April 2020 - Bees

I was casting round for inspiration for this month’s column and thought I’d wander out and see what was in the garden.  I almost immediately found half a dozen bees, so I’ll indulge myself with yet another column about my favourite subject.

The first bee I saw was a solitary bee – the hairy-footed flower bee, a female one to be precise. 

Female Hairy-footed Flower Bee

The Facebook groups have been full of pictures of male hairy-footed flower bees which emerge earlier than the females and they are the ones with the hairy feet.  This female was foraging on some red dead-nettle on my neglected vegetable plot and on some dwarf comfrey that is now in flower and threatening to invade the vegetable patch yet again.  Despite the meaningless name (all bees are flower bees because they all eat pollen), hairy-footed flower bees are mining bees and dig their nests underground. 

Male Hairy-footed Flower Bee - Check out those hairy feet (legs)

On the same comfrey patch I found a buff-tailed bumblebee worker – the first of the year.  She was quite small and collecting pollen which means that she was one of the first workers to emerge from the first batch of eggs laid by the queen.  In another part of the garden I found a buff-tailed bumblebee queen.  That queen was searching for a nest and so must have emerged later than the queen that founded the colony that the worker was from.  Confused? Then I’ll just quickly run through the bumblebee life cycle again.

As a bumblebee colony matures (from mid-summer to late autumn) both males and queens are produced.  Males and queens mate (preferably with ones from different colonies), the males die and the queens hibernate.  When they emerge in the spring, the queens feed themselves up on pollen and nectar to develop their ovaries, then they go looking for a nest.  Old mouse holes or bird nesting boxes that didn’t get cleaned out are perfect because bumblebees can’t dig or carry large chunks of nest material about.  When she finds a suitable nest, she makes a wax pot and fills it with nectar which will keep her energy levels up while she creates brood chambers and lays eggs in them.  The eggs hatch into larvae (the bumblebee equivalent of caterpillars), she feeds the larvae with nectar and pollen.  When big enough, the larvae pupate (pupa = chrysalis) and shortly after emerge as the first batch of workers.  Once the workers have emerged, the queen stays at home, creating brood chambers and laying eggs while the workers feed the next batch of larvae.  The colony will go through several cycles as each batch of workers emerge and the size of the workers increases each time because more workers means more food.  Eventually, the queen starts to lay male eggs as well as female eggs and the females (queens) and males will go off and start all over again.  (The original queen and any workers still alive will then die.)

Early Bumblebee Worker

I also found an Early Bumblebee Queen.  More confusion here – Early refers to the species of bumblebee – Bombus pratorum to give it its Sunday name – not necessarily to the fact that they emerge particularly early.  They are sometimes given the name Spring Bumblebee, not just because they emerge in the spring, but because the colony has a short life cycle and so the colony has ended by late spring. 

The early queen was foraging on our flowering currant bush.  For some reason, bumblebees and some solitary bees are particularly fond of flowering currant pollen.  Experiments with captive bees have shown that they will eat flowering currant pollen in preference to other pollens, even though it has been separated from the flowers.  If you want to recognize the early bumblebee, then look for yellow stripes (maximum of 2) and a gingery red tail.  They are also Britain’s smallest bumblebee.  Not only are they the smallest, but when I used to collect pollen, I could rely on the early workers because they carried huge lumps of pollen out of all proportion to their size.  Perhaps that’s why their colony life is short on the basis of ‘eat fast and die young’.

March 2020

I noticed something curious the other day.  There was a flock of gulls on the field at the back and they were all facing the same way.  There were a couple of magpies there also facing the same way as the gulls.  I then realized that whenever I see a small flock of birds on the field, they invariably face the same way – up the field towards Pett Road.  Is there a reason for this behaviour?  It could be that they are facing the prevailing wind, though they are facing South rather than South-west in the main.  It is possible that it has something to do with feeding, though I can’t think why they would be more successful in one direction rather than another.  If they were facing the sun then the direction would change from morning to evening.  Perhaps the slope on the field means their head is nearer the ground making feeding less energetic.  My theory, for what it’s worth, is that it is part of their escape plan.  If disturbed, they would be flying towards open sky, whereas if they were facing the other way, there are large trees and a hill facing them.  Whatever the reason, I will keep an eye out to see if it applies to all species or just gulls and magpies.  Maybe if I got closer to the ground to take a bird’s-eye view it would be informative.  So, don’t worry if you see me lying face down on the field, occasionally changing direction, I’ll just be working out an escape route.

As I write this storm Dennis is approaching and the wet weather continues.  At least it’s not as cold as 2018 when we had the Beast from the East to contend with, though last year scientists predicted that this year could be even colder.  So far that hasn’t happened and there are signs out there that spring isn’t that far away.  We have snowdrops and daffodils in flower and that ever reliable harbinger of spring, the lesser celandine is just in flower.  Of course, spring will happen whether there are harbingers or not, though exactly when seems less predictable these days.  If I was a real scientist, I would note when the first snowdrop appeared, and when the first daffodil opened and when I saw the first bumblebee, etc.  If I did that I would be called a phenologist – someone who studies the timing of natural events.  As it is, I know that snowdrops are traditionally due to flower on or about the first of February, and this year I think that they flowered round about that time.

Phenology is an important science as it shows how things change on a longer timescale.  It has become an important indicator of the effect of global heating, for example, and is closely linked with monitoring extinctions and new colonizers like the ivy bee I have mentioned before in this column that have only been seen here this century. 

Nowadays citizen science is growing in popularity and more people than ever before are recording sightings from the natural world, so that there are now huge databases showing what was seen, where, when, and how many.  The Sussex Wildlife Trust uses iRecord.  This is an online facility that anybody can use to enter their sightings as well as to search and explore what other people have found.  I use it a lot and each sighting is verified by experts which all helps to improve your identification skills.

February 2020 - Wildfires and Caterpillar Fungus

Wildfires in Australia are much in the news as I write this, and they will still be burning when I write this column next month.  At least 25 people have died in the fires and thousands are now homeless.  That is tragic enough but the scale of destruction is many orders of magnitude greater for the wildlife affected by the fires.  It has been estimated that more than a billion animals may have perished already.  Bushfires have been a fact of life in Australia for thousands of years and a unique ecology has evolved, not only to cope with fires, but to thrive on them.  I have seen grass trees bursting into leaf when all the rest of the vegetation around them is blackened, and some species of eucalyptus trees will not germinate until the seeds have been charred.  There is even a beetle that can detect infra-red radiation and will seek out burned areas to eat the resulting corpses.  But that ecology has developed to cope with occasional fires that blow through relatively quickly one area at a time.  The current fires are on a different scale altogether where several join up and become large enough to create changes in the weather.  On this scale, even animals that can run or burrow their way out of danger will have no habitat to return to and will probably starve as a result.  The loss is not just about the larger animals, the destruction of insect life, and the detritivores that live in the leaf litter, even the microbes in the soil will have been wiped out.  I have seen several posts from researchers studying particular species such as velvet worms and grasshoppers who are unable to enter the habitats they are studying and suspect that their study subjects may now be extinct.

The cause has been firmly established as global heating, a fact that the Australian government will eventually have to accept however reliant they are on their coal-based economy.  Perhaps the general population will also see that driving V8 cars and screaming about in powerboats is no longer acceptable behaviour.

Closer to home, we are not yet affected by wildfires to any great extent but we are in the middle of one of the wettest winters I have ever experienced and major floods and droughts are becoming commonplace.  All of these are predicted by climate change models and not a week goes by without reports of new records being broken, whether that be ocean temperatures, wind speeds, or atmospheric carbon dioxide concentration.

I am concerned that the wet winter may have affected many species of hibernating insects.  The ground has been waterlogged for many weeks now and the bumblebees, solitary bees and wasps may not survive it.  Insects hibernating underground have to try and choose ground that will not get washed away or flooded or too frozen.  Even if they manage that, places that stay damp can harbour species of fungus that invade their bodies and eat them from the inside.  There is a particular genus of fungus called Cordyceps that invades and even changes the behaviour of insects.  There are hundreds of different species and each one targets a different species of insect.   They can attack both active insects like ants as well as hibernating insects such as beetles.  There is a particular species called Cordyceps militaris that is found throughout the northern hemisphere and is commonly known as the caterpillar fungus.  If you see some bright orange club-shaped fungus (Cordyceps means club-headed) sticking out of your lawn, then if you dig it out carefully you may find the remains of a caterpillar at its base.  This is gruesome for the caterpillar, but looking on the bright side the mycelium is very nutritious for us humans and has many vitamins as well as cancer suppressing properties, not to mention its reputed effect on male performance.

My apologies if you ere expecting a picture of a grass-tree.  I need to go back to 1999 and find the right slide.