🏠 Natural Behavior + Housing

Aviary Housing – Tier Arrangement & Navigation Aids

Tier 1
 Ground floor

Navigation Aids – Inside the System
 Perches, terraces/platforms, stairs, ramps

Navigation Aids – Outside the System
 External structures that help birds access tiers safely

Downward Movement in the Air – Hens

Flight Capacity
 Egg-laying hens have limited flight ability

From 1.5 meters
 None could support > 80% of body weight
 Half-clipped hens managed < 50% body weight

Descent Speed
 2.41–3.57 m/s, 2–3× faster than smaller birds (pigeons, zebra finches, diamond doves)

Key Point
 Greater mass → higher kinetic energy at landing → increased injury risk

Perching & Roosting

Motivation
 High nighttime roosting indicates a strongly motivated natural behaviour
 Birds prioritize height over grip when choosing perches

Development
 Chicks start perching at ~ 2 weeks old
 Settled nighttime roosting occurs at ~ 6 weeks of age

Importance of Perches During Rearing
 Supports muscle tone, spatial awareness, and balance

Key Point
 Providing perches early is essential for normal development and expression of natural behaviours

Perching & Roosting – Behaviour and Design

Natural Behaviour
 Hens roost at night for protection against predators
 Highly motivated: hens work to access perches at night
 Up to 100% use perches at night, some use during the day

Perch Design
 Critical for keel bone and foot pad integrity

Key Point
 Nighttime perching is a strong natural behaviour, and perch design affects welfare and skeletal health

Balance & Vision in Birds

Testing
 Birds tested with obstructed sight to exclude visual compensation for body equilibrium

Perch Trials
 Mechanic perch velocities: 0.16, 0.24, 0.34 m/s
 Tested with different perch diameters

Key Point
 Balance in birds relies on multiple sensory inputs, not just vision

Locomotion & Navigation in Laying Hens

Overview
 Laying hens and pullets are bipedal birds with limited flight ability
 Effective navigation in multi-tiered aviary systems depends on: experience, strain, health, and feather condition

Ramp Design
 Ramps angled ≤ 45° between tiers allow easier navigation
 Steeper ramps create movement challenges

Perch Placement
 Birds struggle with diagonal perches > 45°
 Difficulty also occurs with vertical or horizontal perches when spacing > 75–80 cm

Grasping Ability
 Surface friction of ramps, platforms, and perches affects stability and balance

Key Point
 Well-designed ramps, perches, and platforms are essential for safe and efficient movement in aviaries

Binocular and Monocular Sleep

Definition
 Binocular sleep – both eyes closed simultaneously
 Monocular sleep – one eye closed while the other remains open

Function
 Monocular sleep allows vigilance against predators while resting
 Binocular sleep is used when the bird feels safe and protected

Key Point
 Birds alternate between monocular and binocular sleep to balance rest and predator awareness

Comfort / Self-Maintenance Behaviour

Definition
 Comfort behaviours – actions birds perform to maintain their body condition and relieve stress

Examples
 Preening – cleaning and aligning feathers with the beak; spreads oil from the uropygial gland
 Head / Body Stretching – stretches muscles and joints
 Wing-Flapping – loosens muscles and stimulates circulation
 Head / Tail Shaking – removes debris or water
 Feather Raising – adjusts feather position for comfort
 Dustbathing – removes parasites and excess oil

Key Observations
 Birds perform these behaviours seldom in cramped conditions
 When space is restricted, they show rebound behaviour – performing the actions for longer periods when space is available
 Frequent, short preening bouts often occur after a mild stressor or during frustration

Space for Behavioural Expression

Personal Space
 Hens prefer personal space but will clump around resources such as feed

Space Requirements
 Standing: ~475 cm² per hen
 Wing-Flapping: ~1876 cm² per hen
 Caged systems provide much less than required
 Alternative systems allow better expression:
  Floor systems: 9 birds/m²
  Organic systems: 6 birds/m²

Dustbathing

Behaviour
 Hen lays down and tosses loose substrate onto back and wings
 Rubs substrate into feathers and shakes it out
 Often performed with preening

Functions
 Improves feather condition
 Distributes lipids and removes skin parasites

Substrate Preference
 Peat or sand preferred over sawdust or straw
 Longer dustbaths with all elements performed in peat or sand

Frequency & Social Aspect
 Occurs ~every 2 days
 Can be performed simultaneously in groups

Key Point
 Dustbathing is a natural maintenance behaviour essential for feather health and welfare

Sham-Dustbathing

Definition
 Occurs when hens perform dustbathing sequences without suitable substrate

Motivation & Reward
 Not rewarding – hens remain motivated to dustbathe
 Given proper litter after deprivation, hens spend a long time dustbathing

Occurrence
 Similar overall dustbathing in furnished cages and floor systems
 In cages, most dustbathing is sham-dustbathing due to lack of litter

Key Point
 Sham-dustbathing demonstrates hens’ strong motivation for natural substrate and welfare needs

Behaviour Across Housing Systems

Cage Systems (Conventional/Enriched)

Non-Cage Systems (Single-/Multi-Tier)

Key Point
 Housing system strongly affects hens’ ability to perform natural behaviours, impacting welfare and motivation

Furnished/Enriched Cages – Laying Hens

Structure
 Wire enclosure with extra space and elements: perches, nestbox (enclosed nest area), litter area, extra height

Group Sizes
 Small group: 10–12 birds
 Medium group: 15–30 birds
 Large group: ~60 birds
 Reference: LayWel 2009

Feeding & Drinking
 Food trough: 12 cm per hen
 Perches: 15 cm per hen
 Nest box: 750 cm² per hen; Desired: 800 cm²
 Cage minimum area: no cage less than 2000 cm²
 Cage height: 45 cm; Desired: 60 cm
 At least 2 nipple/cup drinkers per cage

Litter Area
 Allows scratching and pecking

Additional Notes
 Claw-shortening devices exist
 550 cm² per hen in conventional cages – EU banned

Key Point
 Furnished/enriched cages provide space, perches, nest area, and litter to support natural behaviors while meeting size and resource standards

Non-Cage Systems – Laying Hens

System Types
 Single-level systems
 Multi-level systems (aviary systems)

Space
 More space per bird: 1,111 cm² compared to 750–550 cm² in conventional cages

Features
 Perches, nests, and large scratching areas (litter)

Group Sizes
 Large groups, e.g., 5,000–30,000 birds

Key Point
 On-cage systems provide more space and resources than conventional cages and support natural behaviors in large flocks

Multi-Tier Systems – Aviary

Definition
 Multi-tier system also called Aviary

Nest Boxes
 Can be integrated or non-integrated

Flooring
 Several levels of perforated floors with manure belts underneath

Feed & Water
 Feeders and drinkers are distributed to provide equal access for all hens

Key Point
 Multi-tier systems allow vertical space use while ensuring nesting, feeding, and drinking for all birds

Covered Verandas/Wintergarden – Laying Hens

Definition
 Area near the house, indoors
 Covered veranda is not counted as usable area

Outdoor Access
 Open run or free range

Flooring & Hygiene
 Concrete floor, usually covered with litter
 Climate similar to outside, except for rain
 Covered with free-draining material to maintain good hygiene inside and outside the house

Access Points
 Pop holes allow hens to move between indoor and outdoor areas

Key Point
 Covered verandas/wintergardens provide protected outdoor-like space while supporting hygiene and movement

Canada’s Transition in Egg-Layer Housing

Enriched Colony Housing
 Also called enriched cages
 Currently houses 37% of hens

Alternative Systems
 Free run (aviaries/single-tier), organic, and free-range farming are increasing
 Now make up around 20% of hens nationwide

Key Point
 Canada is shifting from conventional cages to enriched and alternative housing systems to improve hen welfare

Welfare Potentials and Risks – Laying Hens

Welfare Potentials
 High space allowance → general freedom of movement
 Environmental stimulation → full repertoire of locomotion, body maintenance (sunbathing, dustbathing), exploration
 Additional nutritive and non-nutritive food → e.g., plants, insects, worms, little stones
 High number of birds outside → lower risk of feather pecking
 Fresh air and UV-light → natural disinfection

Welfare Risks
 Destruction of the run → mud, hygiene issues, weeks of regeneration
 Intake of infectious agents
 Predation → can be managed with suitable hybrids, fences dug into the ground, trees and shelter for aerial predators
 Labour, area, and cost demands → higher egg prices are necessary

Key Point
 Outdoor and enriched systems improve hen welfare but require careful management of hygiene, predators, and resources

Laying Hens Prefer to Forage in Fresh Air

Observation
 Hens show a strong preference for foraging outdoors rather than staying inside

Benefits
 Access to fresh air, natural food sources (plants, insects, worms), and space for locomotion and body maintenance

Key Point
 Providing outdoor access supports natural behaviors and improves welfare

Welfare Trade-Offs Among Housing Systems – Laying Hens

Conventional Cages
 Limited space and movement
 Minimal opportunity for natural behaviours like foraging, dustbathing, and perching

Enriched Cages
 Provide more space and amenities: perch, nest box, scratching area
 Allow some natural behaviours but still restricted compared to non-cage systems

Non-Cage Systems
 Greater freedom of movement and access to perches, litter, and scratching areas
 Support a wider range of natural behaviours
 Require careful management to reduce injuries, disease, and feather pecking

Mortality in Laying Hens – Cage vs. Non-Cage Systems

General Trend
 Mortality is generally higher in non-cage systems compared to furnished cages

Mortality Rates
 Commercial indoor & free-range systems: 3–12%
 Furnished cages: 2.8–5.4%
 Non-cage systems: 8–9.4%

Management Impact
 Good management practices can significantly reduce mortality in non-cage systems, e.g., from 22% to 6%

Key Point
 Furnished cages have lower mortality than non-cage systems, but proper management can improve survival in aviary, floor, and free-range systems

Mortality in Brown Layers – Cage vs. Floor Housed (Ontario)

Breeds Studied
 Hyline Brown 40%
 ISA Brown 50%
 Lohmann Brown 10%

Flock Sizes
 Cage-housed flocks: mean 15,194 hens (range 5,180–30,122)
 Floor-housed flocks: mean 8,208 hens (range 1,992–15,065)

Key Point
 Cage-housed flocks tend to be larger, while floor-housed flocks are smaller, which may influence mortality and management practices