Stand still in a healthy forest for a few minutes and the sound quickly separates into layers: a high, thin layer of birdsong from the canopy, a mid-level of rustles and calls from the understory, and a low hum of insects and small movement from the forest floor. Each layer tends to have its own regular cast of callers.

The Canopy Layer

High in the trees, woodpeckers announce territory not with a call at all but with drumming — rapid, mechanical strikes against a hollow branch or trunk that carry surprisingly far. Owls, active mostly after dusk, use low, resonant hoots suited to travelling through dense branches. Songbirds occupy much of the daytime canopy soundscape, each species tending to favour a particular pitch or rhythm that helps it stand out from the crowd.

The Understory and Mid-Level

Deer produce a surprising range of sounds for an animal often assumed to be silent — from a sharp alarm bark to, in some species, a deep bellow or roar during the breeding season known as the rut. Foxes are known for an unsettling, almost scream-like call, most often heard during their own breeding season. Squirrels use a rapid, chattering alarm call to warn others of a nearby predator, often accompanied by tail-flicking.

The Forest Floor and Undergrowth

Cicadas produce one of the most recognisable insect sounds by vibrating a specialised membrane at high speed — in some species loud enough to be uncomfortable at close range. Tree frogs call from low vegetation and puddle edges, particularly after rain, often forming dense, overlapping choruses similar to those found in ponds. Ground-dwelling grouse species in some forest ecosystems perform elaborate drumming displays using rapidly beating wings rather than a vocal call.

  • Woodpecker — territorial drumming, mechanical rather than vocal.
  • Owl — low resonant hoots, active mainly after dark.
  • Deer — alarm barks and, in some species, a deep rutting bellow.
  • Fox — a sharp, scream-like call during breeding season.
  • Squirrel — rapid chattering used as a predator alarm.
  • Cicada — high-volume buzzing from vibrating membranes.
  • Tree frog — chorus calling after rainfall.

Why the Layers Rarely Overlap Completely

Part of what keeps a forest's soundscape from turning into total noise is that different species tend to specialise in slightly different frequency ranges and times of day — a phenomenon researchers call acoustic niche partitioning. A canopy songbird singing at dawn is far less likely to be competing directly for "acoustic space" with a ground-level cricket calling at dusk, even though both are technically active in the same patch of forest.

Sound as a Health Indicator

A forest that sounds sparse or unusually quiet compared to a similar healthy forest can be an early sign of ecological stress — fewer insect calls or a thinner dawn chorus sometimes precedes more visible signs of habitat decline. This is part of why bioacoustic monitoring has become a genuinely useful conservation tool, a topic covered in more depth in how scientists record and study wildlife sounds.

You can listen to real recordings from many of these forest species on the WildVoices creature grid.