Peromyscus leucopus (Rafinesque, 1818)

White-footed mouse

The deer mouse's twin, and the main animal reservoir of Lyme disease.

Order: Rodentia
Family: Cricetidae
Group: Rodents
Ontario status: Native, common; Lyme reservoir

Why it matters

Primary reservoir host of Borrelia burgdorferi, the Lyme disease bacterium, it infects the black-legged ticks that bite it.

Origin

Native to eastern North American woodlands, the mouse of the forest floor.

Behavior

Nocturnal; an agile climber, more arboreal than the deer mouse. Caches acorns and seeds.

Living conditions

Deciduous forest, brushy edges, and nearby homes, sheds, and cabins. Nests in tree cavities, stumps, wall voids, and attics.

Signs of presence

Pointed droppings 3-6 mm in attics, sheds, and cabins
Acorn and seed caches in boxes and wall voids
Nests of shredded bark, leaves, and insulation
Gnawed acorns with neat round holes

Weaknesses

Acorn-driven: mast years predict mouse (and tick) booms the following year
Brushy edges are its highway, clearing vegetation near homes reduces visits
Discrete nests: droppings and caches lead straight to them

Myths and facts

Myth Only deer carry Lyme disease.
Reality Deer feed adult ticks, but white-footed mice infect the ticks. The mouse is the reservoir that matters most.

Research notes

Morphology

Body 85-105 mm, tail 65-100 mm, weight 15-25 g. Grey-brown to reddish above, white below; bicolored tail; large ears. Nearly identical to deer mouse in the field.

Diagnostics

Field separation from deer mouse is unreliable, white-footed averages slightly larger with a proportionately longer tail; definitive ID needs dental or genetic characters.

Easily confused with

Deer mouse (Peromyscus maniculatus) Overlap in every field character; treat Peromyscus sightings as the complex unless lab ID is available.

Life cycle

Adult: Lifespan ~12 months wild; several years captive
Egg: N/A, viviparous
Egg to adult: Gestation 22-24 days; maturity at 6-8 weeks
Generations per year: 2-4 (seasonal, spring, autumn)
Nymph or larva: Pups weaned at ~25-30 days; mature at 6-8 weeks

Development

Viviparous; altricial.

Reproduction

3-5 pups per litter × 3-4 litters/year.

Distribution

Global: North America only
Native range: Eastern North America
Ontario: Native, common; expanding northward with warming winters

Ecology

Forest-floor omnivore; acorn caching drives population dynamics; the keystone host in the Lyme disease cycle, infects larval ticks that later bite humans.

Resistance

Unknown.

IPM implications

Peridomestic tick risk tracks mouse density: reduce brushy edge habitat and acorn-bearing trees near homes, seal ≥6 mm gaps before autumn. Acorn mast forecasting predicts next-year mouse and nymphal-tick abundance, a genuine predictive tool.

Chemical ecology

Urine and plantar-gland scent marking; olfactory mate assessment.

Genetics and DNA

Reference genome published: PGSC P. leucopus reference genome (Sci Rep 2019); chromosome-length Hi-C assembly (eScholarship).

Taxonomy

Order Rodentia › family Cricetidae › genus Peromyscus › P. leucopus (Rafinesque, 1818). Sister species to the deer mouse.

Open questions

Rate of northward range expansion in Ontario and its effect on local Lyme incidence.

References

CDC, Lyme Disease: Transmission
Cornell Cooperative Extension, White-footed Mouse