Fallow Deer numbers are very high, and Roe and Muntjac are frequent, too. Most regular motorists along The High Street, B2110, know the danger from straying Fallow on that adjacent boundary road at dusk and night.
Neighbouring Balcombe Forest, around the south end of the Balcombe Tunnel, particularly on the west side, by Birchangar, is like a fragment of the New Forest's ancient woods. In the darkening evening you can hear deer shifting though the trees, and catch glimpses of parties of Fallow Deer. There is much activity. This is no surprise, for this woodland above the Tunnel is the only place across the 25 mile width of the Weald - from the North Downs to the South Downs - where deer can pass westwards and eastwards without danger from the railway, or roads and houses. This place is a bottleneck, where deer can escape the daunting dangers to their free movement.
In the last 60 years it has probably been an important spot for the re-expansion of Roe Deer from their western refuges into East Sussex and Kent. In a real way (though unwilled and ambivalent in its results) much of Worth Forest has retained more of the character of the medieval Deer Forest than has Ashdown Forest!
Bats are present across the whole Forest in considerable numbers. When a bat detector is taken across the Forest it scarcely ceases to register from end to end. Pipistrelles sp/p. are most frequently seen, sometimes in numbers. Medium sized bat species are frequent too. Serotine is present at Whiteley Hill. Bats with a size and foraging pattern like Brown Long Eared Bats are present, but without verification.
For amphibians Worth Forest is undoubtedly a major 'hotspot'. Whilst amphibian numbers steeply decline in the general countryside, Frog and Toad numbers in most of the Forest's component blocks are very high. In spring the gully streamlets and gill streams in the Stanford Brook watershed, and in the south running headstreams of the Ouse, have abundant spawn and tadpoles.
Additionally, abundant windfall root plate mini-ponds are heavily used for spawning, as are derelict pond sites and made small ponds and seasonally flooded sloughs. Tractor ruts on Forest rides, particularly in Oldhouse Warren, but also in neighbouring sub-forests, are also heavily used for Frog and Toad spawning.
Perhaps more importantly, though, they are used throughout the year by Newts, mostly Smooth Newts, with some Palmate Newts. Many deep flooded tractor ruts will be seen to carry small groups of resting Newts when observed, and the frequent presence of efts and juveniles demonstrates that they are preferred breeding habitats, largely free of competition from Frogs and Toads.
Common Lizards are visible in many spots across the Forest in summer, and in later summer small family parties of dark juveniles are frequently seen basking on logs. Slow Worms are frequent and widespread. Neighbouring observers say that High Beeches Forest has a large population of Adders, but this is unverified. Such large amphibian populations suggest that Grass Snake must be present, but this is unverified. Badger is frequent and often seen at dusk in some places, such as Brantridge and High Beeches Forests, where lack of human disturbance makes them bold. Stoat and Weasel are occasionally seen.
The three Stanford Brook branches and the Monks Forest gill stream held populations of Bullhead, Cottus gobio, in recent years.