Animals with skeletons that look like they can fly have muscles that don’t support that idea. Chickens are better at walking than flying.
The muscle cells in chicken breast are mostly made for short bursts of activity rather than long flights, which is why the meat is white. Muscle cells in the dark meat of the legs and thighs are mostly made for long-term work, like walking. Other types of birds that are better flyers than chickens have all dark meat muscle.
Chicken bones definitely feel lighter and more fragile compared to the bones of mammals and other animals Their unique structure leads to the common question – are chicken bones hollow? In this comprehensive guide, we’ll examine chicken skeletal anatomy in detail to uncover the truth
An Overview of Chicken Bone Composition
Yes, chicken bones are in fact hollow to some degree. Their bones contain a hollow medullary cavity in the center, unlike the solid bones of mammals. However, they aren’t completely hollow. The medullary cavity has some supportive structures inside like trabeculae (a lattice of bony tissue) that provide reinforcement. Plus, bone marrow, fluid and air fill the open space. Dense cortical bone also encapsulates each bone, adding sturdiness.
So while chicken bones have a hollow interior they remain remarkably strong relative to their light weight.
Special Medullary Bone in Laying Hens
Right before an egg-laying hen starts her reproductive cycle, unique medullary bone tissue forms inside her long bones and ribs. This temporary bone acts as a labile calcium reserve to be quickly tapped for eggshell production.
Laying hens need a lot of calcium every day to make their eggshells strong. When an egg forms, the medullary bone quickly releases its stored calcium. This special bone starts to go away when the hen stops laying eggs as quickly.
Similarities and Differences from Other Bird Bones
All bird skeletons have features aiding flight – fused bones, hollow interiors, light weight. The main variation is in shape and structural reinforcement.
Small birds like finches have very thin, lightweight bones with minimal internal bracing. Larger, heavier birds like chickens and turkeys need thicker cortical bone and more trabeculae crossing their marrow cavities to handle greater stresses.
Evolutionary Adaptations Enabling Flight
Weight Reduction
The hollow bones of chickens and other birds evolved to enable flight. Air sacs filling the bones make them very lightweight yet strong. In fact, a chicken’s skeleton is only about 5-8% of its total body weight, versus around 15% in mammals. This major weight reduction lets chickens take off and stay airborne.
Chickens also evolved other weight-saving features – no urinary bladder/teeth, lightweight beaks instead of heavy jawbones, and a long balancing tail. These shed excess mass from non-critical areas, allowing more energy expenditure on takeoffs and evading aerial predators.
Enhanced Breathing Efficiency
Another key flight adaptation is chickens’ highly efficient respiratory system enabling excellent oxygen circulation. Rather than lungs alone, chickens have a system of 9 air sacs integrated with their hollow bones and lungs.
One study found this allows chickens to extract 80% of oxygen from inhaled air, compared to just 15% in mammals. This gives superior stamina and energy for sustained flight.
Their small lungs compared to their bodies make them perfect for activities that need a lot of oxygen, like running or flying.
Impacts on Bone Strength
More Susceptible to Fractures
Due to their lightweight structure, chickens’ bones cannot withstand as much pressure or impact before cracking compared to mammals’ solid bones. Studies show bone fracture rates in laying hens range from 20-35% across housing systems, commonly occurring in the keel and ribs due to collisions.
Fractures negatively impact chicken health and welfare. Breaks can cause hemorrhage, infection, tissue trauma and pain. Broken ribs impair breathing while keel fractures stop hens from perching or lying down comfortably.
Osteoporosis in Laying Hens
Laying hens can also get osteoporosis later in life because they need so much calcium to lay eggs all the time. They get a lot of the calcium they need for their eggshells from specialized structural medullary bone.
Most of this woven, sponge-like bone tissue gets depleted by 20 weeks of age. The resulting osteoporosis makes older hens more fragile and injury-prone, with 3-4 times higher keel bone damage rates.
However, heritage breeds like Plymouth Rocks allowed to live out normal lifespans can recover some bone density over time with proper nutrition and habitat enrichment.
Care and Handling Considerations
Avoid Breaks When Handling
To avoid fractures when handling chickens:
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Pick up adult chickens gently, supporting their body – don’t lift by legs or wings.
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Corner chickens calmly rather than chasing them prior to catching.
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Limit fall heights to under 3 feet when carrying.
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Transport in proper carriers, not stacked crates.
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Ensure housing doesn’t allow collisions into walls or fixtures.
Following these precautions greatly reduces risk of traumatic injuries to chickens’ delicate bones.
Nutrition for Bone Health
Proper diet is crucial for strengthening chickens’ fragile bones. Make sure you get enough zinc, manganese, calcium, phosphorus, vitamin D, and other minerals. Consider bone-boosting supplements too. Chickens’ hollow bones can reach their best structural integrity when they get all the nutrients they need.
Other Birds With Hollow Bones
Many birds possess hollow bones as an adaptation for flight, including:
- Songbirds like finches, sparrows, blue jays
- Pigeons and doves
- Birds of prey like eagles, hawks and vultures
Their specialized bone structure minimizes weight while retaining enough strength for hunting and aerial maneuvers.
This article is from the book:Â
Julie Gauthier is board certified in veterinary preventive medicine.
Rob Ludlow is the author of Raising Chickens For Dummies and co-author of Building Chicken Coops For Dummies and Chicken Health For Dummies.
Are Chicken Bones Safe To Feed Your Pet? The Answer May Surprise You
FAQ
Which bones are hollow in humans?
Hollow bones which are called pneumatic bones comprise the skull, humerus, clavicle, keel, pelvis, and lumbar and sacral vertebrae.
Can dogs pass chicken bones?
While dogs can sometimes pass chicken bones without issue, they can also be dangerous. Chicken bones that have been cooked are less likely to break and hurt the meat inside, while raw bones can hold germs that are bad for you.
Are bones supposed to be hollow?
Structure of a bone Compact bone is the dense, hard, smooth outer part of a bone. It surrounds the medullary cavity and contains blood vessels and nerves. The medullary cavity is the hollow part of bone that contains bone marrow. The bone marrow makes blood cells and stores fat.
Are the bones of birds hollow?
Birds are now considered as the living relatives of dinosaurs, especially the theropods (meat-eating, bipedal dinosaurs). And just like their ancestors, they have pneumatic bones. It means that the bones are hollow and have dense struts to provide strength without excess weight.
Do chickens have hollow bones?
Chickens do have some hollow bones, yes. Although they are not completely hollow, they have some support structures inside, as well as fluid and air. Why Do All Birds Have Hollow Bones? Do Chickens Have Bones in Their Wings? In Summary – Why.
What is the skeletal system of a chicken?
The skeletal system does more than just hold the chicken up. It also stores calcium and, believe it or not, helps the bird breathe. The skeletal system is made up of two types of bones: pneumatic and articular. Pneumatic bones are hollow and connect to the respiratory system through air sacs.
What are the different types of bones in chickens?
Bone types in chickens (and other birds), fused bones, names of bones and more. The chicken skeleton provides structural support for the bird but also has two other functions, respiration and calcium transport. The pelvic bones and the medullary bones are the two main types of bones that make up the skeleton.
Do chickens have a backbone?
Chicken Backbone: Chickens are vertebrates (animals which have a backbone). Depending on the breed of chicken most breeds have about 20 vertebrae. The backbone of the chicken starts at the atlas (a small bone at the top of the spine) which allows the chickens to move their head. The spine of the chicken ends at the cervical bone.
Are all bones hollow?
While hollow, they are by no means weak. The solid portion of these bones is much denser than bones found in mammals. These bones include the ilium, or hip bones, the humerus in the wing, the keel or breast bone, the clavicle, some lumbar and thoracic vertebras, and the occipital bones of the skull.
Where does the backbone of a chicken start and end?
The backbone of the chicken starts at the atlas (a small bone at the top of the spine) which allows the chickens to move their head. The spine of the chicken ends at the cervical bone. The wishbone is the slingshot looking bone and is sometimes pulled apart and a person who gets a larger part makes a wish.