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Threats

The white stork, a species covered by this project, has been listed in Annex I of the Birds Directive. 10 areas selected for the Natura 2000 project are refuges of white storks important in the country and the region (4% of the national population), where populations of this species are characterized by an extremely high density, high stability of the number, and the proper state of preservation. However, socio-economic changes which are rapidly progressing recently, may soon lead to its decrease (mainly due to a decrease in tolerance of nesting on chimneys and roofs of buildings by the white stork). In 5 Natura 2000 areas, this species is under protection. On Ravine Valley of the Narew River, a Natura 2000 area, steps have been taken to recognize the white stork as an object of protection. This is related to the fact that the population of this species in the valley of the Narew river on specific Natura 2000 areas is a coherent and consistent whole in terms of ecology.

Threats.

  1. Reduction of the area of feeding grounds and the number of potential victims, due to river regulation, development of river valleys other than in the form of grasslands, water reclamation and agricultural intensification (Jakubiec 2004). Protection should be based on abandoning afforestation of open wetland areas and meadows in the areas with the highest densities of storks, ban on water reclamation in permanent grasslands, promotion of extensive use and organic farming.
  2. Collisions with power lines, which occurs most frequently in the vicinity of the nest (Jakubiec 1991). The species for which the collision rate of the young is very high is the white stork (APLIC 2012). Also birds of prey belong to this group. Data of the Committee for the Protection of Eagles shows that only in 2001 as much as 44% of wounded or killed birds of prey or owls was connected with collisions with power lines (Anderwald 2009).
  3. Electric shocks - this risk occurs most often on low and medium voltage lines and transformer stations, where the distance between conductive elements of different voltages or between the live element and grounded element is too small. Electric shocks are usually fatal, and mainly birds with a large wingspan are affected. In recent years, an increased mortality of storks on transformer stations and disconnector posts was observed. Only in the Mazovian Voivodeship, in the years 2008-2010, about 550 storks were killed on these devices each year, which represents about 7% of the local population of this species (Kaługa et al. 2011, Kaługa & Tryjanowski 2012). Birds (usually the young learning to fly), by sitting on such a structure touch the live parts and die of electric shock or are permanently crippled due to paralysis of the limbs or damage to internal organs. In some cases they also have broken legs or wings, and are in need of human care in rehabilitation centres (of which there are too few and the number of places available in them is often too small), which entails additional costs. The refuge in the area of ​​Siedlce on its own, in the years 2004-2009, accepted about 150 storks injured in this way. The most effective method for the complete elimination of mortality among storks is the disassembly of disconnectors and transferring them below the upper crossarm of the column. In the same way, arresters and so-called bridges from transformer stations are moved or electrical wires are isolated on small sections of the line. We should also seek to withdraw power poles equipped with standing insulators or equip them with additional shelf, so that the birds do not come into contact with insulators or conductors.
  4. Loss of nesting sites, as a result of roof repairs, eliminating nesting platforms on poles, regrowth of tree branches, etc. (Jakubiec 2004). White stork nests are very durable structures, occupied for many years, even for several decades. During each breeding season, the birds add nesting material to the existing nests, so they can reach the size of 2-3 m in height, almost the same diameter and can weigh over a ton. A majority of nests are situated on the roofs of buildings, mainly farm buildings (e.g. barns, granaries, pigsties, cowsheds) and churches, towers, less often on residential buildings (Guziak & Jakubiec 2006). The oldest, largest and heaviest white stork nests situated on roofs can be dangerous to the construction of the buildings due to their overload (this particularly concerns old, unrenovated farm buildings). Protection of nesting sites consists, among others, in partial reimbursement of expenses for renovation purposes, which are spent by the owners of buildings where storks nest, constructing nesting platforms on poles and roofs of buildings, trimming large branches hindering access to the nest for the birds, etc.
  5. Mortality during migration caused by collisions with wind farms, overhead lines, and recently mainly due to deliberate killing (Syria, Lebanon, Oman). In recent times, many dramatic photos have been made public, showing thousands of storks killed for sport in the Middle East. This practice is difficult to eliminate due to the ongoing destabilization in these countries, among others, in connection with the civil war in Syria. Therefore, we should make even greater effort to ensure the proper protection of this species in countries where the majority of breeding population accumulates (e.g. Poland), so as not to lead to significant losses in the population due to the synergy of adverse factors.
  6. Predation, mainly by martens, especially beech martens (Guziak & Jakubiec 2006, Peterson et al. 1999, Puchalski & Ławicki 2011). Literature indicates that birds nesting on the roofs of buildings are most at risk (mainly chicks), and the best protected are birds nesting on active power poles. This is evidenced by, among others, electrocuted martens found under the posts with white stork nests (Profus 2006). A new, yet unrecognized threat is the recently increasing number of the white-tailed eagle, at the presence of which the white stork shows fear, which causes it to abandon its sites in the vicinity of breeding areas of this bird of prey (Jakubiec & Peterson, 2005). In the case of beech marten, the most effective method of reducing losses to the brood is moving the nests from the roofs of buildings to standalone concrete pillars (e.g. rotating posts). Their structure, shape and smooth surface significantly reduces the possibility of penetration of the nest situated on them.