# Flying Squirrel — Facts, Threats & Conservation

*Tribe Pteromyini — over 50 species in the squirrel family Sciuridae*

> Flying squirrels are over 50 species of nocturnal gliding rodents with a skin membrane between wrists and ankles; they cannot truly fly, and a 2019 study found that all three North American Glaucomys species fluoresce pink under ultraviolet light.

**IUCN status:** Varies by species — North American Glaucomys species Least Concern; some Asian giants threatened  ·  **WARN range:** North America, Europe and Asia, Tropical and temperate forests

## Quick facts
| Fact | Value |
| --- | --- |
| Movement | Gliding on patagium — not true flight |
| Typical glide | About 20–50 m between trees |
| Activity | Mostly nocturnal |
| UV fluorescence | Pink under UV in all three Glaucomys species (2019) |
| Diet | Seeds, nuts, fungi, insects — varies by species |
| Lifespan | About five to six years in the wild |
| Main threats | Habitat loss; hunting of some Asian species |

## Scientific classification
- **Kingdom:** Animalia
- **Phylum:** Chordata
- **Class:** Mammalia
- **Order:** Rodentia
- **Family:** Sciuridae
- **Tribe:** Pteromyini
- **Species:** Over 50 described species

## Conservation status
- **Status:** Varies — North American Glaucomys Least Concern; several Asian species threatened
- **Population:** Varies by species; no global estimate
- **Trend:** Stable for most North American species; decreasing for some Asian giants
- **Assessed:** Varies
- **CITES:** Some Asian species on Appendix II or III
- The family-level Least Concern label reflects widespread North American species. Giant flying squirrels in Asia face deforestation and hunting pressure.

## Key facts: Flying Squirrel
- Flying squirrels glide on a patagium; they cannot gain altitude or fly like bats or birds.
- All three North American Glaucomys species fluoresce pink under UV light — reported in 2019 by Kohler et al.
- Diurnal tree squirrels in the same forests do not show the same fluorescence.
- Most flying squirrels are nocturnal with large eyes adapted for low light.
- Glides typically cover 20–50 metres; longer glides are recorded downhill.
- Old World giant flying squirrels in Asia include threatened species from habitat loss and hunting.
- Flying squirrels are rodents in Sciuridae — relatives of tree squirrels, not related to sugar gliders.

## Gliding mechanics — controlled fall, not flight
A flying squirrel climbs high, launches, and spreads its limbs to extend the patagium — a furred membrane supported by cartilage spurs at the wrist. The tail acts as a rudder; body angle and limb position adjust trajectory. Typical glides cover 20–50 m; downhill glides can exceed that. At landing, the squirrel swoops upward to bleed speed, then grips bark with sharp claws.

This is energetically cheaper than climbing down one tree and up the next, which matters for an animal that commutes between scattered food sources at night. The patagium folds against the body when climbing. New World flying squirrels (Glaucomys) and Old World species (Petaurista, Pteromys and others) evolved gliding independently within Sciuridae — the same solution in separate lineages.

## The 2019 pink fluorescence discovery
The discovery was accidental. In 2017, forester Jonathan Martin noticed a flying squirrel at a bird feeder glowing pink under a UV flashlight in Wisconsin. Allison Kohler, Paula Spaeth Anich and colleagues then examined 109 museum specimens of Glaucomys oregonensis, G. sabrinus and G. volans, plus five wild animals, and found pink fluorescence on both dorsal and ventral fur in all but one specimen. Co-occurring diurnal squirrels — grey, fox and red squirrels — did not fluoresce.

The paper, published in the Journal of Mammalogy in 2019, noted fluorescence across 130 years of collection dates, both sexes, and a geographic range from Guatemala to Canada. The ecological function is not established. Proposed explanations include nocturnal signalling visible to UV-sensitive animals, camouflage against lichen-coloured bark in twilight, or predator confusion — but each remains hypothesis. Subsequent work found fluorescence in some other mammals; Glaucomys remains the best-documented rodent case.

## North American species and ecology
Three Glaucomys species occupy North and Central America: the southern flying squirrel (G. volans) across eastern deciduous and mixed forest, the northern flying squirrel (G. sabrinus) in boreal and montane conifer forest, and the Humboldt's or Oregon flying squirrel (G. oregonensis) of Pacific coastal forest — recognised as a separate species in 2017 after genetic work. All three are Least Concern but face local pressure from habitat fragmentation and, for northern populations, climate-driven range shifts.

Diet is omnivorous: seeds, nuts, fungi, lichen, insects and bird eggs when available. Southern flying squirrels often nest in tree cavities communally in winter — aggregations of a dozen or more share a hollow to conserve heat. Owls, martens and domestic cats are the main predators.

## Old World giants and confusion with sugar gliders
Asia holds the largest flying squirrels — Petaurista species can exceed 1.5 kg with glides spanning over 100 m. Several are threatened by deforestation and hunting. The Japanese dwarf flying squirrel (Pteromys momonga) is a cultural favourite but occupies a vulnerable forest type under pressure from logging and urban expansion.

Flying squirrels are sometimes confused with sugar gliders — marsupials of Australia and New Guinea that also glide on a patagium. The two are unrelated; convergent evolution produced similar solutions in a rodent and a marsupial. Sugar gliders are kept as exotic pets; flying squirrels are protected in many jurisdictions and are not domestic animals.

## What WARN does
WARN publishes free, sourced species education for animal groups where popular misunderstanding is common. Flying squirrels glide rather than fly, and the 2019 UV fluorescence finding is one of the few genuinely new discoveries about a familiar mammal group in recent years.

If this guide helps you understand wildlife and the pressures it faces, a gift to WARN supports habitat protection and free public education in our partner countries.

## Frequently asked questions: Flying Squirrel
### What do flying squirrels eat?
Most eat seeds, nuts, fungi, lichen, fruit and insects — diet varies by species and season. Southern flying squirrels also take bird eggs and nestlings when available.

### Where do flying squirrels live?
Forests across North America, Europe and Asia. North American Glaucomys species occupy deciduous, mixed and boreal woodland. Most species are arboreal and require connected canopy.

### Are flying squirrels dangerous?
No. They are small, nocturnal rodents that avoid humans. They can bite if handled but are not aggressive and carry no more disease risk than other wild rodents.

### How long do flying squirrels live?
Roughly five to six years in the wild; up to about ten years in captivity. Predation by owls and martens limits wild lifespan.

### How big are flying squirrels?
Size varies widely. The southern flying squirrel is about 21–26 cm head-and-body with a tail of similar length. Giant Asian Petaurista species exceed 1 kg — much larger than any Glaucomys.

### Can flying squirrels actually fly?
No. They glide on a skin membrane between wrists and ankles — controlled descent from a height, not powered flight. Bats and birds fly; flying squirrels cannot gain altitude under their own power.

### Why do flying squirrels glow pink under UV light?
A 2019 study found all three North American Glaucomys species fluoresce pink under ultraviolet light. The function is not confirmed; proposed explanations include nocturnal communication and camouflage, but research continues.

## Sources
- [Kohler et al. 2019 — UV fluorescence in Glaucomys (Journal of Mammalogy)](https://doi.org/10.1093/jmammal/gyy177)
- [IUCN Red List — Glaucomys volans](https://www.iucnredlist.org/species/42488/22264544)
- [IUCN Red List — Glaucomys sabrinus](https://www.iucnredlist.org/species/42487/22264543)

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Full guide: https://worldanimalrescuenetwork.org/wildlife-guides/flying-squirrel