In field practice, we repeatedly had to deal with cases of predation by martens in the nests of certain species of birds of prey. In some cases, not only clutches were destroyed and chicks were killed, but also adult birds such as the Common Buzzard. Most frequently these are small birds of prey which are subjected to predation press by mustelids (small falcons, the Sparrowhawk, Long-eared Owl). It is especially unpleasant when martens ruin nests of rare species of birds of prey.
In our practice there was a case where the marten killed on the nest a large chick of the Short-toed Eagle in the age of 6-7 weeks. Therefore, in Chernihiv region in the Regional Landscape Park “Mezhrechenskii” there have been taken measures to protect two trees for one nesting pair of the Short-toed Eagles from attacks of the marten. It is the pair of raptors which lost their chick in 2008. In addition, during regular felling in breeding territory, the certain kind of nesting trees should be specially protected from terrestrial predators: the nesting trees which are easily accessible but selected by the Short-toed Eagle in the areas unsuitable for cutting forest. In this way we increase the probability of the annual use of these trees by birds, thereby reducing human disturbance on reproductive success.
Installing protection against terrestrial predators is also justified in cases of special studies related to the need to visit occupied nests of birds of prey (Galushin, Kostin 2008).
Such activities should be carried out before the birds return from wintering grounds. In species that winter in the breeding area, the protection must be installed in the early winter period. For such species the installation works should take place in the fast mode in order to reduce time spending at the nests.
For the protection of nesting trees, we used a galvanized iron sheet 0.5 mm thick. The length of such a sheet depends on the diameter of a tree trunk. The sheet must overlap the trunk. To protect sufficiently it is enough for the sheet to be 1 m high and locate on the trunk at the height at least 1 m from the ground. On fixing the sheet with nails (the nails used should be 100 mm long or a bit shorter) to the trunk of a tree, wipe it dry with a cloth (if the sheet is wet, for example, because of rain or condensation). Then make prime coating of the sheet using a spray can. This allows the paint which will be on top to hold up well.
When painting galvanized surfaces there are recommended to use 2 types of prime coating: first acid, then the ordinary, or only the ordinary but pre-treating the surface with coarse-grained abrasive. Imitating the color of a tree trunk, apply upper layers of automobile enamel (dark-grey, dark-beige, khaki). Masking the sheet we reduce chances of its accidental discovery by a stranger. The vertical arrangement of the sheet makes it more visible to people. The second option of protection in the form of a collar-umbrella is more visible to hosts of the nest. In our case the nests were located relatively low (up to 15 m from the ground), so we have chosen the first option.
The sheet mounted on the trunk of a tree is a reliable protection of birds’ nests from the encroachments of martens. It is also very important for the branches of the tree protected from predatory animals not to touch each other and be remote from the branches of neighboring trees, because martens are excellent tree-creepers and virtuosic jumpers at high heights.
And, in conclusion I would like to thank Vladimir Galushin for his consultations on this topic.
Konstantin Pismenny, Sergey Domashevsky, Roman Vatrasevich
Galushin, V. M., Kostin, A. B. 2008. Birds of prey and tolerant ornithology. 86−90. In: Latest studies on Birds of Prey and Owls. Proceedings of the 3d International Scientific Conference “Birds of Prey of Ukraine”, Kryvyi Rih, 24-25 October 2008. (eds. M.N.Gavrilyuk, G.V. Fesenko). – Kryvyi Rih, pp. 86-90. [in Russian]