Attraction of Tawny Owl in artificial nests

April 9th, 2010 Posted in Misc, Photos

EXPERIENCE OF ATTRACTION OF TAWNY OWLS TO ARTIFICIAL NESTS IN KHARKIV REGION

Attraction of some species for breeding often allows to increase their numbers. These actions can be performed by everyone for bird conservation. In addition, it is a unique opportunity to monitor populations of nocturnal species. Ukraine still has gained quite a small experience in the attraction of the Tawny Owls for breeding. That is exactly the reason why we introduce this material.

In the late 1970s – early 1980s, students of the biological faculty of Kharkiv University organized year-round observations at the biological station in Haidary Village. They were engaged in bird ringing, hung log houses and studied the biology of different species of flycatchers; manufactured and installed nest boxes for the Tawny Owl. By 1979 the number of the latter reached 55. They were of different designs – like boarded birdhouses and those hollowed out of logs. Although at that time in the upland oak-grove of Homolsha Forests there were enough trees with natural cavities, owls occupied nest boxes with a fair success. Works on the attraction of the Tawny Owl and study of their ecology at that time were led by Ihor Prisada.

Since then, more than 20 years passed. Homolsha Forests over the past few years have changed dramatically. Almost all hollow trees were eliminated. It remains a young oak-grove with very few sites for breeding of owls. As a result, the population of the Tawny Owl started declining. We set out to return lost nesting sites to these birds.
First steps in this direction have been undertaken by us in 1999 in a site of Polianska Forest Cottage. From the rotten-hearted logs left by foresters in areas of sanitary cuttings, we made 5 artificial nests – cut an entrance, nailed a bottom and lid, and put up this constructions (weighing at least 30 kg) in a fork of a tree. Futher observations showed that birds used these nest boxes only for day roosts. Perhaps the reason was in a wrong placement of the artificial nest or maybe the design was wrong.
Next year, we got down to the case more seriously. Throughout the winter we were looking for remained nest boxes using the old maps (kindly given us by Sergey Gashchak, a graduator of the biological faculty of Kharkiv University); of 55 nests we managed to find 9 and 6 of them were still suitable for occupying them by owls! At the same time we were looking for the sites suitable for the installation of new nest boxes (not far from glades and open woodlands – favorite hunting sites of Tawny Owls), and also conducted counts of owls. Thus, we compiled our own scheme of sites to install nest boxes (Vlashchenko et al. 2001).
In 2001, of great assistance to us, in manufacturing artificial nests, was a regional association “Kharkivlis” and his chief forester, D.A. Ovcharenko. Were constructed 55 wooden nest boxes with the design resembling a birdhouse. Dimensions of nest boxes for Tawny Owls can vary widely. The height is from 35-40 to 80-90 cm, the internal size of the bottom – 30 x 30 cm, sometimes more. The entrance diameter – from 12-14 to 20 cm (Grishchenko 1997). One should remember that the Tawny Owls do not build their own nests, so as litter in the boxes we put some sawdust or dry leaves.
We treated nests the whole summer – reinforced them with tin clips, soaked from the outside with a mixture of diesel fuel and resin – for durability, additionally stitched with wire.
Autumn came. For the Tawny Owl it began a period of settlement of juveniles and formation of pairs. We had to hurry to have all owl houses hung by the winter and be able to get the first results of our work in spring. Now it was the most difficult stage – actual hanging of nests. Lacking of suitable transport, nest boxes spread through the forest “by hand” – on our own shoulders. After ten kilometers of rugged terrain with a pair of boxes on one’s back (about 20 kg) to climb up a tree, nearly devoid of branches at the 10-meter height without a ladder, and then pull up and install the 10-kg nest box is not an easy job. Sometimes a nest box detached and flew down, and we had to do everything again. Averagely we mounted 5 owl houses a day; along with to each nest we filled out forms, indicating geographic coordinates (determined with the help of GPS-navigator) and describing types of vegetation.
Along the way, new ideas originated, hanging technology for owl houses was improved. Thus, it was an original design of the rope ladder, a way of transportation of nest boxes, and safety technique when working at height.

Works to attract the Tawny Owls were funded by the Royal Netherlands Embassy in Ukraine. We would like to say special thanks for taking an active part in preparing and hanging nests to Pavel Vlashchenko, Anton Mariushchenko, Sergey Chernyh, Roman Krasovsky, Gennady Goncharov.
As a result of inspections in 2002 (in March, May, July, October, November), it turned out that 10 owl houses, installed in February, were not used by owls during the breeding season. When checking in March 2002, owls or signs of their presence (pellets, feathers) were observed in 16 owl houses, and in 3 of them the breeding was registered. Occupation of nest boxes continued during the year, and by mid-February 2003, owls or traces of their presence were observed in 24 owl houses. It was discovered that owls prefer open areas: glades and clearings or forest edges. Thus, 20 used owl houses were within 300 m from the open areas, and only 4 were located at greater distances. The most readily occupied were nest boxes installed at a distance of 15-30 m from the forest edges: 80% (n = 5) of nest boxes installed in this interval, were occupied. Occupation of the nest boxes, located directly on the edges and at a distance of more than 30 m from the edge of the forest was lower – 50% (n = 28). There wasn’t found any relationship between index of occupancy and the orientation of the entrance in accordance with cardinal points or the height of the placement of the nest. The installation of nests, depending on landscape characteristics of the area, was as follows: in plain ‘plakor’ areas in a forest-steppe watershed landscape it was hung 30 nests (11 inhabited); on forested slopes of gullies in a gently undulating terrain of the forest-steppe watershed landscape it was set 10 nests and 5 were inhabited, in sites of flat gully bottoms of the same type of terrain there were installed 5 and 3 were occupied. In steep slopes in a sloping terrain of a steppe valley landscape of the right bank of the Severskyi Donets River it was installed 8 nests, of which 5 were inhabited (Yatsiuk, Biatov, 2003). Now monitoring of the Tawny Owl population is conducted by an employee of the National Park “Homolsha Forests ” E.A. Yatsiuk.

Reference

Vlashchenko, A., Biatov, A., Yatsiuk, E. 2001. “Owl-2000”. Continuation of the Action. In: Ptah. 2001. Issue 4. [in Russian]

Grishchenko, V.N. 1997. Biotechnical measures on conservation of rare bird species. Chernovtsy, 143 p. [in Russian]

Yatsiuk, E.A., Biatov, A.P. 2003. Attraction of the Tawny Owl (Strix aluco L.) in artificial nests in Kharkiv region: preliminary results of the project “Ark for Owls”. In: Birds of the Seversky Donetsk River Basin. Proceedings of the 7-1oth conference “Study and conservation of birds of prey of the Seversky Donets”. Kharkov, 2003. Issue 8. P. 110-112. [in Russian]

Tatyana Atemasova, project leader.

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