Baby bunnies die at high rates compared to most mammals, whether wild or domestic. Only about half of wild cottontail kits survive long enough to leave the nest, and another half of those die before fall. Domestic kits face a different but equally dangerous set of threats: digestive failure, infection, chilling, and feeding problems. Understanding the specific causes can help if you’re raising rabbits or trying to care for orphaned kits.
Wild Kits Face Overwhelming Odds
For wild cottontail rabbits, the main causes of nest failure are predation and flooding. Cats, dogs, snakes, hawks, crows, and even lawnmowers destroy nests regularly. A cottontail nest is just a shallow depression in the ground lined with fur and grass, offering almost no protection. If a predator finds it, the entire litter is typically lost.
Flooding is the second major killer. A single heavy rainstorm can fill a ground-level nest with water, and newborn kits who get soaked lose body heat rapidly. Kits are born hairless and blind, with almost no ability to regulate their own temperature. Wet and cold is a fatal combination in the first week of life.
Even kits that survive the nest aren’t safe. Roughly 75% of wild cottontails born in a given year will die before reaching adulthood. This extreme mortality rate is the reason rabbits reproduce so prolifically. A single doe can have three to five litters per year.
Digestive Failure Is the Top Domestic Killer
In domestic rabbits, the digestive system is the most vulnerable point. A condition called enterotoxemia kills kits quickly, often within 24 to 48 hours of the first symptoms. The primary cause is a bacterium called Clostridium spiroforme, which produces a powerful toxin. This organism normally lives in the gut in small numbers, but when the balance of gut bacteria is disrupted, it multiplies rapidly and overwhelms the kit.
Diet plays a direct role. Enterotoxemia occurs less often when rabbits eat high-fiber diets. Kits that are weaned too early onto low-fiber food, or that experience sudden diet changes, are at the highest risk. Certain antibiotics can also trigger the condition by wiping out the normal gut bacteria that keep harmful species in check. Oral penicillin-type drugs, lincomycin, clindamycin, and erythromycin are all dangerous to rabbits for this reason.
A parasitic gut infection called coccidiosis is another major digestive threat. Caused by microscopic parasites in the Eimeria family, it attacks the intestinal lining and liver. One study of meat rabbits found an overall mortality rate of 20.9%, with gastrointestinal damage identified as the leading cause of death at necropsy. Kits pick up the parasite from contaminated bedding, food, or droppings, and crowded or unsanitary conditions make outbreaks far worse.
Hand-Feeding Often Goes Wrong
One of the most common reasons people lose baby bunnies is improper hand-rearing. Rabbit milk is radically different from cow or goat milk. It contains about 12.9% fat and 12.3% protein, with an energy density of roughly twice that of cow’s milk. It also has almost no lactose, less than 2%. This unusual composition is what allows rabbit kits to multiply their birth weight by six in just three weeks.
When people try to substitute cow’s milk, goat’s milk, or even standard puppy formula, the kit’s gut often can’t process it. The sugar content is too high, the fat and protein too low, and the result is diarrhea, dehydration, and bacterial overgrowth. Even with a proper kitten milk replacer (the closest commercial match), hand-reared kits still die at much higher rates than mother-raised ones. The margin for error is razor thin.
Aspiration is another risk during hand-feeding. Kits are tiny, and milk delivered too quickly or at the wrong angle enters the lungs instead of the stomach. This causes pneumonia that is almost always fatal in animals this small.
Mothers Aren’t Neglecting, They’re Hiding
Many people assume a mother rabbit has abandoned her babies because they never see her at the nest. This is normal behavior, not neglect. Rabbit does nurse only once or twice per day, usually in the early morning or at night, and they deliberately stay away from the nest the rest of the time to avoid attracting predators.
The signs that kits are being fed properly are physical: round, full bellies, warm skin, and quiet behavior. Kits that are starving will have wrinkled skin, sunken bellies, and will crawl around the nest crying. If you find a nest of wild bunnies and the kits look plump and warm, the mother is almost certainly still caring for them. Removing kits from a functioning nest and attempting to hand-rear them dramatically lowers their survival odds.
True maternal neglect does happen, though. First-time does sometimes fail to build a proper nest, scatter kits on the wire floor of a cage, or simply refuse to nurse. Kits born outside the nest box in a domestic setting can die from cold exposure within hours, even at room temperature.
Temperature and Chilling
Newborn rabbits cannot regulate their body temperature for roughly the first week of life. They depend entirely on the insulation of the nest (fur, hay, and the warmth of their littermates) to stay alive. A single kit separated from the group will chill and die far faster than a kit in a full litter. This is one reason smaller litters can be more vulnerable: fewer bodies means less shared warmth.
If you’re breeding rabbits, the nest box is critical. It needs to be small enough that kits stay clustered together, deep enough that they can’t crawl out, and packed with nesting material. In cold weather, even a brief gap in insulation can be lethal.
Viral Disease Can Wipe Out Entire Litters
Rabbit hemorrhagic disease (RHD) is a highly infectious viral illness that kills 50 to 100 percent of infected rabbits. The newer strain, RHDV2, can infect rabbits at any age, including very young kits. Older strains tended to spare animals under a certain age, but RHDV2 removed that protection.
The virus spreads through contact with an infected rabbit’s blood, droppings, urine, meat, or fur. It also travels on contaminated food, water, bedding, equipment, insects, and even on people’s clothing, shoes, and hands. A rabbit can die from RHD without showing any obvious symptoms beforehand, which is part of what makes it so devastating. In the U.S., RHDV2 has been confirmed in wild and domestic rabbit populations across multiple states, and there is a vaccine available through veterinarians.
Genetic Conditions in Certain Breeds
Some baby rabbits are born with inherited conditions that shorten their lives. The most well-known is megacolon, a genetic digestive disorder that impairs the normal function of the gastrointestinal tract. It’s linked to certain coat color genes. Rabbits with megacolon are typically mostly white with spots of color around the eyes, nose, ears, and spine, though not every rabbit with this pattern is affected.
There is no diagnostic test for megacolon. Veterinarians identify it based on coat pattern, abnormal droppings (often misshapen or unusually small), and ruling out other digestive conditions. Rabbits with megacolon can sometimes be managed with very high-fiber diets and ongoing care, but severe cases lead to chronic pain, gut blockages, and early death. Breeders who pair two rabbits carrying the spotting gene increase the chance of producing affected kits.
What Actually Helps Kits Survive
For domestic rabbits, the factors that make the biggest difference are a proper nest box, a high-fiber diet for the doe, clean living conditions to prevent coccidiosis, and leaving the mother to nurse on her own schedule without interference. Checking kits once daily for full bellies and warm skin is enough. Handling them briefly won’t cause the mother to reject them, despite the common myth.
For wild rabbit nests, the best intervention is usually no intervention. If you’ve confirmed the mother is gone (place two thin sticks in an X pattern over the nest and check after 24 hours to see if they’ve been disturbed), contact a licensed wildlife rehabilitator rather than attempting to feed the kits yourself. Rehabilitators have access to appropriate milk formulas and feeding techniques that dramatically improve survival compared to home attempts.