congress’, 30 June – 4 July 2008, Brisbane, Qld, Australia. p. 243. [CD]

Cronin GM, Hopcroft RL, Groves PJ, Hall EJS, Phalen DN, Hemsworth PH (2018) Why did severe feather pecking and cannibalism outbreaks occur? An unintended case study while investigating the effects of forage and stress on pullets during rearing. Poultry Science 97, 1484–1502.

Dantzer R (2002) Can farm animal welfare be understood without taking into account the issues of emotion and cognition? Journal of Animal Science 80, E1–E9.

Dawkins MS (1988) Behavioural deprivation: a central problem in animal welfare. Applied Animal Behaviour Science 20, 209–225.
Behavioural deprivation: a central problem in animal welfare.Crossref | GoogleScholarGoogle Scholar |

Dawkins MS (1989) Time budgets in red junglefowl as a baseline for the assessment of welfare in domestic fowl. Applied Animal Behaviour Science 24, 77–80.
Time budgets in red junglefowl as a baseline for the assessment of welfare in domestic fowl.Crossref | GoogleScholarGoogle Scholar |

Dawkins MS (2008) The science of animal suffering. Ethology 114, 937–945.
The science of animal suffering.Crossref | GoogleScholarGoogle Scholar |

Dawkins MS, Beardsley T (1986) Reinforcing properties of access to litter in hens. Applied Animal Behaviour Science 15, 351–364.
Reinforcing properties of access to litter in hens.Crossref | GoogleScholarGoogle Scholar |

de Boer SF, Buwalda B, Koolhaas JM (2017) Untangling the neurobiology of coping styles in rodents: towards neural mechanisms underlying individual differences in disease susceptibility. Neuroscience and Biobehavioral Reviews 74, 401–422.

de Jong IC, Wolthuis-Fillerup M, van Reenen CG (2007) Strength of preference for dustbathing and foraging substrates in laying hens. Applied Animal Behaviour Science 104, 24–36.
Strength of preference for dustbathing and foraging substrates in laying hens.Crossref | GoogleScholarGoogle Scholar |

Desiré L, Boissy A, Veissier I (2002) Emotions in farm animals: a new approach to animal welfare in applied ethology. Behavioural Processes 60, 165–180.

Dikmen BY, Ipek A, Sahan U, Petek M, Sozcu A (2016) Egg production and welfare of laying hens kept in different housing systems (conventional, enriched cage, and free range). Poultry Science 95, 1564–1572.

Donaldson CJ, O’Connell NE (2012) The influence of access to aerial perches on fearfulness, social behaviour and production parameters in free-range laying hens. Applied Animal Behaviour Science 142, 51–60.
The influence of access to aerial perches on fearfulness, social behaviour and production parameters in free-range laying hens.Crossref | GoogleScholarGoogle Scholar |

Duncan IJH (2005) Science-based assessment of animal welfare: farm animals. Revue Scientifique et Technique 24, 483–492.
Science-based assessment of animal welfare: farm animals.Crossref | GoogleScholarGoogle Scholar |

Duncan IJH, Kite VG (1989) Nest site selection and nest-building behaviour in the domestic fowl. Animal Behaviour 37, 215–231.
Nest site selection and nest-building behaviour in the domestic fowl.Crossref | GoogleScholarGoogle Scholar |

Duncan IJH, Widowski TM, Malleau AE, Lindberg AC, Petherick JC (1998) External factors and causation of dustbathing in domestic hens. Behavioural Processes 43, 219–228.
External factors and causation of dustbathing in domestic hens.Crossref | GoogleScholarGoogle Scholar |

Edwards LE, Hemsworth PH (2020) The impact of management, husbandry and stockperson decisions on the welfare of laying hens in Australia. Animal Production Science.
The impact of management, husbandry and stockperson decisions on the welfare of laying hens in Australia.Crossref | GoogleScholarGoogle Scholar |

Edwards LE, Coleman GJ, Butler KL, Hemsworth PH (2019) The human-animal relationship in Australian caged laying hens. Animals (Basel) 9, 211
The human-animal relationship in Australian caged laying hens.Crossref | GoogleScholarGoogle Scholar |

Elsasser TH, Klasing KC, Filiov N, Thompson F (2000) The metabolic consequences of stress: targets for stress and priorities of nutrient use. In ‘Biology of animal stress’. (Eds JA Mench, G Moberg) pp. 77–110. (CABI Publishing: Wallingford, UK)

Engel JM, Widowski TM, Tilbrook AJ, Butler KL, Hemsworth PH (2019) The effects of floor space and nest box access on the physiology and behavior of caged laying hens. Poultry Science 98, 533–547.
The effects of floor space and nest box access on the physiology and behavior of caged laying hens.Crossref | GoogleScholarGoogle Scholar | 30165652PubMed |

Faure JM (1986) Operant determination of the cage and feeder size preferences of the laying hen. Applied Animal Behaviour Science 15, 325–336.
Operant determination of the cage and feeder size preferences of the laying hen.Crossref | GoogleScholarGoogle Scholar |

Faure JM (1991) Rearing conditions and needs for space and litter in laying hens. Applied Animal Behaviour Science 31, 111–117.
Rearing conditions and needs for space and litter in laying hens.Crossref | GoogleScholarGoogle Scholar |

Faure JM, Jones RB (1982) Effects of sex, strain and type of perch on perching behavior in the domestic fowl. Applied Animal Ethology 8, 281–293.
Effects of sex, strain and type of perch on perching behavior in the domestic fowl.Crossref | GoogleScholarGoogle Scholar |

Faure JM, Lagadic H (1994) Elasticity of demand for food and sand in laying hens subjected to variable wind speed. Applied Animal Behaviour Science 42, 49–59.
Elasticity of demand for food and sand in laying hens subjected to variable wind speed.Crossref | GoogleScholarGoogle Scholar |

Follensbee ME, Duncan IJH, Widowski TM (1992) Quantifying nesting motivation of domestic hens. Journal of Animal Science 70, 164

Forkman B, Boissy A, Meunier-Salaün M-C, Canali E, Jones RB (2007) A critical review of fear tests used on cattle, pigs, sheep, poultry and horses. Physiology & Behavior 92, 340–374.
A critical review of fear tests used on cattle, pigs, sheep, poultry and horses.Crossref | GoogleScholarGoogle Scholar |

Fraisse F, Cockrem JF (2006) Corticosterone and fear behaviour in white and brown caged laying hens. British Poultry Science 47, 110–119.
Corticosterone and fear behaviour in white and brown caged laying hens.Crossref | GoogleScholarGoogle Scholar | 16641020PubMed |

Fraser D (2003) Assessing animal welfare at the farm and group level: the interplay of science and values. Animal Welfare (South Mimms, England) 12, 433–443.

Fraser D (2005) ‘Animal welfare and the intensification of animal production. An alternative interpretation.’ FAO readings in ethics, 2. (FAO: Rome)

Fraser D, Nicol CJ (2018) Preference and motivation research. In ‘Animal welfare’. 3rd edn. (Eds MC Appleby, IAS Olsson, F Galindo) pp. 213–231 (CAB International: Wallingford, UK)

Freire R, Appleby MC, Hughes BO (1997) Assessment of pre-laying motivation in the domestic hen using social interaction. Animal Behaviour 54, 313–319.
Assessment of pre-laying motivation in the domestic hen using social interaction.Crossref | GoogleScholarGoogle Scholar | 9268462PubMed |

Gray JA (1987) ‘The psychology of fear and stress’. 2nd edn. (Cambridge University Press: Cambridge, UK)

Green TC, Mellor DJ (2011) Extending ideas about animal welfare assessment to include ‘quality of life’ and related concepts. New Zealand Veterinary Journal 59, 263–271.
Extending ideas about animal welfare assessment to include ‘quality of life’ and related concepts.Crossref | GoogleScholarGoogle Scholar | 22040330PubMed |

Guesdon V, Faure JM (2004) Laying performance and egg quality in hens kept in standard or furnished cages. Animal Research 53, 45–57.
Laying performance and egg quality in hens kept in standard or furnished cages.Crossref | GoogleScholarGoogle Scholar |

Guesdon V, Leterrier C, Constantin P, Guémené D, Couty M, Faure JM (2004) Humeral quality and adrenal responsiveness in laying hens reared in standard and furnished cages. Animal Research 53, 235–243.
Humeral quality and adrenal responsiveness in laying hens reared in standard and furnished cages.Crossref | GoogleScholarGoogle Scholar |

Gunnarsson S, Matthews LR, Foster TM, Temple W (2000) The demand for straw and feathers as litter substrates by laying hens. Applied Animal Behaviour Science 65, 321–330.
The demand for straw and feathers as litter substrates by laying hens.Crossref | GoogleScholarGoogle Scholar |

Hemsworth PH (2018) Key determinants of pig welfare: implications of animal management and housing design on livestock welfare. Animal Production Science 58, 1375–1386.
Key determinants of pig welfare: implications of animal management and housing design on livestock welfare.Crossref | GoogleScholarGoogle Scholar |

Hemsworth PH (2020) Cage production and laying hen welfare. Animal Production Science.
Cage production and laying hen welfare.Crossref | GoogleScholarGoogle Scholar |

Hemsworth PH, Coleman GJ (2011) ‘Human–livestock interactions: the stockperson and the productivity and welfare of farmed animals’. 2nd edn. (CAB International: Wallingford, UK)

Hemsworth PH, Mellor DJ, Cronin GM, Tilbrook AJ (2015) Scientific assessment of animal welfare. New Zealand Veterinary Journal 63, 24–30.
Scientific assessment of animal welfare.Crossref | GoogleScholarGoogle Scholar | 25263963PubMed |

Hemsworth PH, Sherwen SL, Coleman GJ (2018) Human contact. In ‘Animal welfare’. 3rd edn. (Eds MC Appleby, IAS Olsson, F Galindo) pp. 294–314. (CAB International: Wallingford, UK)

Hester PY (2014) The effect of perches installed in cages on laying hens. World’s Poultry Science Journal 70, 247–263.
The effect of perches installed in cages on laying hens.Crossref | GoogleScholarGoogle Scholar |

Hetland H, Moe RO, Tauson R, Lervik S, Svihus B (2004) Effect of including whole oats into pellets on performance and plumage condition in laying hens housed in conventional and furnished cages. Acta Agriculturae Scandinavica. Section a. Animal Science 54, 206–212.

Hocking PM, Channing CE, Waddington D, Jones RB (2001) Age-related changes in fear, sociality and pecking behaviours in two strains of laying hen. British Poultry Science 42, 414–423.
Age-related changes in fear, sociality and pecking behaviours in two strains of laying hen.Crossref | GoogleScholarGoogle Scholar | 11572615PubMed |

Hogan JA (1997) Energy models of motivation: a reconsideration. Applied Animal Behaviour Science 53, 89–105.
Energy models of motivation: a reconsideration.Crossref | GoogleScholarGoogle Scholar |

Hogan JA (2008) Motivation. In ‘The behaviour of animals: mechanisms, function and evolution’. (Eds JJ Bolhuis, L–C Giraldeau) pp. 41–70. (Wiley-Blackwell: Malden, MA, USA)

Hogan JA, Honrado GI, Vestergaard K (1991) Development of a behavior system: dustbathing in the Burmese red junglefowl (Callus gallus spadiceus): II. Internal factors. Journal of Comparative Psychology 105, 269–273.
Development of a behavior system: dustbathing in the Burmese red junglefowl (Callus gallus spadiceus): II. Internal factors.Crossref | GoogleScholarGoogle Scholar |

Hughes BO (1983) Headshaking in fowls: the effect of environmental stimuli. Applied Animal Ethology 11, 45–53.
Headshaking in fowls: the effect of environmental stimuli.Crossref | GoogleScholarGoogle Scholar |

Hughes BO, Duncan IJH (1988) The notion of ethological ‘need’, models of motivation and animal welfare. Animal Behaviour 36, 1696–1707.
The notion of ethological ‘need’, models of motivation and animal welfare.Crossref | GoogleScholarGoogle Scholar |

Inglis IR, Langton S, Forkman B, Lazarus J (2001) An information-primacy model of exploratory and foraging behavior. Animal Behaviour 62, 543–557.
An information-primacy model of exploratory and foraging behavior.Crossref | GoogleScholarGoogle Scholar |

Jones RB (1986) The tonic immobility reaction of the domestic fowl: a review. World’s Poultry Science Journal 42, 82–96.
The tonic immobility reaction of the domestic fowl: a review.Crossref | GoogleScholarGoogle Scholar |

Jones RB (1996) Fear and adaptability in poultry: insights, implications and imperatives. World’s Poultry Science Journal 52, 131–174.
Fear and adaptability in poultry: insights, implications and imperatives.Crossref | GoogleScholarGoogle Scholar |

Jones RB (2002) Role of comparative psychology in the development of effective environmental enrichment. Strategies to improve poultry welfare. International Journal of Comparative Psychology 15, 77–106.

Jones RB, Faure JM (1981) The effects of regular handling on fear responses in the domestic chick. Behavioural Processes 6, 135–143.
The effects of regular handling on fear responses in the domestic chick.Crossref | GoogleScholarGoogle Scholar | 24925737PubMed |

Jones RB, Rayner S (1999) Music in the hen house: a survey of its incidence and perceived benefits. Poultry Science 78, 110

Keeling L, Jensen P (2009) Abnormal behaviour, stress and welfare. In ‘The ethology of domestic animals’. 2nd edn. (Ed. P Jensen) pp. 85–101. (CAB International Publishing: Wallingford, UK)

Kirkden RD, Pajor EA (2006) Using preference, motivation and aversion tests to ask scientific questions about animals’ feelings. Applied Animal Behaviour Science 100, 29–47.
Using preference, motivation and aversion tests to ask scientific questions about animals’ feelings.Crossref | GoogleScholarGoogle Scholar |

Koelkebeck KW, Cain JR (1984) Performance, behavior, plasma corticosterone, and economic returns of laying hens in several management alternatives. Poultry Science 63, 2123–2131.
Performance, behavior, plasma corticosterone, and economic returns of laying hens in several management alternatives.Crossref | GoogleScholarGoogle Scholar | 6514660PubMed |

Koelkebeck KW, Cain JR, Amoss MS (1986) Corticosterone sampling of laying hens in different management systems. Poultry Science 65, 183–185.
Corticosterone sampling of laying hens in different management systems.Crossref | GoogleScholarGoogle Scholar | 3754334PubMed |

Koelkebeck KW, Amoss MS, Cain JR (1987) Production, physiological, and behavioral responses of laying hens in different management environments. Poultry Science 66, 397–407.
Production, physiological, and behavioral responses of laying hens in different management environments.Crossref | GoogleScholarGoogle Scholar | 3601849PubMed |

Koolhaas JM, Korte SM, De Boer SF, Van Der Vegt BJ, Van Reenen CG, Hopster H, De Jong IC, Ruis MA, Blokhuis HJ (1999) Coping styles in animals: current status in behavior and stress-physiology. Neuroscience and Biobehavioral Reviews 23, 925–935.
Coping styles in animals: current status in behavior and stress-physiology.Crossref | GoogleScholarGoogle Scholar | 10580307PubMed |

Koolhaas JM, de Boer SF, Coppens CM, Buwalda B (2010) Neuroendocrinology of coping styles: towards understanding the biology of individual variation. Frontiers in Neuroendocrinology 31, 307–321.

Ladd JK, Albright JL, Beck AM, Ladd BT (1992) Behavioural and physiological studies on the effects of music on animals. Journal of Animal Science 70, 170

Lagadic H, Faure J-M (1987) Preferences of domestic hens for cage size and floor types as measured by operant conditioning. Applied Animal Behaviour Science 19, 147–155.
Preferences of domestic hens for cage size and floor types as measured by operant conditioning.Crossref | GoogleScholarGoogle Scholar |

Lang PJ, Davis M, Ohman A (2000) Fear and anxiety: animal models and human cognitive psychophysiology. Journal of Affective Disorders 61, 137–159.
Fear and anxiety: animal models and human cognitive psychophysiology.Crossref | GoogleScholarGoogle Scholar | 11163418PubMed |

Lay DC, Fulton RM, Hester PJ, Karcher DM, Kjaer JB, Mench JA, Mullens BA, Newberry RC, Nicol CJ, O’Sullivan NP, Porter RE (2011) Hen welfare in different housing systems. Poultry Science 90, 278–294.
Hen welfare in different housing systems.Crossref | GoogleScholarGoogle Scholar | 21177469PubMed |

Li X, Chen DH, Li JH, Bao J (2016) Effects of furnished cage type on behavior and welfare of laying hens. Asian–Australasian Journal of Animal Sciences 29, 887–894.
Effects of furnished cage type on behavior and welfare of laying hens.Crossref | GoogleScholarGoogle Scholar | 26954171PubMed |

Lindberg AC, Nicol CJ (1997) Dustbathing in modified battery cages: is sham dustbathing an adequate substitute? Applied Animal Behaviour Science 55, 113–128.
Dustbathing in modified battery cages: is sham dustbathing an adequate substitute?Crossref | GoogleScholarGoogle Scholar |

Lindqvist C, Jensen P (2009) Domestication and stress effects on contrafreeloading and spatial learning performance in red jungle fowl (Gallus gallus) and White Leghorn layers. Behavioural Processes 81, 80–84.
Domestication and stress effects on contrafreeloading and spatial learning performance in red jungle fowl (Gallus gallus) and White Leghorn layers.Crossref | GoogleScholarGoogle Scholar | 19429200PubMed |

Lindqvist CES, Schutz KE, Jensen P (2002) Red junglefowl have more contrafreeloading than White Leghorn layers: effects of food deprivation and consequences for information gain. Behaviour 139, 1195–1209.
Red junglefowl have more contrafreeloading than White Leghorn layers: effects of food deprivation and consequences for information gain.Crossref | GoogleScholarGoogle Scholar |

Mason GJ, Burn CC (2018) Frustration and boredom in impoverished environments. In ‘Animal welfare’. 3rd edn. (Eds MC Appleby, IAS Olsson, F Galindo) pp. 114–138. (CAB International Publishing: Wallingford, UK)

Matthews LR, Ladewig J (1994) Environmental requirements of pigs measured by behavioural demand functions. Animal Behaviour 47, 713–719.
Environmental requirements of pigs measured by behavioural demand functions.Crossref | GoogleScholarGoogle Scholar |

Matthews LR, Temple W, Foster TM, McAdie TM (1993) Quantifying the environmental requirements of layer hens by behavioural demand functions. In ‘Proceedings of the international congress on applied ethology’, 4–6 August 1993, Berlin, Germany. (Eds M Nichelmann, HK Wierenga, S Braun) pp 206–209. (Humboldt University: Berlin, Germany)

Matthews LR, Temple W, Foster TM, Walker J, McAdie TM (1995) Comparison of the demand for dustbathing substrates by layer hens. In ‘Proceedings of the 29th congress of the International Society for Applied Ethology’, 3–5 August 1995, Exeter, UK. (Eds SM Rutter, J Rushen, HR Randle, JC Edison). p. 11. (Universities Federation for Animal Welfare: England, UK)

Meijsser FM, Hughes BO (1989) Comparative analysis of pre-laying behaviour in battery cages and in three alternative systems. British Poultry Science 30, 747–760.
Comparative analysis of pre-laying behaviour in battery cages and in three alternative systems.Crossref | GoogleScholarGoogle Scholar |

Mellor DJ (2012) Animal emotions, behaviour and the promotion of positive welfare states. New Zealand Veterinary Journal 60, 1–8.
Animal emotions, behaviour and the promotion of positive welfare states.Crossref | GoogleScholarGoogle Scholar | 22175422PubMed |

Mellor DJ (2015) Positive animal welfare states and reference standards for welfare assessment. New Zealand Veterinary Journal 63, 17–23.
Positive animal welfare states and reference standards for welfare assessment.Crossref | GoogleScholarGoogle Scholar | 24875152PubMed |

Mellor DJ, Stafford KJ (2004) Animal welfare implications of neonatal mortality and morbidity in farm animals. Veterinary Journal (London, England) 168, 118–133.
Animal welfare implications of neonatal mortality and morbidity in farm animals.Crossref | GoogleScholarGoogle Scholar |

Mellor DJ, Patterson-Kane E, Stafford KJ (2009) ‘The sciences of animal welfare.’ (Wiley-Blackwell Publishing: Oxford, UK)

Moberg GP (2000) Biological response to stress: Implications for animal welfare. In ‘The biology of animal stress; basic principles and applications for animal welfare’. (Eds GP Moberg, GA Mench) pp. 1–21. (CAB International Publishing: Wallingford, UK)

Moe RO, Guémené D, Bakken M, Larsen HJS, Shini S, Lervik S, Skjerve E, Michel V, Tauson R (2010) Effects of housing conditions during the rearing and laying period on adrenal reactivity, immune response and heterophil to lymphocyte (H/L) ratios in laying hens. Animal 4, 1709–1715.
Effects of housing conditions during the rearing and laying period on adrenal reactivity, immune response and heterophil to lymphocyte (H/L) ratios in laying hens.Crossref | GoogleScholarGoogle Scholar | 22445125PubMed |

Newberry RC (1995) Environmental enrichment: increasing the biological relevance of captive environments. Applied Animal Behaviour Science 44, 229–243.
Environmental enrichment: increasing the biological relevance of captive environments.Crossref | GoogleScholarGoogle Scholar |

Newberry RC, Estevez I, Keeling LJ (2001) Group size and perching behaviour in young domestic fowl. Applied Animal Behaviour Science 73, 117–129.
Group size and perching behaviour in young domestic fowl.Crossref | GoogleScholarGoogle Scholar | 11358609PubMed |

Nicol CJ, Guilford T (1991) Exploratory activity as a measure of motivation in deprived hens. Animal Behaviour 41, 333–341.
Exploratory activity as a measure of motivation in deprived hens.Crossref | GoogleScholarGoogle Scholar |

Nicol CJ, Lindberg AC, Phillips AJ, Pope SJ, Wilkins LJ, Green LE (2001) Influence of prior exposure to wood shavings on feather pecking, dustbathing and foraging in adult laying hens. Applied Animal Behaviour Science 73, 141–155.
Influence of prior exposure to wood shavings on feather pecking, dustbathing and foraging in adult laying hens.Crossref | GoogleScholarGoogle Scholar | 11358611PubMed |

Nicol CJ, Bouwsema J, Caplen G, Davies AC, Hockenhull J, Lambton SL, Lines JA, Mullan S, Weeks CA (2017) ‘Farmed bird welfare science review.’ (Department of Economic Development, Jobs, Transport and Resources: Melbourne, Victoria, Australia: )

Norgaard-Nielsen G (1984) Stereotypies and their development in caged layers. In ‘Proceedings of the international congress on applied ethology in farm animals’. (Eds J Unshelm, G van Putten, K Zeeb) pp. 79–83. (Association for Technology and Structures in Agriculture (KTBL): Darmstadt, Germany)

Norgaard-Nielsen G, Vestergaard K (1981) Dustbathing behaviour of uropygial gland extirpated domestic hens: effects of dust deprivation. Acta Veterinaria Scandinavica 22, 118–128.

Öhman A (2006) Of snakes and faces: an evolutionary perspective on the psychology of fear. Scandinavian Journal of Psychology 50, 543–552.
Of snakes and faces: an evolutionary perspective on the psychology of fear.Crossref | GoogleScholarGoogle Scholar |

Olsson IAS, Keeling LJ (2000) Night-time roosting in laying hens and the effect of thwarting access to perches. Applied Animal Behaviour Science 68, 243–256.
Night-time roosting in laying hens and the effect of thwarting access to perches.Crossref | GoogleScholarGoogle Scholar |

Olsson IAS, Keeling LJ (2002) The push-door for measuring motivation in hens: laying hens are motivated to perch at night. Animal Welfare 11, 11–19.

Olsson IAS, Keeling LJ (2005) Why in earth? Dustbathing behaviour in jungle and domestic fowl reviewed from a Tinbergian and animal welfare perspective. Applied Animal Behaviour Science 93, 259–282.
Why in earth? Dustbathing behaviour in jungle and domestic fowl reviewed from a Tinbergian and animal welfare perspective.Crossref | GoogleScholarGoogle Scholar |

Olsson IAS, Keeling LJ, McAdie TM (2002) The push-door for measuring motivation in hens: an adaptation and a critical discussion of the method. Animal Welfare 11, 1–10.

Øverli Ø, Sorensen C, Pulman KG, Pottinger TG, Korzan W, Summers CH, Nilsson GE (2007) Evolutionary background for stress-coping styles: relationships between physiological, behavioral, and cognitive traits in non-mammalian vertebrates. Neuroscience and Biobehavioral Reviews 31, 396–412.
Evolutionary background for stress-coping styles: relationships between physiological, behavioral, and cognitive traits in non-mammalian vertebrates.Crossref | GoogleScholarGoogle Scholar | 17182101PubMed |

Petherick JC, Seawright E, Waddington D (1993) Influence of motivational state on choice of food or a dustbathing foraging substrate by domestic hens. Behavioural Processes 28, 209–220.
Influence of motivational state on choice of food or a dustbathing foraging substrate by domestic hens.Crossref | GoogleScholarGoogle Scholar | 24897606PubMed |

Petherick JC, Seawright E, Waddington D, Duncan IJH, Murphy LB (1995) The role of perception in the causation of dustbathing behaviour in domestic fowl. Animal Behaviour 49, 1521–1530.
The role of perception in the causation of dustbathing behaviour in domestic fowl.Crossref | GoogleScholarGoogle Scholar |

Pohle K, Cheng H-W (2009) Comparative effects of furnished and battery cages on egg production and physiological parameters in White Leghorn hens. Poultry Science 88, 2042–2051.
Comparative effects of furnished and battery cages on egg production and physiological parameters in White Leghorn hens.Crossref | GoogleScholarGoogle Scholar | 19762855PubMed |

Reed HJ, Wilkins LJ, Austin SD, Gregory NG (1993) The effect of environmental enrichment during rearing on fear reactions and depopulation trauma in adult caged hens. Applied Animal Behaviour Science 36, 39–46.
The effect of environmental enrichment during rearing on fear reactions and depopulation trauma in adult caged hens.Crossref | GoogleScholarGoogle Scholar |

Rodenburg TB, de Reu K, Tuyttens FAM (2012) Performance, welfare, health and hygiene of laying hens in non-cage systems in comparison with cage systems. In ‘Alternative systems for poultry – health, welfare and productivity’. (Eds V Sandilands, PM Hocking) pp. 210–224. (CABI Publishing: Wallingford, UK)

Rodenburg TB, Van Krimpen MM, De Jong IC, De Haas EN, Kops MS, Riedstra BJ, Nordquist RE, Wagenaar JP, Bestman M, Nicol CJ (2013) The prevention and control of feather pecking in laying hens: identifying the underlying principles. World’s Poultry Science Journal 69, 361–374.

Schjolden J, Backstrom T, Pulman KG, Pottinger TG, Winberg S (2005) Divergence in behavioural responses to stress in two strains of rainbow trout (Oncorhynchus mykiss) with contrasting stress responsiveness. Hormones and Behavior 48, 537–544.
Divergence in behavioural responses to stress in two strains of rainbow trout (Oncorhynchus mykiss) with contrasting stress responsiveness.Crossref | GoogleScholarGoogle Scholar | 15907328PubMed |

Schreiter R, Damme K, Von Borell E, Vogt I, Klunker M, Freick M (2019) Effects of litter and additional enrichment elements on the occurrence of feather pecking in pullets and laying hens: a focused review. Veterinary Medicine and Science 5, 500–507.
Effects of litter and additional enrichment elements on the occurrence of feather pecking in pullets and laying hens: a focused review.Crossref | GoogleScholarGoogle Scholar | 31267678PubMed |

Schutz KE, Jensen P (2001) Effects of resource allocation on behavioural strategies: a comparison of Red junglefowl (Gallus gallus) and two domesticated breeds of poultry. Ethology 107, 753–765.
Effects of resource allocation on behavioural strategies: a comparison of Red junglefowl (Gallus gallus) and two domesticated breeds of poultry.Crossref | GoogleScholarGoogle Scholar |

Sherwin CM, Nicol CJ (1993a) A descriptive account of the pre-laying behaviour of hens housed individually in modified cages with nests. Applied Animal Behaviour Science 38, 49–60.
A descriptive account of the pre-laying behaviour of hens housed individually in modified cages with nests.Crossref | GoogleScholarGoogle Scholar |

Sherwin CM, Nicol CJ (1993b) Factors influencing floor-laying by hens in modified cages. Applied Animal Behaviour Science 36, 211–222.
Factors influencing floor-laying by hens in modified cages.Crossref | GoogleScholarGoogle Scholar |

Sherwin CM, Richards GJ, Nicol CJ (2010) Comparison of the welfare of layer hens in 4 housing systems in the UK. British Poultry Science 51, 488–499.
Comparison of the welfare of layer hens in 4 housing systems in the UK.Crossref | GoogleScholarGoogle Scholar | 20924842PubMed |

Shimmura T, Hirahara S, Azuma T, Suzuki T, Eguchi Y, Uetake K, Tanaka T (2010) Multi-factorial investigation of various housing systems for laying hens. British Poultry Science 51, 31–42.
Multi-factorial investigation of various housing systems for laying hens.Crossref | GoogleScholarGoogle Scholar | 20390567PubMed |

Shini S (2003) Physiologic responses of laying hens to the alternative housing systems. International Journal of Poultry Science 2, 357–360.
Physiologic responses of laying hens to the alternative housing systems.Crossref | GoogleScholarGoogle Scholar |

Špinka M, Wemelsfelder F (2011) Environmental challenge and animal agency. In ‘Animal welfare’. (Eds MC Appleby, JA Mench, IAS Olsson, BO Hughes) pp. 27–44. (CAB International: Wallingford, UK)

Struelens E, Tuyttens FAM, Janssen A, Leroy T, Audoorn L, Vranken E, De Baere K, Ödberg F, Berckmans D, Zoons J, Sonck B (2005) Design of laying nests in furnished cages: influence of nesting material, nest box position and seclusion. British Poultry Science 46, 9–15.
Design of laying nests in furnished cages: influence of nesting material, nest box position and seclusion.Crossref | GoogleScholarGoogle Scholar | 15835246PubMed |

Struelens E, van Nuffel A, Tuyttens FAM, Audoorn L, Vranken E, Zoons J, Berckmans D, Odberg F, van Dongen S, Sonck B (2008) Influence of nest seclusion and nesting material on pre-laying behaviour of laying hens. Applied Animal Behaviour Science 112, 106–119.
Influence of nest seclusion and nesting material on pre-laying behaviour of laying hens.Crossref | GoogleScholarGoogle Scholar |

Tanaka T, Hurnik JF (1992) Comparison of behavior and performance of laying hens housed in battery cages and an aviary. Poultry Science 71, 235–243.
Comparison of behavior and performance of laying hens housed in battery cages and an aviary.Crossref | GoogleScholarGoogle Scholar | 1546034PubMed |

Tannenbaum J (2001) The paradigm shift toward animal happiness: what it is, why it is happening, and what it portends for medical research. In ‘Why animal experimentation matters: the use of animals in medical research’. (Eds EF Paul, J Paul) pp. 93–130. (Transaction Publishers: Somerset, NJ, USA)

Tauson R (2005) Management and housing systems for layers: effects on welfare and production. World’s Poultry Science Journal 61, 477–490.
Management and housing systems for layers: effects on welfare and production.Crossref | GoogleScholarGoogle Scholar |

Tauson R, Holm KE (2002) Evaluation of Victorsson furnished cage for 8 laying hens according to the #7 Swedish Animal Welfare Ordinance and according to the New-Technique Evaluation Program at the Swedish Board of Agriculture. Report 251. Swedish University of Agricultural Sciences, Department of Animal Nutrition and Management, Uppsala, Sweden.

Tilbrook AJ, Ralph CR (2018) Hormones, stress and the welfare of animals. Animal Production Science 58, 408–415.
Hormones, stress and the welfare of animals.Crossref | GoogleScholarGoogle Scholar |

Toates FM (1980) ‘Animal behaviour: a systems approach.’ (John Wiley and Sons: Chichester, UK)

van de Weerd HA, Day JE (2009) A review of environmental enrichment for pigs housed in intensive housing systems. Applied Animal Behaviour Science 116, 1–20.
A review of environmental enrichment for pigs housed in intensive housing systems.Crossref | GoogleScholarGoogle Scholar |

van Liere DW (1992) Dustbathing as related to proximal and distal feather lipids in laying hens. Behavioural Processes 26, 177–188.
Dustbathing as related to proximal and distal feather lipids in laying hens.Crossref | GoogleScholarGoogle Scholar | 24924327PubMed |

van Liere DW, Bokma S (1987) Short-term feather maintenance as a function of dustbathing in laying hens. Applied Animal Behaviour Science 18, 197–204.

van Liere DW, Siard N (1991) The experience of litter and subsequent selection of bathing substrate in laying hens. In ‘Function and organization of dustbathing in laying hens’. (Ed. DW van Liere) pp. 127–141. (Wageningen Agricultural University: Wageningen, The Netherlands)

van Liere DW, Kooijman J, Wiepkema PR (1990) Dustbathing behaviour of laying hens as related to quality of dustbathing material. Applied Animal Behaviour Science 26, 127–141.
Dustbathing behaviour of laying hens as related to quality of dustbathing material.Crossref | GoogleScholarGoogle Scholar |

van Liere DW, Aggrey SE, Brouns FMR, Wiepkema PR (1991) Oiling behaviour and the effect of lipids on dustbathing behaviour in laying hens Gallus gallus domesticus. Behavioural Processes 24, 71–81.
Oiling behaviour and the effect of lipids on dustbathing behaviour in laying hens Gallus gallus domesticus.Crossref | GoogleScholarGoogle Scholar | 24896430PubMed |

Vestergaard K (1982) Dust-bathing in the domestic fowl. Diurnal rhythm and dust deprivation. Applied Animal Ethology 8, 487–495.
Dust-bathing in the domestic fowl. Diurnal rhythm and dust deprivation.Crossref | GoogleScholarGoogle Scholar |

Vestergaard K, Lisborg L (1993) A model of feather pecking development which relates to dustbathing in the fowl. Behaviour 126, 291–308.
A model of feather pecking development which relates to dustbathing in the fowl.Crossref | GoogleScholarGoogle Scholar |

Vestergaard KS, Kruijt JP, Hogan JA (1993) Feather pecking and chronic fear in groups of red junglefowl: their relations to dustbathing, rearing environment and social status. Animal Behaviour 45, 1127–1140.
Feather pecking and chronic fear in groups of red junglefowl: their relations to dustbathing, rearing environment and social status.Crossref | GoogleScholarGoogle Scholar |

Vestergaard KS, Skadhauge E, Lawson LG (1997) The stress of not being able to perform dustbathing in laying hens. Physiology & Behavior 62, 413–419.
The stress of not being able to perform dustbathing in laying hens.Crossref | GoogleScholarGoogle Scholar |

Waiblinger S, Zaludik K, Raubek J, Gruber B, Niebuhr K (2018) Human–hen relationship on grower and laying hen farms in Austria and associations with hen welfare. [Abstract]. In ‘Proceedings of the 52nd congress of the International Society for Applied Ethology’, 30 July–3 August 2018, Charlottetown, Prince Edward Island, Canada. (Eds M Cockram, T Tennessen, L Bate, R Bergeron, S Cloutier, A Fisher, M Hötzel) p. 187.

Wall H, Tauson R, Elwinger K (2002) Effect of nest design, passages, and hybrid on use of nest and production performance of layers in furnished cages. Poultry Science 81, 333–339.
Effect of nest design, passages, and hybrid on use of nest and production performance of layers in furnished cages.Crossref | GoogleScholarGoogle Scholar | 11902408PubMed |

Weeks CA, Nicol CJ (2006) Behavioural needs, priorities and preferences of laying hens. World’s Poultry Science Journal 62, 296–307.
Behavioural needs, priorities and preferences of laying hens.Crossref | GoogleScholarGoogle Scholar |

Wichman A, Keeling L (2009) The influence of losing or gaining access to peat on the dustbathing behaviour of laying hens. Animal Welfare 18, 149–157.

Widowski TM, Duncan IJH (2000) Working for a dustbath: are hens increasing pleasure rather than reducing suffering? Applied Animal Behaviour Science 68, 39–53.
Working for a dustbath: are hens increasing pleasure rather than reducing suffering?Crossref | GoogleScholarGoogle Scholar | 10771314PubMed |

Widowski TM, Hemsworth PH (2008) Housing hens to suit their ‘needs’. In ‘Proceedings of the XXIII world’s poultry congress’, 30 June–4 July 2008, Brisbane, Qld, Australia. p. 241. (World's Poultry Science Association: Amsterdam, The Netherlands)

Widowski TM, Hemsworth PH, Barnett JL, Rault J-L (2016) Laying hen welfare I. Social environment and space. World’s Poultry Science Journal 72, 333–342.
Laying hen welfare I. Social environment and space.Crossref | GoogleScholarGoogle Scholar |

Widowski TM, Caston LJ, Hunniford ME, Cooley L, Torrey S (2017a) The effect of space allowance and cage size on laying hens housed in furnished cages, Part I: performance and well-being. Poultry Science 96, 3805–3815.
The effect of space allowance and cage size on laying hens housed in furnished cages, Part I: performance and well-being.Crossref | GoogleScholarGoogle Scholar | 29050408PubMed |

Widowski TM, Caston LJ, Casey-Trott TM, Hunniford ME (2017b) The effect of space allowance and cage size on laying hens housed in furnished cages, Part II: behavior at the feeder. Poultry Science 96, 3816–3823.
The effect of space allowance and cage size on laying hens housed in furnished cages, Part II: behavior at the feeder.Crossref | GoogleScholarGoogle Scholar | 29050409PubMed |

Wong RY, French J, Russ JB (2019) Differences in stress reactivity between zebrafish with alternative stress coping styles. Royal Society Open Science 6, 181797
Differences in stress reactivity between zebrafish with alternative stress coping styles.Crossref | GoogleScholarGoogle Scholar | 31218026PubMed |

Wood-Gush DGM, Gilbert AB (1964) The control of the nesting behaviour of the domestic hen: II. The role of the ovary. Animal Behaviour 12, 451–453.
The control of the nesting behaviour of the domestic hen: II. The role of the ovary.Crossref | GoogleScholarGoogle Scholar |

Wood-Gush DGM, Gilbert AB (1969) Oestrogen and pre-laying behaviour of the domestic hen. Animal Behaviour 17, 586–589.
Oestrogen and pre-laying behaviour of the domestic hen.Crossref | GoogleScholarGoogle Scholar |

Yue A, Duncan IJH (2003) Frustrated nesting behaviour: relation to extracuticular shell calcium and bone strength in White Leghorn hens. British Poultry Science 44, 175–181.
Frustrated nesting behaviour: relation to extracuticular shell calcium and bone strength in White Leghorn hens.Crossref | GoogleScholarGoogle Scholar |

Zimmerman PH, Koene P, van Hooff JARAM (2000) Thwarting of behaviour in different contexts and the gakel-call in the laying hen. Applied Animal Behaviour Science 69, 255–264.
Thwarting of behaviour in different contexts and the gakel-call in the laying hen.Crossref | GoogleScholarGoogle Scholar | 10915912PubMed |

Zupan M, Kruschwitz A, Buchwalder T, Huber-Eicher B, Stuhec I (2008) Comparison of the prelaying behavior of nest layers and litter layers. Poultry Science 87, 399–404.
Comparison of the prelaying behavior of nest layers and litter layers.Crossref | GoogleScholarGoogle Scholar | 18281565PubMed |