NOTES ON NEST-SITES OF THE OYSTER-CATCHER AND THE LONG-EARED OWL AS A HOLE BREEDER

Transcription

1 (334) NOTES ON NEST-SITES OF THE OYSTER-CATCHER AND THE LONG-EARED OWL AS A HOLE BREEDER BY FB. HAVERSCHMIDT. (Plates 44-46). THE OYSTER-CATCHER. THE Oyster-catcher (Hcematopus ostralegus) is a bird that sometimes uses strange nesting-places. On the isle of Texel a pair bred from on the thatched roof of a barn as stated by Drijver (Texel, ket vogdeiland, p. 276) and in 1914 a nest was found on the island of Rottum on the top of a wooden pole about two metres above the ground (Ardea, 3, pp: ). It seems that the Oyster-catcher has a strong liking for nesting on high places, as in Holland records of breeding on the top of pollard willows are accumulating year by year. In Limosa, 12, p. 132, there is a note about a pair breeding in on a pollard willow near Kampen, about one metre above the ground. From Friesland one such case was reported to me in 1943 and in 1944, but in both cases I came too late to see the nests, as the eggs had been sucked, apparently by crows. In 1945 a fisherman told me that he knew two nests of Oyster-catchers on the top of pollard willows quite near each other near Hardegarijp. When I visited the place on June 12th one of them proved to have been robbed by crows, but the second one happily was still intact. There were two pollard willows each at a height of about 1.75 metres standing at a distance of about two metres from each other amidst extensive grasslands so characteristic of Friesland. In the same neighbourhood, but not on the same tree an Oyster-catcher had nested on a tree in It was a strange sight on approaching the trees to see an Oystercatcher rising obviously from its eggs on the tree and then flying away. The top of this particular tree was overgrown with grass and in a small depression in it lay three eggs (Plate 44). The bird could easily be photographed, but it had the tiresome habit of sitting always with its back turned towards the camera, so that I had to content myself with a few pictures of the bird on the point of settling on its nest (Plate 45). The eggs hatched safely and the chicks left their high birthplace no doubt by simply tumbling down into the grass beneath the tree. In Holland the Oyster-catcher is an adaptable species and it not only nests on or near the seashore, but it is spreading deeper and deeper into the country hundreds of kilometres from the sea and it is becoming steadily an inland bird. It now breeds regularly in many localities where it was quite unknown twenty or more years ago. At the same time it is not at all particular in its choice of nesting places. It does not only nest in grasslands like the Lapwing

2 VOL. xxxix] NEST-SITES OF OYSTER-CATCHER. 335 or the Black-tailed Godwit, but breeds freely on arable land and even among bushes, shrubbery and in copses. On June 17th, 1927, I found a nest with three eggs among high bushes in the disused duck decoy on the isle of Vlieland, and on June 15th, 1938, I watched a nest with three eggs in a copse in a fine old beech wood near Vogelenzang. It was a very strange sight to see the Oyster-catchers walking in an avenue of magnificent old beech trees. Again in May 1944,1 found in a copse near Wolvega a nest of an Oyster-catcher with four eggs. The accompanying photographs (Plates 44,45) give an idea of the types of landscape the birds were nesting in and of the nest itself, which was placed actually on the stump of a felled oak. In one of the trees at the background a pair of Hobbies (Falco subbuteo) was nesting in an old crow's nest, truly remarkable neighbours for Oyster-catchers. This particular nest contained four eggs, as is seen in Plate 44. In The Handbook of British Birds, Vol. iv, p. 417, it is stated that four eggs occur from time to time in Britain. In Holland clutches of four are quite common, though the majorit}' of nests contain three eggs. From 70 nests with eggs inspected in recent years seven had four eggs, forty-two had three eggs, nineteen two eggs and two one egg only. THE LONG-EARED OWL. IN The Handbook of British Birds, Vol. ii (p. 329) no mention is made of the casual breeding in hollow trees of the Long-eared.Owl (Asio 0. otus), so it seems that this has never been observed in Great Britain. Niethammer (1938) quotes Hartert {1912) anddemuth (1885), and there are some more old records of hole-breeding JL,ong-eared Owls from the Continent, from which, however, it does not seem to be always quite certain that there has not been confusion with the Tawny Owl (Strix aluco). Furthermore the North American Longeared Owl (Asio otus wilsonianus) has been found nesting once in a hollow tree by Bendire, as quoted by Bent (1938). In Holland, though the actual nesting in holes of trees has never been established, the Long-eared Owl seems to nest not uncommonly in baskets fixed in trees to be used as nesting places by semi-wild Mallard (Anas platyrhyncha). It is a century-old custom especially in Friesland to put up baskets of straw in trees near farmhouses, in order to induce semiwild Mallard to lay their eggs in them. Often there are several sucli baskets together in one tree. The eggs are collected for food and a second clutch is left to hatch. In duck decoys great quantities of these baskets are fixed in trees and bushes and even on the ground as nesting-places for the decoy ducks. There are two types of baskets. The one nearly exclusively in use in Friesland is plaited of yellow straw (just like a bee-hive). The entrance is rather wide, then it narrows and ends in a wide bottle. The other type, more in use in

3 336 BRITISH BIRDS. [VOL. XXXIX. the middle and in the west of the country, is plaited of osier stems and therefore is much more durable than the straw one, which becomes worn in a couple of years. The model of the osier type is somewhat different, as it lacks the wide entrance and is more of the shape of a bottle. Payne Gallwey (1886) (p. 200) gives a rather crude picture of the osier type. In duck decoys always paradises for many breeding birds but also in copses, large gardens and estates, several species of birds use these baskets for nesting. Besides the small hole-breeding birds, the Stock-Dove (Columba anas) is a regular breeder in these baskets, as is the Jackdaw (Corvns monedula). The Kestrel (Falco tinnunculus) also very often takes possession of these baskets to lay its eggs in. Now it is of interest that the Long-eared Owl has been found several times nesting in these baskets, so that it seems to be quite a normal habit for these birds to nest in these artificial holes. In May, 1943, I found on an estate not far from Leeuwarden a Long-eared Owl sitting on four eggs in a basket (of straw) in a big lime tree. There were three baskets in that particular tree (Plate 46). In the basket on the upper right a Kestrel had been nesting, but it was destroyed in a storm; the Long-eared Owl was nesting in the basket at the left. On my inspecting its contents again on May 25th, the bird remained motionless on its eggs, so that I was able to take several photographs. The light was very poor under the thick foliage of the trees, as the bird was sitting in the back of the rather deep hole. I could distinguish on the focussing screen nothing else but its golden-orange irides and as the distance between the camera and the sitting bird was so short the edge of the basket was quite out of focus and being much lighter than the inside, this part was much over-exposed. With F.32 I made an exposure of about two minutls and all this time the bird remained quite motionless on its eggs, not even blinking an eye (Fig. ). On June 4th there were four small young in the basket and the old bird stayed on the young when I inspected them, so that I was able to take some more photographs. On the same estate and probably in the same tree, if not in the same basket, a Long-eared Owl was also nesting in 1942, according to de Vries (1942). In 1944, however, this basket was not used. When put up in proper positions these baskets may prove to be very good artificial nesting-places for the larger hole-breeding species. REFERENCES. BENT, A. C. (1938). Life Histories of North American Birds of Prey (Part 2), p HARTERT, ERNST (1912). Die Vogel der palaarktischen Fauna, Bd. II, p NIETHAMMER, GBNTHER (1938). Handbuch der Deutschen Vogelhunde, Bd. II, p. 88. PAYNE-GALLWEY, R. (1886). The Book of Duck Decoys, p DE VRIES, TSJ. GS. (1942). "De ransuil, Asia 0. otus (L.) legt in een eendenkorf." Lirnosa, 15, p. 44. WITHERBY, H. F., el al. (1938). The Handbook of British Birds, Vol. II, p. 329.

4 British Birds, Vol. XXXIX, PI. 44. OYSTER-CATCHER. NEST IN COPSE, JUNE 14TH, (Photographed by Fr. Haverschmidt). OYSTER-CATCHER. NEST WITH THREE EGGS ON TOP OF POLLARD WILLOW, JDNE 12TH, (Photographed by Fr. Haverschmidt).

5 British Birds, Vol. XXXIX, PI. 45. OYSTER-CATCHER. UPPER. BIRD ABOUT TO SETTLE ON NEST ON POLLARD WILLOW, JUNE 12TH, LOWER. NESTING IN COPSE, MAY 25TH, {Photographed by Fr. Haverschmidt).

6 British Birds, Vol. XXXIX, PI. 46. LONG-EARED OWL. UPPER. LIME TREE WITH SIX NESTING-BASKETS FOR DUCKS : THE OWL WAS NESTING IN THE BASKET ON THE LEFT. LOWER. LONG-EARED OWL INCUBATING IN NESTING-BASKET FOR DUCKS, MAY, 25TH, (Photographed by Fr. Haverschmidt).