"The bright gold flowers of these plants open on sunny spring days, closing at night or in dull weather." Darwin noted in The Variation of Animals and Plants Under Domestication Vol. 2 (1868) that although these plants rarely produced seed, "in 1863 I observed seeds on several plants growing near my house." He also observed how in the early spring only the petioles (leaf stalks) of the leaves which forced a passage through the earth were arched; and not those which arose from the bulbs at the soil surface.
For more information see Darwin, C. (1880 ) The Power of Movement in Plants which can be read on the web, under 'The Writings of Charles Darwin on the Web by John van Wyhe.
During the coldest months brimstone butterflies often hibernate amongst ivy whose leaves their wings resemble when closed. Look for them this month, they are the first butterflies to be seen in the spring, often on the wing in March and sometimes as early as February. The long proboscis of these butterflies enables them to reach nectar at the base of flowers such as cowslips and primroses later in the spring, facilitating cross- pollination. For more about primroses and cowslips and Darwin's work on these plants within the site look out for the entry on the What to Look for in April.
Towards the end of the month listen for the call of chiff-chaffs in the woodlands. Repetitive but easy to identify, their call sounds like their name, 'chiff, chaff'. Although some birds now spend winter in Britain, most arrive back in Britain this month from Europe and Africa.
Queen bumble bees which mated last autumn have been hibernating below the ground during the winter but are now flying on warm days looking for sites, such as old mouse holes or holes in old compost heaps, where they can set up new colonies. The queen starts to build the nest using wax and putting in pollen as a food reserve. She initially lays about 6 eggs which hatch and start to eat the pollen. When the larvae are large enough they pupate, emerging as workers which gradually take over the running of the colony; collecting the pollen and nectar and looking after the nest structure.
In The Origin of Species through Natural Selection Darwin used bumble bees as an example of how living things are bound together in 'a web of complex relations'. Personal observations had shown him that only bumble bees were able to fertilise heartsease (Viola tricolor) and red clover (Trifolium pratense) because other bees were unable to reach the nectar. He wrote:-
"I have very little doubt, that if the whole genus of humble-bees became extinct or very rare in England, the heartsease and red clover would become very rare, or wholly disappear. The number of humble-bees in any district depends in a great degree on the number of field-mice, which destroy their combs and nests… Now the number of mice is largely dependent, as every one knows, on the number of cats... Hence it is quite credible that the presence of a feline animal in large numbers in a district might determine, through the intervention first of mice and then of bees, the frequency of certain flowers in that district."
Please record your first sighting of any bumble bee on the Phenology website to try to help build up a picture of any changes in timing of bumble bee activity.
Bumble bee numbers, like those of many invertebrates, have been declining. Why not encourage a greater diversity of invertebrates including bumble bees into your garden by making homes for them like those shown. Solitary bees will often lay their eggs in tubes such as bamboo canes (see photos), while bumble bees which live in small colonies will use boxes similar to bird boxes. To find out more about bumble bees and how to make these boxes, go to: