THE HOLLY AND THE IVY November/December
2008
The Holly and the Ivy, when they
are both full grown, of all the trees that are in the wood, the
Holly wears the crown... goes the Christmas jingle, so lets consider
these native seasonal evergreens from a wildlife perspective.
Many woods, forests and gardens
I visit I see that the ivy has been cut from the trees, an intervention
that is intended to help the tree. I know its the season of goodwill,
but this well-intentioned act could be short-sighted... Ivy is
very important for wildlife. Its berries are a late-in-the-season
treat for many, ie a source of nectar for a variety of insects.
On sunny days look around the ivy to see queen hornets and wasps
and honey bees, or butterflies like Holly Blue and Small Tortoiseshell
and even overwintering invertebrates like the Brimstone butterfly
will hibernate amongst the leaves, thanks to the presence of
glycerol in their blood, acting like a kind of winters 'anti-freeze'.
The ivy is also a critical late-feeding source for the birds,
when there is not much else around to eat. Its a bit of a myth
this notion of ivy 'killing the trees' as in fact they can live
alongside each other for a long time. It all depends on your
perspective. If you consider the individual tree, then the ivy
once its established will of course eventually compromise the
growth of the tree. But if you are thinking about the habitat
as a whole, then please remember that in order to yield the highest
biodiversity, your average woodland should be made up of 60%
of dead or dying trees.....something to think about before cutting
the ivy to 'save' the tree......
Holly is now bearing its fruit and is able to
keep its 'christmas decorations' for longer because its patrolled
by the mistle thrushes, who move in as soon as the berries are
ripe and red to claim this winter larder as their own, seeing
off lesser birds to protect their cache. Of course, if a desperate
flock of birds raid their larder there is little they can do
but share in the plunder...a case of 'if you can't beat them
join them!'
As November moves into December, the beauty of
late autumn turns into the brutality of winter, as foodstocks
diminish and the birds and mammals concentrate on survival.
The surplus of summer led to flourishing animal
numbers but of course it means that inevitably many will not
make it through wintertime....the greatest game-show of them
all plays out each wintertime...the survival of the fittest.
This is a time of year where you are particularly vigilant to
keep your bird tables well stocked in another seasonal gesture
of goodwill. But from Darwin's point of view, is this interfering
with nature's strategy to weed out the weakest? It will help
the individuals but will it hinder the species...?
December of course is the month of diminishing light, just as
we are busy trying to distract ourselves from the introspection
of winter - almost against the rhythm of the natural world, we
humans try and live it up, brighten our towns and living rooms
with artificial lights to keep the darkness and depression at
bay....
But for some, the long nights of winter are optimum
hunting conditions. Our larders may become particularly well-stocked
for Christmas, but at this time of year its hardship for most
of the resident birds and mammals. The Tawny Owl however, is
a consistent consumer throughout - the length of the night means
longer hunting hours and like our shopkeepers with late night
shopping, there is a perverse profit to be made at the onset
of winter.
The Tawny Owl is the commonest of our 6 species,
but of course its rarely seen as it is nocturnal. Its often heard
though, and particularly through the autumn as the juveniles
compete for territory along with the adults beginning to pair
up ready for the next breeding season. The 'toowit' part of their
call is made by the female, but the quavering hoot, the 'toowhoo'
is made by both sexes. When they are silent, they are of course
hunting, and although their eyesight is good, most of their navigation
and hunting is done by sound. Their ears are spaced to enable
them to pinpoint prey with grid-reference accuracy, by the differential
in the time taken for sound to reach each ear, and their disc-like
eye sockets funnel the noise vibrations to their ears. Soft feathers
muffle any sound of flight and so they hunt by surprising their
prey. (By day, they would be poor hunters)
Tawnys have a catholic diet - they have to because
nights are not always quiet, so in windy or wet conditions they
will scratch around on the ground for beetles or worms. Otherwise
their staple is small mammals like voles, shrews and mice but
frogs, birds and bats will also be prey items, and they are also
suspected of poaching fish as they surface from garden ponds!
One intriguing aspect of this creature is the
worldwide perception or characterization of the owl as wise.
I have often wondered whether this is linked to its (apparent)
ability to 'see' in the dark...if it can see what we cannot see,
then it must therefore be wise indeed.......
You would be wise to keep warm this winter, and
don't forget to leave your winter fireside occasionally to indulge
in some winter wildlife treats....
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