Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsiTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
Mammalian milk is made by mammary glands; pigeon and dove crop milk is made by specialized cells in the crop, a pouch in the upper digestive tract. Both nourish young, but they come from different tissues. Many animals—including birds—also feed offspring by regurgitating food or delivering prey, rather than producing a milk-like secretion.
How are mammalian milk and crop milk different?
The key difference is where each food comes from. Mammals produce milk in mammary glands. Pigeons and doves produce crop milk when specialized cells lining the crop multiply and are shed into material fed to their chicks. The crop is part of the digestive tract, not a mammary gland.
| Feeding method | Where the food comes from | Example | What distinguishes it |
|---|---|---|---|
| Mammalian milk | Mammary glands | Mammals, including monotremes such as the platypus | A mammalian secretion; composition varies among species. Monotremes release milk onto skin rather than through nipples. |
| Crop milk | Specialized cells lining the crop | Pigeons and doves | Crop-lining cells proliferate and are shed; parents pass the material to chicks. |
| Other milk-like bird secretion | Crop or another part of the upper digestive tract, depending on the bird | Flamingos and emperor penguins | It serves a similar feeding role, but the source tissue need not be identical to pigeon crop milk. |
| Regurgitated food or prey transfer | Food the parent has eaten or prey it has captured | Many birds | The parent transfers food rather than making a dedicated milk-like secretion. |
These distinctions follow the descriptions of mammalian mammary glands, the British Trust for Ornithology’s account of crop milk, and a review of pigeon crop-milk secretion and parental behavior.
How do pigeons and doves make crop milk?
In pigeons and doves, the hormone prolactin stimulates specialized epithelial cells lining the crop sac. The cells multiply, then are shed and become part of the nutrient-rich material parents feed to newly hatched chicks. The parent delivers it by regurgitation, but the food is not simply ordinary meal regurgitated unchanged: the shed cells make it a specialized secretion.
#1 Best Overall
Both male and female pigeons can produce crop milk. This is a trait of pigeons and doves, not a general rule for birds. A review describes the mechanism and parental behavior in pigeons and doves; a 2012 PLOS ONE study reports that pigeon crop milk contains about 60% protein, 32–36% fat, and 1–3% carbohydrate. Those figures apply to the pigeon crop milk discussed in that paper; they should not be treated as a recipe for every bird secretion or compared as if they described all mammalian milk.
Which other birds produce milk-like secretions?
Flamingos and emperor penguins are also reported to feed their young with milk-like secretions. The phrase “crop milk” is often used broadly in everyday discussion, but it can blur anatomical differences: secretions may come from different regions of the upper digestive tract. A similar purpose—feeding dependent young—does not establish that the tissue or production process is identical across these birds.
Flamingo accounts also need a scope qualification. The Smithsonian National Zoo’s 2026 discussion describes observations of chicks being raised at the zoo; those observations are not, by themselves, a universal rule for every flamingo or every setting.
Free tools Windows power users keep installed
One-click scans. No signup required.
How do animals feed young without producing milk?
Parents can transfer food they have already gathered or eaten. Birds may regurgitate food for chicks or carry captured prey directly to them. In those cases, the parent is providing nourishment, but it is not necessarily producing a specialized secretion. Regurgitation alone does not make food “crop milk”; in pigeons and doves, crop milk specifically includes material from shed crop cells.
To distinguish feeding strategies, ask four questions:
- Where did the food originate? It may be produced in a gland or digestive-tract tissue, or gathered and captured elsewhere.
- What tissue makes it? Mammary glands produce mammalian milk; crop-lining cells produce pigeon and dove crop milk.
- Is it a secretion or transferred food? A specialized secretion differs from a parent passing on ordinary food or prey.
- How is it delivered? Young may suckle, lick milk from skin, or receive food passed by a parent.
Do all young depend on these foods in the same way?
No universal duration or diet pattern applies across the named bird groups. The feeding method and the young’s reliance on it vary by species and context. The cited sources establish that these secretions nourish young, but they do not support one timeline or a single claim that every young animal receives only milk-like food.
Rank #4
Mammalian milk also varies substantially in composition among species. The Smithsonian National Zoo’s Milk Repository describes research and samples spanning more than 200 mammal species; that is a description of the repository’s collection, not a count of all mammal species.
PC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteHow do monotremes deliver milk without nipples?
Monotremes, including the platypus, are mammals, but they do not deliver milk through nipples. Milk is secreted onto the mother’s skin, where young lick it. This is still mammalian milk because it comes from mammary glands; the delivery method differs from the familiar nursing pattern. Animal Diversity Web describes this form of delivery, and a Smithsonian Institution document gives the platypus as an example.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
