Baby rodents, often called “pups” or “pinkies,” are frequently discovered in various environments, from natural wild habitats to urban settings like homes and gardens. Understanding their developmental stages and natural behaviors can help determine the appropriate course of action, which often involves allowing nature to take its course or seeking professional guidance.
Characteristics of Newborn Rodents
Most rodent species, including common mice, rats, and squirrels, are born in an undeveloped state known as altricial. At birth, these pups are hairless, displaying pink skin, earning them the nickname “pinkies.” Their eyes and ear canals are sealed shut, rendering them blind and deaf in their earliest days. Pups are entirely dependent on their mother for warmth, nourishment, and protection. Unable to regulate their own body temperature, they rely on the mother’s body heat and nest insulation for survival.
Developmental Milestones
Rodent pups undergo rapid growth and transformation during their first few weeks of life.
Mice
For mice, fine fur appears around day 6, and their ears develop by day 4. Their eyes open between 13 and 14 days, and they continue nursing until around 21 days.
Rats
Rat pups, born weighing 6-8 grams, start developing a peach fuzz coat around day 6. Their eyes open at 14 days, allowing exploration. By three weeks, they actively play and nibble on solid foods, with weaning completed by four weeks.
Squirrels
Squirrel “kits” are born hairless, blind, and deaf. Their ears open around three weeks and eyes around four weeks. Fur development becomes noticeable by four to five weeks, and they resemble miniature adults with bushy tails by six to seven weeks. Weaning starts around seven weeks, and young squirrels become independent and leave the nest by 11 weeks.
Maternal Care and Nesting
Female rodents construct elaborate nests using soft materials like shredded paper, fabric fibers, insulation, or dried plant matter. These nests provide a warm, secure environment for the pups, helping to regulate their body temperature. The mother rodent provides extensive direct care, including frequent nursing, grooming, and huddling with her young.
She also stimulates urination and defecation in the pups, as they cannot perform these functions independently in their early days. A mother’s protective instincts are strong; she will retrieve any pups that wander from the nest, often carrying them by the scruff of the neck back to safety. This dedicated care is important for the pups’ survival and early development.
Encountering a Baby Rodent
If you discover a baby rodent, the first action is to observe it from a distance. The mother is often nearby, foraging for food or moving her litter, and human intervention can disrupt this natural process. Touching a baby rodent with bare hands is discouraged due to the potential for disease transmission.
Rodents can carry various pathogens, including Hantavirus and Leptospirosis, transmitted through contact with their urine, feces, saliva, or nesting materials. Introducing human scent may also cause the mother to abandon the pup. If the baby rodent appears injured, cold, or has been left unattended for an extended period, contact a licensed wildlife rehabilitator in your area.
For commensal rodents, such as mice or rats found within a home or building, the situation differs. These species reproduce rapidly, and a single sighting can indicate a larger infestation. They can cause property damage by gnawing on wires and structures, and they pose health risks through contamination. In such cases, contacting a professional pest control service is the recommended course of action to address their presence.