Fear of people can cut hens' egg output, but farm studies give mixed results

Fear of people can lower a laying hen's egg output and harm her welfare, Jagonews24 reported in an explainer published on 28 October 2025, drawing on Poultry Hub Australia, a poultry information service based at the University of New England in Armidale. The explainer said a hen that panics, tries to flee or freezes when a person appears is showing a protective response that becomes a problem when it lasts, and that calm behaviour by farm workers can reduce it. The research behind that account comes mainly from Australia, the United States and Europe. It supports the link in controlled experiments, while studies on commercial farms have given mixed results.

Poultry Hub's fact sheet "Fear in poultry", which an Australian research report lists as written by the researcher Lauren Edwards in 2005, describes fear as a protective mechanism. It makes an animal respond to something potentially harmful, real or perceived, by escaping or defending itself. The sheet compares it to hunger and thirst as a state of motivation. It cannot be measured directly, so researchers infer it from how a bird reacts to a frightening situation.

The behavioural signs the sheet lists are:

• escape and avoidance
• defensive behaviour
• freezing and immobility
• vocalisations

Part of this fear is inborn. The Australian Poultry Cooperative Research Centre (CRC) report on human-animal relationships in laying hens, completed in January 2009 under Professor Paul Hemsworth of the University of Melbourne, notes that young chicks with no experience already avoid people, perhaps because a person looks like a predator or simply a new object. A 2019 opinion by the European Food Safety Authority's (EFSA) animal health and welfare panel says domestication and breeding have reduced fear responses in poultry, but birds still see humans as predators. Poultry Hub adds that the first wariness, due to unfamiliarity, may turn into a specific fear of people over time if contact is unpredictable, sudden or unpleasant.

Whether fear amounts to suffering is a question scientists word carefully. The CRC report describes fear as an undesirable emotional state that may constitute suffering and reduced welfare. A chapter on poultry welfare in the Food and Agriculture Organization's (FAO) 2013 Poultry Development Review says animals should not suffer from unpleasant mental states such as pain, fear and distress, and adds that these feelings cannot be measured directly. Freedom from fear and distress is one of the Five Freedoms set out by the United Kingdom's Farm Animal Welfare Council, and a good human-animal relationship is among the twelve welfare criteria that chapter lists.

According to Poultry Hub, the first bodily response is the release of adrenaline into the blood, which raises the heart rate and mobilises energy. If that fight or flight response does not settle the matter, a stress hormone called corticosterone is released as well. This acute stress response can last up to several hours, and during it corticosterone is useful because it raises blood glucose and gives the bird energy to escape or defend itself. If the threat is removed at this stage, the sheet says, the bird suffers no ill consequences beyond a fright and a small loss of energy.

The trouble comes when the stressor continues or acute responses keep repeating. The bird then moves into a chronic stress response, in which prolonged high corticosterone can reduce health, productivity and immunity. The sheet says corticosterone affects the bird's nitrogen balance, increasing protein breakdown and energy use, which in turn affects reproductive output. It presents this as the assumed explanation for lower productivity in fearful birds, not as something proven in every flock. The CRC report adds that repeated exposure to something frightening, such as a stockperson doing daily routine work, can produce chronic stress.

Measuring this is not simple. A 2016 review in Poultry Science by C. G. Scanes says many, but not all, stresses raise corticosterone in chickens, that reported levels differ markedly between studies, and that several measures should be used together, such as the ratio of two white blood cell types, heterophils and lymphocytes, which shifts with stress. Taking a blood sample is itself stressful for a bird. In 2008 the Australian researchers J. A. Downing and W. L. Bryden showed that corticosterone in egg white rises when hens are handled, kept in high heat or moved to new cages, which offers a way to measure stress without touching the bird.

Most of the work on hens and people uses simple tests on caged birds. In the Approaching Human Test, a researcher steps up to a cage and counts how many hens stay at the front with their heads near the wire. In the Stroll Test, the researcher walks along an aisle at one step per second while being filmed, and the distance to the first bird with its head out of the cage is measured. Fewer birds at the front, or a greater distance, is read as greater fear. Other studies use fear of a new object, or tonic immobility, a standard fear measure.

Early Australian work pointed to a clear link. In a 1989 study in British Poultry Science, P. H. Hemsworth and J. L. Barnett found that hens in the top tier of cages avoided an approaching experimenter more and, in the third of three four-week periods, had lower production and poorer feed efficiency than hens in the bottom tier. They suggested that greater fear may have been responsible. In 1992 Barnett, Hemsworth and E. A. Newman studied 16 sheds on 14 commercial farms and found that responses to people accounted for between 23 and 63 percent of the variation in a number of production measures. They concluded that fear of humans may be a factor limiting productivity.

Experiments added weight. A 1994 study by Barnett and colleagues, as the CRC report describes it, gave 19-week-old hens daily positive visual contact with people, using slow and deliberate movements, for 17 weeks. Egg production was 6 percent better than in control hens that had minimal contact. A 2019 paper's summary of such work says extra positive contact also reduced fear and the corticosterone response to handling, and improved immune function.

The CRC project then tested the idea at a larger scale, and the results did not all point the same way. Its field study covered 20 sheds in Australia and 9 in the United States between March 2005 and June 2006, all with conventional cages. There, flocks that avoided people more kept up a high rate of lay for longer and had lower corticosterone in their egg white, the opposite of what was expected. The authors stressed that a field study shows association and not cause. They suggested that loud cleaning with air hoses and leaf blowers may have made hens more fearful while also keeping the sheds cleaner and the birds healthier, and that the eggs sampled may not have represented the whole flock.

The project's controlled experiment used 288 Hy-Line White chicks hatched in October 2006 at the Wooster campus of Ohio State University. From 18 weeks of age, for 20 weeks, some hens had a person stand quietly close to their cage for 30 seconds each weekday. Others met sudden, unpredictable contact: an umbrella opened and shut, a brightly patterned folder, a feather duster swept across the cage, or a person stepping up abruptly. The calm group's adjusted rate of lay was 91.4 percent against 90.2 percent in the other group, a difference the report calls small but significant. Its corticosterone response tended to be lower, though that was only a trend. Fear scores themselves were not directly correlated with production.

From all this the report concluded that the experiment demonstrated that fear of humans can reduce egg production, while the field study did not show a negative link. A 2019 paper in the journal Animals by Edwards, Grahame Coleman, Kym Butler and Hemsworth examined 19 Australian laying houses on 10 farms, with flocks of 1,320 to 121,968 birds. Peak production lasted longer where hens avoided people less and where stockpeople made less noise, each a difference of about five weeks between the extremes. However, the hens that avoided people least had the highest corticosterone, and the authors could not confirm a link between stockperson behaviour and avoidance. Cage width also mattered: cages wider than 60 cm had at least ten more weeks at peak than those of 50 cm or less.

Other work points the same general way. A 2013 study from Wageningen University of 20 commercial parent-stock flocks linked high fear of a stationary person with high mortality in ISA Brown flocks, and high fear of a new object with lower body weight, egg weight and feed intake in Dekalb White flocks.

The Jagonews24 explainer named rough behaviour by people among the main causes of misshapen shells. The research supports a narrower statement. Poultry Hub says negative handling has been found to increase fear and eggshell deformities and to lower productivity. The best-known experiments, however, involve disturbance in general and not shouting in particular.

In 1986 B. O. Hughes, A. B. Gilbert and M. F. Brown reported that moving hens from pens to cages lowered egg production and raised the share of abnormal eggs over the next 18 days. Disturbing flocks on deep litter raised abnormal shells the following day, even in an adjacent flock. Keeping hens out of their nest boxes made them hold eggs in the shell gland and produced more coated eggs. The kind of defect depended on when the disturbance came. Early, when the egg was only lightly calcified, it tended to produce misshapen eggs. Late, when laying was near, it tended to produce eggs coated in extra calcium.

In 1999 M. Reynard and C. J. Savory of the Roslin Institute in Scotland moved ISA Brown hens into cages with unfamiliar hens shortly before they were due to lay, which reliably delayed laying. If the delay was still more than about 2.4 hours when the stress ended, the egg usually came 7 to 15 hours late, white-banded, and the next egg was slab-sided or occasionally soft-shelled. Abnormal shells lead to downgrading and can impair embryo development, they noted, and can serve as an indicator of environmental stress.

Routine handling is not always free of this effect either. A 1976 study by Hughes and Black, described in the CRC report, caught and briefly held hens daily and found more shell deformities but no change in egg production, and its authors called regular handling a mild stressor. In the CRC experiment itself, the abnormal-egg results followed no clear pattern and the treatments explained very little of the variation. Fear is therefore one possible cause of shell problems, not an established leading one.

Poultry Hub notes that panicked escape attempts inside a cage can injure a bird and her cage-mates, and that negative handling has been found to lower feed efficiency, resistance to infection, ease of handling and growth. The FAO chapter says chronic stress can impair immune function and lead to more disease, more deaths and lower production, and that moving hens from pens to cages causes a marked short-term fall in egg output.

The most direct evidence on disease comes from young chickens, not laying flocks. In 1982 W. B. Gross and P. B. Siegel reported in the American Journal of Veterinary Research that chickens talked to, offered food and gently handled for seven weeks showed more than a 60 percent reduction in death and pericarditis after a challenge with E. coli, compared with ignored birds, along with better feed efficiency and antibody response. The CRC report cites work linking fear of humans in broilers with higher first-week mortality and poorer feed conversion. The 2019 paper in Animals also records earlier work on free-range farms in which negative stockperson attitudes went with more feather damage and higher mortality.

The explainer's central advice was calm behaviour, and here the evidence is more consistent. In the CRC field study, hens showed less fear in sheds where stockpeople spent more time standing still and made more close approaches to cages. Noise was the most consistent link with greater fear. Most of it came from air hoses and leaf blowers used for cleaning, at about 90 decibels, and other work cited there found that an hour at that level raised both stress and fear measures in hens. Stockpeople's attitudes tracked their behaviour: negative attitudes went with more noise, faster movement and less time standing still, and attitudes were poorer in larger workforces. The 2019 Australian paper again tied negative attitudes to noise, though not to avoidance.

Closeness mattered more than time. In an experiment on a commercial farm in central Victoria, hens in four sheds received contact for 2, 30 or 90 seconds at 0, 75 or 150 cm from the cage, for 28 days. Those with contact right at the cage showed the least avoidance and the length of contact made no difference. Touch is not required. Poultry Hub says slow, predictable visual contact works and costs nothing, and a 1993 study by R. B. Jones found visual contact at least as effective as gentle stroking in chicks. Close contact need not mean staring: the project team kept test hens in the lower tier of cages, away from researchers' faces, partly because of the possible effect of eye contact on fear.

The report said firm recommendations should wait for a tested training programme, but it listed what such training would target:

• not leaving loud equipment running when it is not needed
• not banging metal objects, such as when cleaning manure scrapers
• putting large or heavy objects down, not throwing them
• standing closer to cages, or running a hand along the feed trough, while walking through the shed
• giving chicks and pullets regular, neutral contact with people

Poultry Hub's January 2013 news item on the work put the benefit modestly: a calmer flock is more pleasant to work with and may be good for productivity.

Early contact showed a lasting effect. In the Ohio experiment, a person standing quietly near the cages for an extra 12 minutes each weekday, from 5 to 16 weeks of age, was followed by lower fear in adulthood, although the groups did not differ at the first test at 18 weeks. Those birds also coped better with startling contact later on.

Official guidance says much the same. England's Code of Practice for laying hens and pullets, in force since August 2018, calls stockmanship one of the most important influences on hen welfare. It says birds should be handled carefully from an early age, that frequent inspection helps hens accept people as a normal part of daily life, and that sudden noise and movement should be avoided. Catching should be quiet and confident, and caged hens should be taken out one at a time and held by both legs. The FAO review says the people who care for poultry should be well trained and should avoid exposing birds to situations that may cause stress. The EFSA opinion, on the killing of poultry, lists staff shouting as a source of fear when birds are handled, with staff training and an end to shouting as the remedy.

The explainer also recommended objects in the cage and breeding calmer hens. Poultry Hub presents enrichment as a theory: birds that meet harmless novelty learn that novelty need not be feared and adapt better later. A 2019 review in Poultry Science by D. L. M. Campbell, E. N. de Haas and C. Lee shows why caution is needed. Balls, buttons, thimbles and drawings changed every three days reduced chicks' fear at three weeks in one study from 1992, and a mix of objects, handling, human presence and radio voices reduced fear at catching in another. But pecking strings, grain and deeper litter had no effect in two later studies, and aviary rearing lowered fear for up to five weeks after transfer, with long-term benefits unclear. The review calls commercial-scale research on objects poor and asks for validation on farms. England's code lists straw bales, pecking objects and dustbathing boxes as enrichment, and recommends perches for roosting and for getting away from other birds, not specifically for reducing fear of people.

Poultry Hub calls genetic selection the most likely long-term way to reduce fear in commercial flocks, while adding that no single method is likely to be enough. Strain differences are real: the CRC report notes that white hens have long been described as flighty and brown ones as docile, and it found much greater avoidance in the white strains on US farms than in the brown strains in Australia. Evidence that calmer birds lay more is thinner. When Swedish researchers at Linköping University bred red junglefowl, the ancestor of domestic chickens, for four generations for low fear of people, the birds grew heavier and laid larger eggs, but they also became more aggressive and dominant. That was a study of junglefowl, not commercial layers.

None of the studies above was carried out in Bangladesh, but the kinds of hen and housing they tested are in use there. A 2020 poultry sector study commissioned by the Netherlands Enterprise Agency says the most reared layer strains include Hy-Line Brown and White and ISA Brown and White. It estimated 74 million layer and layer Sonali birds in 2019 and put the layer segment's output at 12.5 billion eggs, with 50 to 60 percent of layers on independent farms of 4,000 to 8,000 birds using relatively low-tech equipment and basic housing. FAO's 2008 country review recorded a Department of Livestock Services estimate of 21,712 layer farms in May 2008, and gave a caged layer farm with open sheds as an example of a low-biosecurity commercial system. A column in the Daily Observer in October 2024 cited the department's figure of about 19 billion eggs for annual demand and expected nearly 23.74 billion eggs to be produced in 2024.

A fall in laying or poor shells should not be put down to fear without checking other causes. Banglapedia, for example, records that Newcastle disease sharply cuts the quantity and quality of eggs in laying hens and is the principal cause of fowl deaths in rural Bangladesh. This report gives no treatment or drug advice; farmers with sick birds should go to the upazila livestock officer.

Photo: Maqi / Wikimedia Commons (CC BY-SA 3.0). The top picture shows hens in a battery cage on a farm, as background; it is not from any farm or study named in this report.

Sources: Jagonews24 (28 October 2025), Poultry Hub Australia ("Fear in poultry"; "Former Poultry CRC student reducing fear in hens", January 2013), Australian Poultry CRC final report 03-19 (March 2009), Animals (Edwards et al., May 2019), British Poultry Science (Hemsworth and Barnett, 1989; Barnett et al., 1992; Hughes et al., 1986; Reynard and Savory, 1999), Poultry Science (de Haas et al., 2013; Scanes, 2016; Campbell et al., 2019), Physiology and Behavior (Downing and Bryden, 2008), American Journal of Veterinary Research (Gross and Siegel, 1982), Animal (Agnvall et al., 2014), EFSA Journal (November 2019), FAO Poultry Development Review (2013), FAO Poultry sector country review: Bangladesh (2008), UK government Code of Practice for the welfare of laying hens and pullets (England, 2018), Netherlands Enterprise Agency poultry sector study (May 2020), The Daily Observer (11 October 2024), Banglapedia.