April 2021

From about 21st March to September 21st, days will be longer than nights. We are still learning how important this is to us and the natural world. Many of us suffer from Seasonal Affected Disorder (SAD) or low mood due to a lack of day light. A tortoise, dormouse or hedgehog will hibernate and sleep through the dark months. Humans evolved in the tropics where animals don’t need to hibernate. We tend to retire into our houses to keep warm and cosy on dark winter days and nights. Many of us take vitamin D tablets to make up for the lack of sun.

Blue tits are tightly connected to phases of the sun. Male blue tits start singing on 22nd December and from then to March 21st demonstrate potential nest cavities to females. Female blue tits start to take nest material such as honeysuckle bark and moss into the cavity around the 21st March. They aim to have their nestlings fledged and flying by 21st June. Humans have celebrated solstice and equinox for thousands of years and Christian liturgy links its major celebrations approximately to these times (Christmas, Easter, Feast of the Sacred Heart, Harvest Festival). Grasses mature and flower in June and farmers know that June is the time to cut good hay. That is when the grass pollen count is highest. Wind pollinated grasses don’t need the help of insects for that.

In temperate zones, the growing season is from the spring equinox to the summer solstice. Most terrestrial temperate organisms know that, even deciduous trees. I find it fascinating that most trees in the tropics and arctic zones are evergreen, but most trees in temperate zones are deciduous. They decide to shed their leaves in the autumn and grow new ones from the spring equinox to the summer solstice. During this time most folivorous insects such as moth caterpillars flourish and feed on the juicy young arboreal leaves and in turn the birds, such as blue tits, feed the caterpillars to their nestlings. Plant leaves are the solar panels of the planet, generating stored, carbon rich, energy and oxygen for all life. They can also regulate the water cycle as they take water from the soil and release it into the air from their leaves often making it rain in the tropical and temperate rain forests of planet earth.