Thursday, 29 November 2018

At night, nature is busy...

The moon rising - a large pink grapefruit through the bare trunks.

Little owl chick
At night, nature is busy.

From the fields a piping call carries - a male little owl. I think I know exactly where he's calling from. This time last year we sited a nest box in a mature hedgerow oak and it was immediately adopted by little owls. Little owls are the size of a thrush and adult birds have eyebrow markings making them look alternately angry or puzzled. The birds were introduced to this country at the end of the nineteenth century and went on to flourish. They are that rare thing - an introduced species that seems to have had no detrimental effect on native wildlife. They feed on invertebrates and small mammals and are crepuscular - active at dawn and dusk. Little owls are now in decline and get no protection because they still carry the stigma of 'introduced species'.

A little owl box must not allow light to enter as the nesting birds like darkness. The most successful boxes are designed to contain the young for as long as possible. If they emerge too soon, they are easily picked off by predators like tawny or barn owls. And ideally the box can be opened for mid-winter cleaning. That special fragrance of faeces and rotting rodents is characteristic of their successful homes.

Siting little owl nest box
The boxes I make are a foot cube and are a design given to me by Rob Hoare. The entrance hole is sited at the top of the front face of the box with a perching ledge. The hole leads to an L-shaped corridor which excludes light from the main nesting space and is difficult for very young inquisitive little owls to climb up to. Little owls like to lay on a bed of soft material - usually sawdust. Perverse as it may seem, I am hoping to use stinky ferret bedding as the soft material. Not only to add to that special little owl box bouquet but to deter grey squirrels who see the boxes as especially desirable - and fill them with leaves for high-class dreys. The stink of a ferret is said to deter grey squirrels but has no effect on the birds.

In 2018 a pair using one of our boxes successfully raised four young, whilst a second was borrowed by a pair of kestrels who squeezed their nest of five young against the side of the box.

Juvenile kestrel
My winter plan is to add a couple more little owl boxes so that it is not the lack of of nesting sites that is affecting little owl success here.

Next week we plan to tour our tawny, barn and little owl boxes to get them ready for the new season.

There are moths flittering in the gloom: male Northern Winter moths (Operophtera fagata). In late November they mate with their flightless females who climb up into the twigs of deciduous trees to lay their eggs. In the spring, the caterpillars of northern winter moths join with those of winter and other moths and begin eating their way through fresh leaves. In turn, these exfoliating caterpillars become the main food source for woodland birds like tits. A blue tit nest of hungry babies can consume ten thousand caterpillars.

Gardeners are exhorted to put grease rings around their fruit trees to deter moths on their nocturnal climbs. We prefer to let nature take its' course.

Moths can be very active on November nights. The last time we used our moth light we caught, recorded and released forty moths of eight species.



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