Uphill shifts in the distribution of the white stork Ciconia ciconia in southern Poland: the importance of nest quality

Abstract

The aim of this paper is to explain the altitudinal changes that have occurred during the 20th century to the white stork distribution in the Podhale region of the uplands of the Tatra mountains, southern Poland. We analysed both historical data from the white stork censuses and detailed yearly records from 1974 to 2003 on population size, distribution and breeding success.A white stork nest was first recorded at Podhale in 1931 and numbers increased to seven nests in 1933, all located below 650 m altitude. During the 30-years, 1974-2003, both the maximum and upper-quartile altitudes of nests increased significantly. In 1974 the highest nest was at an altitude of 770 m, and the maximum reached 890 m in 1999. In the same period, the breeding population increased significantly. The minimum and lower-quartile altitudes of nests decreased significantly following initial occupation of suitable lower altitude sites before uphill expansion. We noted the positive association between nest occupancy over the study period and breeding performance. As a result, long-occupied nests contributed most of the young produced in the population and chicks from these nests probably colonized new areas. We believe this is the first well-documented evidence of, and mechanism for, a particular bird species to ascend to higher elevations and that the altitudinal shifts reported for butterflies, plants and whole biomes can be detected in birds as well.

Relationship between arrival date, hatching date and breeding success of the white stork (Ciconia ciconia) in Slovakia

“…Higher chick production may be the consequence of a relatively low breeding density (thus a lack of competition between neighbouring storks for resources), and greater food resource availability generally. In Poland, there is a strong pressure on storks with regard to the timing of migration and breeding; the earlier individuals are in better condition and re-occupy better nests located in better territories (Tryjanowski et al 2005). The relationship in our data between the timing of breeding and breeding success was marginally significant providing some evidence that storks hatching relatively earlier (and in reference to their arrival timing) had greater breeding success.…”

Using Corine Land Cover Habitat Database for the analysis of breeding bird habitat: case study of white storks (Ciconia ciconia) from northern Croatia

“…The results of this study highlight that the most important variable for white storks to choose the settlements for breeding is the vicinity of grassland habitats. The importance of grassland habitats in proximity of water for white storks has already been reported by several authors (Schneider 1988;Latus et al 2000;Tryjanowski et al 2005b). One of the important results of this study is detection of small standardized amounts of grasslands in the vicinity of settlements in the research area.…”

“…Currently, as a European Union accession country, Croatia started structural reforms in the field of agriculture and incorporation of subsidies and management practice of EU Common Agricultural Policy (CAP), therefore, we anticipate the intensification of agricultural intensity with the resulting changes in white stork habitat. Although we are aware that all grassland habitats are not of the same importance for white storks, depending on the farming practice and/or presence of grazing animals, as well as on the flooding regime (Tryjanowski & Kuźniak 2002;Tryjanowski et al 2005b), we were not in position to give any further assessment because of the limitations of the database of habitat types, as well as due to the scarce data on white storks. More detailed databases of habitat types are in the process of preparation, however, only on several smaller areas and particularly focused on protected areas.…”

“…The white stork breeding was recorded even at higher altitudes than those in our study where the settlements with and without nests were found up to 300 m and 400 m altitude, respectively. For example the recorded altitude in Poland was up to 890 m (Tryjanowski et al 2005b) or even the altitudes of 2500 m in Marocco and 1000 m in the Tatra Mountains in Slovakia (Creutz 1988). However, those examples are exceptions and much higher densities are found at lower altitudes (Cramp 1997).…”

House sparrows benefit from the conservation of white storks

“…They can reach considerable dimensions with time (e.g. up to 2 m in height and 1.5 m in diameter, Indykiewicz 1998;Tryjanowski et al 2005), and house sparrows can nest mutually in the sides of the white stork nest. White storks are an emblematic species in Poland and receive considerable attention to preserve and enhance their population; Poland is thought to support 25% of the world population of this species (Schulz 1998).…”