Your wildlife questions answered
The County Times has teamed up with the Sussex Wildlife Trust to bring you monthly questions and answers about all things nature.
Charlotte Owen, WildCall officer at Sussex Wildlife Trust, is on-hand to answer your wildlife and conservation queries. As well as answering a variety of wildlife queries, Charlotte is always eager to receive your wildlife sightings in Sussex.
WildCall provides fact sheets ranging from how to make bird cake to beach-combing and can offer advice on environmental and planning issues as well as the best ways to help wildlife such as frogs, birds, bats and bees flourish in your garden.
To talk to Charlotte, call 01273 494777 between 9.30am and 1pm on weekdays, email wildcall@sussexwt.org.uk, write to her at WildCall, Sussex Wildlife Trust, Woods Mill, Henfield, BN5 9SD or visit www.sussexwildlifetrust.org. uk/wildcall
What is Britain’s smallest bird?
You might immediately think of the wren but Britain’s smallest bird is actually the goldcrest. This tiny bundle of feathers weighs just six grams, which is about the same as a ten pence coin.
It is only a fraction heavier than its rarer cousin the firecrest, and these two species, which both belong to the kinglet family, could easily share the crown.
One advantage of being so small is reaching the places that bigger birds can’t, and delicate goldcrests will often perch right at the tips of the flimsiest branches in their constant quest for food.
Deep furrows on the soles of their feet help them grip onto individual pine needles as they flit through the treetops, seeking out springtails and spiders. Such miniature morsels are often overlooked by their competitors but make a perfect meal for a miniscule bird.
But being small brings challenges, too. In frosty weather, a goldcrest can lose up to 20 pre cent of its bodyweight overnight just keeping warm, even huddled together in a communal roost. It’s remarkable that these diminutive creatures can survive the cold at all but even more impressive to think that our resident birds are joined each winter by distant relatives from as far afield as Russia, making an epic flight of thousands of miles and crossing the inhospitable North Sea.
This was a feat so unbelievable that early observers believed goldcrests must hitch a ride among the feathers of migrating woodcock, which arrived here at about the same time.
Why do bees buzz?
The familiar hum of a busy bee is produced by the rapid movement of their wings. Each flap creates tiny
vibrations in the air, which reach our ears as a buzz. It’s similar to the fluttering thrum of a bird in flight but insects move their wings so rapidly that the resulting sound is much higher-pitched.
The frequency of the wing beats determines the pitch of the buzz, so the more flaps per second, the higher the note produced. Generally, smaller insects flap their wings much more rapidly than larger insects – imagine the whine of a mosquito versus the hefty hum of a queen bumblebee – and the pitch will also change as the insect alters its speed.
Some insects move their wings so rapidly that we simply cannot hear them – so tiny fruit flies, for example, appear to fly silently.
Bumblebees can also buzz for a second reason, and will deliberately vibrate their flight muscles when visiting certain flowers. This shakes the pollen free, and the bee will even use her legs and mouth parts to channel the vibrations straight to the anther, where the pollen is held, to maximise the effect: an explosion of pollen, dusting the bee’s furry body with grains that are then groomed into the pollen baskets on her legs, ready for transport.
This behaviour is known as buzz pollination, as some of the pollen will be transferred to the next flower the bee visits.
Tomatoes, aubergines and blueberries all have tubular flowers that have adapted to take advantage of buzz pollination, funnelling the pollen directly onto the desired target, which is one reason that bumblebees are such important pollinators.
Can you identify this insect, right?
This is the hornet mimic hoverfly, Volucella zonaria. At almost 2cm long, it’s the largest hoverfly species in the UK and a convincing mimic of the European hornet – though completely harmless to humans. It even replicates the hornet’s mighty buzz as well as its size and appearance but on close inspection it can be distinguished by its much larger eyes, broader body and lack of a sting.
This elaborate deception provides effective protection from would-be predators, allowing the hoverfly to feed on nectar without worrying about being eaten.
The species first colonised Britain in the 1940s and was once a rarity but is now quite common here in the south, where it’s often seen in gardens.
The adults are migratory and the larvae live inside wasp nests in a happy arrangement, whereby the wasps provide free board in return for the larvae eating their debris, essentially providing a cleaning service for their hosts.
Why do garden birds seem to disappear in late summer?
Birds hide away in late summer while they undergo their annual moult.
Adults can look particularly bedraggled by the end of the breeding season but once their parenting job is done, and while the weather is still mild, there is a window of opportunity to take time out and replenish themselves. They will shed their tired and tatty feathers to replace them with strong and glossy new ones, while this year’s fledglings moult into their adult plumage.
It takes about five weeks for a small bird to complete a full moult, and it’s an intensive process demanding a great deal of energy and plenty of protein, so they avoid any unnecessary exertion.
They can still fly but without a full quota of flight feathers they are more vulnerable to predation, so it’s sensible to stay out of sight. Once the moult is complete, the garden birds will be back, ready to fatten up on autumn’s bounty.