Spring
In March, the hazel and willow bloom. The same applies to sweet violets, yellow star-of-Bethlehem and stinging nettle.
The first herbs grow shoots, and the bees are getting geared up.
The queen bumblebees start house hunting in mouse tunnels and the first frogs pop outside on warm days. The starlings have arrived. The squirrels’ nests are filled with young.
The osprey pair arrive in April and the anemones begin to bloom and, in mid-April, the first beech and birch trees come into leaf. Large flocks of singing redwings migrate overhead. The ospreys return. When the weather turns mild, the relatively rare wader, the green sandpiper, arrives. The cubs of the badgers and the foxes are old enough to spend the warm days of late April outside. The first ducklings and goslings hatch and the colony of cormorants at Stenholt is full of young. The great crested newts emerge from their winter quarters. So do the bats.
In May, the tawny owls have had their young which are now ready to come outside and sit on the branches. The red-backed shrikes have arrived. The woodland meadows start to bloom and attract insects and butterflies. The grass snakes are coming out and sunbathe in wetlands on warm days. The fallow deer lose their antlers. The common goldeneyes have ducklings. The large choir of bird song begins, amongst others, you can hear cuckoos and nightingales. Along Esrum Sø, the gnats dance in big swarms, so keep your mouth closed and squint as you ride your bicycle along Søvejen.
Summer
Fawns are born in June. The edible frogs croak and lay eggs, the ospreys are busy gathering food for their newly-hatched young. The young of the small grebe hatch. The hawthorns blossom and in the bogs the cotton grasses are blossoming. The European honey buzzards migrate north and those which stay behind lay eggs. The female glow worms are sitting in the grassy verges shining in order to attract males.
July is the mating season of the roe deer and you can hear the roebucks barking.
The broad-leaved helleborine blossoms along the forest roads. Butterflies and dragonflies are busy. The forest is teeming with small frogs and toads which have left the waterholes.
The raspberries ripen. It is the time for grasshoppers, young bats learning to fly, and the fallow deer rub their antlers when August arrives. The large hornets are very active and the climbing corydalis blossoms in the coniferous growths in central Gribskov. At the end of August, the green sandpiper is ready to migrate to Africa and the grey geese gather at Solbjerg Engsø to moult.
Fall
Gribskov is known for its abundance and variety of mushrooms, both edible and toxic. The grey geese fly in v-formation between the wetlands and get ready to migrate, the common buzzards migrate in large flocks of up to 20-30 individuals, and the ospreys migrate to Africa. Rowanberries and blackberries are ripe. You are permitted to pick and gather enough for your own consumption. Early in the morning, you can see the dew glitter in the big cobwebs.
In October, time has come to collect chestnuts. Roe deer and fallow deer also like them and eat them. The fallow deer in heat, you can hear them grunt at dawn and dusk. Birds are still migrating, while frogs and newts dig in for the winter. The leaves change colour and the ashes lose their leaves after the first night frost.
Late in the autumn, the winter guests arrive: bramble finches and siskins, which in years with lots of seed can take up the entire forest floor or sit in the cones of the alders. The nuthatches still gather food for their winter cache, squirrels and mice are also busy. Migratory birds fly south. During November and December, the stoats change colour and become ermines. The roebuck loses its antlers.
Winter
Now you can collect moss, mushrooms and more for Christmas decorations; however, spruce and cones may only be collected from the ground. The winter moths can still be spotted flying in the evening at low temperatures before the frost sets in. The goldcrests can be heard in the coniferous forest, and the crossbills cut cone seeds in the tops of the spruces.
There is a chance of spotting dippers by streams where they sit on stones and dive down to catch aquatic insects. It is possible to spot sea eagles. If there is ice on the lakes, sea eagles are often seen sitting, waiting for prey, such as coots, in the openings.
In February, the light begins to return, black woodpeckers begin peck at the trees, crossbills lay eggs, and you can hear the tawny owl and the wood pigeon which may continue until October. Foxes are mating and let out their very characteristic bark or scream.