Woodpeckers of Rock Coppice

By Rosemary Winnall

(This is a summary of a talk given at the Annual Meeting 18th March 2000)

Between 1987 and 1990 I conducted a study of woodpeckers in Rock Coppice, a 65 hectare woodland just south of the main Wyre Forest block near Bewdley. It is ancient semi-natural woodland and a Site of Special Scientific Interest.

During the early spring of 1987 I started to map all observations of drumming and woodpecker interactions in order to ascertain territories. In addition I surveyed the wood for trees showing woodpecker excavation of vertical shafts. These holes were examined three times during the breeding season, in May, June and July and the use of these holes was noted.

The difficulties and dangers of examining holes in trees cannot be understated! Most of these holes were in dead trees and a ladder was required for their examination. Although some were inaccessible, great care had to be taken when ascending those that were! In addition dead branches above occasionally posed a threat, especially in wind! The possibility of an owl being present, although unlikely, was always possible, especially in some of the rot holes.

Special equipment had to be devised for hole examination, and the following were invaluable:

A specially constructed extendible pole with a swivelable mirror on the end. This was made from an old carbon-fibre fishing rod. The mirror was clipped onto the end when it was extended to a length of 2 metres. This piece of equipment was useful to check that the hole visible from below led to a vertical shaft. It also doubled as walking stick, and one metre rule.
A dental mirror with extended handle to 18 cms.
A swivelling jointed book-lite torch adapted to a 4.5 volt battery.
A lead weight on a string which acted as a plumb line to measure the depth of the hole.
A tape measure used to record various dimensions of the holes and the girth of the tree.
A compass used to record the direction of the holes.
A metal tape to establish the height of the hole.
A portable ladder extendible to 4 metres.

During 1987 207 holes were found with an excavated vertical shaft, 20 of which were excavated by woodpeckers during that year. 173 of these were accessible for checking and the following nests were discovered:

Great Spotted Woodpecker8
Lesser Spotted Woodpecker2
Green Woodpecker1
Blue Tit6
Great Tit4
Tit sp. (nest predated)9
Spotted Flycatcher1
Robin (nest from previous year)1
Nuthatch (nest from previous year)1
Grey Squirrel1
Wasps (pendulous nest intact)1
Other occupants:Bat -1, Bumble Bees - several

The history of one hole is of interest. On the 9th May the drumming of a Great Spotted Woodpecker resulted in the discovery of a partly excavated new hole in an old live Wild Cherry tree. On the first approach the adult flew off. There were lots of fresh wood chippings on the ground below the hole. Inspection on the 16th May however, showed that the hole had been extended, but a small breakthrough into a lower hole had occurred. This lower hole had contained Tit eggs on the 2nd May but these had later been predated. On the 24th May and for the next two evenings, a Great Spotted Woodpecker adult was observed entering the hole to roost at about 20.45 hrs. On 30th May nesting material started to appear in the base of the hole. A pair of Great Tits proceeded to nest successfully fledging five young. The clutch of eggs was unusual because of the presence of at least one white unmarked egg.

During the 4 years of study, the same ratios of woodpecker was found annually:

8 pairs Great Spotted Woodpeckers, 2 pairs Lesser Spotted Woodpeckers and 1 pair Green Woodpeckers (although in one year a second Green Woodpecker nest was found in an adjoining orchard, and the pair used the woodland for some of their courtship displays.) In 65 hectares, this was an average territory size of 8 hectares for Great Spotted Woodpeckers, and 32 hectares for Lesser Spotted Woodpeckers.

During the 4 year study insufficient data was collected about Lesser Spotted and Green Woodpeckers, but observations might be made about Great Spotted Woodpeckers (from the 28 nests followed):

The territories stayed approximately the same from one year to the next.
25% of nests found were in a nest hole used by the same species in the previous year.
64% of nests were in a tree that already contained a previously excavated woodpecker hole.
93% nests were in dead trees.
89% of nests were in dead birch trees.
Many of these nest site dead birch trees also showed the presence of the fruiting bodies of the bracket fungus Piptoporus betulinus, the Birch Polypore.
Almost all of the dead birch trees checked showed evidence of Honey Fungus Armillaria mellea, with black bootlace mycelia being evident under the bark.

The study yielded much data, but it also allowed a privileged insight into a fascinating group of birds which are often admired, but little studied.

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