Nature 2005 February

The Birds and the Bees!

Well OK it was not quite a “White Christmas” in the Chiltern Hills this year as I had predicted but it was a near run thing and the hard frosts around Christmas Eve provided a festive picture for early risers!

As has become the custom this time of the year I will start with a summary of the meteorological extremes of the previous 12 months. Coldest day in 2004, March 2nd at -6.9°C (for 2003 -8.5°C). Warmest days were on June 8th and August 7th, both a modest 30.6°C compared to the 36.3°C in August 2003. Last year we had 29.5″ of rain which is slightly above the average. Wettest day October 14th at 29mm (1.25″) and wettest month incredibly was August with 142mm (5.75″). If you are looking for anecdotal evidence of our changing climate last year did not disappoint. Despite August temperatures failing to top those in 2003, last year was still the fifth warmest year since records began. The warmest 10 years have all been since 1990.

Looking ahead for February and March, overall temperatures will be as low as -6° and as high as 19°C. In contrast to a mild, if grey-skied January, these fluctuating temperatures will be the product of some particularly icy-cold and windswept days as February moves into March. Look out for an excessive use of the phrase “wind chill factor” by the weathermen! February will see plenty of drizzle whilst March will be noted for some very heavy downpours.

The mild winter so far has given a kick-start to the wildlife, with all sorts of signs of new life around us such as the first flowering of hazel, primroses, rooks nesting and thrushes singing. Snowdrops (the wild varieties that is) traditionally flowered around Candlemas Day (2nd Feb) but their white flowers have been progressively emerging earlier over the past 10 years. The tips of their spear-like leaves are reinforced with armour-plate to enable them to shear through frozen soil. Frogspawn has already been reported in Cornwall, as I write this in early January, so I would be interested to hear of anyone with a pond full of amorous amphibians emerging from hibernation followed by dollops of the jelly during February. The jury is still out as to whether this early spawning is very successful with these early tadpoles often failing to make it through to the “froglet” stage, compared to later broods, due to lack of food-supply (pond algae and plant life). But gradually there may be a shift in favour of these amphibian pioneers.

By the time February arrives the bird-breeding season will have started. The trigger for the hormones to start pumping around their bodies was the change in day-length at the turn of the year. Birds are unique in growing and “shrinking” with the seasons. In the autumn their metabolism switches to creating fat reserves. Whilst at this time of year its all about looking the part to attract a mate. Size matters in the bird world as does having the right gear. Despite all that is written about the habits of birds, comparatively little is properly understood about how they seek out members of the opposite sex. Mind you perhaps the same can be said of we humans! The phenomenon of speed-dating, which the urban unattached and desperate “twenty-somethings” spend their evenings doing these days – I am reliably informed – is suspected as being how some bachelor birds select their partner for the season. How many they “go steady with” no one has a clue, although the female dunnock (the erstwhile hedge sparrow) is the champion “swinger” of the garden scene keeping a harem of males.

On warmer days in late February bumble bees can bee seen on the wing. These are all females who have hibernated. The males having died after a frantic period of mating which takes place in the Autumn. These males are said to go out on mating patrols. Successive generations of bee visiting the same favoured sites in search of females. The females will have taken advantage of late flowering plants such as ivy to produce sufficient sugar reserves. On emerging from overwintering they are very active, searching out – and pollen-rich flowers already in bloom. This ready-made energy supply will fuel them in their efforts to search out a suitable nest site, usually in the soil, often an old mouse hole to build their honeycomb nest. Only when they have found sufficient pollen will they be stimulated to lay their eggs.

A test of your powers of observation now when you are out on a walk. Trees in winter can be tough to recognise if one normally relies on the leaves. Some can be identified with greater ease, such as the sticky-buds and flaky bark of horse chestnut. For ash look out for black buds and dark bark which on older trees becomes disfigured. Beech has light grey smooth bark and thin pointed reddish-brown buds and usually retains the dead leaves from last season. Oak has distinctive furrowed bark and its buds are clustered around the tip of the twig. Lastly sycamore has distinctive green buds. I have left off the previously mentioned hazel as by the time you read this those yellow catkins or “lamb’s tails” will be dangling about in reckless gay abandon no doubt.

Apart from bats, hedgehogs and dormice (including our resident glis glis), no other mammals in the UK actually hibernate. In fact the smaller the animal the more frenetic they are in winter as the need to obtain energy to offset losing body heat often means they remain active most of the day as well as the night time. To prove this point the bear (no there have not been any sightings around here) is known to hibernate for up to six months of the year. Mice and voles will burrow under the snow where it is that bit warmer and continue to seek seeds, insects and other small animals in the surface litter. Being creatures of habit they take the same route each day so if you peer into the ground inside a hedge you can see these tracks created by the patter of little feet travelling back and forth as they search out a juicy earthworm.

An unlikely fellow gastronome when it comes to worms at this time of year is the buzzard, which can be seen and heard (mew-mew) overhead, although this scouting is more likely to be for rabbits than any invertebrate! Whilst on the subject of worms and specifically the answer to the question: which is the early bird that catches the worm? The answer is the blackbird, 13 minutes ahead of the robin, at least according to the recent “Early Bird” survey carried out at the winter solstice by British Trust for Ornithology and Radio 4’s Today programme.

Concluding with the theme of “whose house is it anyway?” started a couple of articles back, February and March sees the emergence of overwintering butterflies such as small tortoiseshells and brimstones. The chances are in the next few weeks you will be spooked by a battered peacock butterfly that has been clinging to the curtains in the spare bedroom, it is flapping its wings in the vein hope that the “eyes” will scare off a would be predator. Next year we are trying out a butterfly hibernating box which Santa brought me this year. It comes complete with aromatherapy treatment to tune the senses. Whether it turns out that we end up with a tribe of super fit, oversexed butterflies chasing each other about having had a workout at the insect equivalent of Champneys we will have to see.