Nature 2011 February

Most glorious night! Thou wert not sent for slumber!*

With the mercury in the thermometer at last registering temperatures above zero degrees Celsius after a record breaking average of minus one for December, wildlife has once again resumed its normal order. However, darkness still takes hold in the late afternoon and so the nocturnal habits of creatures are all the more noticeable at this time of year.

“Then nightly sings the staring owl – tu-who, tu-whit, tu-who”

As children we learn that owls make a tu-whit tu-who sound. In fact this is a corruption of the actual exchange from a pair of tawny owls calling to each other. The origin of this phonetic variation can be traced back to Shakespeare who coined it in Love’s Labours Lost. In fact the Bard slightly corrupted the phonetic spelling to fit witticisms within his prose! In reality the female typically sounds-off with a kee-wick and the other responding with a whu-whu.

In January, as dusk falls, last year’s tawny owls start to search out a new territory, having half-slept through the daylight hours typically wedged in the crutch of two boughs of a mature tree. They are, seemingly, content to be in full sight during the daytime and assert their presence as dusk descends. Come across an owl in such a position and it will rarely budge: instead will look straight at you with an unstinting stare. Their favourite roost is a clue to their alternative and older name of wood owl. Two birds in the same vicinity may be heard to engage in a rapid exchange of calls, trying to out-call each other with one eventually asserting its dominance and gaining or retaining territory. The tawny owl is the most catholic of owls when it comes to its prey and there is plenty of variety around at this time of year: worms, mice, voles, stoats, rabbits and small birds.

If you stray outside on calm evenings around dusk, the muffled sounds of dry leaves rustling and small twigs snapping can set the hairs erect on the back of your neck. More often than not, stepping through the undergrowth is a muntjac nonchalantly nibbling on green shoots. Startle one that turns out to be a male and you may be rewarded with a sudden bark as it retreats to a thicket. As we know only too well, once the barking has started it seems unable to know when to stop and we are treated to a serenade of increasingly indignant rasping shouts every 30 seconds or so.

Another mammal that makes its presence felt at night around this time is the fox. The male bark is a repetitive raff-raff-raff as it does the rounds reinforcing the extent of its considerable territory. Meanwhile the female may respond with one of those ear-piercing screams which are, in effect, a come hither signal to the males that they are in season.

In February, badger cubs will be born and the mothers become increasingly active making efforts to forage for the additional food needed to support their offspring. The testosterone levels of male badgers increase during the late winter as they seek to add to their dynasty. Together they are frequent visitors to our garden and often the first indication of their arrival is the hoarse grunting and growling as they skirmish and scrap for food along the hedgerow.

There are very few species of insect that thrive during the months of December, January and February. Moths almost exclusively require a much higher ambient temperature. One of the rare exceptions is the winter moth, which is on the wing for the next month or so – or to be accurate only the male flies as the female is wingless. The females stay put, emitting a powerful pheromone which can attract male moths from over a mile or so away. After mating the female lays large numbers of eggs in the deeper crevices of bark or on the scale leaves of leaf buds and remain dormant until the early spring when temperatures reach 13°C. The caterpillars, known as ‘loopers’ because they can move rapidly by pulling their rear end towards their heads with the middle section forming a vertical loop, feed on the leaves of most trees. They are so numerous that they provide a major source of food for insectivorous birds such as blue tits when they build nests and rear chicks.

Frogs and toads awake from their stupor or semi-hibernated state and use the cover of darkness to return to their favourite pond or ditch to mate. During the nocturnal hours of February they can create quite a stir across the water surface as males clamber for position in their pursuit of females.

Finally, I heard on the radio the other day an old farmer who recalled, in the pre-warfarin days when hayricks were in vogue, describing how armies of brown rats moved from field to field at night. Apparently if the wind was in the right (or is it wrong) direction, there was a distinctive pungent odour as a mischief of over 200 rats rolled past you. Today, while the number of city rats has remained stable, the quantum of rurally-based rats has declined considerably. Still I guess this is not a sight or smell for the squeamish!

So take an opportunity to appreciate the darkness and the wildlife that inhabits it at this time of year.

(* The quote used as the title is from Lord Byron.)